Northumberland-Solway Basin: action?
Our report has 30 figures including 19 seismic lines picked. This basin-pair is very under-explored, with only two late 1980s wildcats to date: look at the Solway Basin and Bewcastle area at the west end of the Northumberland Basin. Seismic cover is sparse 2D, exploration strategy must primarily be concept-driven. We think its favourable for companies wanting large acreage holdings with the aim of proving value. The whole area is open, do regional mapping now and ask for blocks to be included in the next Round for seismic commitment.
Its mainly a gas basin. It has not been targetted by shale gas explorers, as it doesn’t have an Upper/Lower Bowland Shale sequence: it does have Lower Carboniferous gas source rocks. The structure style is Irish Sea Basin: large tilted fault blocks with growth-faulted early-mid Mississippian deeply buried, cross-basin shortening in Variscan and again in Tertiary created hangingwall folding and back-thrust rollovers. Naturally-fractured pop-up closures are identified. These plays warrant review:
(i) Rating 1, Bewcastle Anticline’s main ramp has a large inversion structure beneath the shallow-detaching small Border Group folds which outcrop. Lower Border Group Ballagan-equivalent fractured limestones and algal-rich shales are a thick succession. Potential reservoir and source rocks are the same as the source/fractured dolomite play which was established by gas shows at Easton-1. Its an acquisition candidate of considerable interest, bid infill 2D or a local 3D. If (as we expect) its confirmed as closed it will be a large gas prospect.
(ii) Likewise rated 1 by us, onshore Solway around Carlisle has several inverting ramp trends with thick Inverclyde and Border Group fractured dolomites in discrete hangingwall culminations, one ramp runs from Carlisle area northeastwards to Easton. One could bid for Easton on local 3D seismic and a drill-or-drop horizontal well, success could deliver commercial gas.
(iii) The nearshore Solway Firth acreage (classed as onshore for licensing) has Bewcastle-type large fault blocks with dip and fault closure plays in footwall and in hangingwall inversions. Carboniferous sequence is mainly marine here and will include mature source rocks for gas, and viable gas reservoirs. Tournaisian may have mature, high-organic deeper-water mudstones. On-file mapping was poor: get the structure right, risk reduces accordingly.
(iv) On the south side of the onshore Solway Basin, the large extensional blocks have local folds on their sidewalls. This area is prospective with Namurian as well as upper-mid Mississippian reservoir potential and warrants infill seismic.