Geolog 6.6 Determin Tutorial

Transcription

1 Geolog 6.6 Determin Tutorial

2 Contents Introduction to Geolog's Determin Tutorial Prerequisites Document Conventions Tutorial Data Determin Overview The Evaluate Module Crossplots The Xplot Window Format the X and Y Axis Format the Color Axis Color and Symbol Section Color Section Symbol Section Filter To use the Filter Tab Functions Titles Ancillaries Frequency Create and Format a Frequency Display Xplot Functions Geolog Functions User Defined Functions Function Categories CHART CURVE QUANTIFY QUALIFY CHMAP POLYGON MACRO Creating User Defined Functions POLYGON Functions Log Calculation from CHART Function CHART Functions MACRO Functions Fill Missing Values with Reconstructed Log QUALIFY Functions Geolog Determin Tutorial 01/2006 1

3 Deterministic Petrophysics Petrophysics Philosophy Definitions The Precalc Module Borehole Correct the Gamma Ray Log Borehole Correct the Density Log Borehole Correct the Neutron Log Borehole Correct the MSFL Log Borehole Correct the Dual Laterolog Parameter Picking Overview Crossplots Histograms Pickett Plots Analysis Identify Badhole Conditions Identify Coals Calculate Shale Volume Calculation of Porosity Using Sonic Log Calculation of Porosity from Density-Neutron Crossplot Water Saturation Calculation Hydrocarbon Corrected Porosity / Water Saturation Permeability Calculation Matrix Analysis Matrix Parameter Curves Used to Estimate Mineral Content Pay Sensitivity Pay Summary Multiwell Analysis Overview Select the Wells to Process Selecting Intervals to Process Multiwell Histograms Parameter Picking - Histogram Parameter Picking - Crossplot Quick Analysis (Shale Volume Calculation) Geolog Determin Tutorial 01/2006 2

4 Create a New Loglan Program Starting a New Loglan Inserting Variables Specifying Units Specifying Default Values Entering Code and Comments Geolog Determin Tutorial 01/2006 3

5 Introduction to Geolog's Determin Tutorial Welcome to the Geolog deterministic petrophysics tutorial. This tutorial will assist you in understanding how Geolog can be used as a tool for performing deterministic petrophysical well evaluations using the Determin application within Geolog. The purpose of the Determin tutorial is to provide detailed information on the tools available within Geolog for performing a deterministic formation evaluation. This tutorial will: Prerequisites Familiarize you with the Evaluate module. Familiarize you with Geolog s Xplot application. Introduce you to Geolog s Frequency application. Demonstrate the different types of Xplot functions supplied with Geolog. Familiarize you with the tools supplied in Geolog for the picking and application of petrophysical parameters. Demonstrate the workflow through a typical deterministic petrophysical evaluation using Geolog. Explain multiwell processing using Geolog s Well application. Provide an introduction to "Loglan", the Geolog programming tool. This tutorial assumes that the student has a general working knowledge of the Geolog6.6 software, and of basic petrophysics. For those without knowledge of Geolog6.6, it is strongly recommended that the Geolog6.6 Introductory tutorials be taken before commencing this tutorial. Document Conventions In this document, all INPUT to the computer is in Bold Courier New, while all OUTPUT from the computer is in Courier New, but not bold. Geolog Determin Tutorial Introduction 1

6 Tutorial Data The following additional files (files not supplied with software) are used in this tutorial: DATA: determin_master.unl REPORTS: LAYOUTS: (Copy from layout_units) determin_paysum.layout LOGLAN: SECTIONS: SPECS: PLOTS: all (in Stars project) WELLS: botein furud silt Geolog Determin Tutorial Introduction 2

7 Determin Overview The Determin application within Geolog provides advanced deterministic formation evaluation solutions for petrophysicists, geologists and engineers. Determin is a comprehensive suite of individual deterministic modules that allow the analyst to apply all the major modern petrophysical models in the traditional analysis methodology. All common techniques for shale/clay volumes, porosity, saturation and lithology determination are included. Interactive parameter picking and multi-zone/multi-well analysis provide a rapid workflow for the formation evaluation. GEOLOG Determin Tutorial Determin Overview 3

8 Step 1: The Evaluate Module Procedure The Evaluate module allows mathematical, logical or string expressions to be entered (and saved) and applied on a single or multiwell basis. These expressions can be equations utilizing a log or several logs, or can include a call to any function included with Geolog6.6 or created by the user. In this step, you will use the Evaluate module to: Generate a continuous porosity log from a simple expression involving a single density log. Invoke a Geolog6.6 supplied function (LIMIT) and apply it to a log to limit a curve. Exercise 1 This exercise demonstrates the use of the Evaluate module to generate a continuous porosity log from a simple expression involving a single density log. 1. Start Geolog and open the STARS project. 2. Start the Well application and open the BOTEIN well. 3. Select General > Evaluate to open the tp_evaluate module (see Figure 1). Figure 1: Evaluate Module Displayed in Module Launcher Window GEOLOG Determin Tutorial Step 1: The Evaluate Module 4

9 4. In the Value column, enter the following (and as shown in Figure 2): EXPRESSION: imperial: (2.65-RHO)/1.65 metric: (2650-RHO)/1650 This is the simplest form of the density porosity equation assuming RHO_MA=2.65 and RHO_FL=1.00. As a log alias list exists, the RHOB curve is used. UNITS: V/V COMMENT: Simple Density Porosity LOG_OUT: PHIT_DEN Figure 2: Values to Generate a Continuous Log of Porosity 5. Click Start to execute the module. 6. View your data by: creating a new layout inserting a scale track inserting a wireline track displaying your newly created PHIT_DEN in the wireline track setting the Right Limit to -0.5 to view the full range of data Your display should look similar to Figure 3 after applying these changes. 7. Select Well > Save. GEOLOG Determin Tutorial Step 1: The Evaluate Module 5

10 Figure 3: PHIT_DEN Log Displayed in a Layout Exercise 2 This exercise demonstrates the use of the Evaluate module to invoke a Geolog6.6 supplied function (LIMIT) and apply it to a log to limit the values. In Exercise 1 on Page 4, the given values for matrix and fluid density may result in the generation of porosity values that are negative, or greater than 100%. The LIMIT function can be used to define a valid range for a log. Values less than the minimum value will be set to the minimum value, and values greater than the maximum value will be set to the maximum value. The syntax for this function is: LIMIT(Logname, Minimum value, Maximum value) GEOLOG Determin Tutorial Step 1: The Evaluate Module 6

11 1. Display the tp_evaluate module (or select General > Evaluate, if you closed the Module Launcher window). 2. In the Value column, enter the following (and as shown in Figure 4): EXPRESSION: limit(phit_den,0,.5) UNITS: V/V TYPE: REAL COMMENT: Limited Density Porosity LOG_OUT: PHIT_DEN Figure 4: Function to Limit a Curve 3. Click Start. The data displayed in the layout is automatically updated. Expressions can be nested within Evaluate expressions, so that the two previous exercises could be carried out at the same time using a single expression of the form: limit(((2.65-rho)/1.65), 0, 0.5) GEOLOG Determin Tutorial Step 1: The Evaluate Module 7

12 Step 2: Crossplots Procedure Xplot, Geolog s crossplot application, is used for plotting logs or log expressions. It provides a variety of analytical tools to: incorporate standard contractor or user-defined curves, polygons and charts; perform regression analysis, and; calculate new logs. Xplot can be started in either Well or in Project. In this step, you will: Start the Xplot application from within Well to become familiar with the Xplot window and its components. Edit the X and Y axis of an existing crossplot. Format the Z axis. Format the display style (Symbols). Format the data display area (Ancillaries). Exercise 1 The Xplot Window In this exercise, you will change the layout you created in the previous exercise, start Geolog s Xplot application and open an existing crossplot file. 1. Within your layout view, change the displayed PHIT_DEN log to RHOB and click Apply. The defaults are updated automatically when you enter a known log name. 2. Add a second wireline track and insert the NPHI log and click OK. 3. Select Well > View > Xplot... to open the File Select dialog box. GEOLOG Determin Tutorial Step 2: Crossplots 8

13 4. Locate and open rho_nphi_gr.xplot (values of density and neutron porosity with color coding related to values of gamma ray; see Figure 5). Titles Statistics Diagram Y Axis log expression X Axis log expression Color log expression and color bar Functions Figure 5: Xplot Window Displaying RHO_NPHI_GR Xplot 5. Within the Properties dialog box, insert gr on the Z axis, and click Apply. 6. Observe the crossplot is now displayed in 3D, as shown in Figure 6. GEOLOG Determin Tutorial Step 2: Crossplots 9

14 Figure 6: Xplot Window Displaying 3D Xplot For more information refer to the Online Help - Working In 3D Xplot. 7. Remove gr from the Z Axis tab, Log Expression field, and click OK to return the crossplot to 2D. GEOLOG Determin Tutorial Step 2: Crossplots 10

15 The following table describes the components identified in Figure 5 and Figure 6. COMPONENT Titles Statistics Diagram DESCRIPTION Xplot title, well name, selected processing range/ intervals, and filters being used. Shows the number of X and Y values inside and outside the Xplot grid limits. For more information see "Ancillaries" on Page 29. X axis log expression Y axis log expression Z axis log expression (not shown) Color axis Functions The selected X, Y, and Z axis log expressions and units for each axis. For more information on the Z axis log expressions refer to the Online Help - Working in 3D Xplot. The selected Color bar, Color Expression and/or Symbol Expression (not shown) are referred to as the Color Axis. Description of an element inserted on the crossplot such as a chart, polygon or curve. Exercise 2 Format the X and Y Axis In this exercise, you will be guided through the formatting of the X axis you then follow the same procedure to format the Y axis. Formatting display areas in Geolog is performed using the Properties dialog box. To display the Properties dialog box in Xplot you can do any ONE of the following: Select Edit > Properties. Double click on a log expression. Double click on the data display area. 1. Select Edit > Properties If necessary, click on the X Axis tab. This is an example of aliasing, the Xplot layout is formatted to display the logname_cor logs but, as they do not exist, the RHOB and NPHI logs are displayed (see Figure 7). GEOLOG Determin Tutorial Step 2: Crossplots 11

16 Log name to display does not exist, so NPHI and RHOB are displayed. Figure 7: Properties Dialog Box - X and Y AXIS Tabs The X, Y and Z Axis tabs on the Properties dialog box display similar selection and formatting options. GEOLOG Determin Tutorial Step 2: Crossplots 12

17 The following table explains each of the fields on the X, Y and Z axis tabs of the Properties dialog box: SECTION FIELD/BUTTON DESCRIPTION Log Log Expression A log name or expression that evaluates to a numerical result. An X and Y value must be specified to display data (see Figure 5), and a Z value must be specified for a 3D display (see Figure 6). If changing an existing log, the Default units are automatically displayed. This replaces displayed Units, Left/Right and Scale values with the default values specified in the loginfo.loginfo file found in the unit_type/specs directory for your environment. If you change any of the displayed Units, Left/Right and Scale values click on the Defaults button to redisplay the default values. Units Limits (Left / Right Limit - X axis) (Bottom / Top Limit - Y axis) (Lower / Upper Limit - Z axis) Default units are displayed for a log entered in the Log Expression field. Limit values for each axis are displayed according to defaults for the Units selected. These defaults are determined by Left and Right limit values in a loginfo file. For the Y axis, left and right limits are translated to bottom and top, respectively. For the Z axis, left and right limits are translated to lower and upper, respectively. Scale Control Sampling Use the Swap Limits these two fields. The scale is represented by grid lines. icon to quickly swap the values in Note: The Limits specified must be greater than 0 for all but Linear. The sampling rate of one axis (X, Y or Z) can be used to determine displayed log values of the other axes by interpolation. Whichever axis has this toggled ON indicates that axis controls the sampling. GEOLOG Determin Tutorial Step 2: Crossplots 13

