Engineering Study of the Cook Ranch Field, Shackelford County, Texas

Abstract

The Cook Ranch Field produces from a very permeable lens of Cook Sand of lower Permian or upper Pennsylvanian age, occurring at an average depth of 1,300'Ft. The field was discovered in 1926, and has been operated with low pressure gas injection since July, 1927, one of the first such projects in Texas. Cumulative recovery to Dec. 31, 1950, was 14,701,131 bbl of crude oil, an average of 1,013 bbl per acre-ft of oil section, and 72.5 per cent of the oil originally in place. Analysis of the reservoir performance indicates that gravity drainage has been an important factor in the producing mechanism. The high permeability and uniformity of the reservoir were extremely favorable for this type of operation. Introduction The Cook Ranch Field is the largest of a number of relatively small, shallow producing areas near Albany, in Shackelford County, Texas. This field is one of the first to be operated by gas injection in Texas, and probably is the most successful low pressure gas injection project ever attempted. The field is owned entirely by Roeser and Pendleton, Inc., and Continental Oil Co., aud has been operated by Roeser and Pendleton, Inc., since it was discovered. This study has been made possible through the cooperation of Roeser and Pendleton, Inc., in making available a remarkably complete set of records covering all phases of their operations. The purpose of this paper is to present a summary of the history of the operations through Dec. 31, 1950, and to analyze some of the factors which appear to be responsible for the success of the project. Information concerning the physical plant and the early gas injection history has been presented in an earlier paper.

Material Balance Calculations for Solution-Gas-Drive Reservoirs With Gravity Segregation

“…Oil recoveries of the order of 60 to 80% can be obtained with effective gravity segregation. [24][25][26][27] Reservoirs with significant gravity segregation also shoW' low producing gas-oil ratios in structurally lower wells. Craft and Hawkins24 describe these drive mechanisms in more detail.…”