Determination of cam parameters of fixation node of the device for unscrewing of stuck pipes in the well

Abstract

Improvement of repair work efficiency in the elimination of drill pipe accidents  in a well is an extremely urgent task of oil field enterprises, and is achieved using special devices and tools. This paper analyses research and publications on this topic. The authors patented a device for unscrewing pipes in a well, in the fixation unit of which the use of a block of eccentric cams was proposed, and its experimental working model was made for research in a casing with a nominal diameter of D = 114 mm. The cycle of the device for unscrewing pipes in the well consists of three main periods: free running, jamming of the carrier of the device for unscrewing stuck pipes and the period of wedging. The article analyses operating conditions of the device fixation unit in the first two periods. The dependences of the power and geometric parameters of the device fixation unit on the angle of rotation of the cams are derived. Formulas are proposed for determining the force of pressing the cams against the casing during free travel, the moment of friction forces and power for this case. The dependence of the maximum permissible initial jamming angle on the friction coefficient and the geometric parameters of the device has been established. The lifting angle of the working surface of cams is determined. After substantiation of additional parameters of the block of cams to fulfill the condition of strength of its materials, it is planned to test a device for unscrewing pipes in an industrial environment in Factorial LLC, Poltava.