Flushed with the success of its Darwin gas/condensate discovery, on May 11, Borders & Southern started drilling exploration well 61/25-1 on the Stebbing prospect on block PL018 some 170km south of the Falkland Islands.
The rig Leiv Eiriksson’s task is to probe Stebbing, which is a thrust-cored anticline structure with an area of closure of 85sq.km. Objectives comprise Tertiary and Upper Cretaceous sandstone reservoirs.
The well duration is estimated to be 49 days, so a result can be expected late this month, subject to drilling conditions.
Meanwhile, with respect to the Darwin discovery, fluid samples have been shipped back to the UK for detailed analysis. The results are anticipated in Q3 this year as soon as the work has been completed.
Borders & Southern holds five production licences in the South Falkland Basin with 100% interest encompassing almost 20,000sq km.
Prior to spudding the Stebbing well 61/25-1, the company acquired 2,862km of 2D seismic and 1,492sq km of 3D seismic, plus it successfully drilled Darwin.
Analysis suggests that Stebbing is around four times the size of Darwin. The two share the same source rock, so there is a good chance of oil and or gas being encountered.
However, Stebbing is 1,000m (3,300ft) shallower and is just in the oil mature window where as Darwin is in the gas mature window.
Given the same source rock but Stebbing being shallower and in the oil window, it is said that, at the very worst, Stebbing will perhaps be a condensate discovery though the hope is that around 25 Deg API oil will be found.
Consultants BOR had predicted pre-drill that, in the event of oil, Darwin would be 32 Deg API oil and Stebbing would be 25 Deg API oil – sharing the same source rock. The UK’s Foinaven and Schiehallion fields in the West Shetland sector are the same gravity and both are successful commercial developments.