ROCK RESISTANCE WHEN DRILLING WITH SMALL CUTTING DIAMOND TOOLS

Abstract

Relevance. The drilling results are influenced by the effectiveness of the rock cutting tool operation at the bottom of the well. The indicators of the mechanical drilling speed, the quality of well construction and sampling are closely related to the correspondence of the selected rock cutting tool and technology of its application to the physical and mechanical properties of the rocks that make up the geological section being opened. With the technology unchanged, the increase in resistance from the bottom hole leads to a change in the intensity of the well deepening. Information about the resistance coefficient allows you to correctly control the process and timely adjust the nature of the impact of the drilling tool on the bottomhole. The purpose of research is to control the power contact of the drilling tool cutters with the bottom of the well; it is necessary to have a methodological apparatus that allows determining the mechanism of rock destruction taking into account the resistance forces. Objects: rock breaking. Methods: experimental, full factorial experiment method, analytical research, analysis. The article presents a method for studying the resistance of rocks to destruction with a diamond cutter, based on the use of the method of a full factorial experiment with obtaining mathematical models of factors and their graphic interpretation, in particular the dependence of deepening in one revolution on drilling modes on the basis of which the resistance coefficient when drilling at a particular moment is determined. Results. Based on the analytical study of the results obtained, the dependence of the tangential force on the axial force, rock properties, and the friction coefficient was determined. The paper presents the analytical research of the possibility of regulating drilling modes in order to achieve the greatest effect from drilling by assessing the drag coefficient as a function of the intensity of destruction or deepening in one revolution. The authors have derived and proved the validity of expression of the drag coefficient dependence on the cutter penetration depth into the rock, the number of cutters at the end of the drilling tool and their size, the depth of the formed fracture groove, the cutter friction coefficient on the rock and the dynamic component of the drilling tool operation.

Keywords

• drilling
• diamond cutter
• full factorial experiment
• tangential force
• resistance coefficient
• cutting force
• drilling modes
• deepening