EM: New Reservoir Simulation System

Abstract

Abstract During the late 1990's, Exxon and Mobil had each independently developed next-generation reservoir simulation systems. Both next-generation systems embodied a substantial number of step-out simulation technologies, which were extremely complementary. ExxonMobil moved aggressively to combine the best of both companies’ technologies into one industry-leading simulation system called EMpower™. This new simulation system is now being used to actively manage ExxonMobil's global resource base. Key features of this industry-leading simulator are described in this paper. The new simulator employs unstructured grids to more accurately model complex geologic features, near-wellbore flow, and aquifer support. Algorithms for optimal layering and flow-based scale-up on unstructured grids are tightly integrated in the EMpower system. The computations are performed within the unstructured grid fabric. Interactive simulation ties together the geologic and reservoir simulation models with production data yielding high-confidence forecasts of future performance. Emphasis is on minimizing the overall turnaround time between formulation of the simulation problem and generation of results. A comprehensive graphical user interface provides reservoir engineers and geoscientists of all skill levels with easy access to reservoir simulation. The user interface is designed to facilitate the full range of simulation problems—from quick screening studies to large, complex field models. The geoscience and reservoir engineer communicates to the executing simulation through the user interface, thereby allowing simulation progress/results to be monitored, paused, terminated, and/or restarted on command. Results are viewed within the user interface using spreadsheets, charts, or full 3D visualization. The object-oriented design of the new simulator is very flexible. The reservoir flow model is tightly integrated with the well and surface facility models for accurate, smoothly running simulations. Execution of complex well management strategies is specified in an intuitive, graphical format. For added efficiency, the simulator also is designed to take advantage of computing hardware that utilizes multiple parallel processors. The capabilities of this next-generation simulation system are demonstrated through a field study involving complex geologic features (e.g. non-vertical faults and stratigraphic pinchouts) and multiple reservoirs connected to a common production infrastructure. Introduction Reservoir simulator development has historically been an active area of internal research and development at both Exxon and Mobil.1–6 During the late 1990's, Exxon and Mobil each independently developed next-generation reservoir simulation systems. Both next-generation systems employed a substantial number of step-out simulation technologies, which were extremely complementary. ExxonMobil moved aggressively to combine the best of each company's technologies into one industry-leading simulation system called EMpower. This new simulation system is now being used to actively manage resources within ExxonMobil's global asset base. This paper describes the EMpower simulator and some of its key features. Potentially the most significant innovation adopted in the new simulator is unstructured gridding, with computations performed within the unstructured grid. A number of researchers have contributed to developments in unstructured gridding over the past two decades7–9. However, industry generally has been reluctant to apply this capability to practical reservoir simulation due in part to concerns about potential loss in computational efficiency.