LAS Files and Digital Log Analysis. John H. Doveton Kansas Geological Survey

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1 LAS Files and Digital Log Analysis John H. Doveton Kansas Geological Survey

2 "LAS files and Digital log analysis John H. Doveton Kansas Geological Survey Wireline log sources PAPER: Wireline Log Header Database--Search for paper wireline logs archived in the KGS Data Resource Library. RASTER:Scanned Wireline Log Database--Search for the Elogs we have scanned and placed online. VECTOR: LAS files available - Over 2900 wireline logs are available as LAS (Log ASCII Standard) format files. Paper and raster logs are also available from the Kansas Geological Society in Wichita 1

archived in the KGS Data Resource Library.

3 PAPER LOGS Paper logs and scans are also available from the Kansas Geological Society in Wichita Log Header of McCoy #1-31 Banes Trust B 2

4 Gamma Ray Density Neutron phi Photoelectric Factor logs of the Lower Morrow (Keyes) Sandstone Dual Induction Laterolog of the Lower Morrow (Keyes) Sandstone in McCoy #1-31 Banes Trust B 3

5 KANSAS ELECTRONIC LOGS RASTER: Scanned wireline logs (FAX images). VECTOR: LAS digital files (also LIS, g (, DLIS etc., but these are coded in binary) 4

6 1979 Digital logs : Tape storage LIS format (binary) 5

7 1994 Digital logs : Floppy disc storage LAS format What is an LAS file? Log Ascii Standard: Introduced d by the Canadian Well Logging Society as a simple digital log format that can be read by word processors or spreadsheet programs 6

Logging Society as a simple digital log format that can be read by

8 ~VERSION INFORMATION VERS. 2.0 : CWLS log ASCII Standard VERSION 2.0 WRAP. NO : One line per depth step ~WELL INFORMATION STRT.F :START DEPTH STOP.F :STOP DEPTH STEP.F :STEP NULL :NULL VALUE COMP. MCCOY PETROLEUM CORP. :COMPANY WELL. BANE TRUST ʹBʹ :WELL FLD. GENTZLER SOUTHWEST :FIELD LOC. NW NW SE 31 33S 38W :LOCATION COUN. STEVENS :COUNTY STAT. KANSAS :STATE SRVC. HALLIBURTON :SERVICE COMPANY DATE. 07 JAN 1996 :LOG DATE UWI :UNIQUE WELL ID (API) ~CURVE INFORMATION #MNEM. UNIT CURVE DESCRIPTION # DEPT.F : DEPTH CALI.IN : CALIPER GR.GAPI : GAMMA RAY SP.MV : SPONTANEOUS POTENTIAL DPHI.PERC : DENSITY POROSITY (LS EQUIV.) NPHI.PERC : NEUTRON POROSITY (LS EQUIV.) PEF. B/E : PHOTO ELECTRIC FACTOR GRS.OHMM : SHALLOW GUARD RESISTIVITY ILM.OHMM : MEDIUM INDUCTION RESISTIVITY ILD.OHMM : DEEP INDUCTION RESISTIVITY ~PARAMETER INFORMATION #MNEM.UNIT VALUE DESCRIPTION # EKB.F : KELLY BUSHING TD.F : TOTAL DEPTH BHT.F 135 : BHT. RMF.OHMM 1.8 : RMF MFST.F 57 : RMF MEASUREMENT TEMPERATURE # CURVE DATA ~A DEPTH CALI GR SP DPHI NPHI PEF GRS ILM ILD LAS file for McCoy #1-31 Bane Trust CWLS LAS FILE FORMAT: The LAS file consists of two parts: Header information Log data 7

STEVENS :COUNTY STAT. KANSAS :STATE SRVC. HALLIBURTON :SERVICE COMPANY DATE. 07 JAN 1996 :LOG DATE UWI. 15 189 22030 :UNIQUE WELL ID (API) ~CURVE INFORMATION #MNEM. UNIT CURVE DESCRIPTION # DEPT.

