Kosmos opened a significant new hydrocarbon province when it discovered a large accumulation of natural gas under the deep waters offshore Mauritania and Senegal.
Success at Greater Tortue was the result of applying the company’s proprietary knowledge of the overlooked Upper Cretaceous structural-stratigraphic play concept to the unique conditions of this region in which sands bypassed the shelf and deposited in deeper water.
The pmean gross resource estimate for the Greater Tortue Complex is more than 25 trillion cubic feet of gas. Kosmos’ completed its appraisal of the Tortue structure in early 2016.
Drilled in mid-2015, the Tortue-1 exploration well (later renamed Ahmeyim) encountered approximately 117 meters (373 feet) of net hydrocarbon pay in high-quality reservoir sands in the Cenomanian and Albian intervals. It was the industry’s second largest discovery of the year.
Completed in 2016, the Guembeul-1 exploration well encountered 101 meters (331 feet) of net gas pay in two excellent quality reservoirs, including 56 meters (184 feet) in the Lower Cenomanian and 45 meters (148 feet) in the underlying Albian. Importantly, Guembeul-1 demonstrated reservoir continuity as well as static pressure communication with the Tortue-1 well in the Lower Cenomanian, suggesting a single, large gas accumulation. Guembeul-1 was drilled approximately five kilometers to the south of Tortue-1.
The Ahmeyim-2 well was drilled to a total depth of 5,200 meters. As anticipated, in the Lower Cenomanian and Albian, Ahmeyim-2 penetrated the seismic-inferred gas-water contacts, defining the field limit and extending the productive field area from approximately 50 square kilometers to 90 square kilometers. Furthermore, the well confirmed significant thickening of the gross reservoir sequences down-structure and importantly, within the Lower Cenomanian, static fluid pressure communication between the Tortue-1, Guembeul-1 and Ahmeyim-2 wells. The well encountered 78 meters (256 feet) of net gas pay in two excellent quality reservoirs, including 46 meters (151 feet) in the Lower Cenomanian and 32 meters (105 feet) in the underlying Albian. These results demonstrate field-wide reservoir continuity and indicate Tortue West is a large, simple gas field.