SCA 2001- 48
The Preservation or Removal of Solid Bituminous Material, as part of the Core Analysis Programme on The Elgin-Franklin Field
Clive K. Cornwall, Corex (UK) Ltd.
Abstract
The Elgin and Franklin fields are situated 240 km east of Aberdeen, in the southern part of the Central Graben. A number of gas condensate discoveries have been made in the area within Jurassic and Triassic Sandstones. These reservoirs occur at considerable depth (>5000m) and are characterised by high pressure (>1000) and high temperatures (up to 200ºC). The Elgin structure lies within the 'Franklin Terrace' area, just to the north of the Franklin Field. Both structures have a predominant NW-SE orientation.
The Elgin and Franklin accumulations are typically very thick and extensive Upper Jurassic Franklin Sandstone sequences, large parts of which are highly porous and permeable. These sands occur within a large structural closure, which was probably charged by hydrocarbons during the early Teriary. The Upper Jurassic and Lower Cretaceous Shales provide a highly efficient and effective seal. The seal has enabled gaseous fluids to be retained at extreme formation pressures, which approach the formation fracture strength in magnitude.