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目前中国低渗透气藏的储量占未动用气藏储量的比重越来越大,而低渗透气藏一般都采用衰竭式开采,在生产过程中地层压力逐渐下降,导致储层岩石变形,使得孔隙度和渗透率降低,从而导致低渗透气藏开发效果变差。在对苏里格低渗透气藏岩心进行大量应力敏感性实验的基础上,通过对实验数据的分析,比较了线性、指数和乘幂3种典型渗透率随有效压力变化的关系模型。分析结果表明:乘幂变异模型较其他两者与实验数据更为吻合,在此基础上,推导了考虑应力敏感性时的低渗透气藏产能公式。由此提出了刻画岩石介质变形的新参数——岩石变形系数,用此参数可以很好地表征低渗透气藏介质变形的变化特征及其对低渗透气藏产量的影响,并依据该系数对低渗透岩心的变形程度进行分类,得到了比较好的分类效果。
At present, the reserves of low-permeability gas reservoirs in China account for an increasing proportion of the reserves of unused gas reservoirs. However, depleted gas reservoirs are generally used in low-permeability gas reservoirs, and the formation pressure gradually decreases in the production process, resulting in the deformation of reservoir rocks, Degree and permeability decrease, resulting in the development of low permeability gas reservoirs become less effective. Based on a large number of stress-sensitivity experiments on the core of the Sulige low-permeability gas reservoir, the relationship models of the three typical permeability changes with the effective pressure were compared by analyzing the experimental data. The results show that the model of power excursion is more consistent with the experimental data than the other two. Based on this, the formula of productivity for low permeability gas reservoirs considering stress sensitivity is deduced. Therefore, a new parameter of rock deformation, rock deformation coefficient, is proposed, which can characterize the variation characteristics of medium deformation of low permeability gas reservoirs and its effect on the yield of low permeability gas reservoirs. Based on this coefficient pair The degree of deformation of low-permeability cores is classified, and a better classification result is obtained.