Chainomi Fregene and Wayne Pilgrim
Weatherford International
Continuous sucker rod is primarily used as a solution in deviated (unconventional) rod lift wells plagued with rod and tubing failures. It is commercially available in two shapes - round and semi-elliptical (elliptical). For 40 years, the uniquely shaped elliptical continuous rod has been offered as a primary choice for reciprocating rod lift (RRL) applications and touted as a better product over round continuous rod with benefits that until now have not been made public. Methods, Procedures, Process: Performance comparisons of round and elliptical continuous rod in a deviated RRL application are done using mathematical modeling (mechanical engineering principles). Bending stress, rod contact load (side load) and wear are used in the mathematical models for performance comparison. Lab testing with a custom-built reciprocating wear tester is used to verify and validate mathematical modeling on wear. Results, Observations, Conclusions: Elliptical continuous rod showed improvements over round continuous rod in bending stress reduction (up to 30%), side load reduction (up to 60%) and wear volume reduction (up to 50% ) using modeling. Lower side loads in theory should yield improvements in wear performance. This is confirmed by lab testing which shows over 100% increase in wear performance over round continuous rod. Lower stresses in theory improves fatigue life, which consequently yields longer operational life. Novel/Additive Information: The data presented on the operational advantages of semi elliptical continuous sucker rod will be useful to production engineers/ operators working with or exploring the use of continuous sucker rods in unconventional rod lifted wells.