Pressure Maintenance by Gas Injection in the Opelika Field of Henderson County, Texas, by T. W. Clay, Pages 40 - 56
from:
East Texas Geological Society Symposium: The Character of Deep Lime Crude Oils of East Texas
Copyright 1954 by The East Texas Geologic Society. All rights reserved.

Pressure Maintenance by Gas Injection in the Opelika Field of Henderson County, Texas

T.W. Clay

ABSTRACT

The Opelika field, although similar in most respects to other relatively deep Glenrose lime-stone reservoirs in the East Texas area, is unique in that a gas injection program has been in operation since shortly after the field’s discovery. The field is composed of four principal reservoirs, of which only one - the Main Rodessa - is oil productive; here the oil occurs as a deposit on the flanks of a relatively large gas cap. Cycling and pressure maintenance operations were conducted in the gas cap prior to the discovery of oil and, consequently, reservoir pressure was maintained at a high level even though oil was not discovered until several years after gas operations commenced. At the time oil was discovered the field pressure was approximately 3300 psig. Subsequent to the discovery of oil cycling and pressure maintenance operations continued and the current volumetrically weighted average pressure is approximately 3,000 psig.