History of Development of the Tijerina-Canales-Blucher (Zone 21-B) Field High Pressure Extension Area

Abstract

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract This paper presents (1) the results of a combined engineering/geological study that led to the discovery of several million barrels of additional oil in the nearly 30 year old Tijerina-Canales-Blucher (21-B) Field oil column; (2) the results of a two-dimensional, three-phase computer simulation study of the reservoir; and (3) a comparison of actual versus predicted performance. The new oil area was discovered in late 1972 by drilling Exxon's King Ranch-Tijerina Well A-29 to investigate a possible stratigraphic trap suggested by an observed anomalous high pressure area. Twenty additional wells were drilled before extent of the new oil area was known. A computer model simulator study was made to predict future performance, to determine an predict future performance, to determine an optimum water injection program, and to determine if producing rates were compatible with maximum oil recovery.. The oil reserves are now essentially depleted and a favorable comparison can be made between actual and predicted performance. Additional oil reserves predicted performance. Additional oil reserves developed in the high pressure extension area are estimated to be 3.9 million barrels. Fifty-two percent of the oil in place will be recovered, and a volumetric sweep efficiency of 85 percent is indicated. Introduction The Tijerina-Canales-Blucher (21-B) Field is located about 12 miles southwest of Kingsville in South Texas. As shown in Figure 1, this field is situated at the southern end of the Zone 21-B Trend Field, which consists of a large gas cap with several rim type oil columns. Prior to 1975, the Zone 21-B Trend Field had been prorated by the Texas RRC as three separate fields-Borregos, Seeligson, and T-C-B Fields. The T-C-B oil column, which was discovered in 1944, is located along the southern and eastern rim of the structure and was developed by drilling in the 1940's, 1950's, and 1960's. Exxon developed its portion of the oil column with about 110 wells on 40-acre spacing. The 21-B sand in the T-C-B field is located at an average depth of 7,000 feet subsea and is composed of four sand stringers which are in communication with one another in certain areas of the T-C-B field. Sand quality is good as porosity averages 25 percent and permeability averages 186 mds. percent and permeability averages 186 mds. Primary drive mechanism is gas cap expansion Primary drive mechanism is gas cap expansion which has been supplemented by gas and water injection.