INFLUENCE OF THE BOTTOM BOREHOLE ZONE ENVIRONMENT ON THE EFFICIENCY OF ROCK BREAKING BY THE PDC CUTTER

Relevance. The PDC cutter reinforced rock cutting tool has proven itself as a rock cutting tool with good performance. As it is known from drilling practice, a tool of this type, with the correct technology of its application, is capable of providing high rates of penetration of wells and resource. Therefore, one of the priority directions in the development of technical means of drilling is to improve the design of the PDC-type tool. New generation drilling tool design methods should be based on an integrated approach to the study of its work at the bottom. One of the main factors affecting the effectiveness of the implementation of rock cutting tools is the bottomhole resistance. A large number of works have been devoted to the study of changes in the physical and mechanical properties of a geological section with depth. And the liquid medium formed at the bottom of the well as a result of drilling is poorly studied. Often, when conducting scientific research, the presence of cuttings in the bottomhole zone is neglected. However, taking into account the peculiarities of the shape and size of the cutting part of the PDC cutters, the displacement of cuttings and continuously moving drilling fluid can have certain density and create a buoyant force acting on the plane of the cutter and, as a result, affect the efficiency of the drilling tool as a whole. Therefore, an urgent issue is to study the properties of the media, consisting of a flushing agent, cuttings and destroyed rock and determine the degree of its influence on the results of the PDC-type drilling tool. The purpose of the research is to determine the degree of influence of the resistance forces of the medium formed in the bottomhole zone of the well on well drilling. Methods: analytical method, computer simulation method. Results. The medium formed in the near-wellbore zone when drilling a well and consisting of rock, cuttings and flushing fluid, which are in different states, has a pushing effect on the cutter, which reduces the size of the deepening. The index of the resistance degree of the described medium is determined by the cutting speed, the angle of the cutter and the density of its components. The results obtained can be used in the design of a PDC-type drilling tool. Changing the angle of installation or the shape of the cutter can help not only to reduce the resistance forces, but also to improve the destructive ability of the tool due to the decompaction of the rock by intensifying liquid penetration into the rock.