应力敏感性高压气井流入动态分析

我国西部深层气藏往往表现出异常高压的特征，油气藏生产时，由于地层压力下降导致储集层骨架变形和孔隙度、渗透率降低,该类气藏表现出很强的应力敏感性。该类气藏一方面渗透率随压力（或拟压力）变化而变化，在油气藏生产过程中,用单一固定不变的渗透率来表示油气藏的渗透物性显然是不合适的；另一方面，在超高压地层中气体的粘度和偏差因子乘积不是常数，用通常的压力平方来表示和研究产能特性也是不合适的。基于渗透率随压力呈分段的指数变化规律，用拟压力来处理实际气体的渗流过程，建立稳定渗流模型。在求解模型时，引入Pedrosa变换将渗流扩散方程中的非线性项弱化，用正规摄动技术精确地求解出渗流模型的零阶和一阶解，得到应力敏感性高压气藏井流入动态方程。在此基础上，分析渗透率模量变化对气藏压力和产量的影响，分析应力敏感性高压气藏井流入动态。该研究提出的思路和方法对我国西部深层高压气藏的产能评价具有指导意义。

ANALYSIS OF INFLOW PERFORMANCE FOR STRESS-SENSITIVE GAS WELLS WITH HIGH PRESSURE

The deep gas reservoirs in West China have the features of abnormally high pressure commonly. During the reservoir exploiting, the matrix of the reservoir will deform, and the porosity and permeability will decrease as the reservoir pressure downs. This kind of gas reservoirs shows strong stress sensitivity. On one hand, the permeability of the gas reservoir changes as the pressure (or pseudo-pressure) changes. So, it is not correct to use constant permeability to express the permeable performance of the reservoir in the process of the reservoir exploiting. On the other hand, since the product of the gas viscosity and deviation factor is not constant in the reservoir with abnormally high pressure, it is also not correct to use the common pressure square to express and study the productivity performance. According to the permeability changing law by exponent piece-wisely as pressure changes, with pseudo-pressure to process the percolation of real gas, the stable percolation model is developed. Introducing Pedrosa transform to weaken the non-linear item in the percolation diffusion equation when the model is solved, and using the regular perturbation equation to accurately derive the zero-order and first-order solutions of the percolation model, the inflow performance equation is established for the wells of stress-sensitive gas reservoirs with high pressure. Then, the influence of the permeability modulus on the pressure and production of gas reservoirs and the inflow performance of stress-sensitive gas wells with high pressure are analyzed. The idea and method proposed in the article has guiding significance for the productivity evaluation of deep gas reservoirs with high pressure in West China.