The spontaneous imbibition of fracturing fluid in the shale matrix is one of the main reasons for the low hydraulic fracturing flowback rate. The distribution characteristics of fracturing fluid in the shale spontaneous imbibition process are studied by the low field nuclear magnetic resonance (NMR) method. An improved pseudo-potential lattice Boltzmann model is proposed to simulate the spontaneous imbibition behavior in a three-dimensional porous shale structure. The results show that the viscosity, sample length, and permeability of the imbibition solution have an important influence on the imbibition characteristics of the samples. In the imbibition process based on the SC-LBM model, due to the capillary force effect, the imbibition liquid preferentially enters the larger pores of the wetting phase and then gradually distributes in the adjacent pores.

页岩基质中压裂液的自吸是造成水力压裂返排率低的主要原因之一。采用低场核磁共振(NMR)方法研究了页岩自吸过程中压裂液的分布特征。提出了一种改进的赝势格子 Boltzmann 模型来模拟三维多孔页岩结构中的自吸行为。结果表明，渗吸溶液的粘度、样品长度和渗透率对样品的渗吸特性有重要影响。在基于 SC-LBM 模型的渗吸过程中，由于毛细管力效应，