Study on seepage characteristics of fracturing well pattern water injection development in low permeability reservoir

Aiming at the problems of low matrix permeability and insufficient natural energy of low permeability reservoir, the development effect of fracturing well pattern water injection is obvious, but its seepage characteristics and development performance are not systematically understood. According to the characteristics of fracturing fracture well pattern in low-permeability reservoir, this paper establishes an oil-water two-phase seepage mathematical model suitable for water injection development of low-permeability reservoir, considers the influence of stress sensitivity and starting pressure gradient effect, and uses nested discrete fracture model to characterize hydraulic fracturing fractures, forming a numerical simulation technology of water injection development of fracturing fracture well pattern in low-permeability reservoir. Then, a typical fracturing well group model of low permeability reservoir is established, and the oil-water seepage characteristics and production and development performance under different stress sensitivity, starting pressure gradient and water injection pressure parameters are simulated and analyzed. The simulation results show that the water injection development of fracturing well pattern in low permeability reservoir has good effect. Stress sensitivity and start-up pressure gradient effect will produce large seepage resistance to water injection development of low-permeability reservoir, reduce the sweep range of injected water in the reservoir, significantly affect the fluid seepage characteristics in low-permeability reservoir and reduce oil well productivity. The increase of water injection pressure will increase the sweep range of injected water in the reservoir and improve the effect of water injection development of low-permeability reservoir. The numerical simulation method formed in this paper can be used to guide the formulation of water injection development scheme of fracturing well pattern in low-permeability reservoir. The research results are of great significance for in-depth understanding of fluid seepage characteristics in low-permeability reservoir.