In order to investigate the rational injection pressure with different orientation of natural fractures and injection-production pattern,a reservoir fracture propagation model with collinear fractures was established on the base of porous medium mechanics and fracture mechanics, and a calculation method of injection pressures was presented.Fuyu reservoir properties were applied to discuss the influence rules of reservoir fractures azimuth,injection-production well azimuth and fracture distance on water injection pressure.The results showed that under the given injection-production well azimuth,if the natural fractures are parallel to the major principal stress,the injection pressure is minimum.As the angle between natural fractures and the minor principal stress increases,the injection pressure decrease accordingly.When the natural fractures are parallel to the minor principal stress,the injection pressure is maximum,and the injection pressure increases with the injection-production well azimuth and fracture distance increases.For the sake of preventing water channeling to production well and enhancing recovery,a rational injection pressure range was proposed according to Fuyu reservoir parameters.The results were identical with practical logging data,which has a guiding significance for similar oilfield development engineering.
