Understanding the Eocene Reservoirs of the Forth Field, UKCS Block 9/23b

Technical article: Conical sandstone injection structures imaged by 3D seismic in the central North Sea, UK

“…An alternative model to pockmarks is that of postdepositional remobilization and intrusion of fluidized sandstones. Processes of liquefaction and fluidization of previously deposited deepwater sands have been invoked in several recent studies of Eocene reservoirs in the North Sea to explain sandstone dikes and sills observed in cores and on 3D seismic (Alexander et al 1992;Newman et al 1993;Dixon et al 1995;Lonergan & Cartwright 1999;MacLeod et al 1999). Common to these studies is the concept that depositionally isolated sandbodies could have become overpressured during early burial, and then liquefied through an external triggering mechanism such as earthquake shaking or hydrocarbon migration.…”

“…Many clastic Tertiary deepwater oilfields of the North Sea have recently been described with post-depositional sandbody geometries, often with related sandstone intrusion (Alexander et al 1992;Jenssen et al 1993;Newman et al 1993;Dixon et al 1995;Lonergan & Cartwright 1999;MacCleod et al 1999). In all these cases, an isolated deepwater sand has subsequently slumped, faulted or become more mounded in character with an associated complex of sandstone intrusions, of centimetre to metre scale, usually at the top of the host body.…”