The Marsouin-1 well encountered at least 70m of net gas pay in Upper and Lower Cenomanian intervals involving good quality reservoir sands, based on preliminary analysis of drilling and wireline logging results.
In April, Kosmos Energy reported a significant, play-opening gas discovery at Tortue-1 exploration well, also located in Block C-8.
The well drilling was intended to test the Tortue West prospect, which forms part of the Greater Tortue Complex.
The Marsouin-1 well, which is located approximately 60km north of the basin-opening Tortue-1 gas discovery, has been drilled in nearly 2,400m of water using Atwood Achiever drillship.
Kosmos Energy chairman and CEO Andrew Inglis said: "Marsouin-1 is our second major discovery of 2015, extending our 100% success rate in the outboard Cretaceous petroleum system offshore Mauritania and Senegal.
"Well-to-seismic calibration has significantly de-risked the discovered resource base, as well as future prospects in the basin.
"Importantly, the well results have validated our charge model and given us growing confidence in our ability to predict the oil and gas potential of this emerging, large-scale petroleum system.
The company said it plans to undertake exploration and appraisal program to further explore the basin.
Kosmos will move the Atwood Achiever drillship to drill the top-hole section of the Ahmeyim-2 well located in the southern part of Block C-8.
Following completion of Ahmeyim-2 well drilling, the drillship planned to spud Guembeul-1 well, which aims to define the Greater Tortue area, by the end of this year.
