Reservoir Management in the Means San Andres Unit

The Means field, located in Andrews County, Texas provides an excellent opportunity to observe the evolution of reservoir management to meet changing economic and technical challenges. The Means field was discovered in 1934 and developed on 40-acre [16-ha] spacing. Reservoir management techniques began within one year of discovery and have continued with increasing complexity as operations have changed from primary to secondary to tertiary. In 1963, a major portion of the field was unitized as the Means (San Andres) Unit (MSAU), which will be the subject of this discussion. Several papers have been published describing specific programs for the field. 1,2,3,4,5 This paper describes the evolution of reservoir management at Means on an orderly basis. Reservoir management at Means has consisted of an ongoing but changing surveillance program supplemented with periodic major reservoir studies to evaluate and make changes to the depletion plan. This paper concentrates on reservoir description, infill drilling with pattern modification, and reservoir surveillance. The role of reservoir description is followed from relatively simple techniques in the 1930's to the recent use of high resolution seismic to improve pay correlation between wells. The importance of reservoir continuity in determining well spacing and injection patterns is discussed for both secondary and tertiary operations. Although surveillance has been an integral part of reservoir management in the Means field since discovery, a much more detailed plan was developed for surveillance of the CO2 tertiary project.