二氧化氯作为煤储层压裂液破胶剂的可行性实验研究

针对煤层温度低、高黏压裂液无法及时破胶返排的难题,探讨二氧化氯作为压裂液破胶剂的可行性及其对煤层气开采的影响。实验选择清洁压裂液、交联冻胶压裂液和二氧化氯溶液对不同煤阶煤样进行处理,对处理后煤样再分别进行光学显微镜、等温吸附和压汞等测试。结果表明:残留的压裂液会对煤层造成污染伤害,二氧化氯不但具有良好的低温破胶作用,同时还可以提高大孔和中孔的孔容比,使得孔隙连通性得到改善,进而提高储层渗透率;经二氧化氯处理后煤样的朗格缪尔体积显著降低,表明了煤的亲甲烷能力显著降低,从而使得煤层气临界解吸压力、含气饱和度与采收率均得到不同程度的提高。研究表明二氧化氯可以作为煤储层压裂液的破胶剂。

Experimental study on the feasibility of chlorine dioxide as fracturing fluid gel-breaker for coal reservoirs

Based on the difficulty that fracturing fluid with high viscosity is unable to break and flow back timely in the low-temperature coal seams，the feasibility of chlorine dioxide (ClO2) as gel-breaker of fracturing fluid and its impact on coalbed methane (CBM) development were studied.Different rank coal samples were treated with clean fracturing fluid，cross-linked gel fracturing fluid and ClO2 solution，and were tested by optical microscope，isothermal adsorption and mercury porosimetric method，etc.The experiment results show：First，residual fracturing fluid will damage the coal seam.ClO2 not only has a good effect on gel breaking at low temperature，but also it can increase the pore volumes ratio of macropores and mesopores for coal samples treated by ClO2.It improves the pore connectivity and further enhances the permeability of coal reservoirs.Second，the Langmuir volume of coal samples soaked by ClO2 decreases significantly，indicating the coals’ affinity for methane has fallen.As a result，the critical desorption pressure，gas saturation and the recovery factor of CBM will increase to some degrees.The study show that ClO2 can be used as gel-breaker of fracturing fluid for coal reservoir.