4D-stress evolution of tight sandstone reservoir during horizontal wells injection and production: A case study of Yuan 284 block, Ordos Basin, NW China

To investigate the 4D stress change during injection and production in tight sandstone reservoirs, a multi-physical fields modeling method is proposed considering the reservoir heterogeneity, hydraulic fracture and complex injection-production system. The 4D stress evolution of tight sandstone reservoir in Yuan 284 block of Huaqing oilfield, Ordos Basin, during injection-production in horizontal well network is investigated by modeling coupled flow and geomechanics. Results show: (1) Induced by injection and production, the 3D stress increases near the injectors but decreases near the producers, and the horizontal stresses are distributed in obvious strips along their respective stress directions. (2) The horizontal stress difference is the highest at the horizontal wellbore beside injectors during injection and production, while it is the lowest in undeveloped zone between the injectors, and the orientation of maximum horizontal principal stress changes the most near the injectors, which is distributed radially. (3) The hydraulic fracture in re-fracturing well was observed to be asymmetrical in geometry and deflected as the stress changed. The results provide theoretical guidance for horizantal well network modification and re-fracturing optimization design in tight sandstone reservoir.