Study on Construction Parameters of Pressure Bearing Plugging Considering High Stress Difference

As a common technology for the prevention and control of lost circulation in low pressure bearing formations, the theoretical system and plugging materials have made great progress, but the important construction parameters have not been paid enough attention. Therefore, according to the underground in-situ stress environment, this paper selects high-strength plugging materials, and establishes the pressure plugging experimental scheme with different construction parameters and plugging materials while drilling.The self-developed large-scale true triaxial pressure plugging experimental equipment is used to conduct the test on the dense sandstone sample (size: 300 mm×297 mm×297 mm), and the hydraulic-fracture propagation law was observed. Based on the hydraulic-fracture, the pressure plugging experiment was carried out.According to the experimental results, for the formation with weak bearing capacity, the construction parameters will cause the pressure change in the well, thus affecting the plugging effect; repeated plugging operations in the same formation will cause fracture expansion and reduce the plugging effect; the sequence of plugging slurry entering the fracture and the structure of the plugging layer are closely related to the geometric parameters of the fracture. The regular knowledge obtained in this paper can provide some reference for the formulation of pressure plugging scheme.