Dope-Free Tubular Connections, Through Research and Development to Field Trial and Implementation: A North Sea Case History

摘要

In 2000 Vallourec & Mannesman Tubes approached Maersk Oil with the vision of a tubular connection that requires minimum handling in its lifespan from the mill to the well, removing environmental impact from dope and increasing safety at the well site. To realize this, all application of thread compound in the field or yard was to be eliminated, and a protector design developed that enables the protector to be removed only when the tubular is ready to be run in the well. After an initial development period Vallourec & Mannesman Tubes had a final Dopefree product ready for test. The product a transparent waxy compound applied directly on selected premium threads, serving as both storage and running dope, completely eliminate the requirements for cleaning an redoping at the wellsite. It was decided to initially perform a field test and if successful to implement Dopefree on all tubular sizes where avalaible Maersk Oil operates wells offshore in the Danish sector of the North Sea, which are characterized by being long horizontal wells (5,000 – 20,000 ft VS) drilled in chalk reservoirs. The wells are commonly completed with 4?” or 5?” completion inside a 7” liner hung off in a 9-5/8” production casing set just above the reservoir. The liners are in some cases cemented in place to allow for zonal isolation. The driving factors for Maersk Oil to test and subsequently implement Dopefree were: ? Increased safety by minimizing tubular handling, ? Minimize environmental impact by removing dope, ? Increase efficiency for wireline and coiled tubing operations by eliminating excessive dope in the well.