深层煤岩孔隙结构表征及压裂缝导流能力影响因素

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中图分类号：P618.11 文献标志码：A

Abstract：The fracture conductivity is an important index to determine the fracturing effect of deep coalbed methane reservoirs. The three-dimensional digital core of a deep coal-rock reservoir in Daning block was constructed by using high-resolution CT scanning technology and the advanced mathematical algorithm of Avizo visualization software， and the microscopic pore structure characterization of different types of coal-rock reservoirs was carried out from multiple dimensions.On this basis，the linear flow fracture conductivity experimental device was used to evaluate coal rock fracture conductivity. The effects of proppant particle size，sanding concentration，different proppant particle size combinations， closure pressure， proppant embedding and pore throat structure on the fracture conductivity of coal rock were systematically studied. The results show that the pore structure characteristics of different types of coal rock samples in the study area are significantly different. The distribution form of pore throat is mainly continuous or isolated. The pore radius is distributed primarily in 5.23-34.85μm ，the throat radius is mostly 1.31-12.27μm ， and the pore throat coordination number is small. With the decrease in permeability，the connectivity of the pore throat worsens and the heterogeneity strengthens. The fracture conductivity under the support of large particle size proppant is stronger， but the fracture conductivity under the support of small particle size proppant is more stable. The fracture conductivity increases significantly with the increase of sanding strength but decreases with the increase of closure stress. When the propping agent is embedded in the coal and rock strata， the flow space of the fluid in the fracture wil be compressed and blocked，and the fracture conductivity can be decreased by 12.2% Under different proppant particle size combination ratios，the higher the proportion of large particle size proppant，the greater the conductivity. In general， the main controlling factors of fracture conductivity of coal-rock pressure in this area are sanding concentration，proppant particle size，and fracture closure stress.

Key words： coal rock； pore structure； fracture conductivity； proppant particle size； sandingconcentration;closure stress

0 引言

我国煤层气资源储量丰富，抽采量巨大，开发前景广阔[1-4]。（剩余21394字）