Early Results Show Wide Range of Recoveries in Two Texas Panhandle Water Floods
Authors: Gray Robert , Kenworthy J.D. 
Published: December 2007

Abstract
Favorable performance results from each of two pilot water floods conducted in different areas of the Brown Dolomite reservoir in the Texas Panhandle field prompted initiation of full-scale waterflood projects. Although both of the full-scale floods are being conducted in supposedly similar areas of the Brown Dolomite reservoir, flood responses and oil recoveries of the two have been entirely different to date. Kewanee Oil Co.'s Morse water flood located in eastern Gray County, Tex., is an economically successful venture, as evidenced by the fact that two adjacent flood areas have been developed since its completion in 1959, and another one now is under way. On the other hand, flood responses and oil recoveries in Kewanee's Stansberry Brown Dolomite water flood have been discouraging to date, primarily due to premature water breakthrough. Certain reservoir characteristics may exist in the field (such as inherent formation fractures, thin highly permeable sections in some areas and high connate-water saturations) to account for the poor performance, but this has not yet been validated. This paper briefly describes the discovery and over-all development of the Texas Panhandle field, and outlines the development histories of both the Morse and Stansberry Brown Dolomite waterflood areas. Reservoir data, water sources and injection systems, optimum well spacings and injection patterns, operational problems and performance data for the two waterflood areas are compared.

Introduction and History of Development
The Texas Panhandle field, discovered in 1918, produces from Permian dolomites and the "Granite Wash" of Pennsylvanian age. The development of the more prolific Granite Wash and the better dolomite zones occurred during the 1920's and the early 1930's. The advent of the acidizing technique in the late 1930's led to the development of the "tighter" dolomite areas. Subsequent development was minor until 1952 when hydraulic fracturing caused extensive development of areas previously considered submarginal. The field covers over 200,000 productive acres containing 12,500 active wells with a cumulative production of 1 billion bbl of oil. The principal producing mechanism has been solution-gas drive. The original reservoir pressure was 440 psi with an estimated solution GOR of 210 cu ft/bbl. The limited amount of available energy in the reservoir has been supplemented by several gas-injection cooperatives formed in the 1940's. Approximately one-fourth of the field has been subjected to gas injection, with the result that an estimated 50 million bbl of additional oil have been recovered. The Morse waterflood area of eastern Gray County, Tex., was developed originally between 1928 and 1937. Results of a gas-injection project initiated in 1946 were only partially successful. In 1955 water flooding appeared to offer the most economical possibility of increasing the "Brown Dolomite" reservoir's ultimate recovery. Prior to this time, three pilot water floods had been attempted in other areas of the Panhandle field but all were abandoned as unsuccessful. The Morse Brown Dolomite pilot flood in Gray County and another Brown Dolomite pilot flood in Hutchinson County, Tex., were the first two successful pilot floods in the Panhandle field. The regional locations of secondary recovery projects in the Panhandle field are shown on Fig. 1. Morse Water FloodThe Morse Brown Dolomite pilot flood was started in July, 1955 (in the cross-hatched area shown on Fig. 2). Injection Well No. 10 was drilled in a five-spot location for input service, and Well No. 7 was an old oil well which has been utilized as a "gas-injection" well before being converted to water-input duty. Actual performance of the pilot area in the early stages was a text-book example of calculated performance. Two gas-injection wells were converted to water-input duty in May, 1957, to back up the pilot and further evaluate the practice of converting old wells to water-input service. Expansion in 1958 was limited to the addition of 10 injection wells due to lack of cooperation by offset operators.
JPT
P. 1323^