The Hopen boreholes and their insight into Hydrocarbon prospectivity in the northern Barents Sea

Hydrocarbon exploration in the Norwegian Barents Sea is currently not permitted north of 74°30’. Despite recent non-commercial work, the hydrocarbon prospectivity in the area referred to as “Barents Sea North” remains rather speculative. However, prior to the present-day restrictions on hydrocarbon exploration in the area, two boreholes were drilled in the early 1970’s on the island of Hopen, part of the Svalbard archipelago, in the northern Barents Sea: 7625/7-1 (Hopen-1) and 7625/5-1 (Hopen-2).

The potential insight from these wells is enormous; however, until recently, data from these boreholes has been restricted to mostly confidential reports. Some of the materials from these wells form part of the Harland Collection, held by the Sedgwick Museum (University of Cambridge) and have been subjected to a renewed phase of analysis.

Sedimentological, palynological and organic geochemical analysis of samples of core and ditch cuttings from the 7625/7 1 (Hopen 1) borehole indicate that it penetrated Late Ladinian to Carnian stratigraphy. A range of facies is encountered, which correspond to four facies associations: deep marine shelf, prodelta and slope, tide dominated platform and delta front to delta plain.

This core is interpreted to document the arrival of delta complexes from the east or southeast sourced from the evolving Uralian Orogen. Offshore marine environments in the Ladinian deposited organic rich mudstones of the Botneheia Formation. Following this, sedimentation became increasing influenced by delta complexes which prograded into the region and gradually in filled accommodation on the shelf. During the early stages of progradation, a sequence of prodeltaic sediments of the Tchermakfjellet Formation were deposited. Subsequent transgressive events transformed the region into a tide dominated platform area during which a thick sequence of sandstones and mudstones of the De Geerdalen Formation were deposited.

Organic geochemistry of the well suggests that the Botneheia Formation contains a source rock interval which at peak maturity was oil wet. At a lower maturity it would have been oil and gas prone with excellent organic richness. Similar organic‐rich source rocks are found in the Botneheia Formation of Spitsbergen and Edgeøya to the northwest and in the Steinkobbe Formation to the southwest. If these units correlate, it would suggest that the source rock is well developed across the entire western Barents Shelf.