Gemcom Minex and the Corporate Database

Transcription

1 *Gemcom Software was acquired by Dassault Systèmes, the 3DEXPERIENCE Company, in July It is now known as GEOVIA. Gemcom Minex and the Corporate Database Jon Barber - Vice President, Minex, - Gemcom Software International Inc. WHITE PAPER

2 Abstract A mining company s main asset is its ore reserve and the basis of the ore reserve estimation is usually drill hole data. General Mine Planning systems (GMP) have been developed to store drillhole data in a structure that facilitates fast correlation and modelling. GMP databases don t necessarily store all the data required or collected in a drilling program and this data is more appropriately stored in a corporate database. These corporate databases, usually on a SQL Server or Oracle architecture, offer multi-user access, versioning etc which would be a severe governor on a GMP. The GMP should offer direct links to the corporate database via ODBC or appropriate Application Program Interface (APIs) that reduce data rehandling. This paper discusses the Minex borehole database and the GEMS Logger database. The GEMS Logger is a typical corporate database and is closely integrated with Minex. Minex Borehole Database Minex is a mature GMP containing geology, mining, optimisation, blending and survey functions. Minex works at a project level, such as mine A or property B. Minex closely integrates the project borehole database and the resultant project geological model. These geological models are used for reserves, contouring sectioning and mine planning and while obviously important are not the point of this paper; this paper focuses on the borehole database. General mine planning packages (GMPs), such as Minex often use a propriety borehole database rather than a commercial database for drillhole data. Briefly the Minex database consists of five interrelated files. These files are given extensions B31 to B35. Thus a database called FIRESTONE.B31 will have four associated files FIRESTONE.B32.B33.B34 and.b35. Using five files provides significant speed and storage efficiencies as: 1. Drillhole names, drillhole types and variable names and titles are stored in the B31. The B31 consolidates all header information and allows rapid indexing to the more data intensive files. 2. Data such as geophysics, quality and lithology is stored in the.b32 file. If downhole survey data exists, it is held in the.b32 file. Typically many coal projects assume holes are vertical, however in deep coal deposits borehole verticality may affect the real location of a seam. 3. Seam intervals are stored in the.b33. Seams (or intervals) can cover multiple samples and for modelling, displaying or reporting, sample data is composited over seam intervals on the fly. Typically composites are thickness and density averaged. If coal washing occurs product analysis will be further weighted by wash plant yield. 4. The drillhole collar data consisting of X, Y, elevation and total depth is stored in the.b34 file. 5. The seam stratigraphy sequence is stored in the.b35. This file is ASCII and can be edited in a line editor or within Minex. In Figure 1 the stratigraphy listed from top to bottom is B3 B2 B1 B0. Some of these concepts are shown in Figure 1. All files, except the B35, are binary. Data is keyed on borehole name and FROM, TO depths (e.g. a sample goes from 102.6m to 103.8m). The sample location in XYZ coordinates is not stored in the database but is calculated on the fly from the other data. Thus if a user updates a hole collar location all other data is automatically repositioned. Database size and speed is improved by not storing sample XYZ. For voluminous data such as geophysics storing coordinates would be onerous. Copyright 2011 Gemcom Software International Inc. Page 2 of 6

3 COLLAR IN B34 LITHOLOGY DATA IN B32 SEAMS IN B33 GEOPHYSICS DATA IN B32 Figure 1: Borehole data is stored in linked files. The concept of data types is important in Minex. Geology data can have various from to depths. For example geophysics can be sampled at 1cm, or 2cm intervals, while lithology is typically sampled at visible intervals. In some cases these intervals may be thin (measured in cms) or thick measured in metres. Similarly coal quality from to can differ to other data, although it will typically cover a lithological interval. This concept of differing from to depths is described in Minex as a data type. Many planning packages require the seam from to to match the sample or lithological from to depths. Minex separates the seams and samples and allows seams to bridge multiple samples. Minex also allows multiple seam interpretations; Figure 2 shows two such interpretations. For selective mining seams A1 and A2 give 10 and 12% ash respectively; with bulk mining seam X increases the ash to say 15%. Minex considers that seams A1 and A2 or X are interpretations of the data. The data (here ash and lithology) is sacred and should not be composited or smudged within the database. The data should be stored and retained at its finest interval. Figure 2: Seam compositing of ash data. Copyright 2011 Gemcom Software International Inc. Page 3 of 6

4 Missing Seam Concepts Before modelling seam floor and thickness data, Minex extends shallow holes and ensures that all seams are present in all holes. This process of missing seam interpolation uses surrounding known information to estimate where seams would be if: 1. The hole was drilled deeper. 2. The seam was not weathered out. This additional seam data is flagged in Minex with a code Interpolated to differentiate it from a geologist s interpretation of the seams (such as A1 A2 or X in Figure 2). These concepts are illustrated in Figure 3. In this example Model A honours the input data but doesn t reflect the syncline structure. After interpolating missing data Model B reflects this syncline. This interpolation process extracts the maximum value from the data. Figure 3: Interpolation of missing data. Copyright 2011 Gemcom Software International Inc. Page 4 of 6

