Offshore Report

Cost-effective subsea drilling operation on the smallest Norwegian field

Successful development of the Glitne marginal field with four producers and one injector operating from an FPSO depended on efficient and economic drilling and completion

H. Blikra, R. Andersen, H. Hoset and J. Vestvik, Statoil; and H. Berg, Schlumberger Drilling and Measurements

Drilling and completing four horizontal producers and one vertical injection well between October 2000 and May 2001 cost-effectively developed the Glitne subsea field on the Norwegian Continental Shelf (NCS). The operation was completed six weeks ahead of budget time and included an extended drilling program of an additional 5,000 m (16,400 ft) compared to the development plan.

This article will focus mainly on the drilling operation and why it succeeded. It also includes 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 program focused on a well-planned and effective batch-drilling operation for all hole sections, and extended use of cost-effective rotary steerable assemblies.

Introduction

The planning phase for the field development was short. A cost-effective development solution and a development plan were in place in June 2000. Due to the team integration and efficient cooperation between all service companies, and a short decision-making process, the team was able to start drilling in October 2000.

Economic viability of this small project was very dependent on well-performed drilling and completion operations. The project required the very best within the industry, as the drilling / completion budget was 70% of total field investment costs.

Experience with drilling horizontal wells in the area and in comparable formations was very diverse and, thus, could have been a challenge to the operation. Valuable information was gained by experience transfer from ExxonMobil-operated Jotun field, Statoil-operated Sleipner field, and Siri field in the Danish sector.

The cost-effective drilling / 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 4,300-m (14,000-ft) MD horizontal well being reached after only 17.1 days. Overall performance of the five wells resulted in 203 m/day drilled,¹ Fig. 1. Note: Paper IADC/SPE 74508 has additional information on "the best fields drilled from a semisubmersible rig in the North Sea," showing excellent performance on Glitne.²