18 SECTION FIELD/BUTTON DESCRIPTION Grid Style Intervals Appearance Standard - LINEAR scale only Enter a single value for Fine and/or Coarse Grid Intervals for a Standard grid to display linear scale grids. The Grid is calculated using the Left and Right Limits, and the Fine and Coarse Grid Intervals (Left - Right / Grid Interval value; e.g., if the Left limit is 0 and the Right limit is 200, a Coarse Grid Interval of 10 will display grids at 20, 40, ). Variable - ALL scales Enter multiple values for Fine and/or Coarse Grid Intervals for a Variable grid to display grids according to the Fine and Coarse grid values entered. Enter values separated by spaces where grid lines are to appear (e.g , etc.). To quickly remove the grids from the view, toggle View > Grids. To set the appearance of grids, click in an Appearance field to display the Appearance Palette and set the color, line style and width, and text. Text denoting grid positions appears at both ends of the grid lines. As a simple exercise in using the X and Y Axis tabs, do the following: 3. For the X axis, change the Right limit to 0.5 and the Coarse grid lines to Magenta. 4. For the Y axis, change the Bottom limit to 3.2 (3200) and the Coarse grid lines to Blue. 5. Click Apply. Exercise 3 Format the Color Axis Colors, expressions, symbols, and/or text (all referred to as a "Color axis") can be applied to data displayed on a crossplot. 1. Select the Color Tab. GEOLOG Determin Tutorial Step 2: Crossplots 14

19 Figure 8: Properties Dialog Box - Color Axis Tab Color and Symbol Section The following table describes the Color and Symbol section components of the Color tab as shown in Figure 8: FIELD/BUTTON Style DESCRIPTION Determines the style of the displayed symbols. Note: Not available when viewing 3D crossplots. Marker - The marker selected in the Appearance field is shown at the center of each grid cell. Solid Fill - Each grid cell is shown as a filled rectangle. When specifying a Symbol Expression, these styles only apply to the display of indeterminate results. Note: Solid Fill is automatically set when using Accumulation settings on the Filter tab, and automatically set back to Marker when Accumulation is set to None. GEOLOG Determin Tutorial Step 2: Crossplots 15

20 FIELD/BUTTON DESCRIPTION Appearance Connection The Appearance settings (attributes) selected in this field apply to both the Color and the Symbol sections on the Color tab. Click in the Appearance field to display the Appearance Palette to format the style, and color of symbols and lines. Specifies the line style in the Appearance field. However, it does not apply to accumulated values. None - Values are not connected. Line - Values are connected with a straight line. Spline - Values are connected with a smooth curve. Note: Line styles are not available when in 3D mode; and should not be used when plotting arrays on X or Y axes. Show Missing Values Toggled OFF - missing Color or Symbol values are not processed. Toggled ON - missing Color or Symbol values are processed and displayed using the settings specified in the Appearance field. 2. With the Style set to Marker, using the Appearance Palette set the color to Blue and the Marker to Ball. 3. In the Color section remove the Expression GR_COR and click Apply. 4. Observe the changes made to the crossplot. 5. Change the Style to Solid Fill and click Apply. 6. Observe the crossplot. "Ball" is ignored and filled rectangles for each grid cell containing X/Y values are displayed. GEOLOG Determin Tutorial Step 2: Crossplots 16

21 Crossplot with the marker style Crossplot with the solid fill style Figure 9: Crossplots Showing Different Color Styles Color Section The following table describes the Color section components of the Color tab as shown in Figure 8: 1. Change the Style back to Marker and set the Expression to rainbow(gr,20,150) In the Expression field, Geolog converts lowercase to uppercase when you click Apply. 2. Click Apply. The Color Bar specified (i.e., gr.qualify) is ignored and the values are displayed according to the expression. Note the expression displayed beneath the color bar on the crossplot. See Figure 10. GEOLOG Determin Tutorial Step 2: Crossplots 17

22 FIELD/BUTTON Expression Display Value DESCRIPTION A log name or an expression determines the color of the data values. RAINBOW expression A rainbow expression can be used as an alternative to selecting an Expression and Color Bar. For example, for the expression syntax RAINBOW(GR,0,200), GR is a log name and the values represent the range to be displayed. Values within the range are displayed according to the color spectrum between blue and red. WELL_NO expression When processing multiple wells, remove the Color Bar and click on the Dropdown List button to select WELL_NO to have each well display in a default color assigned from the Appearance palette. Alternatively, a Color Bar may be specified to select specific colors from the Color Bar for each well (see WELL_NO as a Color Expression for an example). Note: When using WELL_NO, a Color Bar is not displayed, as the well names in the legend identify the wells and colors. INTERVAL_NO expression When processing multiple intervals, remove the Color Bar and click the Dropdown List button to select INTERVAL_NO to have each interval specified for processing display in a default color assigned from the Appearance palette. This enables you to select the required set of values to display the data: Minimum, Maximum, Average, or Frequency. GEOLOG Determin Tutorial Step 2: Crossplots 18

23 FIELD/BUTTON Color Bar DESCRIPTION If no Color Bar is selected, the data point colors are determined directly by the Color Expression. If the Color Expression evaluates to a string (e.g. "GREEN"), then that color will be used. If the Color Expression evaluates to a whole number, (e.g. WELL_NO), then a color will be automatically selected from the Appearance Palette to represent each number. You can enter/select a qualify function which determines the color representation of expression values using one of the following: The Dropdown List button to select from existing Qualify functions. The default reserved qualify functions Rainbow and Grayscale can be used to automatically create a color bar if an appropriate color bar does not exist. When selected, all displayed data is encompassed within the color (or grayscale) range. For example, if GR is entered and the displayed data is within the range of GR values 21 and 176, the Color Bar encompasses these values within the rainbow or grayscale color range of 20 to 180. The File Select icon to open the File Select Dialog Box to select the qualify function from another location. Frequency Bar The Colormap icon to edit/create a color bar. These colormaps can be changed, or new ones created, when required. Colormaps are located in, and saved to, the /functions directory with an extension of.qualify. This is only available when the Display Value is set to Frequency. The required qualify function is selected to display the data frequencies. If the default reserved qualify functions Rainbow or Grayscale Color Bar is selected, a color bar is automatically created to encompass the range of frequencies for the displayed data. GEOLOG Determin Tutorial Step 2: Crossplots 19

24 Figure 10: Using Rainbow Expression to Identify Formation Colors with Solid Color 3. Change the expression back to GR_COR and click Apply. Colormaps Colormaps are used in Geolog for various functions such as displaying array data image logs (representing vertical and horizontal variation in formation properties), and representing the Color axis on crossplots. These colormaps can be changed, or new ones created, as required. Colormaps are QUALIFY functions, and are located in, and saved to, the functions directory with an extension of.qualify. 4. Click on the Colormap icon to open the colormap currently specified in the Color Bar field (see Figure 11). GEOLOG Determin Tutorial Step 2: Crossplots 20

25 Currently open colormap Color cells Name Figure 11: Colormap Dialog Box Interactive visual guide when changing Function and Direction of colormap indicates the colormap currently displayed. Check this name is the same as the color bar title displayed in the crossplot to ensure you are saving changes to the correct colormap, as it is possible to display the properties of another colormap within the currently open colormap (using File > Import). If a colormap has not been specified before clicking on the Colormap icon, or when you select File > New, a default "rainbow" style colormap titled "no_name" is displayed in Manual mode. To create a new map, you can change this rainbow style, or open an existing colormap (File > Open) and make the required changes. 5. Click the File>> button and select Import... to import the properties of another colormap. 6. Locate and select fms.qualify. NOTE the name displayed in the Name field and the crossplot color bar title are different. 7. Click the File>> button and select New to start a new colormap, and Discard the changes. GEOLOG Determin Tutorial Step 2: Crossplots 21

26 8. Click the File>> button and select Size... to open the Colormap size dialog box. 9. Specify a range of 0 to 200, and 10 intervals. 10. Click OK. 11. Click the Tools>> button. Note all the options are grayed out, this is because there are no color cells selected. 12. Click and drag across the color cells to select them (each selected cell is outlined in red). Selected color cells 13. Click the Tools>> button and select Grayscale. 14. Change the colors back to Rainbow. 15. Select the first (leftmost) cell. 16. Change the Cell To value to 25 and click Apply. 17. Select the resized cell. 18. Click on the Appearance palette icon and change the color of the cell. 19. Select all the color cells. GEOLOG Determin Tutorial Step 2: Crossplots 22

27 20. Click on the Tools>> button and select Interpolate. 21. Click on the Function field Dropdown List button and select an option. 22. Adjust the red control points. Geolog dynamically displays the changes in the Function Colormap area. 23. Select the Reverse direction. 24. Click on the File>> button and save your colormap as mycolors. (Enter the name at the end of the path in the Selection field; if a /functions directory does not exist for your project, Geolog will create one now.) 25. Close the Colormap dialog box. 26. On the Color tab of the Properties dialog box, click the Color Bar File Select icon to locate and select your new colormap. 27. Click Apply. See the Using Geolog online help for detailed information on colormaps. GEOLOG Determin Tutorial Step 2: Crossplots 23

28 Symbol Section You use the Symbol section of the Color tab to select the symbol used to display values. The following table explains the fields in the Symbol section: FIELD / BUTTON Expression DESCRIPTION Note: Not available when viewing a 3D crossplot. Style The Log Select icon enables you to select the required log, or enter a log name or expression. When using expressions, ensure the appropriate Style is selected (e.g. toggle on "Marker" if SYMBOL is entered to display the symbol specified in the well header constants, "Fill" if a lithology log is selected, "Text" if WELL_NO is selected). Ensure a Color Expression has been selected and then click on the Dropdown List button to select one of four special Symbol Expressions: MINIMUM, MAXIMUM, AVERAGE or FREQUENCY to provide direct access to the statistics accumulated for each grid cell for the Color Expression. These special expressions are usually only meaningful when the Symbol Style is set to Text. If the expression WELL_NO is used in Multiwell Processing, values are identified by a number for each well selected for processing. The style of displayed symbols. Marker: If the Symbol Expression evaluates to a string (e.g. "BALL"), then a marker with that name will be used. If the Symbol Expression evaluates to a whole number (e.g. WELL_NO), then a marker will be automatically selected from the Appearance palette to represent each number. If the marker cannot be found, an error message is generated and, in Multiwell Processing, the marker is not displayed in the Well Legend. Fill: If the Symbol Expression evaluates to a string (e.g. "SS") then a fill pattern with that name will be used. If the Symbol Expression evaluates to a whole number (e.g. WELL_NO) then a fill pattern will be automatically selected from the Appearance palette to represent each number. If the fill cannot be found, an error message is generated and, in Multiwell Processing, the fill is not displayed in the Well Legend. Text: Symbol Expression values are displayed as text (e.g. select a depth log as the expression to show the depth for displayed values). GEOLOG Determin Tutorial Step 2: Crossplots 24

