考虑应力敏感疏松砂岩气藏试井分析

疏松砂岩气藏在开采过程中由于岩石骨架结构变形和本体变形，以及存在强烈的应力敏感性，导致孔隙度和渗透率降低，用常规试井模型不能准确地进行试井解释。文中建立了考虑应力敏感均质圆形封闭边界气藏渗流数学模型，分析了该试井模型的特征曲线。研究表明：应力敏感主要表现在中后期的拟稳定阶段，对于指数变化关系的渗透率-压力关系，只有当B>0.1 MPa-1 时对试井动态的影响结果明显。拟压力上翘特征与不存在应力敏感砂岩气藏和不渗透外边界试井模型相类似。考虑应力敏感试井模型可用于疏松砂岩气藏试井分析，对该类气藏开发具有一定的指导意义。

Well test analysis of unconsolidated sandstone gas reservoir in consideration of stress sensitivity

Due to the rock skeleton structural deformation and body deformation in the exploitation of unconsolidated sandstone gas reservoir, permeability and porosity become lower and make strong stress sensitivity ,which results in that the well test data can not be accurately explained by the conventional well test model. A mathematical model of homogeneous circular gas reservoir with closed border in consideration of stress sensitivity is presented, and the typical curves are analyzed. The research shows that the stress sensitivity appears in the latter part of the pseudo-steady stage, and the index change in relations between permeability and pressure has a clear impact on the dynamic test results only when B〉 0.1MPa^-1. The upwarping feature of pseudo-pressure is similar to the well test model of sandstone gas reservoir which does not have stress sensitivity and impermeable boundary. The well test model which considers the stress sensitivity can be used to analyze the well test data in unconsolidated sandstone gas reservoirs and provides some guidance for these reservoirs exploitation.