Reservoirs of the Dinantian (Lower Carboniferous) play of the Southern North Sea

Abstract

Critical to the successful exploitation of the northern margin of the Southern Gas Basin is the development of the Lower Carboniferous (Dinantian, Viséan) play. Whilst the exploration for intra-Carboniferous traps has been unsuccessful, the presence of large Base Permian evaporite sealed closures still holds opportunities. The discovery of hydrocarbons within one of these closures on the edge of the traditional gas basin suggests that migration of gas from Westphalian and Namurian coals and shales has occurred. Thus in this area, the primary remaining risk is the presence and distribution of reservoir. Two potential reservoirs are examined in the subsurface, the Fell Sandstone Formation and the Whitby Member. Onshore analogue data has been combined with the sparse offshore data to explore the distribution of these sandstones. The Fell Sandstone Formation was deposited at a time of high sediment supply resulting in a thick (300 m) succession of fluvial sandstones whose distribution is closely linked to the accommodation space developed in the hanging walls of contemporaneous faults. The Whitby Member (thickness 30 m) was deposited at a time of lower sediment supply which enabled relative sea-level changes to control the vertical distribution of sandstone bodies. It demonstrates some of the features which suggest it could infill a palaeovalley. If active faulting continued throughout this time then a similar hanging wall concentration of sandbodies, as is seen in the Fell Sandstone Formation, could be expected.

Revised stratigraphic framework of pre-Westphalian Carboniferous petroleum system elements from the Outer Moray Firth to the Silverpit Basin, North Sea, UK

“…Such distinctive sandstone units are encountered in wells 41/10-1, 42/10b-2 and 43/02-1, and referred to as the Whitby Sandstone Member ( Fig. 6; Maynard & Dunay 1999). This unit is distinguished on wireline logs by two thick units of sandstone separated by a mudstone interval.…”

Kinematic interaction between stratigraphically discrete salt layers; the structural evolution of the Corrib gas field, offshore NW Ireland

“…The Slyne Basin is divided into three sub-basins which are asymmetric half-grabens or grabens (Trueblood & Morton, 1991). The asymmetry of these sub-basins varies along-strike, with polarity changing across areas of structural complexity linked to underlying Caledonian structural lineaments (Trueblood & Morton, 1991;Chapman et al, 1999;Dancer et al, 1999).…”

“…Two main salt bodies have been proven in this basin, the Upper Permian Zechstein Group and the Upper Triassic Uilleann Halite Member (Fig. 2) and have both been active during the multiphase evolution of the basin from the break-up of Pangea during the Permian through to the opening of the North Atlantic during the Eocene (Dancer et al, 1999;Štolfová & Shannon, 2009;Stoker et al, 2017;Merlin Energy Resources Consortium, 2020;O'Sullivan et al, 2021). Permian salt pillows and rollers have been recorded throughout the Slyne Basin, while observations of Triassic salt walls and salt rollers are largely confined to the Northern Slyne Sub-basin (O'Sullivan et al, 2021).…”

Seismic interpretation of Dinantian carbonate platforms in the Netherlands; implications for the palaeogeographical and structural development of the Northwest European Carboniferous Basin

“…By analogy with northern England, Middle Devonian to Dinantian block faulting has been documented from the Mid North Sea High (Maynard & Dunay 1999) and the northern flank of the London-Brabant Massif (Muchez & Langenaeker 1993;Poty et al 2001). The Southern North Sea is thought to have a similar structural framework to northern England, with a number of granite-cored blocks (Donato et al 1983;Donato & Megson 1990) flanked by half-grabens (Corfield et al 1996).…”

“…extensive carbonate platform (Ziegler 1990;Maynard et al 1997) or a siliciclastic basin (Bridges et al 1995) with some isolated mud-mounds (Gursky 2006). Based on seismic data, Maynard & Dunay (1999) assumed that carbonate facies extend northwards possibly as far as the Cleaverbank High and Schillgrund High. Dinantian carbonate platforms are not expected to be found further north because of the presence of the Yoredale delta system north of Cleaverbank High (Fig.…”