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The ·success of a co 2 flood largely depends on the quality of ~ts injection wells.The wells must confine injection to the desired pay intervals and withstand the corrosive nature of co 2 for the life of the flood.These are difficult goals to achieve considering the primary candidates for co 2 flooding are mature waterfloods where the wells may have been in service for forty years or more.Casing and cementing practices of the past were often inadequate for a long waterflood life, and are certainly unacceptable for a long term tertiary recovery project. This paper describes innovative techniques employed in the MCA Unit, located in southeast New Mexico, for converting old waterflood injection wells into state-of-the-art co 2 injection wells.The solutions de.veloped for tlie MCA CO? Project have considerable application to ofher co 2 projects and can be profitably employed to improve waterflood recovery as well.

This paper presents the success story of an integrated approach to optimize the production performance of the Goldsmith Andector Unit (Gandu) in West Texas. All production is from the Clearfork formation, a typical carbonate reservoir characterized by large and discontinuous pay intervals with low reservoir energy and high residual oil saturation. Redevelopment of this mature field began as a 20-acre infill drilling program in 2001 and has been under waterflood expansion since 2008. A multi-disciplinary team was commissioned to improve production in Gandu. The team used an aggressive approach towards development practices of all aspects including reservoir engineering, geologic, and operational practices. Reservoir characterization and numerical simulation work in conjunction with classical methods validated the 650 MMSTB of original oil in place (OOIP) and the 64 MMSTB estimated waterflood reserves in the reservoir. The team focused on optimizing the base production, monitoring well performance, and identifying opportunities to increase production through workovers, returning-to-production (RTP) jobs and recompletions. This paper details the systematic approach that was followed in order to achieve waterflood expansion success including geological characterization, reservoir engineering, data acquisition, production monitoring, well automation, field optimization, and program development for subsequent years. Details of the workflow implemented under the technical approach, best operational practices, and lessons learned are discussed. As a result, the production of the field increased approximately 70%, with a total increase of 2,800 BOEPD by 2009. The field continues to produce significantly more than it did prior to the waterflood expansion in 2008.2 SPE 169089-MS this day. The most important outcome from this work was the true understanding of synergy and team-oriented efforts. Integration, effective communication, and technical skills, coupled with planning, implementation, and surveillance, were keys to success. All efforts were focused on implementing an effective reservoir management plan needed to maximize the economic recovery of the reservoir.

The Permian Basin in West Texas contains one of the thickest deposits of Permian rocks found anywhere in the world. The Embar-B lease located in southern Andrews County on the Central Basin Platform (a regional structural high in the Permian Basin) has been producing from the Leonardian Clearfork formation for over 70 years. The Clearfork formation is primarily a subtidal and intertidal carbonate rock characterized as moderate quality reservoir. Most Permian Basin fields have multiple stacked reservoirs with varying degrees of reservoir quality and there is typically a need in these maturing fields to increase reservoir contact. In 2009, a drilling campaign was launched in Embar-B with a focus on expanding the completion interval to include what was previously considered marginal pay in the deeper Wichita Albany formation. The Wichita Albany, also Leonardian in age, is composed mostly of marginal quality tidal flat rocks and is characterized by high fracture gradients and low permeability. These characteristics required an advancement in completion practices to achieve a successful stimulation. The combination of improved completions practices and an expanded target interval resulted in production double that of previous wells. This success has driven a need for an innovative development strategy and continued optimization of completion practices. Geomodeling, volumetrics, reservoir simulation, seismic attribute analysis and oil fingerprinting were all used for reservoir characterization and to determine an allocation method for commingled wells. This lead to the identification of several Clearfork/Wichita Albany locations with significant reserves potential. Re-evaluation of the completion strategy using a multidisciplinary approach indicated the need to reduce the number of perforation clusters, add a diversion mechanism, and develop multiple hydraulic fracturing designs based on reservoir quality and presence of natural fractures. Results from recent drilling programs have exceeded expectations bringing lease production up from 200 BOEPD in 2009 to a peak rate of 3153 BOEPD in 2015.