Achieving Statoil Visund's World Record Reach With Intermediate Size Drillpipe- A Case History

摘要

Statoil ASA's Visund project is operated from a floating installation located in the Tampen area of the Norwegian North Sea. The Visund field has been developed through 16 subsea-completed wells over the past six years. Recently, Statoil ASA set a world record by drilling the longest reach well from a floating installation. The well A-6HT2 (A-6) was drilled to a measured depth of 9,082 meters, 819 meters deeper than the Visund A-22 AHT2 (A-22) well. A-22 previously held the record. In addition to setting a new world record, well A-6 was finished ahead of plan, within budget and set a Visund record for the fastest spud to total depth ERD well with an average rate of penetration (ROP) of 108 meters per day. Compared to the A-22 well, a key technology used on A-6 was a full-length, intermediate sized 5 7/8-inch drill string. Well A-22 used a conventional tapered drill string with several different drill pipe sizes. Some of the achievements noted with the intermediate sized pipe were improved running and handling speed, reduced handling tool inventory and maintenance, reduced surface pump pressure and maintenance, reduced drill string weight and a large cost benefit from improved drilling speed. Achieving this record reach has enabled Statoil ASA to hit targets from the floating installation that were previously thought unreachable, reducing the need to develop the field with less economical mobile floating rigs and offset subsea developments. Since its introduction in 1999, the design and operational benefits of intermediate sized 5 7/8-inch drill pipe have been presented in many publishing's. 1,2 Few have focused on specific case histories with documented performance improvements. This paper will present a case history of 5 7/8- inch drill pipe in use and how it allowed a world record to be set. A novel method for equivalent circulating density (ECD) reduction in the troublesome 8 1/2-inch hole section will also be presented.