低渗透煤层气液两相复合压裂卸压增透技术

Pressure relief and permeability enhancement technology of gas-liquid composite fracturing in low permeability coal seam

为了解决低渗透高瓦斯煤层抽采难度大的问题,基于现有研究成果,通过理论分析,提出了煤层气液两相复合压裂卸压增透技术。技术主要依靠注入钻孔的高压酸液和高压碱液起裂煤层,同时液体反应生成的高压CO_(2)气体起到驱替增透作用;具有卸压和增透的双重效应,截断突出的准备阶段;煤层压裂增透后的地应力场和瓦斯压力场降低、均化,抽采效率得到提高。技术的突出特点是:反应产物呈中性、易溶解;少量酸化增透产物支撑作用,减弱裂隙闭合;反应升温,避免CO_(2)过量吸附降低渗透率;技术组合方式灵活多变。

In order to solve the problem of difficult extraction of low permeability high gas coal seams, based on the existing research results, a coal seam gas-liquid composite fracturing pressure relief and permeability enhancement technology was proposed through theoretical analysis. The technology mainly relies on the high-pressure acid and high-pressure alkali liquid injected into the borehole to crack the coal seam, while the high-pressure CO_(2)gas generated by the liquid reaction plays a role in displacing and increasing the permeability;the technology has the dual effect of pressure relief and permeability increase, and cuts off the preparation stage of outburst;the ground stress field and gas pressure field are reduced and homogenized after the coal seam fracturing and permeability increase, and the extraction efficiency is improved. The outstanding features of the technology are: the reaction products are neutral and easy to dissolve, a small amount of acidification and permeability increasing products support the effect and weaken the fracture closure;the reaction temperature rises to avoid excessive CO_(2)adsorption and permeability reduction;the technology combination is flexible and changeable.