GIS information access at the California Well Sample Repository

The California Well Sample Repository is the only public "library" of core material (cylinders of rock recovered from oil wells) in California. The Repository’s web site contains basic information about its inventory in spreadsheet form. Spatial information from the California Division of Oil and Gas was linked to the Repository’s database to create a map of cored wells on file at the repository. The resulting product allows geologists to query the repository database geospatially using a GIS (ArcView). This project provides valuable information to geologists studying areas with potential untapped oil reserves to help increase our domestic petroleum supply.

The history of our planet is "written" in rock layers that can be translated by geologists. Much as an archaeologist uses clues in ancient manuscripts or petroglyphs to locate buried treasure and lost cities, geologists use the clues contained in the rocks themselves to search for treasures hidden by nature: oil and gas, gold, silver and other minerals. While some rocks are easily accessible in surface exposures, others lie buried underground beneath hundreds to tens of thousands of feet of overlying rocks. These deeper rocks can only be accessed by the drill bit—usually as an amalgamation of chips called cuttings. However, the story told by the rocks is most easily interpreted when they are recovered as whole cylinders of rock acquired during more expensive coring operations. Oil and mining companies often take cores of deep rock layers in order to determine the potential value of petroleum or mineral reserves in an area or formation (layer) that are of current interest to them. If, at some time in the future, these formations cease to be of interest, these cores are commonly discarded by the companies to reduce storage expenses and geologists are forever deprived of the information they contain. In fact, a massive core disposal operation may be to a geologist what the sacking and burning of the great, ancient libraries of Alexandria, Egypt are to a historian.

The California Well Sample Repository was established on the campus of California State University – Bakersfield in 1975 to preserve a large collection of core destined for disposal by Superior Oil Company. It is the only facility of its kind in California that is open for use by the public - usually by professional geologists and college students. Over the years, as the oil industry has consolidated, the Repository has accumulated additional collections of cores and other geologic material. The collection now includes cores, well cuttings, mounted microfossil slides, micropaleontological reports, well files, scout books, geologic reports, maps and field guides.

Since the Repository’s inception, cores have been inventoried using index cards organized alphabetically by original operator. Users had to search through a set of dusty file boxes to find out which wells were available in their area of interest. If the original operator wasn’t known, or if the well had changed ownership, the search was difficult, time consuming and often futile. The core catalog system was improved in the late 1990’s by the development of downloadable Excel spreadsheets, which are made available on the Repository’s web site (www.wellsample.org). However, the core catalog remained very cumbersome, and the true extent of the Repository’s core holdings was unappreciated by the oil industry and the public.

We are developing a GIS-based inventory and search system for the Repository. Additional spatial data, such as the Public Land Survey System, oil and gas field outlines, roads and cities have been obtained from the California Division of Oil, Gas and Geothermal Resources, Esri and other sources. Using ArcView 3.2, numerous errors and omissions are being corrected in the Repository’s core catalog. Repository users will now be able to select a location of interest and perform spatial queries to search for core data within a desired radius of the location. This search can be refined by simple queries to select only those cores that contain material from formations or depths of interest. Available cores can also queried by the name of the oil field, by depth, by date drilled or by proximity to cities or roads. The client could also query to see how much core data is available for a particular formation throughout the state and observe how that information is distributed geographically. This GIS project is currently in the development stage, with potential clients being interviewed to assure that the Repository’s limited manpower and financial resources are used wisely. Our goal is to make this new GIS database available online to Repository clients using ArcIMS by the end of 2002. We would also like to customize the GUI to make simple searches possible for those unfamiliar with ArcView.

fcharron@csub.edu

Janice M. Gillespie, Professor

jan@cs.csubak.edu