Design and simulation analysis of drill lock assembly for casing directional drilling

Abstract:

Casing directional drilling technology is a new type of directional drilling technology， which has the advantages of both casing drilling and directional drilling， and can achieve efficient directional drilling targets. As a key component in the casing directional drilling system， the performance of the locking device will have a direct impact on the drilling reliability. In this paper， a structural form is designed to seal all the parts of the moving mechanism of the lock， and the bearing capacity of the torque transfer and axial limit in the lock is calculated and analyzed. The two-parameter Mooney_Rivlin superelastic constitutive model is used to analyze the assembly clearance of the key seal O-rings at both ends and the sealing pressure of the rubber hardness. When the locking core is subjected to the maximum braking torque of 65011N·m， a single torsion key is subjected to the torque of 10835N·m with a stress of 74.86MPa， and a single positioning card can withstand the vertical bearing capacity of 184520N with a stress of 659MPa， both of which are less than the yield strength of the used material of 930MPa. The axial bearing capacity and torsional performance of the lock meet the design requirements. Mises stress and shear stress will increase when the gap is smaller. Excessive stress will damage the seal ring and make it difficult to assemble. The simulation results show that the contact pressure on the surface of the O-ring is greater than the external pressure within the selected tolerance range. Therefore， the fit gap is selected with large value； The greater the rubber hardness， the better the sealing performance of the O-ring and the smaller the deformation of the O-ring under the same medium pressure. By numerical simulation， the O-ring with 90HA hardness can meet the sealing requirements of the lock.

Key words:casing directional drilling;the drill lock assembly;hyperelastic constitutive model;O-ring;sealing performance