29 Exercise 4 Filter The Filter tab in the Properties dialog box is used to: define a filter to display a range of values (e.g. depth range) define frequency accumulation to aggregate multiple values to one point adjust a 3D display To use the Filter Tab 1. Click the Filter tab in the Properties dialog box. Figure 12: Properties Dialog Box - Filter Tab GEOLOG Determin Tutorial Step 2: Crossplots 25

30 The following table describes the components of the Filter Tab: SECTION FIELD/BUTTON DESCRIPTION Filter Expression An expression which defines a range of values to display. Units Examples: NPHI <.1 RANGE (DEPTH, 1200, 1400) TOPS=="MUREE SANDSTONE" TOPS.TOPS=="BURNAMWOOD FM" & GR<80 & LLD>10 If a different unit category from the category stored in the database is required, specify the units. Any log which is stored in that unit category will be adjusted. Accumulation Mode Select a mode to change the grid sampling. Options available are: "None" to use maximum grid resolution (300x300) "Binned" to manually specify a grid resolution; the X and Y bin values set the resolution "Windowed" to use a sliding window average. The X and Y bin values set the size of the sliding window. Sliding window averaging will smooth the display of data. On the Color tab, "Solid Fill" is automatically selected when using Binned or Windowed, and "Marker" is automatically selected when None is specified. Note: Mode is NOT available when a Z axis has been specified. When a Z axis is specified, the Mode is automatically set to "Binned". X, Y, Z (bins) Accumulate Columns Accumulate Rows Drop Threshold Changes the grid resolution. Click on the Dropdown List predefined values. button to select from a list of NOT available if a Z axis has been specified. Row and column accumulation totals are displayed on the top and right sides of the crossplot, and may be displayed as count values (frequency) or histograms. Values not displayed because they are below the Drop Threshold are still included in the totals displayed in the Statistics Diagram. Only available when Mode is set to Binned or Windowed. Cells with count values (frequency) equal to or below the Drop Threshold are not displayed. GEOLOG Determin Tutorial Step 2: Crossplots 26

31 SECTION FIELD/BUTTON DESCRIPTION 3D Histograms Histogram Appearance See the Online Help - Working in 3D Xplot. Only available when Accumulate Columns and/or Rows is/are selected; NOT available if a Z axis has been specified. Displays row and column accumulation totals as a histogram on the top and right sides of the crossplot. Only applicable when Accumulate Columns and/or Rows is/are toggled ON. Click in the Appearance field to display the Appearance Palette and set the color and text appearance of row and column accumulation totals, and color, lines and fill appearance of the histograms. 2. Use Figure 13 to guide you through a frequency accumulation display formatting exercise. 1. Set the filter 2.Toggle ON Column and Row accumulation 3. Adjust the bin values. 4. Select a color 5. Click Apply See Figure 13: Formatting a Frequency Accumulation Display the Xplot online help for further information on using the Properties dialog box. GEOLOG Determin Tutorial Step 2: Crossplots 27

32 Exercise 5 Functions Explained in "Geolog Functions" on Page 34. Exercise 6 Titles The Titles tab is used to format the sheet and axes titles. The title may contain up to four lines of fixed or variable text which are displayed above a crossplot. 1. Click the Titles tab in the Properties dialog box. 2. Format your display area by changing the colors and text for some of the options. 3. Click the Border button and change the appearance of the presentation sheet. 4. Click Apply. GEOLOG Determin Tutorial Step 2: Crossplots 28

33 Exercise 7 Ancillaries The Ancillaries tab is used to modify the appearance of the legends, Statistics Diagram and display box (the area that encloses the displayed values). 1. Click on the Ancillaries tab. GEOLOG Determin Tutorial Step 2: Crossplots 29

34 The following table describes the components of the Ancillaries tab: SECTION Field/Button Description Appearance Well Legend Function Legend Statistics Diagram X, Y and Z Axis Length When multiple wells are open, and/or Functions exist, legends are automatically created at the bottom of the crossplot. Click in each of the fields to display the Appearance Palette to select the required formatting options. Shows the number of X and Y values inside and outside the Xplot grid limits. The top number inside the box (in this example, 3521) indicates the total number of samples inside the Xplot grid; the lower number (3524) indicates the total number of samples. The numbers outside the box represent the number and location of the samples outside the grid. In this example there are two samples off to the right of the grid and one below. Number of displayed values is reduced not only by crossplot limits but also filter expressions and intervals selected for processing. Change the appearance using the Statistics Diagram field on the Ancillaries tab. The length in paper units from limit to limit of each axis as determined by the default unit system. Alternative dimensions can be entered with scroll bars appearing when a length exceeds that which can be displayed in the Xplot window. Box Edge Click in these fields to open the Appearance Palette to format Background the background and edge appearance of the graphical display box. 2. Change the color of the Statistics Diagram in the Appearance Section. 3. Change the color of the box edge. 4. Click OK to apply your changes and close Properties Dialog box. GEOLOG Determin Tutorial Step 2: Crossplots 30

35 Step 3: Frequency Procedure Geolog s Frequency application is used to display the data distribution of a single log as a histogram and as a cumulative frequency curve. Statistical information about the log is also displayed. Single (Well) or multiwell (Well or Project) frequencies can be displayed. In this step, you will: Create and format a Frequency display. Exercise 1 Create and Format a Frequency Display Note that the functionality of the Frequency application is similar to that of the Xplot application, and the following instructions are to only familiarize you with the application. Further details are provided in "Histograms" on Page Select Well > View > New > Frequency. 2. Open the Properties dialog box. 3. On the Data tab, enter RHO_COR as the log to display. 4. Click Apply to display the data. 5. On the Filter tab, add the following Filter Expression to filter out specific data: GR_COR<50 6. Click Apply to display the results (see Figure 14). GEOLOG Determin Tutorial Step 3: Frequency 31

36 7. On the Accumulation tab, change the Appearance of the Cumulative display to RED and make the line thicker. 8. Click Apply to view the changes. 9. Change the Appearance of the Frequency to a solid Fill and select a color. 10. Click Apply. Figure 14: Displaying RHO_COR as a histogram 11. Change the appearance of the Frequency so that the histogram is displayed as a Line rather than a bar. 12. Click Apply (see Figure 15 for an example). GEOLOG Determin Tutorial Step 3: Frequency 32

37 13. On the Ancillaries tab, change the color of the Statistics Diagram. 14. Click OK to close the dialog box and apply your changes. 15. Select Frequency > Report. Figure 15: Histogram Displayed as a Line 16. Change the report file name using today s date (e.g. 28_05_histogram). 17. Click OK to close the dialog box and create the text file 28_05_histogram.rpt in the project s /reports directory. The report is automatically displayed as a PDF in a separate window. 18. Take a look at the report and then close the PDF. GEOLOG Determin Tutorial Step 3: Frequency 33

38 Step 4: Xplot Functions Within Geolog, there are two main categories of functions, Geolog supplied and user defined/created. In this step, you will: Create a POLYGON function. Perform log calculation from CHART functions. Create a CHART function. Construct a MACRO function to reconstruct a log. Fill missing values with a reconstructed log. Create a QUALIFY function to construct a lithology log. Note: Functions are not displayed when viewing a 3D Xplot. GEOLOG Functions Geolog supplied functions are described in detail in the Well and Xplot online help documentation. They include many mathematical and trigonometric functions, in addition to many other functions for performing manipulation of data, such as LIMIT, MIN, MAX, LOCASE, RAINBOW, ROUND, etc. These functions can either be used in Loglan programs, where they are incorporated as part of a multi-line sequence of commands and compiled, or within the Evaluate module, where they are included into a single line expression. In the following example, an Sw curve is calculated: Sw = SQRT((a*Rw)/(PHIE**2*RT)) where: is the function: SQRT to derive a square root * for multiplication / for division ** for exponentiation GEOLOG Determin Tutorial Step 4: Xplot Functions 34

39 User Defined Functions The user defined functions are data relationships that are created by you, the Geolog6.6 user, to carry out analysis or manipulation of data. Geolog supplies many predefined functions such as logging company charts for use in borehole corrections. You can create or modify your own functions by one of several methods: Keyboard input. Interactive input using the mouse within the Xplot application. The use of formatted ASCII files. Using Geolog-provided statistics programs. User defined functions are stored in the functions directory in the local project area, and can be moved to the functions directory of the site area for use by other users. They can be used either in Loglan programs, or within Evaluate module expressions. There are several different categories of user defined functions. The generation of user defined functions is usually carried out within Geolog s Xplot application. Exceptions to this general rule are: Creation of macros within the Statistics tools found in Geolog s Well application. Digitizing of logging contractor charts. The user defined functions described in "Function Categories" below are stored in the project functions directory in text format. They can be modified with any text editor, just as any function created outside Geolog6.6 can be used as long as the Geolog6.6 format for the respective function is adhered to. All user defined functions can be used within the Evaluate module and within Geolog s Loglan application to generate data. GEOLOG Determin Tutorial Step 4: Xplot Functions 35

40 Function Categories CHART CHART functions are x,y,z orderings of data values. The most obvious examples of these types of functions are the logging company charts for borehole corrections, porosity calculations, etc. A large selection of these charts are already digitized and present within Geolog6.6. An example of the use of a CHART function would be a Neutron-Density chart being used to derive a value for porosity when values for bulk density and neutron porosity are known. The CHART function could equally be used to derive a value for Neutron porosity if bulk density and porosity are known. Example CHART function # spec: No description given. CONTRACTOR = Schlumberger X_MIN = X_MAX = 0.45 X_LENGTH = 5 X_SCALE = Linear X_LOG = NPHI_COR X_UNITS = V/V Y_MIN = 1.9 Y_MAX = 3 Y_LENGTH = 5 Y_SCALE = Linear Y_LOG = RHO_COR Y_UNITS = G/CC Z_MIN = 0 Z_MAX = 1 Z_LENGTH = 1 Z_SCALE = Linear Z_UNITS = "" APPEARANCE_COLOR = BLACK GEOLOG Determin Tutorial Step 4: Xplot Functions 36

41 APPEARANCE_LINE_STYLE = SOLID APPEARANCE_LINE_WIDTH = 0.01 APPEARANCE_TEXT_FONT = hershey\:simplex_roman APPEARANCE_TEXT_SIZE = APPEARANCE_TEXT_HJUST = LEFT APPEARANCE_TEXT_VJUST = BOTTOM X: Y: Z= CURVE CURVE functions define x-y coordinates and return a y-axis value for an input log on the x-axis. Examples of CURVE functions include: Neutron equivalence curves, where an input value of neutron porosity for one lithology type will return the equivalent neutron porosity for another lithology. Pore pressure as a function of depth curves. Sw-Height functions. Example Curve Function # spec: Demo Curve CONTRACTOR = "" X_SCALE = Logarithmic X_LOG = OH.RT_1 GEOLOG Determin Tutorial Step 4: Xplot Functions 37

42 X_UNITS = OHMM X_MIN = 0.2 X_MAX = 2000 X_LENGTH = 5 Y_SCALE = Linear Y_LOG = GR Y_UNITS = GAPI Y_MIN = 0 Y_MAX = 200 Y_LENGTH = 5 APPEARANCE_COLOR = BLACK APPEARANCE_LINE_STYLE = SOLID APPEARANCE_LINE_WIDTH = 0.01 APPEARANCE_MARKER_STYLE = "" APPEARANCE_MARKER_SIZE = APPEARANCE_TEXT_FONT = hershey\:simplex_roman APPEARANCE_TEXT_SIZE = X: Y= GEOLOG Determin Tutorial Step 4: Xplot Functions 38

