Cairn Energy is to plug and abandon its FAN South-1 well in the South Fan prospect offshore Senegal, and move to its next drilling target in the region, the SNE North, or Sirius, prospect.
FAN South-1 was drilled in ~2175m water depth, about 90km offshore in the Sangomar Deep Offshore block and 30km south west of the FAN-1 exploration well.
Cairn says the latest well encountered hydrocarbon bearing reservoir (Lower Cretaceous) and oil 31° API oil samples were obtained. Cairn says further work is being undertaken to integrate this discovery with FAN-1 to establish the potential commerciality of the deep water, basinal resource seen in the two wells.
GMP Research said the net pay in the well was less than expected (at the lower end of the potential range) and the reservoir quality mixed. The firm says the prospect was similar to the 2014 FAN-1 discovery. The well was also targeting an Upper Cretaceous prospect, where no hydrocarbons were encountered. "Further work is being undertaken to establish potential commerciality," said GMP, adding: "The commerciality of FAN-1 was already uncertain and it is not clear if FAN South-1 is improving the picture as the encountered volumes are much less than expected."
FAR Managing Director Cath Norman said: “The discovery of oil in FAN South-1 yet again verifies the quality of the oil and gas generating system in our offshore Senegal permits and is another significant result." However, she added: "The basinal fan play offshore Senegal is clearly a very large, but technically complex system which will require further evaluation to understand the commerciality of this deepwater basin area."
The Stena DrillMAX drillship completed the FAN South-1 well ahead of schedule and under budget. The well reached total depth of 5343m, targeting dual prospects: an Upper Cretaceous stacked multi-layer channelized turbidite fan prospect and a Lower Cretaceous base of slope turbidite fan prospect, similar to the FAN-1 oil discovery in 2014. FAN South-1 is being plugged and abandoned.
The rig is now moving to start operations at the SNE North exploration prospect, 15km north of the SNE-1 discovery well, and the most northerly location yet tested, on trend with the highly successful SNE field.
SNE North is targeting a prospective volume of more than 80 MMbbl of total resource in multiple objectives. The well is in about 900m water depth and the projected total depth of the well is 2800m.
Simon Thomson, CEO of Cairn Energy PLC said: "FAN South is our tenth well in Senegal in the last three years and our second well to encounter oil in the deep portion of the basin, adjacent to the FAN discovery. The results of FAN South will be integrated with FAN-1 and SNE to help the joint venture’s ongoing evaluation of the large, deep water basin potential offshore Senegal.
"As planning for the phased development of the SNE field moves ahead, we will shortly commence operations on the SNE North prospect, which has the potential to enhance our total resources in Senegal.”
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