基于大尺寸地层模型的砂岩储层油基钻井液侵入模拟

选用扇形砂岩地层模块作为大尺寸地层模型，以钻井液侵入多功能物理模拟系统为平台，实施了长时间油基钻井液侵入实验，总结了侵入过程中地层模块径向电阻率、油基钻井液滤液滤失流量和侵入深度的变化规律，获得了不同物性条件下的油基钻井液侵入特征；实现了地层条件下的砂岩储层油基钻井液侵入数值模拟。研究结果表明：油基钻井液侵入过程中，地层模块径向电阻率向远离井壁方向依次开始增大，且增大速度随径向深度增大而降低。侵入初期，滤液滤失流量迅速减小，累计滤失量增幅变缓，侵入深度较浅；侵入达到动态平衡后，滤液滤失流量趋于稳定，累计滤失量随侵入时间线性增加，侵入深度增大速度极慢。与高孔渗砂岩储层相比，低孔渗砂岩储层中的滤液滤失流量和累计滤失量更大，侵入更快、更深，径向电阻率率先增大且增大速度更快。

Simulation of oil-based mud invasion in sandstone reservoir based on a large-sized formation model

By choosing a sectorial sandstone formation module as the large-sized formation model, and a multifunctional physical simulation system of drilling mud invasion as the platform, this study carries out long-term oil-based mud invasion experiments, summarizes the variation laws of the radial resistivity of formation module, the filtration rate and invasion depth of oil-based mud filtrate, obtains the characteristics of oil-based mud invasion under different reservoir physical properties, and finally realizes the numerical simulation of oil-based mud invasion in sandstone reservoir under formation conditions. The results show that the radial resistivity of formation module increases in turn during oil-based mud invasion, and its increase rate slows down with the increasing of radial depth. At the beginning of invasion, the filtration rate decreases rapidly, the increase rate of the cumulative filtrate volume slows down, and the invasion depth is shallow. After the invasion reaches a dynamic equilibrium state, the filtration rate tends to be stable, the cumulative filtrate volume increases linearly with time, and the increase rate of the invasion depth tends to be very slow. For the low porosity and low permeability sandstone reservoir, as compared with the high porosity and high permeability sandstone reservoir, the filtration rate and cumulative filtrate volume are greater, the invasion is faster and deeper, and the radial resistivity increases earlier and faster.