页岩气裂缝性地层剪切滑移坍塌机理与水基钻井液稳定方法

页岩气裂缝性地层长水平段钻井过程中，钻井液侵入降低裂缝壁面摩擦力，产生剪切滑移，易引发井壁坍塌。目前国际上强抑制强封堵钻井液无法解决该类剪切滑移井壁坍塌难题。本项目拟围绕页岩气裂缝性地层剪切滑移坍塌机理与水基钻井液稳定方法的科学问题，通过研究水基钻井液侵入对页岩气裂缝性地层力学特性的影响规律，厘清考虑钻井液润滑作用的裂缝壁面剪切滑移机制，探明裂缝性地层剪切滑移坍塌影响因素，揭示页岩气裂缝性地层剪切滑移坍塌机理；研制能够高效抑制页岩裂缝剪切滑移的粘结功能型固壁剂和有效阻止钻井液侵入裂缝的自适应封堵剂；以研制的两种处理剂为核心，优选与之相配伍的水化抑制剂及润湿调节剂等，建立一套“粘结裂缝、强化封堵、高效抑制、润湿适宜”的多功能一体化稳定页岩裂缝的有效方法，构建适合于页岩气裂缝性地层长水平井钻井的高性能水基钻井液，为我国页岩气安全高效开发提供理论与技术支撑。

During the process of long horizontal drilling in shale gas fractured formation, the invasion of drilling fluids reduce the friction between fracture walls and cause shear slip, which lead to wellbore collapse. At present, drilling fluids with strong inhibition and plugging can’t solve the problem of shear slip and wellbore collapse around the world. This project focuses on the scientific problems of the shear slip and collapse mechanism in shale gas fractured formation and the stabilization method of water-based drilling fluids. By studying the influence of the invasion of water-based drilling fluids on the mechanical properties of fractured formation, the shear slip mechanism of fracture wall considering the lubrication of drilling fluids is clarified. In addition, the influencing factors and shear slip and collapse mechanism in shale gas fractured formation are explored. Then, the project will develop the adhesive functional wall fixing agent and self-adaptive plugging agent which can effectively inhibit the shale fracture slip and prevent the invasion of drilling fluids，respectively. Based on the two developed treating agents, the project optimizes the hydration inhibitors, wetting regulators and other treatment agents, establishes an effective multifunctional integrated method to stabilize shale fractures with “adhesive fracture, enhanced plugging, high-efficiency inhibition and suitable wetting”, and build a high-performance water-based drilling fluids suitable for long horizontal well drilling in shale gas fractured formation, which provides theoretical and technical support for the safe and efficient development of shale gas in China.