The Research Of Well-net Array And The Optimization Of Injection-production Parameters For Super-low Permeability Reservoir

Among all the recent proved reserves in China, the proportion of low permeability reserves reaches 66% and ultra-low permeability and super-low permeability reservoirs account for more than half of them. The development is difficult. An appropriate approach of well-net array and injection-production parameters is the key to the successful development of the ultra-low permeability and super-low permeability reservoirs, which is of considerable importance to the development of Chinese oil industry.Based on the investigation of development status of super-low permeability oil fields and the main characteristics of super-low permeability reservoirs, the single-phase nonlinear steady seepage flow model, the research object of which is the Chang6 layer of the Changqing oil field, is presented in this page. The model, built on the condition of irreversible deformation of super-low permeability reservoirs, analyzes the influence of the coefficient of deformation to the limit of drainage radius; researches methods to determine the critical spacing and appropriate injector-producer spacing and discusses factors which affect reasonable producing differential pressure under single-phase steady seepage condition. The result shows that when the ? 01 increases, the layer permeability reduces and actuating pressure gradient increases, leading to the decrease of limit of drainage radius.The reasonable critical spacing of Changqing super-low permeability reservoirs is 310-343m and the appropriate injector-producer spacing of the rectangular five spot pattern is 240m. The greater the deformation coefficient of medium, the lower the maximum of productivity index. With the increase of differential pressure, the productivity index reduces considerably and the reasonable production differential pressure reduces. When considering the actuating pressure gradient, the reasonable production differential pressure is 10.4~11.4Mpa determined by pressure maintenance level and flowing pressure.On the base of theory research, the geological model of super-low permeability reservoir development is built via numerical simulation. The model is used to optimize the well-net array and injection-production parameters. The research shows that the result of super-low permeability reservoir development is better if using five spot pattern (Injectors parallel to fractures while the well spacing is 360m and the array pitch is 150m.) Fracture conductivity is 200-230mD.m; the penetration ratio is 0.4; the pressure maintenance level is 117%; the injection-production ratio is 1.0 and the production rate is 1.7%.