A Successful Story Of An Integrated Geologic And Reservoir Engineering Approach Of The Gandu Unit

Abstract

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.