The Prudhoe Bay Field-Sadlerochit Reservoir presents many complexities which make reservoir simulation of this large oil accumulation difficult. The presence of major faults, the existence of large shale complexes, the enormous gas cap and associated coning of wells, and the heavy oil/tar mat could cause, even if each existed separately, major problems for a standard reservoir simulation model. This paper describes the techniques which were used by ARCO Oil and Gas to overcome these difficulties in modeling the Prudhoe Bay Field. Because of the large areal extent of the field, a unique grid in radial coordinates was used to reduce the number of grid cells to a manageable number. A new form of velocity-dependence was introduced into the gas/oil relative permeability and capillary pressure pseudo function relationships in order to more accurately model the gravity drainage and coning behavior in the field. A special pressure solution technique was developed to handle the extensive faults throughout the reservoir. Finally, an overall well and facility management routine was added to control the production/injection of the field and to give realism to the complex boundary conditions involved in these controls. Validation of the modeling techniques was carried out in small scale models, larger cross-sectional models, and finally through history matching of the field. These validations gave excellent results.

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