The Victory gas field, West of Shetland

Abstract

The Victory gas field is located 48 km northwest of the Shetland Isles, in UKCS Block 207/la. The structure was first drilled in 1977, the discovery well 207/1-3 encountering 224 ft (68 m) of gas-charged Lower Cretaceous sandstone at a subsea depth of 4144 ft (1263 m). No gas–liquid contact was recorded in the well. Five wells have been drilled on the Victory trend to date with the most recent, 207/la-5, being drilled in 1996. The Victory Field was originally mapped with 2D seismic data as a structural high associated with a rotated fault block. In 1996, 3D seismic data were acquired over the area as part of a Shell-operated group-shoot and the improvements in resolution and data quality have prompted a re-evaluation of the field. The 3D seismic data have demonstrated that the Rona Ridge and the linked West Shetland Basin in this area have undergone a complex geological history with multiple phases of Cretaceous tectonism. The structural elements that affect trap configuration and reservoir sand distribution are related to faulting which follows both a NE–SW Caledonian trend and an offsetting NW to SE fault trend. The reservoir is of Early Cretaceous (Late Aptian–Late Albian) age and comprises shallow to marginal marine sandstones and conglomerates overlying Precambrian basement. Reservoir quality is consistently high. Geochemical analyses of both gas and oils encountered within the Victory field area have been undertaken and tied both to basin-scale modelling of the petroleum system and structural mapping at a field-scale. These studies demonstrate the complex, multi-phase charge and alteration history of the trapped hydrocarbons of the Victory Field.