裂缝性地层封堵系统突变失稳机理与控制

With petroleum exploration and development pointing towards deep formation, lost circulation has becoming one of the obstacles to safe and effective drill operation. The project studies lost circulation in typical fractured formation in China, and bases on system science ideology to take formation, rock and plugged zone as a sealing system. From the view of sealing system structure instability, experimental evaluation and numerical simulation were used together to study influence of geometrical morphology parameters, strength parameters, fraction coefficient and other mesomechanics parameters of sealing system on pressure-bearing stability of sealing system, and then mesomechanics mechanisms of pressure-bearing destabilization of sealing system was analyzed. On this basis, catastrophic model was built using catastrophic theory in system science considering rock structure parameters, fracture-plugged zone contact parameters and mesomechanics parameters of plugged zone; besides, pressure-bearing destabilization mechanism of sealing system was revealed; in addition, experimental evaluation and case analysis were used together to demonstrate the applicability of the model. Taking sealing material property, pressure-bearing effect and formation damage control as assessment criteria, optimizing principle of high pressure-bearing temporary sealing materials was explicated and method of reinforcing bearing-pressure capacity of sealing system in fractured formation was established through optimal experiments on pressure-bearing capacity of plugged zone and sensitivity factor analysis on pressure-bearing capacity of sealing system.

随着油气资源勘探与开发走向深部，井漏问题已成为制约安全、高效钻井的主要障碍之一。项目以我国典型裂缝性地层漏失为研究对象，基于系统科学思想，将地层、岩石-封堵带界面、封堵带三者看成一个封堵系统，并从封堵系统结构破坏角度出发，采用实验评价和数值模拟相结合的手段研究堵漏材料几何形貌参数、强度参数、摩擦系数等细观力学参数对封堵系统承压稳定性的影响，分析封堵系统承压失稳细观力学机制。在此基础上，通过引入系统科学中的突变理论，考虑岩体结构参数、裂缝-封堵带接触参数，封堵带细观力学参数，建立封堵系统承压失稳突变模型，揭示封堵系统承压失稳机理，并结合实验评价与案例分析验证模型可靠性。以模型分析为指导，将堵漏材料性能、承压效果及储层保护作为评价指标，通过开展室内封堵承压优化实验，并结合封堵系统承压能力敏感性因素分析结果，明确高承压暂堵堵漏材料优选原则，并构建裂缝性地层封堵系统承压能力强化方法。

井漏问题是制约安全、高效钻井的主要障碍之一。本课题以我国典型裂缝性地层漏失为研究对象，开展了裂缝性地层封堵系统突变失稳机理与控制研究，并取得了如下成果：（1）从封堵系统结构破坏角度出发，采用实验评价手段重点研究了堵漏材料摩擦系数变化特征以及摩擦系数对封堵的影响；（2）通过引入系统科学中的突变理论，考虑岩体结构参数、裂缝-封堵带接触参数，封堵带细观力学参数，建立封堵系统承压失稳突变模型，揭示封堵系统承压失稳机理，并结合实验评价与案例分析验证模型可靠性；（3）通过开展室内封堵承压优化实验，并结合封堵系统承压能力敏感性因素分析结果，明确高承压暂堵堵漏材料优选原则，并研发了致密储层纳微米暂堵材料和可酸溶固化堵漏材料；（4）明确了钻井液漏失对非常规储层碱液侵蚀损害和水相圈闭损害机制；（5）研发了用于评价钻井堵漏材料性能及封堵带酸溶解除效果装置，并获得了发明专利授权。以上研究成果进一步丰富了钻井液漏失控制理论体系，且具有较大成果转化潜力。