Kosmos this week announced that its most recent exploration well offshore Mauritania, Lamantin-1, was water bearing.
The well is the second disappointment in a four well exploration campaign offshore Mauritania and Senegal designed to test the outboard basin floor fan fairway. Since its Tortue-1 discovery in 2015, the company had enjoyed a 100% success rate in the region, with 25 Tcf discovered across five wells.
These original successes, eg Tortue, Marsouin and Teranga, all encountered lean gas in channel sands along the inboard slope. For the second exploration phase, Kosmos shifted its focus further offshore and to outboard basin floor fans, where modelling suggested that the greatest chance of finding oil was in northern Mauritania.
The first well in this campaign, Yakaar-1, located in Senegal, was the most southerly of the target prospects and encountered an estimated 15 Tcf of gas in thick good quality stacked Lower Cenomanian reservoir. The discovery has provided the opportunity, together with Teranga, for a second LNG hub in Senegal and the results gave the company confidence that its play concept was working.
The second well, Hippocampe-1, was targeting 12Tcf gas in Lower Cenomanian and Albian reservoirs in Block C8 in Mauritania, though the company was also hoping to find evidence of liquids. However although good quality Cretaceous sands were encountered, they proved to be water bearing. Kosmos now believes that this was due to a lack of charge access in this part of the fairway.
Lamantin-1 was being keenly watched since, as the most northern of all the wells, it had the highest chance of all the independent prospects to encounter oil ( estimated pre-drill to hold a gross unrisked resource potential of 2-3 bnboe). However the well, in Block C12, was found to be water bearing with residual oil. The Lower Campanian target was a combination structural/stratigraphic trap and the company believes it failed due to a lack of trap.
The fourth and final well of the 2017 programme will be drilled on the Requin Tigre prospect. Located in northern Senegal and around 50km west of Tortue, the well will target a very large basin floor fan, estimated to hold 60Tcf.
In Mauritania, Kosmos is exploration operator and holds 28% WI with BP (62%) and SMHPM (10%)
In Senegal, Kosmos is exploration operator and holds 32.5%WI with BP (32.49%), Timis Corporation (25%) and Petrosen (10%)