Field Life Extension in Abu Dhabi Through Hybrid Development Concept

Abstract

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 181598, “Prospective Unlocking of Future Reserves in Offshore Abu Dhabi: Field-Life Extension Through Hybrid Development Concept,” by T. Nakashima, SPE, D. Ouzzane, SPE, G. Dudley, SPE, and M. Al-Marzouqi, ADMA-OPCO, prepared for the 2016 SPE Annual Technical Conference and Exhibition, Dubai, 26–28 September. The paper has not been peer reviewed. Field A, a giant field consisting of many subreservoirs, is offshore Abu Dhabi and has produced for 50 years, mainly through peripheral water injection. A long-term development plan (LDP) for the field aims to extend the production plateau by 25 years through infill drilling and waterfloods. This paper describes an approach for optimizing the number and type of drilling centers required to enable the development plan to be flexible in design to accommodate infrastructure, facilities, drilling, and subsurface constraints. Introduction Field A, a giant carbonate field, has been developed for 50 years. As the field reaches maturity, it moves to another phase of development. Design of the next development phase, the LDP, began in the early 2010s. The LDP assessment stage, which screened the surface and subsurface development concept, was recently completed, and the development planning team is preparing for the selection stage. The assessment-stage conclusion was for drilling from artificial islands (AIs), wellhead towers (WHTs), or a combination of both and leaves a degree of freedom. This paper describes the optimization approach of the drilling-center options. The LDP is just the first phase of a large-scale long-span offshore reservoir redevelopment that aims for a further 50 years of production. The complexity of the field is significant because of limited seabed space, the age of the existing surface facilities and pipelines, and challenging drilling circumstances. These complexities differentiate the development project from other offshore projects, and an appropriate selection of drilling centers is one of the more important keys to project success. Field and Development History The field of carbonate reservoirs is in shallow water. The field is 40×20 km, and different reservoirs have been developed by two different operators. The stack of reservoirs is divided into shallower reservoirs (U Reservoirs) and deeper reservoirs (L Reservoirs). The L Reservoirs are geologically divided into two major reservoirs, L1 and L2, which have been developed similarly. The development began with natural production with original reservoir energy. Beginning in the 1970s, pressure maintenance through dump flood-water injection by connecting the target reservoirs with a shallow aquifer was conducted for 10 years. For further reservoir-pressure maintenance, powered peripheral water injection was started, and the development scheme has been continuous, with reinforced pressure maintenance through immiscible gas injection from the top structure.