煤中粗糙裂隙表面接触模式表征及其对渗流的影响OA

To further explore the control mechanism of contact characteristics of rough fracture surfaces in coal on coalbed methane(CBM)migration,enhance the understanding of CBM seepage laws,and better support the efficient exploitation of CBM,this study proposes a 3D rough fracture generation algorithm with controllable surface contact modes by combining the quaternary structure generation set(QSGS)algorithm and the Weierstrass-Mandelbrot function.Equivalent modeling was conducted on multiple groups of rough fractures with different directional growth probabilities,clarifying the control parameters of surface contact modes.Mean-while,the lattice Boltzmann method(LBM)was adopted to simulate the CBM migration process in rough fractures at the pore scale.The influence characteristics of surface contact mode control parameters on CBM seepage were analyzed,and the control mechan-ism of contact modes on fracture flow was revealed.The results show that:the preset contact area ratio is basically consistent with the statistical contact area ratio,which verifies the effectiveness of the proposed rough fracture generation algorithm in characteriz-ing complex surface contact modes;moreover,surface contact modes can be quantitatively described by the anisotropy factor of con-tact regions;under the same pressure gradient,fluid flow velocity depends to a certain extent on the surface contact mode,especially in fractures with significant anisotropy differences in contact regions,the differences in surface contact modes will directly alter flu-id flow paths,thereby affecting the overall permeability of fractures;in addition,hydraulic tortuosity shows a good linear relation-ship with contact modes,and the fitting coefficient is correlated with the contact area ratio,indicating that fluid seepage behavior is jointly affected by contact modes and contact area ratios.