Optimization Study Of Unstable Water Injection In Low Permeability Reservoirs

As an effective post-adjustment measure,unstable water injection is currently implemented in some low-permeability oil fields,but the seepage mechanism of unstable water injection in low-permeability reservoirs needs to be further clarified.Aiming at the practical problems of block B of XF oil field,this paper uses a combination of physical experiments and reservoir numerical simulation to study the unstable water injection mechanism,adaptation conditions and injection-production parameter optimization of low-permeability reservoirs.First,the dynamic analysis of the well groups with unstable water injection in the study area was carried out to clarify the influencing factors that affect the development effect of unstable water injection in low-permeability reservoirs,including reservoir heterogeneity,reservoir connectivity,fracture and unstable injection-production policy.Secondly,based on the influencing factors,from the perspective of physical simulation experiments,parallel core experiments and double-layer core experiments were conducted to demonstrate the mechanism of unstable water injection to reduce the difference between layers and promote inter-layer seepage.The mechanism of unstable water injection to strengthen the water injection and promote oil-water imbibition was further analyzed by numerical simulation.Finally,the adaptability analysis of continuous water injection,periodic water injection and asynchronous injection to low-permeability reservoir anisotropy,fracture development degree,intra-layer heterogeneity and interlayer heterogeneity was studied,and typical well groups were used to optimize unstable injection-production parameters.The research results of this paper have certain guiding significance for the use of unstable water injection methods to control water and stabilize oil in low permeability reservoirs.