Fluid-solid Coupled Flow Simulation And Remaining Oil Distribution Research In Unconsolidated Sandstone Reservoirs

During oil & gas reservoir depletion, the reservoir pressure degrades and the alteration of terrestrial stress imposing on the rock frame causes elastic-plastic deformation of the rock, which leads to variations in porosity, permeability, rock density and reservoir compressibility etc. These variations in the aforementioned parameters affect fluid flow through porous media and ultimate recovery. As the traditional percolation theory can't describe effects of changes in these physical properties on reservoir fluid percolation, the process of the complex percolation should be studied by using fluid-solid coupled flow method.In this article, in view of characteristics of easy-sanding and easy-deforming in unconsolidated sandstone reservoirs, according to the domestic and abroad research advance in the distribution of remaining oil and the existed dominant problems in Guantao group Lao 19 faulted block unconsolidated sandstone reservoir, on the one hand, the fine reservoir descriptions were successfully carried out by applying multi-disciplinary research methods, on the other hand, its numerical simulation and remaining oil distribution research with fluid-solid coupling were implemented. Based on both the remaining oil distribution research and re-adjustable development program research, in view of the injection-production system adjustment, the development plans with and without fluid-solid coupling were contrasted. In addition, effects of fluid-solid coupling on fluid flow through porous media in unconsolidated sandstone reservoirs were analyzed and optimal re-adjustable development program was selected. Main research findings: The fine reservoir descriptions in Guantao group Lao 19 faulted block unconsolidated sandstone reservoir were successfully carried out by applying multi-disciplinary research methods such as high resolution sequence stratigraphy, log-constrainted seismic inversion and random modeling technology. A new coupled multi-phase flow mathematical model, taking effects of variations in permeability and porosity into account, was developed to study fluid flow in unconsolidated sandstone reservoirs. The mathematical model was numerical solved and the existed BOAST II code was modified to simulate coupled multiple-phase flow in unconsolidated sandstone reservoirs. Applying IMEX simulator and MATLAB 6.5, under the consideration of fluid-solid coupling, researches of numerical simulation and remaining oil distribution were conducted in Guantao group Lao 19 faulted block unconsolidated sandstone reservoir. Based on both the remaining oil distribution research and re-adjustable development program research, in view of the injection-production system adjustment, the development plans with and without fluid-solid coupling were contrasted. In addition, effects of fluid-solid coupling on fluid flow through porous media in unconsolidated sandstone reservoirs were analyzed and optimal re-adjustable development program was selected.