Oil Field History and Current Activities, Midway-Sunset Oil Field, California

Michael F. Ponek, Hana Ciembronowicz, and Steven Mathias
Chevron North American Exploration Company, 9525 Camino Media, Bakersfield, CA 93311

Midway-Sunset Oil Field is the largest thermal operation in the Continental United States and has been an economic success. Review of this field initiates with discussion of the first known producing oil well in the field which was a 100 foot Tulare Formation producer drilled in 1887. More than 100 gushers roared in between the years of 1909 and 1912 greatly increasing daily production. A decline in field production after two world wars, the subsequent decrease in demand and need for new heavy oil production methods dominated the 1920’s to the 1960’s. Ultimately, thermal recovery methods have been applied to continue the life of the field for both sand and diatomaceous intervals.

The producing sandstones, conglomerates and fractured diatomaceous shales range in age from late Miocene, Monterey Formation to the Pleistocene Tulare Formation. The excellent porosity and permeability of the shallow oil sands have made thermal EOR an economically successful operation starting in the mid 1960’s with diatomite being the more recent thermal recovery target. Understanding field wide oil depletion and remaining heat requirements has been a challenge in development of the shallow intervals. Recent 3D geologic models help to better define the major controlling geologic features for both oil depletion in the flow units as well as steam migration paths.

Items to be covered will include recent 3D model usage for reservoir characterization and identifying current oil in place. This includes a brief discussion on incremental oil identification and targeting using both vertical and horizontal wells.

AAPG Search and Discovery Article #90076©2008 AAPG Pacific Section, Bakersfield, California