World's First Downhole Flow Control Completion of an Extended-Reach, Multilateral Well at Wytch Farm

Abstract

The world's first down hole flow control completion of an extended reach, multilateral well was implemented, achieving all objectives without any safety incident. The economics indicators are favourable. All the key parts of the Projects are captured here in a structured manner and in some detail. A great deal of learning has been covered, with an intention to cater for a variety of engineers and co-ordinators. After introductory notes including the challenges, the completion objectives were set out to which the remainder of the paper ties back. The mechanics of the Project was described next, i.e. how the completion looked and how things were done. Considerations of key engineering issues were detailed, demonstrating a sound design. Then some of the key processes in managing the Project were shared, touching on a range of topics from common sense practices and a novel economic evaluation tool to risk and crisis management. Lessons learnt revealed some most astonishing battles against potential disasters and how the Team came out stronger. The main conclusions included that downhole flow control can be achieved safely, fittingly and cost-effectively, and that the techniques developed and processes used in managing the project by the Team have shown to work well. Introduction This paper tells a success story of a unique down hole flow control completion carried out under extraordinary circumstances at Wytch Farm1. The extended-reach, multilateral well M15, that looked unable to pass the technical and financial hurdles initially, ended up with at least half a dozen world records and the costs still under the AFE. An extraordinary Team from all over the world made it happen. However, it was not without problems. The unprecedented challenges both technical and economical, the lateral thinking and creativity, the crises and recoveries from them, the conviction and the team work, all make this Project worthwhile, and worth finding out about. On an incremental basis, the net present value for reserves recovery alone on a three year projection for the flow control system is ca $4m, and the capital efficiency of >6. There are some other significant benefits delivered by this completion too. Today, the completion is performing as expected and designed, and M15 is on course to deliver business success. The Project won a BP Amoco 1999 Technical Achievements Award. This was a great honour for the Team, but the satisfaction of seeing the technical and financial success coming true would not be any less without it. Background on Wytch Farm Well M15 Wytch Farm oil field is the largest onshore oil field in Europe, and is known for its Extended-Ranch Drilling (ERD) and Completion2,3 in the Sherwood reservoir. Well M15 was based on an old ERD well M2 drilled in 1994, which had more than ints fair share of problems from the start. For example, the 5 ½" liner did not get cemented because the cement flash set and the liner was subsequently perforated without cement behind it. High water cut developed shortely afterwards with the characteristics of a conducting fault. A subsequent water shut-off job was unsuccessful. As a result, the reserves around M2 were not adequately recovered and it became apparent that side tracking would be a more reliabel option than others to access the surrounding reserves. The initial plan was to pull the old 5 ½" liner that was set in an 8 ½" hold and extended this hole by another thousand meters. Two more laterals were then to be added to this "main bore", one to the north and the other to the south.