ANALYSIS OF MODERN DESIGNS OF DRILL COLLARS TOOL JOINTS

Abstract

The analysis of failures of the drill columns elements showed that, despite the constant improvement of the design of their thread connections, the percentage of thread failures does not decrease. Today, world-wide manufacturers
have developed new designs of double shoulder joints, which contain additional support of pin and box. According to it, the distribution of loads in the thread connection is improved. In its turn, it increases the make-up
torque up to 70% compared to the standard single shoulder connection. However, there is a doubt that the increased make-up torque of double shoulder joints will not lead to such redistribution of stresses, at which the probability of rapid destruction of the structure of both the pin and the box in the area of the additional thrust face. The constructive methods, which are not indicated in any information sources, are used for the redistribution of stresses in a double shoulder joint. That`s why, the imitation modeling is used to determine the distribution of the stress-strain state of double shoulder joints. According to the results of the use of the additional end face, the distribution of stresses in the cavities of the threads is improved. But the value of the overlap of the ends should be strictly regulated. It is determined that the optimal value of the overlap of the main end face is 0.1 mm, and the additional one is 0.2 mm. If the value of the overlap of the additional end is 0.3 mm, it will lead to the destruction of the joint on the body of the box. Otherwise will lead to the destruction of the pin in its first thread. Thus, it is necessary to control strictly the magnitude of its tension for the use of the considered construction of the double shoulder joint of drill collar.