9 LAS Header : Records that give well and logging information. Comment records start with pound sign, # containing information which is useful to the user, but can be ignored by LAS reading software. Section records begin with a tilde, ~ andstart a new section in the header where the next letter signifies what the section is: ~V contains version and wrap mode information VERS. Either 1, 2, or 3 WRAP. YES means there are multiple lines per depth step; NO means there is one line per depth step. ~W contains information about the well ~C contains information about the log curves ~P contains information about the parameters from the well. The third kind of record contains information listed in the header sections. Each of these records is divided into three parts with a period (.) between the first and second and a colon (:) between the second and third. LAS log data section : The log data section starts with a record that begins with ~A and gives the mnemonics for the log curves in the order that they appear. (The mnemonics are tabulated in the header section ~C. The ~A record is followed by the ASCII log data. 8

Either 1, 2, or 3 WRAP. YES means there are multiple lines per depth step; NO means there is one line per depth step.

10 Petrophysical societies with useful LAS file information: 9

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12 Log scan files: 11

13 LAS files: GEMINI Quicklook view of log curves 12

14 ~VERSION INFORMATION VERS. 2.0 : CWLS log ASCII Standard VERSION 2.0 WRAP. NO : One line per depth step ~WELL INFORMATION STRT.F :START DEPTH STOP.F :STOP DEPTH STEP.F :STEP NULL :NULL VALUE COMP. MCCOY PETROLEUM CORP. :COMPANY WELL. BANE TRUST ʹBʹ :WELL FLD. GENTZLER SOUTHWEST :FIELD LOC. NW NW SE 31 33S 38W :LOCATION COUN. STEVENS :COUNTY STAT. KANSAS :STATE SRVC. HALLIBURTON :SERVICE COMPANY DATE. 07 JAN 1996 :LOG DATE UWI :UNIQUE WELL ID (API) ~CURVE INFORMATION #MNEM. UNIT CURVE DESCRIPTION # DEPT.F : DEPTH CALI.IN : CALIPER GR.GAPI : GAMMA RAY SP.MV : SPONTANEOUS POTENTIAL DPHI.PERC : DENSITY POROSITY (LS EQUIV.) NPHI.PERC : NEUTRON POROSITY (LS EQUIV.) PEF. B/E : PHOTO ELECTRIC FACTOR GRS.OHMM : SHALLOW GUARD RESISTIVITY ILM.OHMM : MEDIUM INDUCTION RESISTIVITY ILD.OHMM : DEEP INDUCTION RESISTIVITY ~PARAMETER INFORMATION #MNEM.UNIT VALUE DESCRIPTION # EKB.F : KELLY BUSHING TD.F : TOTAL DEPTH BHT.F 135 : BHT. RMF.OHMM 1.8 : RMF MFST.F 57 : RMF MEASUREMENT TEMPERATURE # CURVE DATA ~A DEPTH CALI GR SP DPHI NPHI PEF GRS ILM ILD Or downloaded onto a PC, unzipped and opened as a plain text LAS file Log curves produced by Schlumberger s DataView from downloaded LAS file 13

15 LOG ANALYSIS SPREADSHEET SOFTWARE The Log Analysis Yellow Pages or just plain EXCEL Log analysis: The Archie equation S = a Rw m w * ( ) Φ R t 1/n 14

16 ESTIMATION OF Rw IN THE LOWER MORROW SANDSTONE FROM THE SP LOG The well is located in Stevens County, Kansas where the mean annual surface temperature is 55 degrees Fahrenheit. Data from the log header: Total depth (TD) = 6397 feet Bottom-hole temperature (BHT) = 135 degrees F Resistivity of mud filtrate (Rmf) = 1.8 ohm-m of Rmf measurement = 57 degrees F Static self-potential (SSP) from log = -122 mv Temperature Results: Formation temperature = degrees F Rw at formation temperature = ohm-m Log header information used in SP calculation of Rw 15

Data from the log header: Total depth (TD) = 6397 feet Bottom-hole temperature (BHT) = 135 degrees F Resistivity of mud filtrate (Rmf) = 1.

