EMpower: New Reservoir Simulation System

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.

Parallelization on Unstructured Grids

“…Linearization of the molar flow term, U m , in discrete form with respect to the independent variables pressure (P) and moles (N m ) as well as the dependent variable saturation (S v ) yields equation (3). Varying the terms included in the discretization yields all the available formulations.…”

“…ExxonMobil's EM power comprises a suite of applications including an object oriented database 1 , an unstructured gridding package, a GUI, a multi-platform simulation engine, and a variety of utilities to allow reservoir engineers to run the simulator on remote compute servers in both interactive and batch modes. A more complete overview of the simulator may be found elsewhere 2,3 . Fundamental to the initial design is the concept of using an unstructured grid to keep the model size relatively small and parallelization to improve the runtime of these models.…”

Integrated Characterization of UAE Outcrops: From Rocks to Fluid Flow Simulation

“…The model was exported in Rescue format and loaded into ExxonMobil's next generation reservoir simulator, EM power . 3 A one square kilometer area of study encompassed the Wadi Rahabah outcrops and provided sufficient volume for meaningful flow simulations. Before the model could be built, however, a top was needed for the model "container."…”

Optimizing Waterflood Management in a Giant UAE Carbonate Oil Field Using Simulation-Based Streamlines

“…Most of the streamline studies use streamline simulators which are fast but simplistic. The methodology developed in this study utilizes history-matched simulation models to generate streamlines from the pressure field and fluxes computed by a finite difference simulator, EM power , Beckner et al (2001). A finite difference simulator is more rigorous than streamline simulators in terms of its ability to model complex fluid flow, and therefore, provides a more realistic solution.…”