Improvement and research of the pump rod treaded connections

Abstract

On the basis literary sources analysis, it was defined, that failures of the pump rod threaded connections are the most common exceed one-third of the total number of the rod string failures. It is due to non-uniform load distribution across thread turns of the pump rod threaded connections.

The simulation modelling of standard design of pump rods was performed and graphic dependencies of stress distribution were developed on the gaps the pump rod threaded connections.

The methods to reduce load non-uniformity across thread turns of the pump rod threaded connections were considered.

The design of the pump rod connection was proposed; it shall have the variable mean diameter of the nipple thread by adding one more element, fitted in the nipple body hole.  The comparison of stress distribution dependencies on the gaps the pump rod nipple of the standard and proposed design showed that stress decrease in the first gap of the thread turn by 60  MPa, and in the third and next turns stresses increases and become uniform by the value. This change of stresses on turn gap, when it is operated in the well.