Abstract: Direct Detection of Hydrocarbons by Acoustic Logging in the Wilmington Field, CA

Daniel Moos, Chris Phillips, Andrew Hooks, Kwasi Tagbor, Don Clarke

The Department of Energy Near-Term Class III Oil Program in Slope and Basin Clastic Reservoirs has recently agreed to co-fund a multi-year project to evaluate new technologies to enhance production in the Wilmington field, CA. The Wilmington Field has been waterflooded for over 40 years. However, due to a variety of factors, including reservoir heterogeneity and poor injection profiles, significant quantities of unswept oil still remain.

We plan to use new, high-power, low-frequency multi-pole acoustic logging techniques in existing (cased) holes to detect sands with high oil saturations. We will improve reservoir characterization by integrating the wealth of existing data on the geology, structure, and production history of the field. Improved production will be achieved through selectively recompleting sands with high oil saturations detected acoustically, utilizing gravel packed inner liners and ultra-short and short radius lateral completion techniques. Significantly lower economic and environmental costs will result from exploiting existing wells, compared to drilling new wells.

Some of the proposed technologies were tested in Well M-499, a new well which was selectively completed into the Upper Terminal Zone (late Miocene age) of Fault Block IV. Completion was based on conventional open hole log analyses of sands with over 40% oil saturation. Porosity and saturation calculated from cased-hole monopole and dipole acoustic logs compared favorably with conventional determinations from open-hole logs. Production tests over a seven-month period demonstrated a significant reduction in water-oil ratio to 19 in Well M-499, compared to 27 in offset wells which were completed with slotted liners throughout the zone.

AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California