DIRECTED SLANT DRILLING METHOD Russian patent published in 1995 - IPC

FIELD: oil and gas industry. SUBSTANCE: method for directed slant drilling of wells with prescribed intensity of deviation involves determination of a place of mounting of an elastic centralizer on its guiding rod. The axial load value is calculated taking into account rigidity of support laths of the centralizer. The axial load value is calculated from the following equation , where D,D₀,D_t,D_c are values of diameters of the bit, centralizer in the free state, and bearing surface area at the upper end of the guiding rod and borehole respectively, m; L, l and l_o are distances from the upper end-face of the guiding rod to the working end-face of the bit, bearing surface of the centralizer, and center of masses of the guiding rod respectively, m; m is mass of the guiding rod, kg; σ_str is strength of the rock to be drilled, kN/mm; S_cont is effective area of the bit contact surface, mm; h is the rock anizotropy factor; θ_o is the rock bed pitch angle, deg; ϕ` is the borehole vertical deviation angle, deg; f is rigidity of the support laths of the centralizer frame, N/m; and i is the borehole deviation intensity in the well bottom interval, rad/m. In the interval of drilling of the vertical deviation angle stabilization section, the axial load is set to be equal to the calculated value, and in the vertical deviation angle growth interval the value of axial load is set to exceed the calculated value. EFFECT: higher efficiency; higher drilling accuracy. 1 dwg