Improved Oil Recovery Through Integration of Geologic and Engineering Data in Comprehensive Programs of Reservoir Management

Beverly Seyler, Emmanuel O. Udegbunam

Aux Vases (middle Mississippian) oil fields in the Illinois Basin highlight the need for an integrated approach to reservoir management. Integration of geologic and engineering data into a comprehensive program for reservoir management has led to excellent recovery efficiencies in overlapping sandstone bars at Zeigler field. The Zeigler waterflood program monitored reservoir pressure flue. through time, enabling identification of compartmentalization. In contrast, primary recovery efficiencies were lower in several Aux Vases sandstone bar reservoirs in portions of Dale Consolidated field due to the lack of concerted reservoir surveillance and pressure maintenance programs.

A reservoir quality index (RQI) is used to compare spatial variations of reservoir quality in these and other fields and as a tool for comparison of reservoir compartmentalization. Integration of petrographic and petrophysical analyses indicate that reservoir quality and the development of flow units in these fields is controlled by deposition, diagenesis and natural and man-induced fracturing.

Implementation of the reservoir quality index method was possible at Zeigler because core analysis data were gathered at one foot intervals through every well in the field. Modem suites of well logs and several core analyses from representative wells provided the data for reservoir quality index at Dale Consolidated and Energy field. These data permitted accurate reservoir simulations of Zeigler, Dale and Energy fields.

Results from this comparative study demonstrate the effects of geologic and man-made heterogeneities on compartmentalization. This information on compartmentalization will aid in the design of recovery programs in similar fields.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995