Study On Optimization Of Advanced Water Injection Scheme And Matching Measures Combination In Yuan271Block

In conventional conditions, once the low-permeability reservoirs are put into production,the formation pressure drops rapidly and it is difficult to restore. It leads to production decline,reservoir pore structure change and rock deformation. Thus, the porosity of reservoirdecreases and the permeability reduces, which is adverse to the production oflow-permeability reservoirs. Therefore, to avoid the formation pressure declining is the key tosolve the difficulty in the process of low-permeability reservoir exploiting. Advanced waterinjection is the technology to improve the development effect of this kind of reservoir, whichis proposed according to the characteristics of low or extra-low permeability reservoirs withthe start-up pressure gradient and reservoir with the elastic-plastic deformation. In the paper,we simulate the reservoir conditions of Yuan271block in Daqing peripherallow-permeability oilfield and conduct optimization of advanced water injection schemes andstudy the combination of supporting measures in order to provide theoretical and technologicinstruction for the effective development of Yuan271block.In the paper, we analyze the feasibility of advanced water injection in Yuan271blockaccording to the pressure sensitivity experiments and the results show that strong stresssensitivity exists in Yuan271block. By the method of advanced water injection, formationpressure of yuan271block can keep above the original formation pressure, which can reducethe formation damage caused by pressure drops. Use the method of numerical simulation toconduct the optimization research of advanced water injection schemes. Optimal scheme ofadvanced water injection is obtained as the following: the reasonable water injection intensityis4m3/d·m; the best injection pressure is14MPa; reasonable water injection timing is theformation pressure level118%and the reasonable bottom-hole flowing pressure is3-5MPa.Establish the virtual model of horizontal well and use numerical reservoir simulation toconduct optimization of advanced water injection supporting measures combination: injectionwells Y196-66and Y199-68on both sides of horizontal Wells Y198-P67stagger cycle waterinjection; injection wells Y199-S62, Y202-S62and Y200-60, Y201-S63around thehorizontal well Y201-P61stagger cycle water injection. The appropriate time for advancedwater injection is1month. The fracture measure scheme is that all production wells arefractured with the directional fracturing direction135°. According to the optimization schemeand combination of supporting measures, after10years production by forecasting, the cumulative oil production is3495.98t higher than the conventional. It shows that overalldevelopment effect is improved obviously by advanced water injection supporting measures.