低渗气藏储层应力敏感性实验研究

Study on reservoir stress sensitivity of low-permeability gas reservoir

戴强 段永刚 焦成

Dai Qiang Duan Yonggang Jiao Cheng

西南石油大学, 四川成都 610500; 辽河油田曙光采油厂, 辽宁盘锦 124009

SWPU, Chengdu 610500; Shuguang Production Factory of Liaohe Oilfield, Panjin 124009

低渗透气藏的开采会导致地层压力发生变化, 从而引起储层孔隙度和渗透率发生相应的变化。实验表明, 孔隙度随有效应力变化很小, 而渗透率随有效应力变化较大。利用第二次增减压应力敏感实验的数据进行分析, 避免了因为地层压实对渗透率伤害的过高估计, 更符合生产实际。使用应力敏感指数对低渗气藏岩心进行评价, 得到渗透率较高的岩心应力敏感指数要高于渗透率较低的岩心, 这是由于其内部在覆压增加时小孔道闭合比后者要严重;地层压缩所引起的渗透率伤害是可以恢复的。

The reservoir pressure will change as a result of development of low-permeability gas reservoir, which lead to change of porosity and permeability. Through experiment, it is shown that porosity changes quite a little, whereas permeability varies more relatively. It avoids higher estimate of permeability damage resulting from formation compaction to use the data for analysis of second increase-decrease stress sensitive experiment, which suits production practice better. Analyzing core of low-permeability gas reservoir, stress sensitive index of higher permeability core is greater than that of lower one. That is because small-size porous channels in the former close are more seriously than the latter. And the permeability danage induced by formation compression can be recovered.