The spiral seam submerged arc welded steel pipe rotates and starts to enter the soft formation. Under the action of the tri-cone, the drill bit first produces elastic shear deformation of the formation, and then it is removed under the pressure of the tri-cone. In the simulated environment, the soft soil is a homogeneous clay, regardless of the formation and cracks in the soil. Horizontal directional drilling is carried out in abrupt formation, where the formation is in random dynamic contact with the roller cone bit. Friction occurs when the cone is in contact with the formation. The impact force makes the spiral seam submerged arc welded steel pipe vibrates. When the tri-cone bit moves from soft formation to hard formation, it will inevitably generate large lateral vibration and up-and-down vibration.
When the drilling speed is 0.008m/s and the bit speed is 2 radians/s, the pseudo-strain energy curve during the advancement of the roller cone bit mainly includes viscosity and elasticity. However, since the viscous term usually dominates, the conversion of most of the energy to pseudo-strain energy is irreversible. The deformation energy of the spiral seam submerged arc welded steel pipe is the main energy consumed to control the deformation of the hourglass. If the pseudo strain energy is too high, the strain energy controlling the deformation of the hourglass is too large, and the mesh is refined or modified. To reduce excessive spurious strain energy. The pseudo-strain energy mutation in this model mainly occurs when the drill bit enters the soft soil layer and the roller cone bit passes through the abrupt formation interface. The greater the formation hardness, the greater the pseudo-strain energy of the drill bit into the formation. The drilling process of the spiral welded pipe in the sudden change formation is simulated, and the change of the drilling trajectory of the drill bit is predicted.
(1) The sudden change of pseudo strain energy mainly occurs when the drill bit enters the soft soil layer and the roller cone bit passes through the interface of the abrupt formation. The higher the forming hardness, the greater the pseudo-strain energy of the spiral seam submerged arc welded steel pipe when it enters the forming process.
(2) When the stratum is drilled suddenly, the spiral seam submerged arc welded steel pipe moves longitudinally and the drill bit vibrates. The greater the formation hardness, the greater the drill bit amplitude.
(3) Under the condition of a certain formation inclination, the greater the drilling speed of the drill bit, the greater the longitudinal deviation of the drilling trajectory, and the greater the rotation speed of the drill bit, the smaller the longitudinal deviation of the drilling trajectory. When the bit speed is lower than 2.2rad/s, the effect of the speed on the longitudinal deviation of the drilling trajectory is reduced.
(4) Under a certain bit rotation speed, when the local formation dip is 0° and 90°, it does not affect the drilling trajectory; when the local dip gradually increases, the longitudinal deviation of the drilling track increases; when the local dip exceeds 45°, the influence on the longitudinal deviation of the drilling trajectory is reduced. The research results in this chapter are of great significance for improving the prediction accuracy of the tricone bit drilling trajectory in steep formations, and laying a theoretical foundation for correcting the drilling trajectory of the spiral seam submerged arc welded steel pipe through the horizontal pilot hole.