Yurych A. Improvement of design methods and technologies using non-directional bottom-hole assemblies.

The thesis is dedicated to drilling efficiency increasing through improved methods of selecting and adjusting of the undirected BHA parameters based on the actual conditions of their work. The factors that cause deviations between actual and design well path are analyzed. The theoretical study of destabilizing factors effect on the stability of the BHA and experimental study of the zenith angle and axial load effects on the magnitude of the bending moment along the length of unsupported BHA are provided. Method for estimation of the influence of local irregularities on the borehole stress-strain state of the BHA is improved. The recommendations for improving the reliability of undirected design of BHA are developed.