Abstract: “This paper deals with simulating the regimes of drilling deep curvilinear bore - holes with presc ribed geometrical imperfections of their axial lines. The interpolation techniques (spline approximation) are used for the well shape representation. On the basis of the theory of curvilinear flexible elastic rods, the 3D “stiff - string” drag and torque mod el of the drill string bending is elaborated. With its application it is shown that the contact and friction forces generated by interaction of the drill string with the bore - hole surface can be calculated and regulate, after their analysis, the regimes of buckling and dead lock states of drill strings in the curvilinear cavities of the bore - holes are simulated.”

Keywords: bore-hole channel, elastic drill string, contact forces, resistance forces, critical buckling