3D-RESERVOIR SIMULATION OF EKOFISK COMPACTION DRIVE

In late 1984, the seafloor at the Ekofisk field in the Norwegian North Sea was discovered to have subsided by more than 10 ft as a result of production-induced reservoir compaction. Subsidence was not expected and its detection suggested that reservoir compaction was perhaps a more important mechanism for hydrocarbon production than previously assumed. This paper describes procedures developed to account for compaction drive in the 3D reservoir simulator that is used for the Ekofisk field. The procedures involve the incorporation of results from a subsidence model into the reservoir simulator to describe the compressibility of the reservoir chalk as a function of porosity, rock type, reservoir pressure, and position in the reservoir.