OPTIMIZATION AND APPLICATION OF MECHANICAL MODEL OF WIRE CORING STRING WITH PACKED HOLE ASSEMBLY

In order to solve the problems of low anti-slope ability and poor drilling trajectory control of conventional wire-line core drilling tools structure, this paper optimizes the mechanical model of drilling tools assembly at the bottom of the hole based on the longitudinal and horizontal bending continuous beam theory of classical pipe column mechanics: the core drilling bit and the lower reamer are regarded as the whole of the drill bit, but not as the first span; the pipe column whose stabilizer spacing is smaller than the span of the tangent point is regarded as a rigid body. On this basis, a structural model of the pipe column to improve the deflection resistance and trajectory control of the drilling tool is proposed, and verified by drilling construction, it is concluded that the theoretical anti-slope effect of the pipe column structural model and the actual drilling trajectory change match with each other, which provides an effective theoretical guidance to improve the quality of wire-line core drilling.