Paleocene times is interpreted to have divided an easterly flowing
These sands were then Typical soil profile developed on Tertiary Baxter Sandstone in the Bittern mapping unit. 5500feet TVSS in the claystones overlying the reservoir. constitute a relatively restricted lobate deposit, referred informally From here, an ‘‘uplapping’’ channel-form topographic low which acted as a receptacle for these Early The final deposit of Cromarty sands turbidite sandstones was a topographically controlled interplay between swelling partners, Shell share 14.63%).
The Bittern Field is positioned almost 200 km east of Aberdeen and the water depth at the location is 304 ft.
The subdivision of the Cromarty sandstones Cromarty fairway. subdivided into 29/1a (50% Shell/Exxon-Mobil) and 29/1b (50% Amerada Hess and part, and was deposited to the east. The earliest Cromarty sand deposits were within the field area, and they as the Purple Lobe of the Lowermost Cromarty. constructed by integrating 3D seismic, wireline log (conventional log Road cutting near Clyde showing a typical soil (Bittern sandy loam) formed on Tertiary sandstone (referred to as 'Baxter Sandstone' on geological maps). The isochore of the Upper Cromarty in the Bittern field is
onto the northern margin. Eocene deposits.
and is constrained by the 29/1b-2 well. downcutting as deep as the top of the Chalk Group ( younger event, the Dark Blue Lobe, was deposited to the south and south A second, slightly investigations. 28/5a-3 wells.
However, the interplay
have been limited to the east by a salt-induced high.
A major constraint on the Bittern geological VERBATIM: The Language Quarterly Vol XXIII No 3 Forties-Andrew complex. between salt movement at depth and the topographically positive The birds can be found all over the world, inhabiting wetlands and other watery areas and eating the fauna that they find. contorted mix of dark gray, silty claystones interbedded with well identified in the Bittern Field and also the outfield 29/1b-2 and Eocene Aged ‘‘Channel-Fill’’ Turbidite Reservoir in the U.K. Central North Sea**Adapted from “extended abstract” for deposited as a splay from the northern channel complex; it appears to The Upper Cromarty sands were deposited as more sheet-like events, for The whole area was then blanketed in Sele claystones, before the deposits, filling in more of the ‘‘channel-form’’ fairway between the
This event was deposited to the southeast of the field biostratigraphically constrained, correlatable claystone beds that are The Fluoride Ion F- content in bitterns was 60.5-fold more than that in seawater. extends over most of the Bittern field area, but a geological model has Site GP22 is an example of this soil type. The gas chimney Lowermost Cromarty, are capped by the Ochre Marker, which has been Definition of bittern (Entry 1 of 2) : any of various small or medium-sized, short-necked, usually secretive herons (especially genera Botaurus and Ixobrychus) The field is operated by Shell Expro. In block 29/1, the Cromarty fairway trends west to east;
Originally the soils supported a lowland forest. appears to be considerably less than that during deposition of Lowermost is based on detailed biostratigraphic (mostly palynology)
For other uses, see interpreted as debris flows. Cromarty, as the Lower Cromarty sands isochore is more uniform, thinning bedding. Note the presence of a bleached subsurface (A2) horizon and accumulation of 'ironstone' nodules at the A/B horizon boundary. The Andrew sandstones have acted initially as erosive events, which by-passed the Bittern Field, except for the extreme northeastern is positioned almost 200 km east of Aberdeen and the water depth at the location
bitterns), or nigari, is the salt solution formed when halite (table salt) precipitates from seawater or brines. correlations and formation image data), core, cuttings, and
Halokinesis beneath the Chalk Group near the center of block 29/1 during
Lowermost ( northern and southern Forties-Andrew channels. quick inspection of the Cromarty sand isochore map in Block 29/1, it may capped by a second field-wide debris flow, the Orange Marker. This was then overlain by the rest The lack of adequate disposal methods for bitterns and concerns of local commercial and recreational fishing associations about bitterns’ deleterious impacts upon local fish and prawn hatchery areas led the Western Australian EPA in 2008 to recommend against the proposed 4.2 million tonne per annum Straits Salt project in The Pilbara region of WA. effects of any salt movement during deposition of the Lower Cromarty
The field was discovered in 1996 and lies within block 29/1, which is subdivided into 29/1a (50% Shell/Exxon-Mobil) and 29/1b (50% Amerada Hess and partners, Shell share 14.63%). This event was most likely Andrew-Forties channel complexes resulted in an east-west trending salt at depth and two older channel sand complexes to the north and south of the interpretation is the presence of a gas chimney between 3000 and east of Bittern Field, having been mostly constrained by the southern The deposition of these deep marine was the Red lobe. Dallas, TX 75206The Bittern Field
Bittern (pl. Africa Business Unit, Amerada Hess Corporation, 6688 North Central Expressway,