Troll Reservoir Monitoring, Optimization of Well Placement and Oil Recovery in a Mature Field

The Troll Field is one of the most significant oil fields offshore Norway as well as one of the largest offshore gas fields in the world. The field is subdivided into Troll East which is the main gas field, and Troll West, where a thin oil leg (initially 13–27m) is present below the gas cap. The oil from the thin oil leg is produced by means of long horizontal wells. The key to successful well placement is a multidisciplinary approach combining all available data, including 4D seismic. The 4D seismic data is used in combination with other information, such as production history, inflow profiles, permeability, well completion and the geological/seismic models. This allows us to understand the 4D seismic responses and makes it possible to determine from which area a specific well has produced and which sands that are poorly drained. The use of 4D seismic data for well planning and target maturation has over time proven to be a success for Troll. The use of 4D seismic significantly impacts the production from new wells and therefore secure the total oil recovery for the Troll oil field.