43 QUANTIFY QUANTIFY functions are used to return numeric values for a given input from an alphanumeric log. An example of this could be the use of a lithology code log to return values of matrix density. For example: ALPHANUMERIC INPUT NUMERIC OUTPUT SS 2.65 LS 2.71 DOL 2.84 SH 2.5 Example QUANTIFY function # spec : Quantify Fn SYMBOL: VALUE= SS LS SH DOL ANHY ST GRAN QUALIFY QUALIFY functions are used to generate alphanumeric output for a given input numeric range. An example of the use of a QUALIFY function is to generate a lithology code log for given ranges of a matrix density log. For instance: FROM TO OUTPUT CO (Geolog6.6 code for coal) SH (Shale) ST (Siltstone) SS (Sandstone) LS (Limestone) QUALIFY functions can also be used in the Xplot application as color bars, mapping color codes to given ranges of the z-axis log. GEOLOG Determin Tutorial Step 4: Xplot Functions 39

44 Example QUALIFY function # spec : color by gamma ray FROM: TO: SYMBOL= BLUE \#0071FF \#00E2FF \#00FFA \#00FF \#38FF \#AAFF \#FFE \#FF RED CHMAP CHMAP functions are used for the generation of an alphanumeric log for given input of another alphanumeric log. An example of the CHMAP function could be to convert existing lithology codes to Geolog6.6-recognized lithology codes, or for converting formation names to Geolog6.6 lithology codes. For example: INPUT CODE BRENT LIME DOLO KIMM OUTPUT CODE SS LS DOL SH Example CHMAP function # spec: Lithology Conversion INPUT: RESULT= LIMEST LS SANDST SS SHALE SH GEOLOG Determin Tutorial Step 4: Xplot Functions 40

45 SILTST ST DOLO DOL GRANITE GT BASALT BS POLYGON POLYGON functions are pairs of values of x,y that define a polygon, typically within a crossplot. They return a logical value (TRUE/FALSE), and can be used to assign the polygon name to any point that is found within the polygon. An example of this could be to insert polygons in the density/neutron Xplot to define shale, sandstone and limestone regions, and then create a lithology log from the x,y data. Example POLYGON function # spec: No description given. CONTRACTOR = Schlumberger X_SCALE = Linear X_LOG = NPHI X_UNITS = V/V X_MIN = X_MAX = 0.45 X_LENGTH = 5 Y_SCALE = Linear Y_LOG = RHO Y_UNITS = G/CC Y_MIN = 1.9 Y_MAX = 3 Y_LENGTH = 5 APPEARANCE_COLOR = GREEN APPEARANCE_LINE_STYLE = SOLID APPEARANCE_LINE_WIDTH = 0.01 APPEARANCE_FILL_STYLE = SOLID APPEARANCE_FILL_SIZE = GEOLOG Determin Tutorial Step 4: Xplot Functions 41

46 APPEARANCE_TEXT_FONT = hershey\:simplex_roman APPEARANCE_TEXT_SIZE = X: Y= MACRO MACRO functions are expressions applied to a single, or multiple, input variable(s). Examples of macros are regression equations (single input variables), and multiple regression expressions (multiple input variables). Example MACRO function # spec : Regression Logs: SCAL.PHITCR_AMB, SCAL.PHITCR_OB, CC: MACRO = "MACRO phiob_regression (x) \n( *(x))\n" APPEARANCE_COLOR = BLACK APPEARANCE_LINE_STYLE = SOLID APPEARANCE_LINE_WIDTH = APPEARANCE_TEXT_FONT = hershey\:simplex_roman APPEARANCE_TEXT_SIZE = 0.25 APPEARANCE_TEXT_HJUST = LEFT APPEARANCE_TEXT_VJUST = BOTTOM Creating User Defined Functions Geolog s Xplot application is the ideal location to create user defined functions. POLYGON, CHART, and CURVE functions can be entered interactively on screen while actual data is being displayed. GEOLOG Determin Tutorial Step 4: Xplot Functions 42

47 CHMAP, QUANTIFY and QUALIFY functions can be created using the Create button on the Functions tab of the Properties dialog box. All function types can be viewed and edited using the Function Maintenance dialog box. These functions can also be accessed via View > Function Maintenance. MACRO functions can be created using the regression tools provided in the Xplot application, or by the use of the Statistical functions found on the General > Statistics menu in Well or Project. Exercise 1 POLYGON Functions In this exercise you will learn how to create POLYGON functions on a Xplot, display the corresponding points within a layout, and calculate a log from the POLYGON functions. 1. Select Well > View > Close All to close all open views, and Discard all changes. 2. Open a new Layout view. 3. Add a depth (Scale) track and GR in a wireline track. 4. Select Layout > Datum... and set: Interval Log: TOPS.TOPS Top Limit: ARCHERFIELD SANDSTONE Bottom Limit: TD 5. Open the rho_nphi_gr.xplot crossplot. There are three main groupings of data points on the Xplot: A grouping around the sandstone (uppermost) function line. These are probably data in sandstone lithologies. A grouping below the dolomite (lowermost) function line. These are probably shale data points. Data points within the area between these groupings. These are probably siltstone or limestone data points. GEOLOG Determin Tutorial Step 4: Xplot Functions 43

48 Sand Region Shale Region Dolomite Region To identify where each of these groups is represented on logs, POLYGON functions can be created for each data type. 6. Select Insert > Polygon from the Xplot menu to create a shale polygon. Give it a name of SH (the Geolog lithology fill code for shale) and click OK. The cursor changes to a pencil. Draw the polygon around the shale grouping by clicking a series of points around it with the left mouse button, and terminating with the middle mouse button or ESC key. This creates a colored polygon surrounding the shale data points, and is reflected in the Xplot polygon track in the layout. GEOLOG Determin Tutorial Step 4: Xplot Functions 44

49 7. Repeat Step 6. for the sandstone points; use Geolog s code, SS, for the name, and the limestone/siltstone points; use Geolog s code, DM, for the name. 8. Tile the layout and crossplot views. 9. Ensure the Xplot view is active (selected) and select Tools > Highlight Polygons. The following occurs: a temporary HIGHLIGHT set is created; when highlighting is cancelled, this set is deleted; in the layout, blocks of color (corresponding to the polygon colors) at the relevant depths for the selected values (values within the polygons) are displayed behind the Scale track; in the crossplot displaying the polygons, there is no change; if there is another crossplot or crossplots open, the Z axis color bar is turned off (if it exists) and the selected values (values within the polygons) are displayed in the corresponding polygon colors; all other values are displayed in black; See Figure 16 for an example. GEOLOG Determin Tutorial Step 4: Xplot Functions 45

50 SS SH DM Figure 16: Polygons inserted on a crossplot and displayed in layout - Scale track 10. Select Tools > Highlight Cancel to remove the highlighting in all views. 11. Select Tools > Calculate Log... from the Xplot menu to open the Calculate Log dialog box. The Polygon function is automatically selected and uses your inserted polygons to generate continuous logs of lithology codes for the points lying within them. 12. Enter WIRE.LITH for the output log, insert the comment Lithology from polygons. and click OK. 13. Insert a Lithology track in the layout and specify WIRE.LITH as the log and click OK. 14. Maximize the layout to view the relevant Lithology codes displayed. GEOLOG Determin Tutorial Step 4: Xplot Functions 46

51 Exercise 2 Log Calculation from CHART Function This exercise will show you how to create a user defined CHART function within Xplot and generate a continuous log from the function. 1. Open the Xplot Properties dialog box and select the Functions tab. Note the names of the 3 POLYGON and 2 CHART functions attached to the crossplot display. Figure 17: Properties Dialog Box - FUNCTIONS tab 2. Remove each POLYGON function by highlighting the POLYGON function name 9e.g., sh_polygon) and clicking Remove. 3. Click OK to close the Properties dialog box. On the crossplot the CHART functions are represented by: A matrix density chart shown by three lines (Sandstone, Limestone and Dolomite) trending from bottom left to top right of the crossplot. A porosity chart shown by a series of equi-porosity lines between the matrix density chart. GEOLOG Determin Tutorial Step 4: Xplot Functions 47

52 Porosity chart (mi_cple.chart) Matrix Density chart (mi_cple_p.chart) 4. Select the porosity chart mi_cp1e.chart or if using metric units mm_cple.chart, by left mouse clicking on one of the equi-porosity lines. 5. Select Tools > Calculate Log. As the chart is selected, the Chart function is invoked automatically. 6. Complete the Calculate Log dialog box as follows: Output Log: WIRE.PHIT Units: V/V Comment: Porosity from Xplot 7. Click OK. 8. To view this log, insert it into a wireline track on the layout. GEOLOG Determin Tutorial Step 4: Xplot Functions 48

53 Exercise 3 CHART Functions This exercise will show you how to use the tools within the Xplot application to create a user defined CHART function. As the data in the Xplot trends from clean sand (upper left data points) to shale (lower right), a CHART function can be created to define this linear transition, and thereby calculate a Volume of Shale curve. 1. Make the Xplot view active. 2. Select Insert > Chart to display the Insert chart dialog box. 3. Enter the following values (and as shown in Figure 18): Name: dnvsh (a suffix is not required) Description: Vshale from Density-Neutron Method: parallel Z Start: 0 (Clean Sand) Z End: 1 (100% shale) Z Increment: 0.1 (displays lines every 10% increment of shale volume) 4. Click OK. Figure 18: Insert Chart Dialog Box GEOLOG Determin Tutorial Step 4: Xplot Functions 49

54 5. A pencil icon is displayed within the crossplot for you to define the line denoting the Z Start value (0): Open the Position dialog box to aid with insertion at precise locations. Begin inserting a baseline by left mouse clicking on the first end point of the line towards the zero % point on the sandstone line at the data points RHOB=2.5 NPHI=0.00 (RHOB=2500, NPHI=0.00). To specify the other end point of this baseline insert this point in the upper right quadrant of the crossplot, intersecting the sandstone cluster of data points RHOB=1.95 NPHI=0.3 (RHOB=1950,NPHI=0.00). The full baseline (0% Vshale) is now be drawn (see Figure 19). Sand baseline Figure 19: Inserting Baseline of Parallel Chart dnvsh Insert a point that lies on the 100% shale line. The length and orientation are controlled by the baseline. This point should be somewhere in the shale cluster of data RHOB=2.6, NPHI=0.3 (RHOB=2600, NPHI=0.3). GEOLOG Determin Tutorial Step 4: Xplot Functions 50

55 The full chart, with incremental values of 0.1, is drawn and remains selected (see Figure 20). This chart can now be used to calculate a continuous log of shale volume. Figure 20: Completed parallel chart dnvsh 6. Select Tools > Calculate Log... If the dnvsh chart is currently selected, the chart is automatically invoked. If the dnvsh chart is NOT currently selected: click on the Chart radio button; click on the Dropdown List button and select dnvsh. GEOLOG Determin Tutorial Step 4: Xplot Functions 51

