Abstract

A tightly integrated high performance parallel simulator for the management and optimization of multiple reservoirs, wells, and surface facilities is presented with subsea and giant field example applications cases. These cases have helped to develop and improve subsequent simulator releases. Specialized production management algorithms are implemented by flexible user-developed procedures written in a specialized object-based Fortran-like language. Tight coupling enables accurate prediction of all phase production rates and multiple gas and water injection rates.

The new reservoir simulation tool was applied to the multireservoir Greater Plutonio (GtP) field in offshore Angola and to the giant Prudhoe Bay Unit (PBU) field in Alaska. These cases have provided the greatest challenges to the simulator in the BP system and have driven development. In both cases, the simulations were developed coupling the reservoir to the surface facilities, and user-developed procedures were included to manage and optimize production. Numerous algorithmic improvements were made to the base code to accommodate additional required functionality for the user management procedures and to achieve sufficient performance for the extensive PBU network model.

For GtP, four fields were included in the full network model with multiple wells, risers, manifolds, and seabed pipeline connections. Procedures were used to model the gas injection, export, riser gas lift optimization, and facility and production constraints. Another procedure replicated the yearly production engineering optimization by shutting in wells by water-cut class for week-long tests each January. From these tests, the procedure selected the best combination of wells to accelerate oil production for the remainder of the year. Results have shown good agreement with actual production.

For the PBU, a development campaign is underway to enable predictive simulation, including algorithms for predictive well management (PWM), seam tuning, and automatic drilling. The PWM algorithm for the optimal allocation of wells to low- and high-pressure systems in each of the six PBU flow stations will be implemented by user procedures. New functionality is also being developed to improve parallel operation of the network and to enable intelligent selective use of the network over time. The effort is expected to lead to substantially improved simulator performance in terms of flexibility and practicality. Many of the new features have benefited other assets.

The updated simulator represents a step change in reservoir engineering management capability for the operator, resulting from increased accuracy, performance, and user flexibility. Tight coupling with scalable high performance enables accurate and stable prediction and operation. The inclusion of an extensive user procedure facility for customizable production management algorithms enables both mirroring of existing management practices and the testing of a variety of proposed alternatives. User procedures can be reused and shared among assets.

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