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CAPE TOWN — With South Africa’s dysfunctional power grid and its diesel-guzzling power generation plants, Total’s Brulpadda natural gas discovery off Mossel Bay holds out the hope of a cheaper, more environmentally-friendly alternative fuel source. That’s if Total’s technicians can overcome extraction problems in the ocean deep where the world’s fastest-moving Aghulhas current and notoriously unpredictable weather conditions are making potential extraction costly and time-consuming. The size of the field may be even bigger than the current estimate of 1bn barrels of oil – 3D seismic surveys together with four more exploration wells are planned. The find will require cutting edge technology in weather and water-speed forecasting to enable extra bracing measures to handle extraction in rough seas. With PetroSA’s 29-year-old Mossel Bay refinery – the only one in SA able to process the light crude oil condensates that accompany the gas find – the possibility of upping its capacity from the current 40,000 barrels a day looms large. However, it may take years – the Brulpadda field lies way below both the ocean surface and its floor. The first beneficiaries would almost certainly be the PetroSA gas-to-liquids plant and the Gourikwa (diesel) power station, both near Mossel Bay. – Chris Bateman
Drilling Oil in World’s Fastest Ocean Current Sets Total a Test
But the prospect is surrounded by the Agulhas Current, a fast-moving flow of warm water where the Atlantic and Indian oceans converge, which travels the country’s east coast and can cause waves the height of a multi-story building. Total says it’s found solutions to the problems, but not every explorer has the financial resources or harsh-environment experience of the French oil major.
When Total returned for a second attempt in December, with the Deepsea Stavanger rig to finish a well, it employed previously unused engineering techniques. While rigs are usually carefully stabilised in the water by thrusters as drilling takes place, Total further secured the platform with a tug boat to provide support.
Total had to cancel an initial drilling attempt in 2014. The highly anticipated attempt had to be abandoned because of mechanical failures caused by the rough environment.
The first try lasted a few months and cost about $190m, according to Dave van der Spuy, resource evaluation manager at Petroleum Agency South Africa, which promotes exploration for the South African government.
The French oil major cited repairs needed to the Eirik Raude rig, and its commitment to another contract, as reasons for suspending activity.
While the North Sea is harsh, at least it’s predictable, said Adewale Fayemi, general manager for Total E&P South Africa. “Here in South Africa, waves and currents are most of the time in opposite directions, which generates very bad seas and the wind can be very high and changes direction.”
The second time around, Total also used onshore high-frequency radar to keep ahead of the Agulhas current, Fayemi said. It also used a simplified riser system, which is a pipe that connects an offshore production structure on the water’s surface to sub-sea facilities, that could be accessed and repaired on location, specifically to avoid problems which ended the team’s effort four years earlier.
“Total deployed a suitable rig for the operation and a sophisticated weather forecasting system, coupled with the presence of an on-site specialist, in order to more accurately assess prevailing weather and ocean conditions,” Fayemi said.
The second attempt also took less time and was cheaper, costing about $160m, according to Van der Spuy. “It’s an incredible achievement in terms of engineering and in terms of taking a risk.”
Total plans to acquire 3-D seismic for the license this year, to help determine its next prospects there, which it plans to follow up with as many as four exploration wells.
Sasol Ltd. and Eni SpA also jointly hold a license offshore South Africa and are analysing seismic of the area “to help confirm the prospect and firm-up potential drilling,” said Gilbert Yevi, Sasol’s vice president of international exploration and production.
“There is no doubt that the most recent discovery offshore South Africa is good news for the country,” Yevi said.
The two companies have submitted an environmental impact assessment for potential future drilling and are awaiting approval.