The implementation of autonomous inflow control device (AICD) has been a success at the Troll field with the objective to limit gas production for long horizontal wells in a thin oil column reservoir. First installed in 2008, recently the AICD was adopted as part of the standard lower completion solution at Troll. To date more than 30 wells have been completed with AICD, demonstrating significant increase in cumulative oil production.
Troll is a large subsea development offshore Norway which started oil production in 1995. Troll multilateral horizontal wells are drilled with total reservoir length typically 3 to 5 km within the thin oil column. Production has been aided by inflow control devices to ensure contribution from all reservoir sections and limit gas production by postponing gas breakthrough and choking gas production after breakthrough.
The Autonomous Inflow Control Device (AICD) provides the same functionality as a passive ICD in that it helps to create a more even inflow along the horizontal section prior to gas breakthrough, but also has a self-regulating adjustable design to provide greater production choking where gas breakthrough occurs. This chokes production from compartments producing large amounts of gas leading to greater oil recovery and lower gas production.
To evaluate the performance of the AICD a comprehensive multi-phase flow model of the autonomous performance has been developed and workflow created for simulation of performance within the reservoir.
This paper will describe the advances in the technology since the first field installation in 2008, and the development and challenges of performance prediction and assessment.