Design of double-shoulder threaded joints of drilling string elements

Abstract

Purpose. Development of a method for simulating the screwing torque/moment and researching the design of double-shoulder threaded joints while preserving their geometric parameters. Determination of the optimal length of the additional shoulder pin part for the developed drill collar (DC) of NC50, NC55 type of various standard sizes. Establishing the dependence between the pin part length of the additional shoulder and other geometric parameters of the double-shoulder joint of the DC for further use when developing other standard sizes of similar design threads. Methodology. The development of design and the method for simulating the screwing torque of double-shoulder threaded joints was carried out using the finite element method and parametric modeling. Finding. A method for simulating the screwing torque of threaded joints was proposed and developed, which made it possible to improve the model of their automated design. The optimal lengths of the pin part of the additional shoulder of the developed design of double-shoulder threads of the NC50, NC55 types were determined. For planning threaded joints of similar design with the above-mentioned types of threads, a dimensionless coefficient was derived and its value was calculated. A nomogram was built to determine the length of the joint additional shoulder pin part due to the value of this coefficient. Originality. The model of automated design for double-shoulder threaded joints of drill string parts has been improved. This model preserves their geometric parameters and enables modeling a wide range of standard sizes of similar joints. Practical value. The optimal geometric parameters of the developed structures of double-shoulder threaded joints of the drill string elements were determined. A nomogram was built to determine the length of the additional shoulder pin part of the joint by the value of the dimensionless coefficient.