Tullow, Partners Discover Additional Hydrocarbons Offshore Sierra Leone
by Jon Mainwaring
Tuesday, February 21, 2012
Africa's leading independent oil company Tullow Oil announced Tuesday that the Jupiter-1 exploration well in Block SL-07/B-11 offshore Sierra Leone has encountered hydrocarbons. The discovery has been confirmed by the results of drilling, wireline logs and samples of reservoir fluids, said the firm.
Oil analysts at London-based investment bank Westhouse Securities described the discovery in one of the newer sub-Saharan basins of Sierra Leone as "encouraging" and that it also adds to Tullow partner Anadarko Petroleum's African credentials.
The well, located more than 15 miles (25 kilometers) west of the Mercury-1 well
which discovered oil in the block, intersected 98 feet (30 meters) of hydrocarbon pay in the primary Upper Cretaceous objective and did not encounter a hydrocarbon water contact. The well has been preserved for possible future re-entry, as the area is likely to require additional evaluation.
Jupiter-1 was drilled by the Transocean Discoverer Spirit (UDW drillship)
to a total depth of 21,210 feet (6,465 meters) in a water depth of 7,210 feet (2,199 meters). On completion of operations, the drillship will move 9 miles (15 kilometers) northeast to the Mercury-2 well which will target several reservoir levels including extensions of the oil accumulations discovered by the Mercury-1 well.
Westhouse said that the absence of oil-water contact at total depth implies that the reservoir drive system is yet to be determined, although it may be encountered at a greater depth and pressure data gathered as part of the logging program will yield important information about the pressure gradients within the reservoir system.
Anadarko (55 percent) is operator of offshore Block SL-07B-11 along with partners Repsol (25 percent) and Tullow (20 percent).
"Jupiter is the third discovery in the Liberian Basin
by Tullow and its Partners and provides further support for the stratigraphic play in the region," said Tullow Exploration Director Angus McCoss. "The presence of a working petroleum system producing gas and light oil in the basin is encouraging. Our technical teams will continue evaluating prospectivity across our significant regional acreage position. We will further test the play through the drilling of Mercury-2 in Sierra Leone and Kosrou-1 which is currently drilling in Côte d'Ivoire."
Westhouse added: "These are early days for Sierra Leone's oil industry but another discovery in the Cretaceous sequence is very positive and also has read‐across implications for the future potential of Liberia."
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