56 7. Enter the following in the Calculate Log dialog box: Output Log: WIRE.VSH Units: V/V Comment: Vshale from neutron-density 8. Click OK. The log is calculated and can then be viewed in a layout. Exercise 4 MACRO Functions This exercise will show you how to construct a MACRO function using the multiple regression tool, to facilitate the reconstruction of the density log. This is a useful facility if a section of log data is missing. 1. Reset the Datum as follows: Top Limit: MALABAR FM Bottom Limit: BURNAMWOOD FM 2. Select General > Statistics > Multiple Regression to open the tp_regress_multiple module. 3. Fill in the fields for this module as follows (and as shown in Figure 21): FILE_OUT: rename from regression to mreg. FILTER_EXP: CALI<9 (CALI<228) This limits the regression to data points where the caliper log is less than 9 inches (228 mm). MACRO_NAME: rho_recon BATCH: Middle mouse click to change YES to NO for statistics produced for each well/interval. This creates a single report and function for the entire well. LOG_DEP: RHOB LOG_INDEP: DT and GR GEOLOG Determin Tutorial Step 4: Xplot Functions 52

57 4. Click Start to execute the module. This calculates the regression, places the MACRO function in the project s functions directory, places the regression report in the project s reports directory, and automatically displays the report. 5. Close the report. This macro function can now be used to create a log. 6. Select General > Evaluate. 7. Enter the following for this module: EXPRESSION: rho_recon(dt,gr) The logs to be input into this function must be in the order in which they were entered/selected in the multiple regression calculation, as this is the order in which they appear within the macro. UNITS: g/c3 (k/m3) COMMENT: RHO from DT, GR OUTPUT_LOG: RHOB_RECON 8. Click Start. Figure 21: Multiple Regression Module 9. Create a new layout and view the original WIRE.RHOB curve with the new WIRE.RHOB_RECON curve. GEOLOG Determin Tutorial Step 4: Xplot Functions 53

58 Exercise 5 Fill Missing Values with Reconstructed Log This exercise uses the reconstructed density log created in Exercise 4 to replace missing values in the original density log. 1. Display the Module Launcher (or select General > Evaluate, if you closed the Module Launcher in the last exercise). 2. Fill in the fields for this module as follows: EXPRESSION: ifc(rhob<>missing,rhob,rhob_recon). UNITS: g/c3 (k/m3) COMMENT: Density Log This means: If the RHOB curve is not missing, then use the RHOB curve; if it is missing, then use the RHOB_RECON curve. LOG_OUT: RHOB. This creates a new version of the curve. 3. Run the module. 4. Look at the result. What has happened? 5. Now on the Module Launcher make GR the Sampling Control Log (in the Selection section) and repeat steps 2 and 3. Exercise 6 QUALIFY Functions This exercise will demonstrate the construction of QUALIFY functions and the use of these functions in the calculation of continuous alphanumeric data responding to a given numeric log input. The Gamma Ray curve will be used to estimate lithology. 1. Display the Xplot view. 2. Select View > Function Maintenance to open the Function Maintenance dialog box. GEOLOG Determin Tutorial Step 4: Xplot Functions 54

59 3. Click the New>> button and select Qualify. 4. Using Figure 22 as a guide, fill in the fields in the Function Maintenance dialog box. Click the Table Menu icon and select Insert Row. Enter the data and then press ENTER to go to the next cell. In the last cell, press ENTER to insert another row. Figure 22: Xplot Function Maintenance Dialog Box In this dialog box, any function can be created, viewed or edited. 5. Click the Save As... button and save as grlith. 6. Close the Function Maintenance window. 7. Take a look at grlith.qualify using a terminal window. QUALIFY functions are applied within the Evaluate module or within Loglan programs. 8. Display the Module Launcher (or select General > Evaluate, if it was closed). GEOLOG Determin Tutorial Step 4: Xplot Functions 55

60 9. Fill in the fields for this module as follows: Remember, EXPRESSION: grlith(gr). This means: Apply the grlith function to the GR log. The ranges specified in the function will map lithology codes to their corresponding data points in the log. UNITS: leave blank, as there are no units for lithology codes. TYPE: ALPHA*8. This is an alphanumeric data type of 8 characters long. The default data length for an ALPHA log is 4, so you must ensure that the number of characters is at least as long as the longest output code. you can change this data later, so ensure that the character length allows for this. COMMENT: Lithology from the GR log LOG_OUT: LITH_GR 10. Click Start to calculate the lithology log. 11. Add to your layout: GR in a wireline track shade to the right limit with LITH_GR as the shading log. 12. Close all open views Well > View > Close All and Discard changes. GEOLOG Determin Tutorial Step 4: Xplot Functions 56

61 Step 5: Deterministic Petrophysics Procedure This section explains the Petrophysical workflow, which includes the Determin workflow. Deterministic petrophysics in Geolog6.6 follows a well structured path that reflects the expected workflow through a full analysis. This is reflected in the Petrophysics menu structure of the online help documentation, and is also reflected on the Petrophysics menu in Geolog s Well application. Petrophysics Data Preparation (including Precalc and Corrections) Determin Quickin Figure 23: Online Help Menus in Workflow Form GEOLOG Determin Tutorial Step 5: Deterministic Petrophysics 57

62 This analysis path is: 1. Precalc This is a pre-calculation module that calculates continuous curves of formation temperature and pressure, mud resistivities, mud cake thickness, salinity of mud and mud filtrate, conductivities of the flushed and unflushed zones and the photoelectric cross-section. Many of these output parameters are used throughout the Petrophysics modules, and within the environmental/ borehole correction modules. 2. Environmental / Borehole corrections These are a group of modules for the correction of raw wireline log data for the effects of borehole conditions, etc., and are based on digitized borehole correction charts or coded algorithms provided by the wireline logging contractors. 3. Analysis There are three types of petrophysical analysis within Geolog Quicken (Quick-Look analysis), Determin (Deterministic analysis) and Multimin (optimizing MULTI-MINeral analysis). In this tutorial, the Deterministic analysis approach is used. GEOLOG Determin Tutorial Step 5: Deterministic Petrophysics 58

63 Step 6: Petrophysics Philosophy Procedure The Petrophysics menu in Geolog s Well application provides a variety of modules to perform deterministic petrophysical analysis. Modules have been constructed to incorporate the concept of total and effective porosities and saturations. This concept is illustrated by the following diagram. MATRIX CLAY FREE WATER HYDROCARBON Quartz Calcite Dolomite Dry Clay Clay Bound Water Includes SW irr φ cwb φ fw φ h φ e φ t In this step, you will: Use the precalc module to create borehole and formation condition logs. Use various other modules to borehole correct the logs required for analysis. Definitions 1. φ t = φ e + φ cwb 2. φ t = φ e + V sh φ tsh 3. S we = φ fw φ e GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 59

64 ( φ S fw + φ cwb ) wt = φ t ( φ S t φ e ) wb = φ t φ h = φ t ( 1 S wt ) = φ e ( 1 S we ) ( S S wt S wb ) we = ( 1 S wb ) Free water consists of all water that is not clay bound water and as such, includes irreducible water. Hydrocarbons occupy only non-clay pore space. Shales are considered to be composed of clays and very fine grained material (silt). The above definition excludes silt and confines volumes to clay minerals. Consequently, the most clay rich indicators should be selected (to point of extrapolation, if necessary). The "Vshale" terminology is retained throughout, following traditional petrophysical conventions. Exercise 1 The Precalc Module In this exercise, you will execute the precalc module, creating the borehole and formation condition logs that are required for environmental corrections and petrophysical analysis. 1. Open the SILT well and Save changes. 2. Select Petrophysics > Precalc. 3. Select Launcher > Datum... and set the following: Process: Range Interval Log: set to none (blank) Top Limit: WELL_TOP Bottom Limit: WELL_BOTTOM The PEF log failed in this well and therefore, the data is not available. GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 60

65 4. Click OK to apply the changes and close the Datum window. Note: Two views are open, the module (precalc) and a layout (precomp). Some modules are linked to predefined layouts which can be tailored for your requirements. The Well header constants are already loaded for this well, so all the input fields in this module should be completed. If constants are not yet entered, they can be entered at this point. GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 61

66 5. Click Start to run the module. 6. Display the precomp layout. Figure 24: Precomp Layout Displaying Results of precalc Module 7. Select Well > Save As. The Save As dialog box with a list of all new curves created in the current session is displayed. At this point, you can deselect those curves that you do not wish to save back to the database. GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 62

67 8. Leave all curves selected and click OK. We want to save this data as it is basic data that does not change through the evaluation process, and is required as input for modules run later in the tutorial. Exercise 2 Borehole Correct the Gamma Ray Log This exercise shows you how to correct the Gamma Ray curve for the effects of mud weight and hole size. 1. Select Petrophysics > Environmentals > Schlumberger Charts > Gamma Ray (Por7). 2. Ensure all input fields are filled, and CORR_GR is set to Yes, as shown in Figure 25. GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 63

68 Figure 25: Gamma Ray (Por7) module 3. Click Start. You will notice a new layout (neutron_density_env) has been opened to display the new set of curves. This is another example of the automatic display of a layout when certain modules are launched. This layout is also used to display the corrections applied to all the nuclear tools (GR, RHOB, and NPHI). Exercise 3 Borehole Correct the Density Log Using this exercise you will environmentally correct the density log. 1. Select Petrophysics > Environmentals > Schlumberger Charts > Density > LDT(Por15a). 2. Ensure all the input fields are completed as shown in Figure 26. GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 64

69 Figure 26: LDT(Por15a) module 3. Click Start. The corrected log is included in the neutron_density_env layout, with the difference between the corrected and raw logs shaded. Exercise 4 Borehole Correct the Neutron Log Using this exercise you will correct the neutron log for borehole conditions. 1. Select Petrophysics > Environmentals > Schlumberger Charts > Neutron > NPHI Open (Por13a, 14b). This is the environmental correction for the NPHI tool in open hole. 2. Ensure the inputs are completed as shown in Figure 27. If only certain corrections for the borehole are required (for example, the mudweight correction option is not required), they can be toggled from YES to NO. In this example, all corrections will be applied. GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 65

70 Figure 27: NPHI Open (Por13a, 14b) Module 3. Click Start. The resulting corrected neutron log is placed into the layout (see Figure 28). For logs run with automatic caliper correction, use the Caliper log that was run with the Neutron log. For logs without automatic caliper correction, enter the fixed (constant) value of the Panel Setting and use this to satisfy the input for the CALI_POR log. If no hole size correction was applied on acquisition, then set OPT_CACO to NO. GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 66

71 Figure 28: Results of NPHI Open (Por13a, 14b) Module Exercise 5 Borehole Correct the MSFL Log Using this exercise you will correct the MSFL log for borehole conditions to derive a true resistivity of the flushed zone, Rxo. 1. Select Petrophysics > Environmentals > Schlumberger Charts > Micro Resistivity > MSFL MicroSFL (Rxo3). GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 67

72 2. As shown in Figure 29, ensure that the input fields are completed. Most of these inputs are calculated in the precalc module. Figure 29: MSFL MicroSFL (Rxo3) Module 3. Click Start. This is not placed into the neutron_density_env layout, but is included in the layout attached to invasion corrections in the next exercise. Exercise 6 Borehole Correct the Dual Laterolog This exercise will correct the Dual Laterolog curves for borehole conditions, and apply invasion corrections to derive a True Formation resistivity log (Rt). 1. Select Petrophysics > Environmentals > Schlumberger Charts > Laterolog Invasion. 2. Ensure that the input fields are completed as shown in Figure 30. GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 68

