煤层水力压裂裂缝导流能力实验评价

水力压裂技术是煤层气井增产的重要手段,而由于煤层气储层与常规石油天然气储层存在较大的差异,对煤层压裂裂缝导流能力的研究不能照搬常规石油天然气储层的研究结论,有必要开展煤层水力压裂裂缝导流能力的针对性研究。使用FCES—100裂缝导流仪,用从现场取出的煤块加工而成的煤板进行了裂缝导流能力实验研究。根据实验结果,研究了闭合压力、铺砂浓度、时间和天然裂缝对煤层裂缝导流能力的影响。研究认为:随着闭合压力的增加,煤层裂缝导流能力下降幅度达50%以上;高铺砂浓度下的导流能力明显高于单层铺砂浓度下的导流能力,提高铺砂浓度有利于形成高导流能力的裂缝;随着闭合压力作用时间的增加裂缝导流能力逐渐下降,降幅为20%—35%。煤层天然裂缝对导流能力有着直接的影响,这种影响在闭合压力较高的情况下表现的尤为明显。

Experimental Evaluation on Conductivity of Hydraulic Fracture in CBM Wells

The hydraulic fracturing technology is an important means of coalbed methane well stimulation. There are big differences between CBM reservoirs and conventional oil and gas reservoirs. The research conclusion of coalbed hydraulic fracture conductivity is different from that of conventional oil and gas reservoir. Thereby it is necessary to carry out the research of coalbed hydraulic fracture conductivity. In this paper, fracture conductivity of coal rock is evaluated by FCES-100 fracture conductometer. The effect of closure pressure, sand concentration, time as well as the natural fractures of coal rock on fracture conductivity are studied. The study shows that as the closure pressure increases, there is a decline of more than 50% about coalbed fracture conductivity. The conductivity under high sand concentration is significantly higher than that under single layer sand concentration. Thereby, increasing the concentration of sand is conducive to the formation of high conductivity fracture. With the time increase, fracture conductivity is decreased with a decline of 20% -30%. Natural fracture has a direct impact on conductivity, and this impact is performed particularly evidently in the case of a higher closure pressure.