Effect of Threaded Connection Misalignment to Rod String Operation
Year: 2025
Type: article
Abstract: One of the most important tasks of the oil industry is to increase the efficiency of production by increasing the inter-repair period (MCI) of deep-pumping equipment. Currently, a significant number of fields in the Russian Federation are in the final stages of operation, while the method of oil production using downhole rod pumps has become widespread to reduce operating costs. Pumping rods are an important part of such installations. Most wells operated using downhole rod pumps (USPS) have an obliquely directional profile and areas of increased curvature, where, in addition to longitudinal dynamic loads on the rods, additional friction forces, bending and twisting loads occur due to the geometry of the well. The largest number of failures of the rod columns can occur due to the reasons for the deviation of the rods from straightness, misalignment of the axes of the thread and the rod body, leading to the appearance of a «knee» in the column assembly. When the rods are operating in a rectilinear borehole, misalignment in the threaded connection does not significantly affect the rotational motion. However, in the curved section, this defect already significantly affects the rotational movement of the rod column. In this paper, the causes of rod column failures are considered, and the moment of resistance for the rod coupling is determined in the presence of misalignment of the thread axes and the rod body («knee») in a curved section of the well. According to the calculation results, it is shown that in real conditions, geometric defects in the rod column can cause a significant moment of resistance to rotation of the column during operation in spatially curved wells. The stresses that arise in this case can lead to the failure of the rod column.
Source: Oil and Gas Business
Language: English
Subfield: Ocean Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4408295784