The petroleum characteristics and filing history of the Froy field and theRind discovery, Norwegian North Sea

The Brent Group reservoirs of the Fray held and the Rind discovery, Norwegi an North Sea, show complex distributions of petroleum and aqueous fluids. M ultiple fluid contacts are present in the Rind discovery, and the fields sh ow various extent of compartmentalisation due to faulting. Geochemistry dat a of core extracts indicate that the two fields have different petroleum so urces (Bhullar, Karlsen, Helm, Backer-Owe & Tran, 1998). Late diagenetic mo difications of the reservoir quality consist of quartz cementation followed by carbonate and kaolinite cementation and dissolution of K-feldspar. Flui d inclusion results indicate that filling of the reservoirs occurred after the main phase of quartz cementation at pressure-temperature conditions clo se to the present. Differences in fluid properties between fault compartmen ts in both fields have been identified. Fluid inclusion data have proved es pecially valuable for evaluation of the sealing capacity of faults through time, and given evidence for the fault lineament north of both fields to be a time-integrated pressure seal. Except for a lower gas condensate zone in the 25/2-13 compartment of Rind, the present reservoir fluids are volatile oils close to gas saturation. The previous presence of an oil in the lower reservoir zone of 25/2-13 has also been demonstrated. The fluid inclusion data indicate that the condensate in 25/2-13 represents a second episode of migration/filling rather than phase separation. (C) 1999 Elsevier Science Ltd. All rights reserved.