盐穴储气库微渗层注浆封堵试验研究

Experimental study on grouting method for plugging micro-permeable layer in salt cavern gas storage

我国盐穴地下储气库大多建造在具有不同渗透性的层状盐岩地层中,因此保证储库拥有良好的密闭性至关重要。针对盐穴井筒“裸眼段”意外跨越微渗地层而导致储气库密闭性失效的问题,自主研发了渗漏地层注浆封堵试验平台,并结合现场地质渗漏情况设计了注浆封堵可行性试验方案。在确定了兼具流动性和填充密实性的浆液配合比后,开展了超细水泥封堵岩芯的试验研究。结果表明,超细水泥可以有效填充岩芯孔隙并降低其渗透率,注浆后岩芯孔隙率和渗透率降幅分别达到近16%和95%。封堵试验数据显示浆液封堵范围与注浆时间呈幂函数关系,浆液流型满足幂律流,而非牛顿流。该研究成果可为盐穴储气库微渗地层注浆封堵提供必要的理论和试验依据,对类似密闭性失效井筒的二次利用具有重要意义。

The salt cavern underground gas storages in China are mostly built in layered salt rock strata with varying permeability.Ensuring good airtightness of the salt cavern gas storages is important.To solve the problem that the“open-hole section”of the wellbore accidentally traverses the micro-permeable layer and causes the airtightness failure of gas storage,a grouting test platform for plugging the micro-permeable layer was independently developed and a feasibility test of grouting plugging was designed based on the geological leakage situation on site.After determining the proportion of slurry with fluidity and filling compactness,an experimental study on plugging cores with ultra-fine cement was conducted.The test results show that the ultra-fine cement can effectively fill the pore and reduce the core permeability.The porosity and permeability of the cores are decreased by about 16%and 95%after the grouting tests.The plugging test data show that the plugging range is in the power function relationship with the grouting time,and the grout flow pattern satisfies the power law flow instead of the Newtonian flow.This study can provide theoretical and experimental basis for the grouting method to plug the micro-permeable layer in salt cavern gas storage,and it is critical for the secondary utilization of similar airtightness failure of the wellbore.