By OGJ editors
HOUSTON, May 24 – Cairn Energy PLC will drill as many as four exploratory wells off western Greenland in 2011 at a cost of $600 million following the three it completed in 2010.
The government has approved seven exploratory drillsites, which allows Cairn some flexibility in program planning and options for appraisal wells in the event of a discovery.
The main elements of the primary 2011 exploratory program are:
• Drilling one well each on the Atammik and Lady Franklin blocks west of Nuuk and one in each on the Napariaq and Eqqua blocks in the southern Baffin Bay West Disko area (see map, OGJ, Aug. 24, 2009, p. 38);
• Shooting as many as three 3D seismic surveys with 4,500 sq km of combined coverage, one in northern Baffin Bay, one in southern Greenland, and one in a contingent location to be decided dependent on operational results.
• The four-well campaign will test prospects with different structural styles and play types and targets a gross unrisked mean prospective resource potential of 3.2 billion bbl of oil equivalent at target subsurface depths of 2,500 to 4,750 m.
• In each case the principal target is oil, but evidence of both oil and gas generation is found regionally. In view of the frontier nature of the exploration and paucity of offset well information the individual prospects are estimated to have 10-20% chances of success. The wells will be drilled in 288-1,530 m of water.
As was the case in 2010, the program will be carried out with a focus on safety, including the deployment of two drilling vessels.
Atammik and Lady Franklin blocks
Cairn increased its equity and acquired the operatorship of these blocks as of Jan. 1, 2011.
The final selection of prospects for the 2011 exploration campaign is the LF-7 prospect on the Lady Franklin block and the AT-7 prospect on the Atammik block.
Both prospects contain multiple structural targets in the Tertiary and Cretaceous sections with expected mean prospective resources of 480 million and 350 million bbl, respectively, with the probability of success estimated at 10-20% dependent on the individual target horizons. Planned TDs are 3,600 m at AT-7 and 4,500 m at LF-7.
Follow-up prospects are present in both blocks with an estimated combined gross mean in-place resource of more than 8 billion bbl or 14 tcf.
The exploration well in this Baffin Bay block will target the Delta prospect, a large structural culmination in the Cretaceous section where overlying Tertiary volcanics are prognosed to be thin or possibly even absent (see map, OGJ, Jan. 3, 2011, p. 71).
The Delta prospect has an expected mean prospective resource of 530 million bbl 10% probability of success. The potential for stacked pay could add to the estimate. The well is to be drilled to 4,750 m and targets the potential reservoirs of Cretaceous age not reached in the Alpha-S1 well drilled in 2010.
Alpha-S1 encountered oil shows in the thick (>1 km) Tertiary volcanic section. Geochemical analysis of the oil samples confirm three types of oil, one of which comes from a pre-Tertiary source rock that is presumed to be Cretaceous in age as it has similarities with known Cretaceous oil seeps seen onshore in the Disko area. The Delta well is important for understanding the potential of a regional Cretaceous play in the offshore Disko area.
The Eqqua block lies south of the Sigguk block where the 2010 activities were focused and it was acquired by Cairn in the Disko West license round in late 2007.
The Gamma prospect in the Eqqua block is a combination structural-stratigraphic trap in an interpreted Tertiary basin floor fan at 2,500 m overlying a deeper Mesozoic structural culmination at around 4,500 m. The fan targets potentially thicker reservoir sands 100 km from the T-8 well but at the same stratigraphic level as the gas seen in thin sands in the T-8 well drilled in 2010.
The Tertiary Gamma Prospect has a mean prospective resource of 1.84 billion bbl or 7 tcf and 10% probability of success. The planned Gamma well is not designed to drill to the deeper Mesozoic target this year as this prospect will require proof of offshore Cretaceous reservoirs from the Napariaq Delta prospect well.
Pitu and Southern Greenland blocks
The Pitu block was acquired in the December 2010 Baffin Bay Bid round, and the southern Greenland blocks were acquired in 2008.
Two 1,500 sq km 3D seismic surveys are planned to be acquired in each of these areas over structural complexes where leads and prospects with material potential have been identified.