Discussion

The general goal of the project is the application of existing cost-effective recovery technologies to extend the economic life of selected fields producing from shallow shelf carbonate reservoirs, and the innovative dissemination of the data, methodologies, and results for the purpose of fostering wider application of demonstrated technologies to other fields. The specific goal is to identify areas of unrecovered mobile oil in Osagian and Meramecian (Mississippian) dolostone reservoirs in western Kansas through integrated, multi-disciplinary reservoir characterization, and the demonstration of incremental primary recovery at the Schaben Field Demonstration Site.

At the Schaben site, integrated, descriptive reservoir characterization provided the basis for development of a reservoir model. Descriptive reservoir characterization entailed integration and creative application of existing data, drilling and coring three new wells through the reservoir interval. Descriptive core analysis, petrophysical and petrographic analysis, calibration of logs and core data, and integration of existing well data into a computerized three dimensional visualization/simulation were used to develop a descriptive reservoir model for the Osagian and Meramecian rocks at the Schaben site.

Acquisition and consolidation of geologic, digital log, and production data are complete and all data have been entered into a database management and analysis system. Digital data used in constructing geologic maps and cross-sections and reservoir analysis is available through the Internet (http://www.kgs.ku.edu/Class2/index.html and http://www.kgs.ku.edu/DPA/Schaben/schabenMain.html). Log analyses, core analyses and descriptions were completed to better understand the pore geometry of the carbonate reservoir in the Schaben Field. All of the complexities existing in an evaluation of an extremely heterogeneous reservoir, are present in the producing reservoir in the Schaben Field. Satisfactory determinations of pore size, throat size, irreducible water saturation, permeability, effective porosity, and movable oil are possible with the techniques being used in the Schaben Field project.

Field Activities

From late 1996 through 1998, a total of twenty-two infill locations were drilled or recompleted at the Schaben Demonstration Site (Table 1). The locations were selected based on the results of the reservoir management strategy developed in Budget Period 1. All three major field operators (Ritchie Exploration, Pickrell Drilling and American Warrior) used the Schaben reservoir simulation to evaluate multiple locations and select optimum locations. The history of each well is being evaluated and incorporated into a final revised full-field simulation. The current reservoir simulation has provided excellent full-field and good individual history matches for all existing wells. The simulation also provides an estimate of additional incremental oil as a result of targeted infill drilling (Figure 2.1).