Numerical Optimization of Hydraulic Fracture Stage Placement in a Gas Shale Reservoir

摘要: The upstream oil and gas industry focuses increasingly on unconventional resources to maintain the level of its hydrocarbon reserves. To unlock full potential shale reservoirs, horizontal wells are drilled active stimulation in form multi-stage hydraulic fracturing, is performed. This new technique has radically changed energy future United States forefront changing it Europe as well. fracturing treatment a costly, resource intensive potentially environmentally dangerous procedure. objective this thesis create realistic versatile reservoir model optimize placement number fracture stages along well bore, thereby maximizing production while minimizing amount money that spent do so. On basis computationally efficient ensemble based optimization vertical placement, an idea coined investigated by Leeuwenburgh et al. (2010), postulated numerical can aid finding optimal bore equally manner. Three gradient-based algorithms (Ensemble Optimization: EnOpt (Chen, 2008), Simultaneous Perturbation Stochastic Approximation: SPSA (Spall, 1998) finite difference gradient estimation) work with continuous variables, used approximate gradient. Because stage locations simulator commonly treated discrete variables (well grid block indices), standard implementations not applicable for placement. We propose three distinct variable parameterizing methods overcome inherent conversion issues. After theoretical arguments about strengths weaknesses proposed routines, both single multiple scenario experiments Good results obtained from various which favor algorithm combination interval method.