不同层理倾角与间距对深部煤层水力裂缝扩展规律的影响研究OA

Deep coal seams often have low permeability and high in-situ stress,and the expansion process of hydraulic fractures in deep coal seams is more complex.To investigate the influence of bedding dip-spacing on the hydraulic fracturing of deep coal seams,a finite element model covering various bedding dips(0°,20°,40°,60°,80°)and spacing(4 m,6 m,8 m)of coal rock hydraulic fracturing fracture propagation is established based on the second-order nominal stress criterion of zero-thickness Cohesive element.The hydraulic fracturing effects of coal rock under different bedding dip-spacing conditions were characterized by the hydraulic frac-ture morphology,the maximum fracture width,fracture length,and bedding dip-spacing ratio,and validated in the ZS67 well of Zhengzhuang Block of Qinshui Basin.The study shows that:when the bedding dip is 40°,the fracture network morphology is the most complex;when the bedding spacing is 6 m,the number of fracture branches reaches its maximum value;when the bedding dip is 40° and the bedding spacing is 6 m,the hydraulic fracture area reaches 0.27 m2,showing the best expansion characteristics,form-ing a multi-layered and multi-directional fracture network structure.Under this condition,the fracture extends 19.57 m along the bed-ding plane,with 14 branches,the maximum fracture width of 5.63 mm,and the fracture length of 48.47 m,with the bedding dip-spa-cing ratio of 7.15.The optimization of 40° and 6 m bedding combination scheme significantly enhances the permeability of the frac-turing fluid through Zhengzhuang Block ZS67 well.