【摘要】 有效致密封堵微裂缝是钻井液稳定泥页岩井壁的主要技术措施之一。微纳米封堵颗粒和微裂之间存在着复杂的力学作用关系,简单的理论分析无法精确描述这一复杂的物理过程。为了进一步说明泥页岩微裂缝的微观结构和固体颗粒封堵剂的封堵过程,利用离散元PFC 2D模拟软件对封堵颗粒侵入微裂隙封堵过程进行模拟,分别研究了4种不同裂缝倾角、3种不同开度的纳米级和微米级裂缝、3种不同压差下的封堵过程。结合观察分析缝内封堵状况,结果表明:地层倾角对封堵颗粒侵入地层程度影响较小;符合1/3规则的颗粒较适合于封堵裂缝;压差增大到1.5 MPa时,达到最佳封堵状态,再随着压差的增大,封堵效果变差;随着封堵颗粒浓度增加,封堵效果会趋于稳定。更多还原

【Abstract】 Effective sealing and micro-cracking is one of the main technical measures for drilling fluid to stabilize mud shale shaft wall. There is a complex mechanical relationship between micro-nano-blocking particles and micro-cracks, and simple theoretical analysis cannot accurately describe this complex physical process. In order to further explain the micro-fracture of micro-fractures of mud shale and the plugging process of solid particle plugging agent, the discrete element PFC 2 D simulation software was used to simulate the process of plugging particles into micro-crack sealing, and four different cracks were studied respectively. Inclination, three different levels of nano-scale and micro-scale cracks, three different pressure differential blocking process. Combined observation and analysis of the sealing condition inside the seam, the results show that the formation inclination. It has little effect on the degree of intrusion of the sealing particles into the formation;the particles conforming to the 1/3 rule are more suitable for sealing the crack;when the pressure difference increases to a certain value, the optimal sealing state is reached, and then the pressure difference increases. The plugging effect is deteriorated; as the concentration of the plugging particles increases, the plugging effect tends to be stable.更多还原