The Bruce Field

Abstract

The Bruce Field is a giant gas condensate accumulation which lies on the western side of the Viking Graben at the northern end of the Beryl Embayment. Although discovered in 1974, the Annex B was not approved until 1990 by which time the field had been shown to extend across three exploration licence blocks (9/8a, 9/9b and 9/9a) and to be extremely complex. There are three main elements to the complexity: structure, reservoir distribution and hydrocarbon charge.The major structural elements are the Western Flank (a rotated fault block) and the Eastern High with a central low between, the Central Panel; however, relatively poor seismic data quality makes detailed structural interpretation difficult. Each of these structural elements has a different hydrocarbon–water contact, with a proven range of nearly 500 m. The shallowest contact is found on the Eastern High and though the contact in the central low is nearly 350 m deeper, pressure data indicate that the gas leg is in communication with that in the Eastern High. The distribution of the main reservoir, the Middle Jurassic Beryl Group, and the magnitude of the unconformity that underlies it, appear to be controlled by earlier faults which are cross-cut by the present structure. The result of these complexities is that long hydrocarbon columns can be found in the structural lows, and thick reservoir successions can occur on the structural highs.