Reservoir evaluation of Upper Permian buildups in the Jameson Land basin, East Greenland

Abstract

The Upper Permian Wegener Halvø Formation buildups form an important reservoir target in the Jameson Land basin. Due to absence of subsurface information from the basin, reservoir properties of the buildups are tentatively evaluated by timing the different diagenetic modifications seen in outcrop relative to hydrocarbon migration.The buildups became cemented during deposition and the ultimate porosity was dose to zero. Post-depositional porosity appears to be related to freshwater dissolution of aragonite cement during Permian exposure events. Reservoir potential is mainly confined to the buildup cores and the proximal flank deposits. Porosity prior to hydrocarbon migration is estimated to average 10% in the buildups and 5–6% in the proximal flank deposits. Pores became filled by hydrocarbons probably in the Late Cretaceous; the reservoirs became flushed by hot, hydrothermal fluids c. 20 Ma ago and pores are now filled by iron-rich calcite, baryte and fluorite. The flushing of the reservoir may be related to the Tertiary uplift of Wegener Halvø, and it is most likely a local event not affecting the basin as a whole.