UK-based Cairn Energy and its Senegalese partners have made an oil discovery, which has the potential to be a “significant standalone development”, on the deepwater FAN-1 well.

The well, drilled using the semisubmersible Cajun Express, reached 4927m target depth and was targeting multiple stacked deepwater fans. It discovered 29m of net oil bearing reservoir in Cretaceous sandstones. No water contact was encountered in a gross oil bearing interval of more than 500m

Cairn’s CEO Simon Thomson said the find, in 1427m water depth about 100km offshore Senegal in the Sangomar Deep block, was an important event for Senegal and its joint venture.

“We have encountered a very substantial oil bearing interval which may have significant potential as a standalone discovery,” he said. “Furthermore, this result materially upgrades the prospectivity of the block with a proven petroleum system and a number of deep fan and shelf prospects established.”

The well was the first drilled in deep water offshore Senegal and was the first well drilled in the country’s offshore waters for more than 20 years, says Australia-based partner Far Ltd.

Initial gross STOIIP estimates for the FAN-1 well range from P90, 250 mmbbls, P50, 950 mmbbls to P10, 2,500 mmbbls and are broadly in line with pre-drill STOIIP estimates

The FAN-1 well was the third well in Cairn's North West Africa program and first in Senegal.

Cairn said there are no plans for immediate well testing. Further evaluation will be required to calibrate the well with the existing 3D seismic in order to determine future plans and optimal follow up locations to determine the extent of the discovered resource, said the firm.

Once operations have completed on the FAN-1 well, the Cajun Express will move to complete the second well, SNE-1, where the top hole has been drilled pending re-entry. This Shelf Edge Prospect targeting a dual objective in 1100m water depth is also in the Sangomar Deep block.

Partner Far Ltd said SNE-1 was targeting prospective unrisked best estimate resources of 600MMbo.

Cairn has a 40% Working Interest (WI) in three blocks offshore Senegal (Sangomar Deep, Sangomar Offshore and Rusifique) ConocoPhillips has 35% WI, FAR 15% WI and Petrosen, the national oil company of Senegal 10% WI. The three blocks cover 7490sq km.

Cairn and Conoco farmed into the block, then operated by Far, in 2013. Far says, in its exploration on the three blocks, particular focus has been drawn to analogue fields including Cantarell, recognized as a super-giant accumulation being Mexico’s and perhaps North America’s largest. In pre-rift time, Senegal was considered to be adjacent to Mexico before the African and American continents pulled apart.

Source: www.cairnenergy.com / www.oedigital.com