Drilling Optimisation on the Norwegian Continental Shelf: Opportunities in Well Design Practice

• Main Author: Harris, Patrick James
• Other Authors: Aadnøy, Bernt Sigve, Tvedt, Magnus
• Format: Master Thesis
• Language: English
• Published: University of Stavanger, Norway 2018
• Subjects: slim well design; drilling optimisation; slender well design; reduced casing string well design; petroleumsteknologi; boreteknologi; Barents Sea; Norway; Norwegian Sea
• Online Access: http://hdl.handle.net/11250/2494413

Master's Thesis in Petroleum Engineering The purpose of this thesis was to attempt to provide evidence that Norway’s drilling fraternity is long overdue for a re-think in the way it drills wells. In so doing, the author has chosen to focus on slim well drilling as a means of reducing drill costs. It was postulated that slim well drilling could lead to much lower drilling investment costs. This body of work therefore focuses on the regulatory, economic and technical implications of slim hole drilling in Norway. The study examined the historical trends of drilling optimisation, particularly in light of the recent downturn. It was discovered that drilling investment costs in Norway have increased three-fold since the year 2000 with drilling and wells contributing 50% of that overall investment (>NOK100B per year). Whilst there has indeed been some improvement in efficiency since 2014, there is still a major issue with hidden NPT and overall rig crew efficiency. There are, however, some exciting developments in play for slimming down explorations wells in Norway, with the possibility of even drilling with a single casing string being considered. To attempt to indicate that slim wells are indeed possible, six hypothetical exploration wells were examined. Two in the North Sea, another two in the Norwegian Sea and the remainder in the Barents Sea. These regions were chosen to give the broadest possible outlook for the opportunities and challenges at play for the Norwegian sector. For each region, one conventional well design and one slender well proposal was analysed and despite an absence of some data, realistic assumptions were made based on publically available data from Norwegian operators. From a technical standpoint, our analysis concluded the following: • For each conventional well presented, it was technically possible to remove one or two casing strings, with no lost production and well integrity remaining intact; • The limiting technical factor in slim well design is kick tolerance. All slim hole options ...