First Intelligent Well Completion in the Troll Field Enables Feed-Through Zonal Isolation: A Case History

Abstract

Abstract Statoil operates the Troll Field in the Norwegian Sector of the North Sea and wished to run a deep sidetrack from the mother bore in a multilateral well that would exit through the 10-3/4-in. liner in the reservoir. The plan would have to address several new challenges, including an intelligent completion that would offer zonal isolation for four zones and dual pressure and temperature for all oil zones; these were not usual requirements for the standard multilateral wells in the field. Statoil had evaluated several zonal-isolation methods, and based on previous experience, they decided to use swellable packer technology. Since this would be the first intelligent-well completion in Troll field and the first ever for Statoil using feed-through swellable packers, a full scale test to qualify the technology was required. Swelling and differential-pressure tests were initiated using oil from the Troll field. Testing revealed that this type of completion actually would exceed the necessary requirements. The lower completion was designed with 7-in. inflow-control-device (ICD) mesh screens and three openhole swellable packers to isolate the reservoir into three separate oil zones and to separate the gas cap. The inner completion string was designed with three dual gauges, three 3-1/2-in. feed-through swellable packers, three 3-1/2-in. hydraulic flow-control valves, and a hydraulically operated gas-lift valve below the production packer to allow natural gas lift. The installation was performed from a semi-submersible rig without an HSE incident 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. The paper will discuss the swellable packer design, qualification testing, planning, installation, and the results of this intelligent completion, which was the first in the Troll Field.