How to Make a Billion-Barrel Oil Field in Offshore California Commercial

J. C. Patterson, J. H. Ballard

The major obstacles and challenges involved in exploration and development of a giant deep-water low-gravity oil field are exemplified in the undeveloped Sword field of offshore southern California.

In 1979, Conoco Exploration identified a northeast-southwest-trending basement high in the 800 to 2,000-ft deep federal waters 12 mi southwest of Pt. Conception at the western end of the Santa Barbara Channel. The intended reservoir was fractured Miocene Monterey chert, silicic shales/siltstones, and dolomites that are draped over the axially faulted structure. Drilling of the initial well in OCS P-0322 in 1982 resulted in discovering the giant Sword field. A confirmation well drilled in OCS P-0320 indicates in-place reserves of well over 1 billion bbl. While the discovered potential is significant, the low gravity (8.5°-10.5°API) of the oils discovered to date, along with water depths in excess of 1,500 ft, currently pose economic challenges to successful field development.

Conoco and its partners are addressing the current economic barriers on a number of fronts. Three-dimensional seismic surveys are being conducted to better delineate reservoir geometry and to define probable variations in lithology, fracturing, and oil gravity. A market feasibility study will be undertaken to assess the demand for low-gravity crude from offshore California.

Finally, Conoco has developed proprietary technology called OCHOS (Offshore California Heavy Oil System), which uses an innovative oil/water emulsion technique to allow for more economic recovery of high-viscosity/low-gravity crudes.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.