2D Petroleum System Modelling in Northern Viking Graben

Abstract

1D and 2D basin modelling together with seismic interpretation has been done on four 2D lines in the Northern North Sea. The thesis presents the development of the basin from the structural point of view and the results shows thermal and maturity history by using Petromod software. The structural development of the basin was constructed from seismic and data from two wells to account for tectonic and thermal history. The major source rock is the Upper Jurassic Draupne Formation, which is a marine organic rich shale. The results of the modelling show, that, the source rock reaches a temperature of about 180°C at the present day in the deepest parts of the basin. According to Sweeney and Burnham (1990), the vitrinite reflectance data shows that the source rock is matured and has passed the oil window from main oil to dry gas, and large amount of oil was generated in the late Cretaceous to present. From the transformation ratio it shows that 95% to 100% of the source rock is transformed. At 155 Ma most areas were immature and these areas had been buried at the depth of 1200m, At 151 Ma the source rock was mature enough to initiate the onset of early oil generation, At 149 Ma there was onset of main oil generation. At 140 Ma there was onset of late oil generation, and at 100 Ma the source rock was mature enough for wet gas generation, At 65.50 Ma there was onset of dry gas generation at the depth of 4200 m, and at 50 Ma the source rock started to be overmature at the depth of 6200 m, At present time large parts of the area is still generating gas as well as oil generation. Significant amounts of gas generation in the Upper Jurassic source rock formed when higher formation temperatures were attained during middle-late Tertiary. The source rock and reservoir rock of the study area shows significant prospect of hydrocarbon generation and accumulation. Along the 2D lines, Mass of generated oil from the source rock ranges between 2.25-2.40 Mtons to 2.40-2.60 Mtons. The mass of gas generated from the source rock is between 0.36-0.39Mto0.49-0.52 Mtons.