Overpressure Mechanisms and Their Distribution in the Central North Sea
G.S. Yardley and K.K. Nwozor
Event name: First EAGE Workshop on Pore Pressure Prediction
Session: Poster Session 2B
Publication date: 19 March 2017
Info: Extended abstract, PDF ( 1.28Mb )
Price: € 20
Pressure prediction methods are based on assumptions about the processes that cause the overpressure and their relationship to rock properties. This study examines the causes of overpressure in the Jurassic and Triassic reservoirs of the Central North Sea. These reservoirs can have overpressures approaching the fracture gradient. The age, temperature, rock properties and proximity to mature source rocks implies that multiple pressure generation mechanisms have contributed to the pressures. Two methods are used to assess the amount of overpressure generated by disequilibrium compaction and also by “Late” geopressure mechanisms. The two methods give similar results and indicate that on the cooler flanks of the basin most overpressure can be attributed to disequilibrium compaction. However, in the deep Graben in excess of 70 % of the overpressure is generated by other mechanisms. These results are consistent with expectations for the geological environment. The fact that most over pressure in the deep basin is not produced by disequilibrium compaction has implications for choice of prediction method and interpretation of rock properties in terms of stress and overpressure.