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.
- © 2014 EAGE/The Geological Society of London