Case History: First Intelligent Well with Feed-Through Zonal Isolation in a Multilateral Sidetrack Completion in the Troll Field

Abstract

The Troll Field is located approximately 80 km northwest of Bergen in the Norwegian Sector of the North Sea around 65 kilometers west of Kollsnes, and is operated by Statoil. The field is comprised of the main Troll East and Troll West structures in blocks 31/2, 31/3, 31/5 and 31/6. Although the field historically had produced large amounts of oil, it is now also a major gas producer, as it contains approximately 40% of total gas reserves on the Norwegian continental shelf. The gas reservoirs that are 1,400 meters below sea level are expected to produce for at least another 70 years. Statoil, wishing to run a deep sidetrack from the mother bore of a multilateral well, decided to evaluate several zonal isolation methods and to combine this with intelligent well completion technology. Since this would be a "first time" Statoil Troll field deep sidetrack from the mother bore in a multilateral well application, regardless of the technology selected, a full scale test to qualify the technology for the application would be required. After evaluating several zonal-isolation methods, and their previous experiences with isolation concepts, Statoil decided to use a combination of intelligent well completion design with feed-through swellable packer technology. This combination concept would not only be the first intelligent well completion of its kind in the Troll field, it would also be the first ever Statoil use of feed-through swellable packers. Swelling and differential pressure tests were initiated using oil from the Troll field. The testing revealed that this type of completion exceeded the sought-after requirements for the project. This well design was then approved and installed on a semi-submersible rig without any HSE incidents and ahead of plan. The well was put on production shortly thereafter, and zonal isolation was confirmed by selective closure of the flow control valves. Additionally a second nearly identical completion well design was installed in May 2013. The paper will discuss the swellable packer design, qualification testing, planning, installation, and the results of the first intelligent completion with feed-through zonal isolation on the Troll Field.