低渗透应力敏感性油藏产能及影响因素

基于低渗透非达 西和变形介质拟稳态渗流理论及油相和水相相对流动能力方程,建立了低渗透应力敏感性油藏具有最大产量点的三相流流入动态曲线方程,据此可计算出油井或油藏的最低允许流动压力。在此基础上,结合大庆葡西油田生产数据,对影响油藏产能的油层启动压力梯度、变形系数、供给半径、平均地层压力和含水率进行了研究,结果表明,启动压力梯度、变形系数等因素对低渗透油藏产能和最低允许流压均有较显著的影响。该方法能有效评价和预测低渗透应力敏感性油藏的产能变化,也为油井合理工作制度的确定,充分发挥油井产能提供了依据。

Productivity and Influencing Factors of Oil Reservoir with Low Permeability and Pressure Sensitivity

Low permeability reservoir is not only of existence of threshold pressure gradient, but also could be deformed when the reservoir permeability exponentially decreases with formation pressure decline. This phenomenon most occurred in reservoirs with abnormal pressure and low or super-low permeability. Based on the pseudosteady state theory of non-Darcy flow and deformed media percolation and relative flow behavior equation of oil and liquid phases, the three-phase flow IPR curves with maximum flow rate point in low permeability and pressure sensitivity oil reservoir are derived, by which the allowable minimum flowing pressure in oil well o reservoir can. be calculated. Also, combining with the production data from Puxi oil field in Daqing, the threshold pressure gradient, deformation cofficient, drainage radius, average formation pressure and water cut that affect the reservoir productivity are studied. The results show that the threshold pressure gradient, deformation coefficient have remarkably influences on the reservoir productivity and the allowable minimum flowing pressure. This method can be used to effectively evaluate and forecast the variation of productivity in oil reservoir with low permeability and pressure sensitivity, meanwhile, provide bases for determination of reasonable flow pressure and routine of work as well as sufficiently displaying well flow capacity.