考虑煤体层理方向效应的液态CO2致裂增透规律
Fractures and Permeability Improvement Law of Liquid CO2 Considering Direction Effect of Coal Bedding
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摘要: 为研究循环注入液态CO2过程中煤体层理方位对致裂效果的影响,利用非金属超声波检测分析仪与低场核磁共振仪研究了不同循环注入液态CO2煤样的损伤程度及孔隙发育程度。结果表明:煤层层理对煤体的冻融损伤破坏模式及内部孔隙发育均有一定程度的影响;层理方位首先影响煤体裂纹的起裂位置,进而影响其破坏模式及孔隙扩展、延伸、连通;随着循环注入液态CO2次数的增加,煤体表面因冻胀融缩作用引起的裂纹逐渐增多、变宽,煤体内部原有孔隙增大并产生新孔隙,不同层理方位效果不同。Abstract: To study the effect of the coalbed bedding orientation on the fracturing effect during the cyclical infusion of liquid CO2, the non-metallic ultrasonic detector and low-field NMR spectrometer were used to study the degree of damage and pore development of different liquid CO2 injection. The results show that coal seam bedding has a certain degree of influence on the freeze-thaw damage mode and internal pore development of coal. The bedding orientation firstly affects the crack initiation position of the coal body, and then affects its failure mode and pore expansion, extension, and connectivity. With the increase of cycle numbers of injecting liquid CO2, the cracks caused by frost heave expansion and contraction of the coal surface gradually increase. The original pores in the coal increase and produce new ones, and different bedding azimuth effect is different.
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Keywords:
- liquid CO2 /
- coal bedding /
- cyclic injection /
- degree of damage /
- porosity /
- fractures and permeability improvement
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