73 This module carries out borehole corrections upon the Laterolog curves, and then applies invasion corrections to them to derive values of True formation resistivity (Rt) and diameter of invasion. 3. Click Start. Figure 30: Laterolog Invasion Module All corrected resistivity curves and diameter of invasion are displayed in the laterlog_env layout (see Figure 31). GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 69

74 Figure 31: Results of Laterolog Invasion Module GEOLOG Determin Tutorial Step 6: Petrophysics Philosophy 70

75 Step 7: Parameter Picking Procedure There are several methods available within Geolog6.6 to interactively pick petrophysical parameters for use in deterministic analysis. These methods include picking lithology points from Xplots, picking minima and maxima for log values from histograms, and the interactive determination of water resistivity (Rw) and saturation constants from Pickett plots. In this step, you will: Overview Format the Datum to set the location where the parameters are to be stored. Pick matrix, shale, and coal points on crossplots. Pick petrophysical points from a distribution of a single log on a histogram. Determine parameters used within water saturation calculations on a Pickett plot. The petrophysical parameters, when named correctly, are automatically used by the analysis programs supplied with Geolog. The location for storing these parameters is dependant upon the processing mode chosen from the Datum dialog box: If intervals are being processed, then the parameters are stored within the interval set as new logs. If a range is being processed, then the parameters are stored within the well_header constants. GEOLOG Determin Tutorial Step 7: Parameter Picking 71

76 Exercise 1 Set the datum to specify the location to store the parameters: 1. Select Well > View > Close All. 2. Select Well > Default Datum. 3. Set the datum as follows: Process Intervals Interval Log: TOPS.TOPS Intervals to Process: A 4. Click OK to accept the changes and close the Datum window. Exercise 2 Crossplots This exercise will show you how to pick matrix, shale, and coal points from the density-neutron crossplot for use in log analysis programs supplied within Geolog6.6. Xplot allows the picking of petrophysical parameters by the insertion of a point representing a petrophysical constant. An example of this is the use of the densityneutron crossplot to determine the points representing matrix, shale and coal. 1. Select Petrophysics > Parameter Picking > rho nphi gr. This starts the Xplot application and opens a density-neutron crossplot that has extended axes to reflect the appearance of minerals with petrophysical properties that are not normally seen when the standard axes are used. To aid in accurately picking points, turn on the Histogram display: 2. Select Edit > Properties. GEOLOG Determin Tutorial Step 7: Parameter Picking 72

77 3. On the Filter tab set the following parameters (as shown in Figure 32): Accumulation Mode Binned X and Y axis fields 100 Accumulate Columns Toggle on Accumulate Rows Toggle on Histogram Toggle on Figure 32: Setting the Histogram Display 4. Click OK. The modified param_rho_nphi crossplot is displayed in Figure 33. GEOLOG Determin Tutorial Step 7: Parameter Picking 73

78 Geolog6.6 Figure 33: RHO NPHI GR crossplot with Points, Extended Axes and Histogram Display Set There are a number of points positioned in the crossplot to denote relative positions of lithologies. These points are SH (Shale), MA (Matrix), CCUT (Coal Cutoff), and COAL. recognizes certain petrophysical parameter names that can be generated in this way. In this crossplot, the x and y axes are defined by the NPHI and RHOB curves, respectively. When the SH point is entered, values of NPHI_SH and RHO_SH (i.e., Logname_Pointname) are generated and placed in the Constants area (in the case of complete-well analysis), or the Interval log (in the case of interval/range-based analysis). If these constants are to be recognized, then they must be named correctly. 5. Select the MA point, click and hold the middle mouse button to drag the point to the formation matrix position, and release the mouse button. GEOLOG Determin Tutorial Step 7: Parameter Picking 74

79 After releasing the mouse button, the Point dialog box is displayed. 6. Adjust the NPHI and RHO values as required and click OK. This writes the values for NPHI and RHO to new logs in the interval set. 7. Move the SH and CCUT points to a location you think best represents the shale and coal cutoff points. 8. To move to the next interval, select Xplot > Datum. 9. Change the processing interval to B and click OK. 10. Move the points to the appropriate location for this interval. Even if a point does not need adjusting, you still have to double click the point (to open the Point dialog box) and click OK to create the new log/ constant and close the dialog box. 11. Open a Text view, select the interval (TOPS) set for the well, and click on the Log Values tab to view the values for the points. 12. Close the crossplot and the text view, and discard the changes. If you save a crossplot after adjusting points, the file will be saved with the new point locations (on the crossplot, not in the database) to the currently open project s /layouts directory. Then, when you select that crossplot from the menu, this file will be opened, and the points will be in those locations, even if you are using a different well. You must open the crossplot from the release directory, or remove the crossplot from your project directory, in order to open the original crossplot with the unadjusted points. GEOLOG Determin Tutorial Step 7: Parameter Picking 75

80 Exercise 3 This exercise will show you how to pick a shale point from the gamma ray/sonic crossplot and transit time values to reflect values for shale, for use in the calculation of shale volume and porosity. 1. Select Petrophysics > Parameter Picking > dt gr cali to start the Xplot application with a gamma ray sonic crossplot (see Figure 34). 2. Select A for the processing interval. Figure 34: DT GR CALI crossplot 3. Shift the shale point to reflect the gamma ray and transit time of the shale in this interval. 4. Do not worry about the matrix values at this stage. 5. Change the processing interval and repeat for B. GEOLOG Determin Tutorial Step 7: Parameter Picking 76

81 Exercise 4 Histograms Parameter picking from histograms allows the picking of petrophysical points from a distribution of a single log. In this exercise, you will fine tune gamma ray values to reflect values for matrix and shale, for use in the calculation of shale volume. To fine tune the matrix and shale points from the gamma ray distribution: 1. Open a new Frequency histogram Well > View > New > Frequency. 2. Re-select interval A in the Datum dialog box. 3. Select Edit > Properties to open the Properties dialog box. 4. On the Data tab, specify the GR_COR log to be displayed in the histogram. 5. Click OK. GEOLOG Determin Tutorial Step 7: Parameter Picking 77

82 The gamma ray distribution reflects a bimodal distribution with separate populations defining the matrix and shale regions. 6. Select Insert > Point... and insert a point in the population that reflects a clean sand region. 7. Name the point MA. Figure 35: GR_COR Histogram 8. Insert another point in the shale region of the histogram and name it SH. The 5th, 50th, and 95th percentiles are displayed on histograms by default. These can be useful when picking the matrix and shale points. If other percentile values are required, then open the Properties dialog box, select the HISTOGRAM tab and specify the values to be displayed. 9. Change the processing interval to B. GEOLOG Determin Tutorial Step 7: Parameter Picking 78

83 10. Move the points, SH and MA, to the appropriate location for this interval. 11. Close the Frequency view and discard the changes. 12. Open a Text view to view the points reflecting values of gamma ray for matrix and shale, as well as the percentile values. Exercise 5 Pickett Plots Pickett plots are a log-log Xplot of porosity versus resistivity and are used to estimate water resistivity (Rw), and saturation constants. Use a Pickett plot to estimate Rw and cementation factor 'm'. This exercise uses the Pickett Plot facility supplied with Geolog to determine parameters used within water saturation calculations.the Pickett plot templates in Geolog display the log data required, in addition to a chart reflecting values of water saturation. With the correct petrophysical parameters, the chart selected in this exercise will match the water saturations seen in the data. 1. Close all open views Well > View > Close All. 2. Select Well > Save to save the logs you have created in the previous exercises. 3. Open the FURUD well. 4. Change the Default Datum back to well. 5. Select Petrophysics > Parameter Picking > Pickett Plots > nphi rxo gr to start the Xplot application and open the required Pickett Plot template. The chart can be modified in one of two ways; via a dialog box or graphically, using the mouse. 6. Set the Xplot datum as follows: Process: Range Interval log: TOPS.TOPS Top Limit: MULBRING SILTSTONE Bottom Limit: BRANXTON FM GEOLOG Determin Tutorial Step 7: Parameter Picking 79

84 7. Open the Properties dialog box. 8. On the Filter tab, enter the following Expression: IMPERIAL/MIXED: CALI<9.5 & GR_COR<75 OR METRIC: CALI<242 & GR_COR<75 Figure 36: Applying a Filter to the Pickett Plot 9. Click OK to apply the filter and close the dialog box. To modify the R o Chart via the dialog box 10. Select the R o chart (equi-saturation lines) and select Edit > Edit Object (or double click on a line). The Edit Pickett dialog box opens with values for a, Rw and m. If any of these values are changed, then this will be reflected in the chart (see Figure 37). GEOLOG Determin Tutorial Step 7: Parameter Picking 80

85 Pivot point for adjusting gradient of lines The Edit Pickett dialog box defines the positioning of a R o line and additional water saturation lines. The R o line is defined where Sw=100% or 1. The line is labeled: R o Line; S w =100%; a*r w =<value>; m=<value> Additional water saturation lines are defined according to the percentage saturation (e.g is 75% saturation). S w lines are labeled: S w =75% 11. Change M to 1.7. Figure 37: NPHI RXO GR Pickett Plot 12. Click OK and note the change in the chart ohmm represents the value of Rmf in this well. GEOLOG Determin Tutorial Step 7: Parameter Picking 81

86 To modify the R o Chart graphically 13. Move the chart by middle clicking and dragging so that the 100% S w line lies to the left of the data points. Rxo data can be useful for fine tuning the m value in some wells. 14. The gradient of the chart "m" can also be adjusted by: selecting the R o chart and then selecting Edit > Edit Object OR double clicking on the chart the Edit Pickett dialog box opens and a pivot point appears on the leftmost line (see Figure 37) click and release on any one of the lines but NOT on the pivot point; (changed your mind? press ESC to restart) make adjustments, as required, until the gradient of the chart lines reflects the gradient of the data points click OK in the Edit Pickett dialog box to finish modifications. 15. Now, select Petrophysics > Parameter Picking > Pickett Plots > nphi rt gr. 16. Use the same M value (1.7) and filter expression (CALI<9.5 & GR_COR<75) or CALI<242 & GR_COR<75), and estimate Rw. These parameters can be fine tuned once a shale corrected PHIT has been calculated. GEOLOG Determin Tutorial Step 7: Parameter Picking 82

87 Step 8: Analysis Procedure The petrophysical programs supplied within Geolog are represented on the Determin menu structure, in the order that most analyses would be carried out (i.e., identify coals/badhole - calculate shale volume - calculate porosity - calculate water saturation). Figure 38: Determin Menu Showing Typical Workflow In this step, you will: Identify badhole conditions. Identify coals. Calculate shale volume. Calculate porosity using a sonic log. Calculate porosity from a density-neutron crossplot. Calculate water saturation. GEOLOG Determin Tutorial Step 8: Analysis 83

88 Calculate porosity and water saturation with corrections applied for hydrocarbon effect. Calculate a log derived permeability curve using the Coates Free Fluid Index method. Calculate values for matrix density, transit time and photoelectric cross-section and the application of these curves for the determination of matrix mineralogy. Create mineralogy percentages for matrix. Output a net pay report and pay averages. Carry out sensitivity analysis on the effect of cutoffs to pay characteristics. Create a specification which includes all lumps to be applied over multiple intervals and wells, and then apply that specification to the two intervals. Exercise 1 Identify Badhole Conditions 1. Close all open views and Discard any changes. 2. Open the SILT well and Discard any changes. 3. Open the determin_analysis layout. 4. Select Petrophysics > Determin > Badhole. 5. Change the Launcher Datum as follows: Process: Intervals Interval Log: TOPS.TOPS Intervals to process: A and B 6. Within the Badhole (module) window set the following inputs (also shown in Figure 39). Select the ALL checkbox to enter the values simultaneously for both intervals. DRHO_MAX for zones A and B 0.2 (200) DCAL_MAX for zones A and B 1.5 (38.1) GEOLOG Determin Tutorial Step 8: Analysis 84

