An assessment of stress and production rate of sucker rod heat pipes in oil well pumping system

Abstract

The implementation of the heat pipe concept in sucker rods for oil pumping systems negates the requirement for an external heat source, thereby eliminating the necessity for expensive approaches such as separate heating systems. This method enhances the production rate by minimizing heat loss to the wellbore formation, facilitating direct heat transfer, and maintaining a lower viscosity of the oil. This study aims to assess stress evaluation and oil production through the utilization of a sucker rod heat pipe across lengths of 1.5, 2.0, 2.5, and 3.0 km within an oil pumping system. The assessment is conducted for the sucker rod heat pipe, for various inner to outer diameters of 15–27, 20–32, 25–37, and 30–42 mm, with a ratio of 0.550, 0.625, 0.670, and 0.710, respectively. This analysis considers polishing rod stroke lengths ranging from 2 to 4 m, pumping speeds between 3 and 9 strokes per minute, and different plunger diameters from 32 to 50 mm. A conceptual framework is established that incorporates the weight of the sucker rod heat pipe working fluid and its frictional impacts throughout an entire operational cycle. The observed relationship between the outcomes and the established oil well data highlights the efficacy of the method employed. The findings indicate a significant increase of 46.2% in extreme upstroke load as the inner and outer diameter changes from 15–27 to 30–42 mm, with a length extending from 1.5 to 3.0 km. Additionally, the diameter ratio and length of the sucker rod heat pipe is found to be directly correlated with the pumping speed and polishing rod stroke length during the stress evaluation. The production rate increases by 3.4%, 6.7%, 12.2%, and 21.7% for 1.5, 2.0, 2.5, and 3.0 km sucker rod heat pipe respectively, when the inner-outer diameter is changed from 15–27 to 30–42 mm and by considering higher values of polishing rod stroke length, plunger diameter, and pumping speed. In addition, it is inferred that the production rate is influenced by the material's elasticity, which decreases as the length of the rod increases. The mathematical method that enables the selection of an appropriate sucker rod heat pipe for oil pumping within the permissible limits of available equipment is delineated.