煤层气井压裂裂缝导流能力实验

Experimental study of conductivity of hydraulic fracture in CBM wells

为了研究煤岩压裂后裂缝导流能力的变化特征,进行煤层气井压裂裂缝导流能力实验,分别考虑裂缝闭合压力、时间、铺砂浓度、煤岩天然裂缝及煤岩性质对煤岩压裂裂缝导流能力的影响.结果表明:裂缝闭合压力是影响煤岩裂缝导流能力的重要因素;在一定闭合压力下,裂缝导流能力随着时间的推移而呈现下降的趋势;高铺砂浓度下的导流能力明显高于低铺砂浓度下的;煤岩中天然裂缝对导流能力的影响不容忽视;在较高闭合压力作用下,支撑剂的嵌入和煤粉的产生对质软的煤岩裂缝导流能力伤害更为严重.煤岩裂缝导流能力表现出与砂岩裂缝不同的一些特征,在煤层气开发中需要考虑煤岩裂缝的特性,从而获得较高导流能力的煤层气井压裂裂缝.

In this paper,fracture conductivity of coal rock is evaluated by the experiment.The effect of fracture closure pressure,time,sand concentration,the natural fractures as well as the properties of coal rock on fracture conductivity are analyzed.The study shows that fracture closure pressure is the important factors affecting the coal rock fracture conductivity.In certain closure pressure,fracture conductivity decreases with time.The conductivity under high sand concentration is significantly higher than that under low sand concentration.The effect of natural fracture in coal rock on conductivity can not be ignored.Under the conditions of high closure pressure,the embedment of proppant and braize will cause more damage to the conductivity of softer coal rock.It can be concluded through the experiment that the fracture conductivity of coal rock is different from the conductivity of sandstone.It is necessary to consider the particularity of the coal fracture in the coal bed methane development process.