Petroleum column-height controls in the western Hammerfest Basin, Barents Sea

Abstract

Hydrocarbon leakage is a major exploration challenge in the western Hammerfest Basin. Most exploration failures in the area have been attributed to leakage; hydrocarbon-bearing traps are rarely filled to their structural capacity, and almost all traps have hydrocarbon shows down to their structural spillpoint or below. We have investigated to what extent the hydrocarbon column heights can be explained by vertical leakage along faults or at fault intersections. For the fields that we evaluated we observe that: (a) all dry structures have fault intersections at top reservoir level up dip of the well position: (b) the only structure where no faults intersect at top reservoir level is the only structure that is clearly filled to structural spillpoint; and (c) all fluid contacts in underfilled structures broadly coincide with the position of intersecting faults. The underfilled structures have less than two fault intersections up dip and above the gas-bearing reservoir. We suggest that vertical leakage at fault intersections has exerted a main control on the position of the gas–water contacts in the western Hammerfest Basin, and therefore that hydrocarbon column-height predictions can be improved by addressing the positions of such intersections at the top reservoir surface.

Use of pore pressure data from the Norwegian Continental Shelf to characterize fluid-flow processes in geological timescales

“…The top of the shallowest structure in a strongly overpressured cell is closest to the fracture pressure and most likely to vent, unless there are weak areas in the cap rock at other locations. Hermanrud et al (2014) concluded that leakage rates in the hydrostatic system in the Hammerfest Basin were higher from areas where the seal is weakened by fault intersections. Since overpressures in the strongly overpressured regime are preserved, it must be assumed that venting takes place over a geological timescale.…”

Role of Faults in Hydrocarbon Leakage in the Hammerfest Basin, SW Barents Sea: Insights from Seismic Data and Numerical Modelling

“…Based on hydrocarbon flow lines and catchment areas (Figures 9 and A5), the hydrocarbons migrate to the western edge of the Snøhvit field and are controlled by the faults and their intrinsic properties (FCP and permeability). In the Askeladd field (Figure 1), dry structures are thought to result from leakage of hydrocarbons along the junctions between several first order fault intersections [86]. The fault networks above the Snøhvit field form a dense network of deep first order tectonic faults (Figures 3 and 5), linking the Paleocene-Early Eocene strata with the underlying Jurassic reservoirs and second order faults ( Figure 5), which are sealed below the Early Cretaceous [17].…”

Key controls on hydrocarbon retention and leakage from structural traps in the Hammerfest Basin, SW Barents Sea: implications for prospect analysis and risk assessment

“…Jurassic to Early Cretaceous rifting established classic rotated fault blocks and horst structures, which have been the main targets for early exploration (Gabrielsen et al 1990;Faleide 2008;Hermanrud et al 2014).…”

“…Negative effects of the Cenozoic uplift event have been largely blamed for disrupting the petroleum system. Issues such as reactivation of faults, erosion of top seal, gas expansion, differential tilting, secondary migration and cooling of source rocks have all been proposed as causing depleted targeted reservoirs (Doré 1995;Doré & Jensen 1996;Doré & Lundin 1996;Duran et al 2013;Hermanrud et al 2014;Ostanin et al 2017).…”