基于FDEM-flow方法研究非均质性对水力压裂的影响

Effect of Heterogeneity on Hydraulic Fracturing Based on FDEM-flow Method

用FDEM-flow方法作为工具,研究材料的均质度、空间排列对水力压裂的影响。研究表明,随着注入水压的增大,圆孔周界的最大主应力增大,增大到一定值,产生裂隙,裂隙主要由受拉破坏产生。裂隙穿过的区域出现拉应力释放,裂隙端部的应力集中区随裂隙的扩展而向外移动。均质度系数较小时,分叉裂隙较多,裂隙扩展路径不平整,并呈现出非对称性;均质度系数增大,分叉裂隙减少,裂隙扩展路径越平直,呈现的对称性越明显。起裂压力也随均质度系数的增大而增大并趋于稳定。材料的空间排列不同,其起裂位置、扩展形态均有较大的差别,起裂压力也随之波动。

The effect of heterogeneity and spatial distribution of the material on hydraulic fracturing was investigated by the FDEM-flow method. It is concluded that,with the increase in the injection pressure,the maximum principal stress of the perimeter hole increases,when it increases to a certain value,cracks were generated mainly by tensile failure. Tensile stress release at the region cracks pass through. Stress concentration zone moves outward with the expansion of cracks. When homogeneous coefficient is small, fissures bifurcation were produced, crack propagation path is not smooth and asymmetry; however,when heterogeneity coefficient increases,the bifurcation of fissures were reduced,and,the crack propagation path is more straight,symmetry is more obvious. Initiation cracking pressure increases with homogeneity coefficient and tends to constants. The initiation pressure and crack propagation is different,when the spatial arrangement of materials is different