Mechanism and Material Development of Temperature Activated Bonding Plugging for Lost Circulation Control in Deep Fractured Formations

Summary Lost circulation is a significant challenge during drilling operations. To mitigate this issue in fractured formations, the most commonly used methods are bridging and plugging, which help seal off fractures and prevent the loss of drilling fluids. However, the sealing layer formed by bridging materials is inherently discontinuous, relying on physical forces such as elastic force, friction, and interlocking to maintain its stability. This limits the further enhancement of pressure-bearing performance. Consequently, in deep and ultradeep formations with harsh environments, challenges persist regarding insufficient pressure-bearing capacity for fracture sealing and poor unplugging efficiency. Therefore, enhancing interparticle forces through the introduction of chemical adhesion has become a key strategy to improve the pressure-bearing capacity and overall stability of the sealing layer. To address this technical challenge, we developed a novel core-shell structured plugging agent TPA-1 with high-temperature-activated bonding characteristics. The thermal activation time of TPA-1 at 110~140°C ranges from 2.75 hours to 6.25 hours, ensuring safety during on-site plugging operations. When combined with bridging plugging materials, TPA-1 effectively sealed a 3-mm fracture, achieving a maximum pressure-bearing capacity of 15.4 MPa. Furthermore, when mixed with self-degradable materials for temporary plugging of reservoir fractures, the post-unplugging fracture permeability reached 9785.8 md. The temperature-sensitive adhesive plugging agent TPA-1, as proposed in this study, remains functionally identical to conventional bridging plugging materials at ambient temperature, aiming to provide a simple and highly safe functional adhesive plugging material for field applications.