Cost-Effective Subsea Drilling Operation on the Smallest Norwegian Field Development

Abstract

Drilling and completing 4 horizontal and one vertical injection well during the months from October 2000 to May 2001 cost-effectively developed the Glitne subsea field in the Norwegian Continental Shelf. The operation was completed six weeks ahead of budget time and included an extended drilling programme of additional 5000 m compared to the development plan. This paper will focus mainly on the drilling operation and why it succeeded. It will also include a brief description of the whole field development solution. As time is the main cost driver on a subsea operation, beating the time schedule was the primary goal for this operation. The drilling programme focused on a well planned and effective batch drilling operation for all hole sections, and the extended use of cost-effective rotary steerable assemblies. Introduction The planning phase for the development of the field was extremely short. A cost effective development solution and a plan for development was in place in June 2000. Due to the team integration and efficient co-operation between all the service companies and a short decision-making process, the team was able to start drilling in October 2000. The economic viability of this small project was very dependent on good performed drilling and completion operations. It needed to be compared with the very best within the industry, as the drilling and completion budget was 70 % of the total field investment costs. The experience with drilling horizontal wells in the area and in comparable formations was very diverse and could have been a challenge to the drilling operation. Valuable information was gained by experience transfere from the ExxonMobil operated Jotun Field, the Statoil operated Sleipner Field and the Siri Field in the Danish sector. The cost effective drilling and completion operations became very successful, with the rig performing the most effective subsea drilling operation in Statoil. The production wells were batch drilled, with TD of the first 4300 mMD horizontal well being reached after only 17,1 days. The overall performance of the five wells resulted in 203 m/day drilled ref. Rushmore benchmarking1 (Fig. 1 and Fig. 2). The Overall Glitne Field Development Solution Introduction. The Glitne Field is located app. 40 km north of the Sleipner field close to the border between Norwegian and British sectors in block 15/5. The field is the smallest independent field development on the Norwegian Continental Shelf with 4,0 MSm3 of developed oil reserves and a planned production period of only two to three years. The field was first discovered in 1994. The development solution called for four horizontal production wells and one combined water and waste-gas injection well. The wells were drilled from conventional exploration PGB's and completed with re-use of old x-mas trees with production risers to a FPSO, Petrojarl 1. Fig. 3 shows the overall Glitne Field development layout. The License group for the Glitne field is:Statoil (operator)58,9 %Total Elf Fina 21,8 %Pelican 9,3 %Det Norske Oljeselskap 10,0 % The FPSO Petrojarl 1. The Petrojarl 1 underwent major modifications so as to be able to meet the Norwegian regulations and to handle the production from the Glitne wells. The planned and designed maximum oil production rate from the field was 6400 Sm3/day (40.000 bbl/day). The production came early up to the design rate and has produced up to 8000 Sm3/day (50.000 bbl/day). Petrojarl 1 has a storage capacity of 30.000 m3 (190.000 bbl/day). Introduction. The Glitne Field is located app. 40 km north of the Sleipner field close to the border between Norwegian and British sectors in block 15/5. The field is the smallest independent field development on the Norwegian Continental Shelf with 4,0 MSm3 of developed oil reserves and a planned production period of only two to three years. The field was first discovered in 1994. The development solution called for four horizontal production wells and one combined water and waste-gas injection well. The wells were drilled from conventional exploration PGB's and completed with re-use of old x-mas trees with production risers to a FPSO, Petrojarl 1. Fig. 3 shows the overall Glitne Field development layout. The License group for the Glitne field is:Statoil (operator)58,9 %TotalElfFina21,8 %Pelican 9,3 %Det Norske Oljeselskap 10,0 % The FPSO Petrojarl 1. The Petrojarl 1 underwent major modifications so as to be able to meet the Norwegian regulations and to handle the production from the Glitne wells. The planned and designed maximum oil production rate from the field was 6400 Sm3/day (40.000 bbl/day). The production came early up to the design rate and has produced up to 8000 Sm3/day (50.000 bbl/day). Petrojarl 1 has a storage capacity of 30.000 m3 (190.000 bbl/day).