剪切闸板防喷器剪切钻杆断口凸起高度评估

The fracture sectional raised height is an important aspect of the fracture sectional deformation degree and the degree of deformation of the drill pipe fracture is an vital basis for evaluating the shear performance of the shear ram blowout preventer (BOP), which is directly related to the recycling and efficiency of the drill pipe. In order to make a reasonable assessment of the raised height of drill pipe fracture section, based on the basic laws of kinematics, the motion equations of the shear ram were established and the construction parameters were comprehensively considered. After that based on the matrix form of the coordinate conversion formula and the theory of slip line, the theoretical prediction of the fracture sectional raised height of the drill pipe caused by the single shear point at any time and the final were derived. Then the position of fracture sectional raised height of the drill pipe was identified and the evaluation model of the fracture sectional raised height of the drill pipe caused by the single shear ram was established. The shearing experiment of shear CT90 coiled tubing was carried out with a shear ram blowout preventer, and the fracture data of the CT90 coiled tubing was acquired to verify the evaluation model. The results showed that the assessment model established in this paper is close to the height of the fracture elevation obtained by the shearing test. The relative error is within 10%, with high reliability and applicability. The impact of the critical structure parameters of the shear ram impact block and drill pipe, such as V-angle and edge chamfer, on the fracture sectional raised height of the sheared drill pipe was further analyzed. The study showed that with the increase of the V-angle, the drill pipe fracture sectional raised height increases, and with the increase of edge chamfering, the height of fractured of the drill pipe changes in a wave shape, and the troughs gradually increase. When the edge chamfering angle is 20 °, the height of the drill pipe fracture bulge is minimum, and the drill pipe fracture sectional raised height increasies with the increase of the length of the shear point to the center point of the V-shaped angle. In the case of meeting well control requirements, when designing the shear ram, the edge chamfer of the impact block should be 20 °. The smaller the V-angle, the better and shorten the length of the shear point to the V-shape as much as possible. The height of the fractured drill pipe increases with the increase of the drill pipe inner diameter and wall thickness in meeting the drilling and mining requirements, choosing smaller-diameter thinner-walled drill pipe.