Drilling is about to start on the Southern North Sea East Breagh prospect which, if successful, could clear the way for the largest UK Continental Shelf dry gas development for years.
Breagh is on North Sea block 42/13, roughly halfway between Easington gas terminal 110km to the south-west and the Teesside CATS terminal 105km to the east.
There is talk of a one trillion cu ft gas in place development if it turns out that East Breagh is as large as calculated and is connected with the promising West Breagh probe of late-2007.
This suggests a $1billion-plus development based on recoverable reserves of about 600billion cu ft.
Among companies set to benefit from success would be Aberdeen-headquartered Faroe Petroleum.
The Ensco 70 jack-up drilling unit has been contracted to drill at least two wells on Breagh this year and, by Christmas, the overall scale of the potential development will be better defined, according to Stratic Energy, a minor partner.
The East Breagh probe is expected to be vertical and will not be tested.
Breagh was originally drilled and tested by Mobil in 1997 via the 42/13-2 well. The well encountered gas and was perforated and tested over five intervals within “tight” Carboniferous formations at an unstimulated rate of 3million cu.ft per day.
An earlier well 42/13-1 drilled by BP in 1968 to the east of 42/13-2 encountered 13m (43ft) of wet Scremerston Sandstone.
Last year’s 42/13-3 well was drilled into the Carboniferous target previously encountered by the 43/13-2 well of 1997 and established a total gas column of 140m (460ft). The well was suspended as a potential gas producer.
However, this most recent well was drilled through the reservoir interval using an oil-based mud to avoid the formation damage experienced in the discovery well. The well was flow tested successfully at up to 17.6million cu ft per day – a big lift from the original well, though still not enough to unequivocally demonstrate commerciality.
It was interpretation of 3D seismic shot over the licence that suggested East Breagh might be large, since when there has been further processing of that data prior to Ensco 70’s campaign, which Stratic says includes at least one more West Breagh well.
The objective will be to establish whether commercial flow rates can be achieved from a horizontal bore, though it is already being assumed by some that a 240billion cu ft project at least is in that bag and that this will establish a new Southern Gas Basin production hub.
About to be drilled East Breagh is reckoned to hold a prize of at least 340billion cu ft of gas.
According to analysts at Tristone Capital, and assuming success with the latest well, only Dana Petroleum’s recent Babbage discovery of some 300billion-plus cu ft can rival Breagh in size.
Tristone says “the partners believe seismic interpretation shows Breagh to be a single structure with a low or depression zone connecting the east and west segments”.
For now, the gross reserves estimate range for West Breagh is 151-373billion cu ft, while the East Breagh range is thought to be 346-888bcf. This suggests gross in-place reserves for the duo is 1.261trillion cu ft.
Tristone’s analysts say that, should there be future success in drilling the nearby Airidh prospect, this could further expand the prospectivity of Breagh. Indeed, a number of prospects have been identified on block 43/13, suggesting the possibility of multi-trillion cu ft of gas.
Airidh may be drilled late year, otherwise possibly early-2009, and the objective is thought to comprise some 100billion cu ft of gas.
Operator Sterling has the Ensco 70 on hire until September, 2009, so there is scope for some flexibility in the schedule.
Breagh partners comprise Sterling with a 45% stake; EnCore with 15%; RegEnergys, 15%; Stratic, 10%; Faroe, 10%, and Petro Ventures, 5%.