17 or from the header of the LAS file ~VERSION INFORMATION VERS. 2.0 : CWLS log ASCII Standard -VERSION 2.0 WRAP. NO : One line per depth step ~WELL INFORMATION STRT.F :START DEPTH STOP.F :STOP DEPTH STEP.F :STEP NULL :NULL VALUE COMP. MCCOY PETROLEUM CORP. :COMPANY WELL. BANE TRUST 'B' :WELL FLD. GENTZLER SOUTHWEST :FIELD LOC. NW-NW-SE 31-33S-38W :LOCATION COUN. STEVENS :COUNTY STAT. KANSAS :STATE SRVC. HALLIBURTON :SERVICE COMPANY DATE. 07-JAN-1996 :LOG DATE UWI :UNIQUE WELL ID (API) ~CURVE INFORMATION #MNEM.UNIT CURVE DESCRIPTION # DEPT.F : DEPTH CALI.IN : CALIPER GR.GAPI : GAMMA-RAY SP.MV : SPONTANEOUS POTENTIAL DPHI.PERC : DENSITY POROSITY (LS EQUIV.) NPHI.PERC : NEUTRON POROSITY (LS EQUIV.) PEF. B/E : PHOTO-ELECTRIC FACTOR GRS.OHMM : SHALLOW GUARD RESISTIVITY ILM.OHMM : MEDIUM INDUCTION RESISTIVITY ILD.OHMM : DEEP INDUCTION RESISTIVITY ~PARAMETER INFORMATION #MNEM.UNIT VALUE DESCRIPTION # EKB.F : KELLY BUSHING TD.F : TOTAL DEPTH BHT.F 135 : BHT. RMF.OHMM 1.8 : RMF MFST.F 57 : RMF MEASUREMENT TEMPERATURE # CURVE DATA ~A DEPTH CALI GR SP DPHI NPHI PEF GRS ILM ILD EXCEL calculation of Rw from SP log 16

NW-NW-SE 31-33S-38W :LOCATION COUN. STEVENS :COUNTY STAT. KANSAS :STATE SRVC. HALLIBURTON :SERVICE COMPANY DATE. 07-JAN-1996 :LOG DATE UWI. 15-189-22030 :UNIQUE WELL ID (API) ~CURVE INFORMATION #MNEM.

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20 EXCEL log analysis 19

21 McCoy #1-31 Banes Trust B DRILL-STEM TEST: DST #1: Gas to surface in 2 minutes, recovered 20 feet condensate and 270 feet saltwater (chlorides 98,000 ppm) PRODUCTION Perforated: IP : 4249 MCFGPD, No water Determining the cementation exponent (m) in Kansas... From Dan DeBoer KWLS (1990) 20

22 EXCEL The Crash Course in Log Analysis : An Excel Workshop An overview of common log types, and log analysis techniques using Kansas examples, for estimation of porosity and water saturation, as well as prediction of fluid recovery. EXCEL freeware log analysis will be distributed to participants as well as course manual. Participants will be instructed in how to access logs, both paper and digital, over the Internet. Instructors John Doveton & Dana Adkins-Heljeson Location: Kansas Geological Survey, Lawrence, Kansas Date: Thursday October 14, 2010 Time: 9 am - 12:00 pm and 1:00-4:30 pm. Refreshments: Sandwich lunch and coffee provided Cost : $45 (covers participation, course manual, EXCEL log analysis software, lunch, parking, and refreshments) The course is offered for 6 hours of professional education (0.6 CEU). 21

Building the Wireline Database and Calculation of Reservoir Porosity

Building the Wireline Database and Calculation of Reservoir Porosity This presentation is a publication of the Bureau of Economic Geology at The University of Texas at Austin. Although it is posted here as a source of public information, those wishing to use information