Grytsiv V. Improved methods of predicting resource elements of the drill string

The thesis is devoted to solving problems of reliable operation of the drill string elements by improving methods of forecasting their resource. The three-dimensional model of the threaded joint with full reproduction of its design and process parameters, which allows evaluating the stress-strain state using simulation modeling has been developed. The method of predicting of the drill pipe resource on the basis of C-criterion by taking into account the local stresses arising in the threaded joint drill pipe, determined by the simulation results has been improved. Experimental researches of the kinetics of fatigue cracks of the drill pipe material have been conducted by taking into account peak loads. Experimental researches of the longevity of full-scale specimen of the threaded connections of the drill pipes have been conducted. The method of predicting the longevity of the drill pipes including operating load has been improved. Experimental researches of the corrosion-electrochemical behaviour of tubular steel in mud have been conducted