煤岩渗透率对酸化作用响应规律的试验研究

Experimental study on response law of permeability of coal to acidification

酸化手段是油气井提高产能的重要手段,较小的酸化规模有可能极大地提高油气井产量,这对具有低渗透性特点的煤层气井开发具有重要启示。通过室内试验测定了酸液作用前后煤粉的矿物成分极限反应率和煤岩芯的渗透率,分析了酸化作用后煤粉极限反应率和煤岩芯渗透率的变化规律。结果表明:煤层中原始的孔裂隙发育和矿物成分组成对渗透率的大小具有重要影响;酸化手段可有效提高煤层渗透率,对于试验煤样,渗透率最大提高了18.42倍,盐酸质量分数在12%~15%为最佳。酸化时间过长会造成渗透率小幅度降低,应控制反应时间在12 h左右。

Acidification method is an important mean in oil and gas wells for increasing production. Small scale acidifi- cation measure can greatly enhance the hydrocarbon production capacity. This has important enlightenment on the ca- pacity of coal-bed methane wells productivity improvement. Through the indoor experiment to determine the acid disso- lution rate of pulverized coal and coal core permeability variation, the analysis of the acid effect on coal reservoir per- meability change rule was conducted. The results showed that the original fracture development in coal reservoir and mineral composition have a significant effect on permeability. Acidification method can effectively improve the permea- bility of coal seam with about 18.42 times improvement. The mass fraction of acid at 12% -15% is the best concentra- tion. The long time of acidification will cause the decrease of permeability, and thus the control response time is about 12 hours.