89 Figure 39: Badhole Module 7. Click Start. Bad hole conditions are flagged in the depth track of the layout. Exercise 2 Identify Coals This exercise shows you how to identify coals in the logged interval for use in later analysis routines. 1. Select Petrophysics > Determin > Coal. 2. Enter the values in the fields (as shown in Figure 40: RHO_CCUT: (2188) for density of coal NPHI_CCUT: 0.28 for neutron porosity of coal 3. Remove the input logs DT and RT. GEOLOG Determin Tutorial Step 8: Analysis 85

90 Figure 40: Coal Module 4. Click Start. 5. Investigate the layout to identify the coal zones flagged by this routine. The coal indictors are available to turn on or off for any intervals selected if Datum is set to "Intervals". If any of the coal indicators are not required, then the corresponding input log name must be set to MISSING this is done by clicking on the appropriate value box and pressing BACKSPACE. Some editing of the coal values on the shoulder regions may be required. This can be done by selecting Well > View > Text. Exercise 3 Calculate Shale Volume This exercise calculates a shale volume curve from the gamma ray log. 1. Select Petrophysics > Determin > Shale Volume > Gamma Ray. Geolog automatically uses the values for the parameters MA and SH that you picked from the histogram in Exercise 4 on Page The default Vshale model is LINEAR. GEOLOG Determin Tutorial Step 8: Analysis 86

91 Your module should look similar to the one shown in Figure 41. As OPT_COAL is set to "No", the coal flag (COAL) for Interval B is not applicable. 3. Click Start. 4. View the resulting shale volume curve displayed in the layout. 5. Save the well. Figure 41: Shale Volume Module 6. Repeat using the Density/Neutron Shale Volume module. 7. Compare the results using Xplot. Which one seems more reliable? GEOLOG Determin Tutorial Step 8: Analysis 87

92 Exercise 4 Calculation of Porosity Using Sonic Log This exercise calculates a porosity curve using the sonic (DT) log. 1. Select Petrophysics > Determin > Porosity > Sonic. 2. Enter the following module input parameters (as shown in Figure 42): OPT_PHITYPE TOTAL This means the module outputs both effective and total porosity. Total porosity is only calculated if a value for PHIT_SH is nominated. OPT_SON: FLD_OBSA (field observed). DT_MA: 55 us/f ( us/m) for matrix transit time for zones A and B. DT_SH: The shale transit time is picked up from the parameters chosen on the DT-GR Xplot. PHIT_SH: 0.1 for shale total porosity (this is equal to the volume of clay bound water in the true shale) for both Zones. GEOLOG Determin Tutorial Step 8: Analysis 88

93 3. Click Start. Figure 42: Porosity from Sonic Log Module The values of PHIE and PHIT (effective and total porosity values) are displayed in the layout. Exercise 5 Calculation of Porosity from Density-Neutron Crossplot This exercise shows you how to calculate: a porosity curve using the density-neutron method, and a secondary porosity index from comparison to the porosity calculated from the sonic log. 1. Select Petrophysics > Determin > Porosity > Density/Neutron > Bateman-Konen. GEOLOG Determin Tutorial Step 8: Analysis 89

94 The density and neutron values interactively picked from the Xplot are utilized by default. If a value for PHIT_SH is supplied, then total porosity is calculated based on that parameter. Alternatively, that value can be set to missing and a value for RHO_DSH (dry shale density) can be used. Figure 43: Density/Neutron Bateman-Konen Porosity Module 2. Click Start. GEOLOG Determin Tutorial Step 8: Analysis 90

95 The new values for PHIE and PHIT replace the previously calculated curves in the layout. A secondary porosity index log is calculated from the comparison of the porosity curve from the sonic log with the newly created density-neutron porosity curve. This is displayed in the layout as SPI. 3. Compare the results between the Density neutron porosity and the Sonic porosity. Which one looks more reliable? 4. Save the well. 5. Try some of the other porosity methods and compare the results. If you want to know how a porosity is calculated in Geolog, select Help > On Petrophysics..., click on Determin and then select the method you are interested in. Click on the Module Help button to quickly view information on the equations behind the calculations. Exercise 6 Water Saturation Calculation In this exercise, you will calculate a water saturation curve using the Total Shale equation. 1. Select Petrophysics > Determin > Water Saturation > Total Shale. 2. Fill in the fields as follows: RWS: 0.3 ohmm for Rw (for both Zones) RWT: 77 DEGF (25 DEGC) (for both Zones) RT_SH: 3.5 ohmm for shale resistivity in A 4.5 ohmm for shale resistivity in B 3. Ensure that the remaining fields are completed as shown in Figure 44. GEOLOG Determin Tutorial Step 8: Analysis 91

96 Figure 44: Total Shale Water Saturation Module 4. Click Start. 5. To view the curves displaying values for Swe and Sxoe, change the SWT log name in the right track in the layout. Values for bulk volume of water in the flushed and unflushed zones are displayed and shaded within the porosity curve track, indicating the amount of movable hydrocarbon. Your layout should look similar to Figure 45. GEOLOG Determin Tutorial Step 8: Analysis 92

97 Figure 45: Results of Deterministic Analysis Thus Far Exercise 7 Hydrocarbon Corrected Porosity / Water Saturation This exercise will show you how to use the Geolog supplied program to calculate porosity and water saturation with corrections applied for hydrocarbon effect. 1. Select Petrophysics > Determin > HC Corrected Porosity > Density/Neutron. 2. Use a value of 0.7 for RHO_HC (hydrocarbon density). 3. No other values need to be changed. GEOLOG Determin Tutorial Step 8: Analysis 93

98 Figure 46: Hydrocarbon Corrected Porosity / Sw Module 4. Click Start. The re-calculated porosity and water saturation curves will replace the already existing logs displayed in the layout. GEOLOG Determin Tutorial Step 8: Analysis 94

99 Exercise 8 Permeability Calculation This exercise calculates a log derived permeability curve using the Coates Free Fluid Index method. 1. Select Petrophysics > Determin > Permeability > Coates Free Fluid Index. 2. Use a value of 0.22 for SWE_IRR (irreducible water saturation) in both intervals. This is an estimate from the water saturations we have just calculated. 3. Ensure that the remaining fields are completed as shown Figure Click Start to run the module. Figure 47: Permeability Module Exercise 9 Matrix Analysis This exercise shows you how to calculate values for matrix density, transit time and photoelectric cross-section, and the application of these curves for the determination of matrix mineralogy. 1. Select Petrophysics > Determin > Lithology > True Matrix Properties. GEOLOG Determin Tutorial Step 8: Analysis 95

100 Figure 48: True Matrix Properties Module 2. Leave all values as shown and click Start. Values for Matrix density (RHO_MAT), Matrix transit time (DT_MAT) and Matrix cross-section (U_MAT) are calculated and output as logs. These are true shale corrected matrix values. The true values are used for the apportionment of mineral volumes. Initially values for apparent matrix values (e.g. RHO_MAA,...) can be calculated and crossplotted for the identification of the types of minerals present. Exercise 10 Matrix Parameter Curves Used to Estimate Mineral Content This exercise shows you how to use the curves calculated in Exercise 9 on Page 95 to create mineralogy percentages for matrix. 1. Select Petrophysics > Determin > Lithology > 3 Mineral Rhoma Dtma (MID). GEOLOG Determin Tutorial Step 8: Analysis 96

101 This module allows ternary mineral distribution of any three of quartz, calcite, anhydrite and dolomite. If the default matrix values are changed, then any other mineral of known properties can be incorporated into the analysis. 2. Ensure the fields are completed as shown in Figure 49 and then click Start to process the module. Figure 49: Matrix Mineral Identification Module The mineral proportions are placed into the layout shaded between the Vshale and porosity curves. GEOLOG Determin Tutorial Step 8: Analysis 97

102 Exercise 11 Pay Sensitivity This exercise explains how to carry out sensitivity analysis on the effect of cutoffs to pay computations. The output is a report file. 1. Select Petrophysics > Pay Summary > Pay Sensitivity. This module uses cutoff logs specified to calculate a pay summary for each permutation of these cutoffs. 2. Enter values (as shown in Figure 50): REPORT_FILE_OUT paysens.rpt PHI_CUTOFFS: SW_CUTOFFS: CUTOFF_VALUES1: CUTOFF_TYPE1: < (less than) PHI: PHIE CUTOFF_LOG1: VSH GEOLOG Determin Tutorial Step 8: Analysis 98

103 Figure 50: Sensitivity Analysis Report 3. Click Start. Because a file extension.rpt was specified for the report file, paysens.rpt, the report is generated in ASCII format and automatically opened for viewing within a text viewer, and is written to the reports directory in the local project area. If no file extension is specified, by default, the report file is generated as a pdf. For more information refer to the online help, Using Geolog - Report Creation and Printing. GEOLOG Determin Tutorial Step 8: Analysis 99

104 Exercise 12 Pay Summary This module is used to define the cutoffs, flag generation, lumping, averaging and output of processed results. It is an interactive specification file builder that enables you to specify and save the functionality required for a particular well, field, or oil company philosophy. The advantage of the pay summary function is that all lumps can be created in a single specification, and then applied over multiple intervals and wells. To build a pay summary specification that produces a summary of the following LUMPS: SAND phie 0.08 RESERVOIR phie 0.08 & vsh 0.3 PAY 1 phie 0.08 & vsh 0.3 & SWE 0.4 PAY 2 phie 0.08 & vsh 0.3 & SWE Select Petrophysics > Pay Summary > Pay Summary Edit to start the Pay Summary specification editor. Select the Paysum menu or click on the Toolbar icons for functions such as New, Open, Save, Exit. Select the View menu or a Toolbar button to display the relevant window. Figure 51: Pay Summary Specification Editor Window GEOLOG Determin Tutorial Step 8: Analysis 100

105 2. Select Paysum > New to open the default paysummary specification. Figure 52: Default Pay Summary Specification - Cutoff and Flags Screen Once the default specification has been loaded, it can be: customized and saved (Paysum > Save) to create a new default pay summary specification; or modified and saved to create a new pay summary specification (Paysum > Save As). The new specification is saved in the specs directory of the current project. To make the new default file available to all users at your Site, copy it to the specs directory of the Site project. 3. Using Figure 53 as a guide; Define the logs to be used as cutoff logs in the Cutoffs section by modifying the existing logs and deleting any redundant ones. Define the flags (one for each lump) and the cutoff criteria each flag must pass. GEOLOG Determin Tutorial Step 8: Analysis 101

106 Figure 53: Modified Cutoffs and Flags 4. From the Toolbar click on Flags and Lumping. The Flags section is the same as the one previously defined in the Cutoffs and Flags window. The Lumping section is used to define each lump and its standalone thickness, minimum include thickness, and maximum separation thickness. You can also choose to create an output set of the cumulative results for each lump. The "Create Interval Set" is not currently functional. 5. Change the lumping criteria to create output sets for RESERVOIR and GOODPAY, and no output set for SANDA (as shown in Figure 54). GEOLOG Determin Tutorial Step 8: Analysis 102

