考虑裂缝和含水饱和度的致密砂岩应力敏感性

致密砂岩气藏裂缝发育和有效应力高的特征使其易发生应力敏感性损害，钻井完井液侵入或凝析水在近井地带聚集也将影响砂岩应力敏感性，这些因素都会对致密砂岩气藏的经济开发产生影响。考虑裂缝和含水饱和度的影响，选取鄂尔多斯盆地上古生界典型致密砂岩岩样，分别用干岩样、人工造缝岩样和含水饱和度低于束缚水饱和度的岩样进行了致密砂岩基块与裂缝的应力敏感性实验，并从岩石学特征入手，利用毛细管渗流模型和化学压实等理论分析了裂缝和含水饱和度对岩石变形的影响，探讨了致密砂岩应力敏感性损害机理。研究结果表明，致密砂岩应力敏感性损害严重，应力敏感性系数与基块渗透率线性负相关，而与裂缝岩样渗透率的对数线性正相关；水的存在加剧了致密砂岩应力敏感性程度，且含水饱和度越高应力敏感性越强。

Stress sensitivity of fractured tight gas sands in consideration of fractures and water saturation

Tight gas ,sands have potential damage of stress sensitivity due to its fractures development and high effective stress, and the drill-in fluids and condensate water near boreole can also affect stress sensitivity, which prevent eccnonical development of reservoirs. Considering the effects of fractures and water saturation on stress sensitivity of tight gas sands, experiments of stress sensitivity were conducted under pressure repetitive increasing and lowering, and various water saturations that are lower than irreducible water saturation with dry oore sample, tight gas sandstone matrix and man-rnade fractured oores from Ordos Basin. And the effects of water saturation and fractures on stress sensitivity of tight sandstones were investigated by capillary flow model and chemical compaction theory. The results suggest that the severity of stress sensitivity is linear inverse correlation with permeability of matrix, and linear positive correlation with logarithm of the pemeability of fractures. Water saturation and fractures strengthen the severity of stress sensitivity, and the severity increases with water saturation increasing.