低渗气藏储层应力敏感性实验研究

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。

Study on reservoir stress sensitivity of low-permeability gas reservoir

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.