Rockhopper Exploration's Sea Lion well (14/10-2) was spudded on 15th April 2010 and was declared an oil discovery after encountering 53m of net hydrocarbon pay and recovering samples of medium gravity crude oil ranging from 26.4° to 29.2° API. The well was suspended for flow-testing and subsequently flowed oil at around 2000 barrels per day (bpd) in a well test in September 2010.
Since its declaration as a discovery area, the Sea Lion prospect has been appraised with 6 further wells and extensive coring. Additionally, a second well test involving an Electric Submerged Pump (ESP) system and Vacuum Insulated Tubing (VIT) resulted in a stabilised flow rate of 5508 barrels per day during the test, and a maximum flow rate of 9036 barrels per day from the upper Sea Lion sandstones.
In addition to providing more information about the Sea Lion Main Complex (SLMC), the company's penultimate well and respective sidetrack (14/10-9 and 14/10-9z) of the drilling camping confirmed a gas and oil discovery in the Casper target, with 18m total net hydrocarbon pay, porosity of up to 27% and permeability of 232mD. 14/10-9 also penetrated the Kermit sandstone (beneath the SLMC), which was found to be water-wet with oil shows.
Rockhopper's final well drilled with the Ocean Guardian was in PL004b, a licence formerly operated by Desire Petroleum, but now under Rockhopper operatorship with a 60% equity stake compared to Desire's retained 40%; this well (14/15-4) well penetrated four prospects: Beverley, Casper South, Casper and the Sea Lion Main Complex, with a total gross reservoir of 89m and total net pay of 57m. Beverley and Casper South were declared wet gas and oil and wet gas discoveries, with 25.8m and 11.6m of net pay respectively. Meanwhile, the appraisal of Casper and the Sea Lion Complex was considered successful, encountering 2.4m and 8m of net pay respectively. No oil-water contact was encountered. The well was consequently sidetracked (14/15-4z) and 115m of core retrieved to surface for further analysis.
Rockhopper's Ernest and Sea Lion North prospects, drilled in 2010 and early 2011, were plugged and abandoned as a dry well and with oil shows respectively.
Should the Sea Lion Main Complex and surrounding prospects prove commercially viable, Rockhopper Exploration will look to move into a production phase in the coming years and has begun work on possible field development and production options.
The Ocean Guardian campaign also saw the first well drilled in the Falkland Plateau Basin. The then operator, BHP Billiton, used the Ocean Guardian to drill its Toroa prospect with partners Falkland Oil & Gas Limited. The well did not encounter any reservoired hydrocarbons, but did provide invaluable information for the previously undrilled basin.
BHPB have since relinquished their interest to partners Falkland Oil & Gas, who have become 100% operators in all their licences.
Exploration in the South Falklands Basin is set start in earnest in February with the arrival of the dedicated harsh-environment rig Leiv Eriksson. The rig is expected to drill two wells for South Falkland Basin operator Borders & Southern Petroleum and a maximum of two wells for Falkland Oil & Gas Limited.
Fig.1: The Sea Lion Discovery Area
Fig.2: Location of wells drilled up to January 2012