基于LB方法的非均质砂质砾岩渗吸规律数值模拟

采用随机四参数法对非均质砂质砾岩孔隙结构进行重构, 基于改进的SC-LBM(Shan-Chen格子玻尔兹曼)模型研究润湿流体在多孔介质中的渗吸行为。结果表明: 初始阶段的界面动力学与孔隙骨架的排列有很大关系, 会形成以基质为主的渗吸界面; 流体流经孔喉部分时, 流动断面瞬间缩小, 导致压力梯度和流动阻力迅速增加, 孔吼压力的存在导致流动断面瞬间缩小, 提高了流动阻力, 说明孔隙半径变化对渗吸速率影响较大; 后期阶段, 润湿流体会形成优势渗吸通道, 降低了波及面积, 大幅度降低了渗吸驱油速率。研究结果有助于理解流体在非均质孔隙中的自发渗吸规律, 对发挥裂缝性致密油藏渗吸驱油作用具有重要意义。

Numerical Simulation of Imbibition Law of Heterogeneous Sandy Conglomerate:Lattice Boltzmann Method

A random four-parameter method is used to reconstruct pore structure of heterogeneous sandy conglomerate. Imbibition behavior of wetting fluid in porous media is studied with an improved SC-LBM (Shan-Chen lattice Boltzmann) model. It shows that interfacial dynamics at the initial stage is closely related to the arrangement of pore skeleton, and the imbibition interface is mainly formed by matrix. As fluid flows through the pore throat, the flow cross section shrinked instantly, leading to a rapid increase in pressure gradient and flow resistance. The presence of hole roar pressure leads to the flow cross section shrinked instantly, which increases the flow resistance, indicating that the change of pore radius has a great influence on imbibition rate. In the later stage, the wetting fluid forms a dominant imbibition channel, which reduces the swept area and greatly reduces the imbibition displacement rate. This study is helpful to understand the spontaneous imbibition of fluid in heterogeneous pores, and is of great significance to imbibition and oil displacement in fractured tight reservoirs.