At present, rotary steerable systems are widely used for drilling wells with a large departure from the vertical. The article presents the reasons for the decrease in the system's operability when drilling wells in the territory confined to the Verkhnekamskoye deposit of potash-magnesium salts. The design of the control system of the drilling device is determined, which is pin-joint shaft, which is rolled in supporting node. The shaft angle change is made by creating a deflection force with three wedges located at a radial offset of 120 degrees relative to each other. Each wedge is set in a motion by an electric motor with a planetary gear. The maximum angle of the shaft is 2.5 degrees.
The pin-joint shaft is subjected to strength calculations, which are acted on by axial load, torque and pressure of the drilling fluid during drilling, since the greatest loads arise in the joint of the pin-joint shaft. Mathematical strength calculations evaluated the efficiency of the pin-joint shaft at various parameters of the well drilling mode with horizontal termination. Under the most severe loading conditions, the safety coefficient of the pin-joint shaft at the design maximum contact pressure is equal to 2.75, the calculated value of the contact stresses is lower than permissible. In addition, in the software multi-processor complex ANSYS, the shaft is modeled by the finite element method. The maximum stresses obtained in the contact zone of the keys with the cylindrical grooves of the driven shaft are lower than the design tolerances. This confirms the correctness of the materials choice and design of the control system.
During the construction of directional wells with a large deviation from the vertical in fields confined to the Verkhnekamskoye deposit of potash-magnesium salts, the control system should provide transmission to the bit with an axial load of up to 180 kN, a torque of up to 10 kN∙m and a flush fluid pressure of up to 40 MPa.
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