Vibration-Impact Damper for Controlling the Dynamic Drillstring Conditions

With the present surface hole drilling technique and technology, all forms of drilling are accompanied by considerable vibrations, which have a deleterious effect on the life of the drillstring elements and the surface equipment, worsen the working conditions of the rig crews, and are responsible for an inefficient process of rock disintegration [1‐3]. Analysis of the experimental data and the models of well-deepening processes that describe them has established that the axial static load and the drilling bit rotation speed must be increased to ensure greater mechanical speed and penetration with sufficient flushing. That possibility is limited by the growing drillstring vibrations, especially when drilling ou t very hard rock or when rocks with different mechanical properties alternate very frequently (e.g., in near-Carpathian regions). The following special vibration-protecting devices must be used to solve the problems. The use of such devices in oil- and gas-well drilling has a specific nature: the vibrations need not be completely damped; a certain balance must be created between the dynamics of the drillstring and its level of vibration protection, which increases the drilling efficiency and at the same time improves the operating conditions of the drilling equipment. Vibration protection of drilling equipment and control of the dynamic conditions of the drillstring are provided by devices that differ as to operating principle and design. flexible couplings; • screening of elastic waves, propagating from the drilling bit and from the source, by special “reflectors;” • preventing transverse vibrations and relaxation self-oscillations by decreasing the radial clearance between the tool joints and the hole walls with the installation of centralizers, stabilizing reamers, and centralizing reamers; • dissipating the vibrations and changing the dynamic conditions of the drilling drillstring by means of dynamic