5 Corporate Databases The Minex borehole database is a mature GMP database; it is fast, composites on the fly and can be quickly accessed for section, 3D or plan display. It also handles the problems of missing seams, seam splitting and father son. Minex is not however an ideal corporate storage database. A corporate database has a number of features that are not consistent with a GMP system. Typical distinguishing features of a corporate database and a GMP are: 1. The corporate database can and does store many projects and is thus a true company wide database. The GMP database is usually a project sized subset of the corporate database. While a GMP could store multiple projects, this would not be best practice in data management or speed. The GMP is focused on a single project. 2. The corporate database has an open structure which allows access from other applications such as GIS or even public web access. 3. As the GMP is very fast, multiple user access is either not allowed or is limited. In Minex the first user can read and write to the database but subsequent users can only read. This is necessary with a GMP as correlation or missing seam interpolation changes happen quickly and would cause conflict if done by several users. 4. The GMP typically only stores what it needs. The GMP doesn t care when, who or what logged the data. Extra information, such as what laboratory made the quality measurements, what laboratory preparation techniques were used, who logged the lithology information and what coordinate systems are used etc. should be stored, but not in the GMP. This extra information should be in the corporate database. 5. Some GMP systems mix interpretations and raw data such that reverting to the original observations and measurements can be problematic. This is not the case with Minex, where seams are stored separately to the sample data. This data mixing can however cause problems with JORC or other reporting standards. While the GMP is focused on a single geology user and delivers speed of processing etc., a corporate database has a multi-user focus. The corporate data allows efficient multi-user access; manages security and privileges on the data; handles data back-ups; manages versions and roll-backs and keep the data secure and safe. As a database it also allows flexible data selection and query, tracks changes in the data, and manages the who, what when of the data. In summary it is critical to separate the capture, management and delivery of the original observations from the modeling process. The corporate database stores the original observations with the associated metadata (contracts, standards etc) and feeds the data to client systems. The GMP (as one such client) uses the data in a specialised way appropriate to its needs. Minex has focused on the modelling rather than the database. Its strength lies in manipulating rather than in storing data. Adding database functions such as multi-user, metadata, versioning etc functions to GMPs would make them unnecessarily slow. Minex interfaces to a variety of databases using ODBC. ODBC Over the last thirty years large in-house corporate databases have been progressively replaced by commercial systems usually based on Oracle, SQL Server or Access. These databases store all data, including metadata, handle versioning and change tracking etc. A common feature of these databases is Open DataBase Connectivity or ODBC. ODBC allows users to connect to databases such as Oracle or Access and extract data into a GMP system. This connection avoids double handling of the data and thus avoids errors. The Minex5 ODBC interface maps the database to Minex using a drag and drop process. ODBC is the basis for connection to the GEMS Logger. Copyright 2011 Gemcom Software International Inc. Page 5 of 6

6 GEMS Logger Gems Logger is a borehole database system based on Microsoft Access (for small clients or smaller data sets) or SQL Server for larger accounts. The GEMS logger allows holes to be logged in Access then uploaded to SQL server. Holes can also be borrowed from the SQL Server and edited by the user in Access. Borrowed holes can t be accessed by other users so duplicate data is avoided. The GEMS Logger has been customised to the Minex lithology dictionary so users can enter codes such as SS (sandstone) or MS (mudstone). These codes are also available in pull down lists. Writing Back to the Database As previously discussed, when modelling coal, Minex creates extra seam intervals for missing data. This helps maximise the value of the drilling. Holes are extended up and down to locate deeper or weathered seams (refer Figure 3). This extra data is flagged in Minex as interpolated to distinguish it from real or logged data. Generally this interpolated data should not be stored in the corporate database. However it could be stored in the corporate database as a unique table, to avoid confusion between logged and estimated data. The recommended process would be as follows: 1. Extract the data required for modelling into Minex. 2. Interpolate the missing seams. 3. Validate the model and associated borehole database. 4. Publish the model. By publish we mean release within the mining company as the annual accepted model (say model 2006 or model 2007). 5. Store the seam picks associated with this model in a database table for model 2006 or model Link this table to the original data with appropriate date stamping. This document gives only a general description of products and services and except where expressly provided otherwise shall not form part of any contract. Changes may be made in products or services at any time without notice. Copyright 2011, Gemcom Software International Inc. Gemcom, the Gemcom logo, combinations thereof, and Gemcom Minex are trademarks of Gemcom Software International Inc. All other names are trademarks, registered trademarks, or service marks of their respective owners. The solutions you expect. From the people you trust. Copyright 2011 Gemcom Software International Inc. Page 6 of 6