摘要：As shale gas resources become more prominent in China's energy development plan, the problem of wellbore stability is one of the thorny issues affecting the development progress. It is necessary to effectively solve the problem of wellbore instability. To achieve efficient development of high-efficiency shale gas, the plugging performance of drilling fluid is an important basis for the stability of the borehole wall, and the plugging agent is an important agent that contributes to the good performance of drilling fluid. The mud shale formation has many microcracks and pores, or even nanoscale pores, making shale very low permeable. The traditional plugging agent has a large particle size, which makes it difficult to effectively block the micro-nano-scale pores in the formation. To solve this issue, a nano-blocking agent NFD-1 was synthesized in this paper. The experiment shows that the nano-blocking agent is nano-dispersed in water with a particle size of about 130 nm, which has little effect on the rheology of the system, and is also blocked by artificial mud cake. Compared with other nano-blocking agents, the plugging agent has strong plugging performance. When the concentration is 3%, the API fluid loss of the drilling fluid can be reduced from 6.3mL to 3.6mL. The HTHP fluid loss is determined by 13.0mL was reduced to 6.9mL, and the blocking ability of the micro-nano pore formation was close to 80% at 5% concentration. At the same time, the plugging mechanism of the plugging agent was studied, which provided technical support and application direction for efficient plugging of drilling fluid.
