Optimization of Acid Fracturing Program In the Khuff Gas Condensate Reservoir of South Ghawar Field Saudi Arabia by Managing Uncertainties Using State-of-the-ArtTechnology

摘要

The Khuff reservoir in South Ghawar, Saudi Arabia is arnheterogeneous tight carbonate reservoir. Acid fracturingrnprogram has been initiated to enhance gas production fromrnthis reservoir to deliver 1.2 BSCFD of gas. The complexrnnature of the tectonic stresses, geomechanical properties,rnreservoir geology and quality, coupled with aerially varyingrnfluid properties (H2S) have sometimes reached the limits ofrnreservoir simulation and stimulation.rnDuring the early stages of development, numerousrndiagnostic tests were conducted on every well before, during,rnand after fracture treatment. These tests include pre- and post-fracturernpressure transient analysis, radioactive tracer orrntemperature log runs during mini and main fracture treatments,rnproduction tests, and production logging. Several acidrnfracturing fluids, such as, 28% HCl, emulsified 28% and 15%rnHCl, were applied to achieve optimum fracture length andrnconductivity, and avoid CO2 corrosion. Complete reservoirrncharacterization, history matching of actual fracture treatmentrnand production forecasts were performed for every well. Thernobjective of these tests and detailed evaluation is to optimizernfuture acid fracture design.rnThis paper presents in detail the integrated optimizationrnprocess of acid fracturing in the Khuff reservoir. The paperrndemonstrates that early investment in technology,rnmanagement of uncertainties, and state of the art reservoir andrnfracture modeling significantly improved the optimizationrnprocess.rnThe paper presents detailed assessment of several keyrnwells, comparison between various acid fracturing fluids andrntechniques, and calibration of results of the stress and fracturernmodels. The paper also discusses the need and importance ofrnsome of the tests and the quality of the results that may bernobtained from them.rnFinally, the paper presents reservoir modeling and historyrnmatching of acid fracture treatment using state of the artrncoupled geomechanical single well simulation model.rnPredictions of acid fracture performance versus time under thernKhuff abnormal stress conditions are presented.