Lower Cretaceous: the next target for oil exploration in the Barents Sea?

Abstract

During the early days of exploration in the southwestern Barents Sea, Lower Cretaceous wedges and mounds were identified on seismic data along the margins of the Hammerfest Basin above rotated Jurassic fault blocks. They were ranked as secondary targets after the giant Jurassic closures in the central part of the basin. Drilling of the latter proved the Snøhvit area gas fields and Snøhvit’s thin oil leg. However, the majority of the wells drilled in the Hammerfest Basin have oil shows in Lower Cretaceous strata. Even the claystones in the most basinal part have oil shows, interpreted by the industry to be remnants of oil leaked from Jurassic reservoirs to the surface. Lower Cretaceous sandstones have also been drilled along the Troms–Finnmark Platform, Loppa High and Senja Ridge, where almost all wells have oil shows. Three wells drilled along the southern margin of the Loppa High have even proved small amounts of oil ranging from 31° API to 38° API and the westernmost well, 7120/1-2, is ranked as an oil discovery. Thick (123–157m) massive sandstones of Valanginian to Hauterivian age in wells 7120/1-2, 7122/2-1 and 7120/10-2 represent the reservoir analogues for a possible Lower Cretaceous oil giant. The Gamma gas discovery 7019/1-1 at the eastern margin of the Tromsø Basin could be an indication of such a giant. Lower Cretaceous sandstones were also the primary target for 7120/10-2. The reservoir sandstones were deposited as submarine fans and the drilled massive sandstones have good reservoir parameters.