History Of A Successful California Waterflood Main And 99 Zone Pools, West Coyote Field
Authors: Bergeson J.R. , Stoddard W.B. 
Published: December 2007

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This paper is to be presented at the 39th Annual Fall Meeting of the Society of Petroleum Engineers on Oct. 11–14, 1964, in Houston, Tex., and is considered the property of the Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of JOURNAL OF PETROLEUM TECHNOLOGY or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in JOURNAL OF PETROLEUM TECHNOLOGY or SOCIETY OF PETROLEUM ENGINEERS JOURNAL is granted on request, providing proper credit is given that publication and the original presentation of the paper.

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The West Coyote Field Main and 99 Zones waterflood, initiated twelve years ago, has been a highly successful project from both a recovery and economic standpoint.

The field is an east-west trending anticline located twenty miles southeast of Los Angeles. A northeasterly striking barrier fault divides the field into east and west fault block pools. Solution gas drive, aided by gravity drainage, has been the predominant primary depletion mechanism of the 3100–4700 foot deep Main and 99 Zone pools. The multilayered intervals with gross thickness of 1350 feet include up to 700 feet of net oil sand. Original productive limits encompass 1,150 acres. Reservoir and fluid parameters for these pools are described.

Pilot waterflooding of the East Block Main and Upper 99 Zones was initiated in 1952 with expansion to full scale peripheral flooding in 1956. The West Block project which includes the Main, Upper 99, and Lower 99 Zones was started as a full scale peripheral flood in 1961, without pilot flood operations. The two projects currently include 179 producers and 39 injectors. The majority of producers and injectors are unsegregated, multi-interval, slotted liner completions. Unfiltered and untreated oil-field brine is being injected at 70,000 B/D with a current oil production rate of 5,650 B/D. The waterflood performance to date is compared to estimated primary performance and to preflood performance predictions.

Serious injection profile problems exist due to the extreme vertical permeability variations in the extensive interbedded sand and shale section. Corrective measures and results involving both stimulation and thief interval plugging agents for profile control are evaluated. Injection facilities and operating problems are also discussed.

Introduction

The West Coyote Field is located approximately twenty miles southeast of Los Angeles, California, (see Figure 1). The first commercial producer was completed in the Main Zone in 1909 following discovery of oil during water well drilling operations in 1906. This discovery of oil on a surface structure containing no oil or gas seepages resulted in exploratory drilling on other topographic highs.