Optimization of the Damping Element of Axial Vibrations of the Drilling String by Computer Simulation
During well-drilling in conditions when bedding of solid rock is at shallow depth (from the first meters) there are significant vibrations of drilling string and connected equipment. In such situation when length of a drilling string is small and axial load on drilling bit is minimum, the effective device is necessary for compensation of axial pushes and vibrations. At the same time the geometrical shape of the damping element has to ensure the stability at significant excess of limit load and reliability. Warranty of shape retention at drilling depth increase (and respectively, increase of drilling string length and weight) will allow to avoid the additional round-trip operations for extraction of the damping device. The study considers the main stages and features of computer simulation of damping elements operating at shallow depth of solid rock bedding by finite element method and also the subsequent optimization of its design which has allowed to increase a compliance from 0.8-15 mm and at the same time to provide sufficient strength reliability. The calculation model of the analysis and also boundary conditions for modeling of multicontact interaction of slot surfaces of damping elements is described in detail. The computer simulation allows to perform optimization of model at a designing stage. It considerably reduces costs for creation of new model of a design as excludes need of production of several natural samples and their bench testing for durability verification.