Adjustment Strategy of Injection-Production Patterns for Low Permeability Sandstone Reservoirs

When low-permeability reservoirs turn to waterflooding,injection-production well pattern,it is difficult to meet the actual needs of the subsequent development.By using reservoir engineering and numerical simulation,the ratio of producer to water injector,injection-production well pattern adjustment,adjustment timing and proper water injection regime of new and old wells are studied systematically.Considering the seepage flow in low permeability reservoirs,formation pressure difference between the producer and water injector,the formula of producer to water injector ratio for low-permeability reservoirs was derived.According to the distribution of fracture and remaining oil,the pattern with high sweeping coverage factor should be selected for adjustment.The adjustment in Aonan Oilfield involves the conversion of inverted nine spot well pattern to five spot well pattern in areas with undeveloped fractures,and linear water injection in blocks with developed fractures.Prediction of development effect at different adjustment timing shows the sooner the adjustment,the better the effect.After the pattern adjustment,injection in old wells should be restricted while injection in new wells should be strengthened to make the reservoir pressure distribution more reasonable.The results show that the well pattern modification method is feasible for low-permeability reservoirs and will provide technical support for well pattern modification of low permeability reservoirs.