US oil giant ExxonMobil has announced it has struck oil offshore Guyana yet again this time at the Longtail-1 exploration well.

This represents eight out of ten successful exploratory wells for the Houston based oil giant, in an industry with an average success rate of 20 to 25 per cent.

This discovery, announced yesterday, was made approximately five miles west of the Turbot-1 well and follows previous world-class discoveries on the Stabroek Block at Liza, Payara, Liza Deep, Snoek, Turbot, Ranger and Pacora.

ExxonMobil said in a press release that along with the Turbot find, the latest discovery will raise reserves by over 500 million barrels and “creates the potential for additional resource development in the southeast area of the Stabroek Block” which comprises 6.6 million acres (26,800 square kilometres) and is located approximately 120 miles (193 kilometres) offshore Guyana.

“The well encountered approximately 256 feet (78 meters) of high-quality, oil-bearing sandstone reservoir….Longtail drilling results are under evaluation; however, the combined gross recoverable resources of Turbot and Longtail are estimated to exceed 500 million barrels of oil equivalent,” the oil company said.

The Stena Carron drillship began drilling at Longtail on May 25. Having made this latest discovery, the ship is being sent off to a new target, Hammerhead-1, located nine miles southwest of Liza 1.

ExxonMobil is accelerating exploration activity with an additional drill rig expected in the next few months. This would mean two engaged in exploration while another rig develops the Liza 1 field set to start production in early 2020.

ExxonMobil’s affiliate, Esso Exploration and Production Guyana Limited (EEPGL) is the operator of the Stabroek Block, holding a 45 per cent interest, Hess Guyana Exploration Ltd. holds 30 per cent interest and CNOOC Nexen Petroleum Guyana Limited holds 25 per cent interest.