107 Figure 54: Pay Summary Specification - Flags and Lumping Screen 6. Click the Results and Averaging button on the Toolbar. The Pay Summary Specification - Results and Averaging window is displayed. GEOLOG Determin Tutorial Step 8: Analysis 103

108 Figure 55: Pay Summary Specification - Results and Averaging Window 7. Using Figure 55 as a guide, define in the: Results section: which logs are to be included in the results tabulation, and which averages are to be applied to each of those logs. Note that when you change the logs in this section, the change is reflected in the Averaging section. Averaging section: which results are to be included into each of the lumps (e.g. it makes no sense to have Sw included in the SAND lump). GEOLOG Determin Tutorial Step 8: Analysis 104

109 8. Save the specification as silt_ps. 9. Close the Pay Summary window. 10. In the Well window, select Petrophysics > Pay Summary > New Pay Summary to open the tp_paysummary module. 11. Set the values in the module as follows: REPORT_FILE_PFX: silt_paysummary REPORT_DEPTHS: none REPORT_ZONES: no PAYSUMMARY: silt_ps (or whatever name you used to save your pay summary specification). Figure 56: New Pay Summary Module 12. Click Start to process the module. 13. Open the determin_paysum layout to view the results. 14. Save the well. GEOLOG Determin Tutorial Step 8: Analysis 105

110 Step 9: Multiwell Analysis Procedure This step describes how to analyze multiple wells in the Well application. You will: Overview Select multiple wells for processing. Select specific intervals to process. Create a histogram of all wells. Insert matrix and shale points in the gamma ray histogram. Insert matrix and shale points using parameter picking. Calculate a shale volume curve for multiple wells. Multiwell analysis is carried out within Geolog s Well and Project applications. In Well, several wells can be loaded into memory, processed, and the changes saved to the database or discarded, as required. You should use the Well application where only a few wells need to be open at one time. Where a large numbers of wells are to be processed simultaneously, use the Project application, as the wells are not stored in memory, and data is immediately processed, and saved to the database. Interactive parameter picking is still allowed on a multiwell basis, with any parameters being written back to all of the selected wells. Exercise 1 Select the Wells to Process This exercise shows you how to limit the selection of wells to be analyzed by picking them within the Well application. 1. Select Well > View > Close All and Discard any changes. 2. Select Well > Open Multiple... to display the Select Multiple dialog box. 3. Select BOTEIN and FURUD for processing. 4. Click OK. GEOLOG Determin Tutorial Step 9: Multiwell Analysis 106

111 Exercise 2 Selecting Intervals to Process In this exercise, you will select the intervals for analysis for the two wells selected in Exercise Select Well > Default Datum... and set the following: Select the Intervals radio button. Interval Log: TOPS.TOPS Intervals to Process: select the Branxton FM interval 2. Click OK to apply the changes and close the dialog box. Exercise 3 Multiwell Histograms In this exercise, you will display a histogram of both the wells at the same time. 1. Select Well > View > New > Frequency. 2. Select Edit > Properties to open the Properties dialog box. 3. In the Log Expression field on the Data tab, enter or select the GR. 4. Click Apply. The GR logs for both wells is displayed. These are stacked so that the frequency distribution for all wells selected for processing are shown (see Figure 57). GEOLOG Determin Tutorial Step 9: Multiwell Analysis 107

112 Figure 57: Histogram Displaying GR log for 2 Wells 5. On the Accumulation tab, change the Frequency Style to Line. 6. Click OK. This changes the histogram display from a stacked bar style to a style with each of the well frequency distributions displayed unstacked, with a further line display representing the average frequency distribution for both wells (see Figure 58). GEOLOG Determin Tutorial Step 9: Multiwell Analysis 108

113 Figure 58: Histogram Displayed in Unstacked (Line) Style To view data for each individual well use the to view data for multiple wells. icons or click Exercise 4 Parameter Picking - Histogram In this exercise, you will insert matrix and shale points in the gamma ray histogram. 1. Select Insert > Point. 2. Click with the pencil at about 25 API. 3. Within the Gr Point dialog box, name the point MA and click OK. GEOLOG Determin Tutorial Step 9: Multiwell Analysis 109

114 4. Repeat the process for the shale point, and name this point SH (about 150 API). 5. Save the wells. The MA and SH values are written back to each of the wells, as indicated by the Message area (see Figure 59). Note: If you were using Project to insert the matrix and shale points, the values would be automatically written back to the wells, and saving the wells would not be required. Figure 59: Messages Displayed After Inserting Points for Multiple Wells 6. Select Well > View > New > Text and look in the TOPS set to verify the values are written to each well. 7. Close the text view. Exercise 5 Parameter Picking - Crossplot In this exercise, you will insert matrix and shale points in the RHOB NPHI GR Xplot. 1. Select Petrophysics > Parameter Picking > rho nphi gr. 2. Open the Position dialog box and use the co-ordinates to position the two points as shown in the step 3. and 4. GEOLOG Determin Tutorial Step 9: Multiwell Analysis 110

115 3. Select MA with the middle mouse button and move the point to about 2.64 g/cc RHO and 0.0 v/v NPHI). 4. Repeat the process for the shale point, positioning it at about g/cc and v/v). Figure 60: Adjusting Matrix and Shale Points on a Multiwell Crossplot GEOLOG Determin Tutorial Step 9: Multiwell Analysis 111

116 Exercise 6 Quick Analysis (Shale Volume Calculation) In this exercise, you will calculate a shale volume curve on a multiwell basis. 1. Select Petrophysics > Quickin > Shaley Modules > Vsh Gamma. Parameter location indicators The module is identical to the Quickin modules in single well analysis, with one exception to the right of the Name column there is an additional column that denotes the location of the parameters to be used in the analysis. There are 3 options: P S Prefer well value If the parameter exists within the well being analyzed, then this is used. If it is absent, then the value placed in the input cell on screen is used. Screen values MUST be placed in the input cells. Screen value only This forces the module to use the value placed in the input cell on screen. This means that all the wells in the current analysis session have the same parameters used in the calculation. This allows for quick sensitivities of specific values. W Well value only This forces the module to use the parameter(s) within the well. If the parameters are missing in any well, then this well is skipped by the calculation. GEOLOG Determin Tutorial Step 9: Multiwell Analysis 112

117 2. Enter the following values: GR_MA: 25 API GR_SH: 145 API 3. Click Start to calculate continuous shale volume curves for each well,. 4. Close the Well application and discard any changes. GEOLOG Determin Tutorial Step 9: Multiwell Analysis 113

118 Step 10: Create a New Loglan Program Procedure Loglan is a multi-document interface (MDI) application and therefore, multiple views can be displayed concurrently (e.g., a Text view, Layout view and 2 Xplot views). This step shows you how to create and run a simple Loglan program for use in Geolog. Exercise 1 Starting a New Loglan Loglan programs can be created via the program development interface, mui_loglan, which is launched by: Clicking on the Loglan button on Geolog s Launcher Bar. Selecting Applications > Loglan on Geolog s Launcher Bar menu. Selecting General > Loglan... from within an applicable application (e.g., Project or Well). Loglan programs can also be created using a text editor. This exercise will introduce you to the Loglan interface, and show you how to create a simple program for use in Geolog s Module Launcher. Loglan is the programming language supplied with Geolog. Once you have written the code, and the code has been debugged, the program is first translated from Loglan to C, and then compiled using an ANSI C compiler. For Loglan creation, an ANSI C compiler MUST be available on the same type of computer as the loglan is to be run. For Geolog 6.6, these are: C/C++ COMPILER VERSION Sun Solaris 8 or 9 (64 bit) SunOne Studio 7 SGI IRIX m or later (64 bit) SGI MS Windows SP2 MS Visual C++ V6 MS Windows XP Red Hat Enterprise Ed 3 GNU gcc 3.2 GEOLOG Determin Tutorial Step 10: Create a New Loglan Program 114

119 1. Click the Loglan button on the Geolog Launcher Bar to start Loglan (see Figure 61). Figure 61: Loglan Interface 2. Select Loglan > New to display the Details dialog box which prompts for details on the Loglan you are about to create. Figure 62: Properties Dialog Box 3. Enter the following information: Program: hr_por (name of the program). This program calculates porosity using the Hunt-Raymer method. Description (Brief): Hunt-Raymer Porosity Layout: DO NOT enter a Layout name. If a layout is specified, it is opened automatically when the module is invoked. GEOLOG Determin Tutorial Step 10: Create a New Loglan Program 115

120 4. Click OK. Inserting Variables The Loglan window displays the Input/Output tab. You can insert variables with a mode of input, input/output, and output and Local variables. In this example, you will insert three rows on the Input/Output tab for variables DT,DT_FL, DT_MAS, PHIE_HR, and PHIE. 5. Select Edit > Insert (or press Insert on the keyboard) to display the Insert Row window. 6. Enter DT (for the sonic log) as the Name, set the Location to Log and the Mode to Input, and click OK. 7. Repeat steps 5. and 6. using the data provided in the following table. NAME LOCATION MODE DT_FL This specifies an interval-based constant, and writes it back to the interval set (or constants area if an interval set is not specified). Interval Input/Output DT_MA Interval Input/Output PHIE_HR Log Output GEOLOG Determin Tutorial Step 10: Create a New Loglan Program 116

121 PHIE This is a copy of the PHIE_HR curve limited between zero and 1. ALPHA Local variables are used within the program for "local" processing, and are not input or output. Log Local Output "greyed out" 8. On the Input/Output tab, for PHIE_HR change Visible to False, so this log is not visible to the user. The Input/Output tab displays the data entered. Specifying Units 9. Ensure the units for the variables are set as: DT_FL, DT_MA and DT as US/F (US/M) PHIE_HR and PHIE as V/V GEOLOG Determin Tutorial Step 10: Create a New Loglan Program 117

122 Specifying Default Values 10. Specify the default values for: DT_FL as 189 DT_MA as 55.5 PHIE_HR and PHIE as PHIE_HR and PHIE, respectively. These values will be placed into the Module Launcher if they are not found in the constants/interval area. This specifies the default curve names for the output logs, and they will be placed into the default set within the well being analyzed. Entering Code and Comments Code for use within the loglan is typed into the Source section. For any step to be carried out on every depth frame, it must be carried out within the dowhile GETFRAME ()... enddo loop. Outside this loop, steps are carried out only as many times as specified. 11. Select the Source tab and enter the Comments and Code as shown in Figure 63. GEOLOG Determin Tutorial Step 10: Create a New Loglan Program 118

123 Figure 63: Completed hr_por Loglan 12. When coding is complete, select Loglan > Save. This creates two separate files in the loglan directory of the local project: filename.lls is the raw source code, and filename.info is a file which controls the way in which the input and output variables are represented in the Module Launcher. Once saved, the program is ready to compile. 13. Select Tools > Compile to compile your program. Once compilation has been completed successfully, this program can be run in the same way as any Geolog supplied program. 14. Close the Loglan application. GEOLOG Determin Tutorial Step 10: Create a New Loglan Program 119

124 15. Start the Well application and open the SILT well. 16. Select General > Module... to open the File Select dialog box. 17. Select the hr_por.info module to invoke the Loglan program you have just created. Figure 64: Using the hr_por Loglan 18. Click Start. 19. Create a layout to display the resultant porosity log. 20. Close all the open views and the Well application. GEOLOG Determin Tutorial Step 10: Create a New Loglan Program 120