MAJOR STEPS IN WELL LOG STUDIES

SummaryThe following is a brief sketch of the major tasks involved in computer assisted geologic and reservoir studies using digital well log data as the main data source. This summary is an outline of how Hitchner Exploration Services Limited (HESL) views the steps of a multi-well analysis project and how HESL in its consulting role would address the project analysis.The comments provided are based on HESL using LOGMAP, a proprietary well log analysis and mapping software package. Other software packages can provide help with some of the same tasks mentioned below but may not be as well integrated for multi-well project work as LOGMAP.Project DefinitionIn consultation with the client a project area is defined and the scope of the analysis expected is agreed upon based on known available data. Preparing a list of the wells to be analyzed is the next step. Then representative base maps are ordered or downloaded for the project area. Data CollectionAll available LAS, raster, core analysis and relevant geological and reservoir data for the wells in the project area are collected. Any required data that is missing or deficient is purchased or retrieved from commercial data sources if available. Well location data is checked against a master list to confirm accurate well locations.Print Well LogsIt is always handy to have paper copies or raster images for reference. Now, with most of the well log data available in raster format, it can be an easy task to refer to the raster images for any questions related to the digital well log data without specifically having a specific hard copy for reference.HeadersBuild well header forms, collect and enter the required data. Header forms have all well information, location, latitude and longitude as well as what curves are digitized, the types and properties of the drilling mud used when the well logs were generated. General information as to the well logging company and vintage of the data is built into the header as well. Available DST (drill stem test) and production information specific to each well location is added into the analysis database at this time as well.DigitizationFor wells without existing digital data, the data will have to be digitized. If the data has to be digitized, a decision has to be made as to whether the digitization will be done by hand or by getting a commercial digitizing company to generate the digital data. Hand digitizing is viable for single zone projects with less than 30 wells to analyze. For multi-well, multi-zone projects, HESL recommends getting a commercial digitizing company involved. For hand digitizing, the well log and core analysis data will be retrieved from microfiche, paper copies of the data or prints of the raster or TIF images of the data where available. For projects greater than 30 wells, use commercial digitizing services as they can provide reasonable turnarounds on the digitization. They also generally digitize the available well log data from surface to total depth. So that, even if only a couple of zones are of immediate interest, the digits will have been captured over the total well interval, ready future use (highly recommended). With hand digitizing, what generally happens is that only enough of the stratigraphic interval required for normalization procedures and analysis is digitized. So, if other intervals of interest surface later, then more time must be spent digitizing those intervals.The added benefit of using the commercial digitizing companies is that the client does not have to copy any logs from microfiche or raster images and that the commercial digitizing companies do all the set up related to digitizing. Plus, the client gets CDs or DVDs with files stored in LAS format, which are easy to handle within LOGMAP, or for that matter any well log analysis software. The digitizing aspect of the project can be a formidable and costly task. Fortunately the digitization program within LOGMAP is very easy to use and can provide quality digits in a reasonable time frame especially for small numbers of wells (