The calculations revealed that a circular cross-section would be a very efficient solution for a rotating string. Hollow sucker rods have such a cross section, and the design of such rods maintain strength uniformity. Application of such
hollow rods makes it possible to increase the reliability and durability of the driving string by multiple times, as strength and rigidity characteristics of the string are increased, thereby increasing the operating time of the PCP unit
and extending the time between well repairs. The parting of rods, both hollow and solid in section, is very strongly influenced by dogleg severity. Hollow rods with uniformly strong structure have been implemented as a driving string in
6 wells of JSC Sheshmaoil. To reduce the influence of curvature on the service life of the rods, a centralizer with functions of bearing and bow spring centralizer has been developed, which undergoes bench tests at the moment.
Materials and methods
The conditions of strength and stiffness for rods of various designs were determined. Technical calculations were carried out to determine the polar moments of resistance and inertia. A special test bench has been manufactured for testing the centralizer, where it was possible to adjust the speed of the centralizer shaft.
progressive cavity pumping unit, rod parting, hollow rods, dogleg severity