Performance of a Multizone Peripheral Waterflood, Main and 99 East Pool, West Coyote Field, California
Authors: Messer P.H. , Dobeck H.R. 
Published: December 2007

This paper was prepared for the 43rd Annual California Regional Meeting of the Society of Petroleum Engineers of AIME to be held in Bakersfield, Calif., Nov. 8–10, 1972. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made.
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Abstract
A peripheral waterflood program was initiated in the Main and 99 East Pools, West Coyote Field, in 1952. The current production rate is 1350 B/D with 32,000 B/D of water injection" The performance of this mature, multi-layer, peripheral project was evaluated by allocating the total water injection to each sand interval for the purpose of determining the water swept regions and the flood fronts in each sand. This evaluation was necessary to design an injection realignment program and to predict reserves. This paper presents the procedures incorporated in this particular evaluation and demonstrates a method for handling large volumes of production-injection history in other similar projects. projects

Introduction
In predicting the performance of an established secondary recovery operation in a mature field, the type of analysis, the time involved, and the accuracy of the results are completely dependent upon the quantity and quality of the basic reservoir data. Many mature fields were initially concerned only with establishing production and the limited fundamental data production and the limited fundamental data available can sometimes be incomplete and at best questionable; although the production and injection accounts are often well documented. In such an instance, a simple, straightforward procedure based mainly on production and procedure based mainly on production and injection history can be useful in predicting production and injection modification to production and injection modification to maximize the reserves in the field.

RESERVOIR HISTORY
The Main and 99 East Pools are located in an East-West trending anticlinal fold bordered on the west side by a non-communicating thrust fault. The 99 pool is further bordered on the north flank by another thrust fault. The producing intervals are composed of the Lower producing intervals are composed of the Lower Pliocene Repetto formation and are interbedded Pliocene Repetto formation and are interbedded with shales which provide excellent interval segregation. From discovery in the early 1900's until a pilot water injection program initiated in late 1952, the primary depletion wall due to solution gas drive, gravity drainage and limited water encroachment.
When primary production had declined to 1450 B/D a peripheral waterflood program was initiated. The oil production rate was stimulated to a maximum of 3400 B/D through the years 1960 to 1963 as a result of flood operations. Oil production has declined steadily thereafter to the current rate of 1350 B/D.