By Toyin Akinosho
For the five years between 2003 and 2008, the deepwater Rio Muni basin, off Equatorial Guinea, was the graveyard of optimism of operators looking in to share in the spoils that Hess Corporation was enjoying.
After Triton discovered the La Ceiba in 1999 and opened the Rio Muni basin, operators trooped to Equatorial Guinea and lined up drilling prospects around the new field.
But as Triton and latterly Hess (which bought out Triton), improved their fortunes in La Ceiba, the companies operating around and adjacent to the field came up with one frustrating result after another.
Pioneer Resources and partners, including the Australian independent Roc and the Nigerian minnow Atlas, drilled an early dry hole in Block H.
Chevron, and its partner, Sasol, dropped Block L, in 2007, after plugging and abandoning two wells in the lease. Devon and Hess, both partners in Block P, gave up their interests. Like Chevron and Sasol, Devon exited the country completely.
Petrobras and Petronas remain, unhappy with the two dry holes they have each drilled, but staying put either because they believe in the saying that “it takes more than five successive dry holes to write off a basin” or because, as state companies, they are not answerable to shareholders the way the private firms are, or something in between.
Still, as the story of a widening dust bowl dominated the headlines out of deepwater Equatorial Guinea, Noble Energy showed up with a harvest. The company had flowed 24million standard cubic feet per day (MMscf/d) of gas and 1,225BCFD of condensate in the O-1 wildcat on the Belinda prospect, in Block O. This was in October 2005. The story was largely ignored. The well was drilled in 250 feet of water, hardly the sort of geography that’s classified as deepwater; the fluid type was gas and condensate (these still don’t make hits in the Energy press in Africa) and three, the well wasn’t located in the Rio Muni basin.
In fact, the frenetic pace of work around Rio Muni basin had led to a fixation, in the public mind, that deepwater exploration in Equatorial Guinea was squarely about Rio Muni.
But Noble Energy had set up shop in the unheralded Douala Basin, farther up north from the Rio Muni cluster and closer in geology to the Niger Delta basin, in which the Zafiro field, Equatorial Guinea major oil field, was domiciled. Noble Energy’s operated blocks O and I are the Douala Basin.
As significant as any other data; Noble was chasing Miocene age targets in Douala basin, contrary to Cretaceous targets that everyone was looking for in Rio Muni.
What kept Block O in the news was Noble’s own loud press centre. The news just kept on coming. By August 2007, the Belinda pool had been extended by the appraisal well O-3, which established significant downdip resources. “Reservoir quality at the O -3 location, in 521metres of water was even better than was encountered at the O-1 discovery location while maintaining reservoir thickness”, the company release said.. Test results showed condensate-rich natural gas producing at maximum flow rates of 30.4 million cubic feet per day of natural gas and 1,540 barrels per day of condensate,
There was more to come…
Adjacent to Block O to the south is Block I where Noble Energy really got lucky.
In June 2007, the company encountered a Miocene reservoir on Block I while testing the Benita prospect, containing 41.5 meters of net hydrocarbon pay. Production tests from well I-1 yielded flow rates of 1,038 barrels per day of condensate and 34.3 million cubic feet per day of natural gas.
In October of the same year, Noble Energy announced results for well I-2, its first appraisal well on the Benito structure reporting approximately 45metres of net pay of which there is an estimated 10metres of net gas pay underlain by 35metres of net oil pay. The 1-2 well lies 42 km east of Bioko Island and 3 km southwest of the I-1 well, the original Benita discovery. I-2, in 951 metre water depth, was drilled to a TD of 3,225metres. The well wasn’t tested.
In December 2007, Noble announced it had found hydrocarbons in the I-3 well, drilled on the Yolanda prospect block. The well tested at 371 BCPD of condensate and 36 MMcf/d of natural gas in 896 metres of water is approximately 48 km east of Bioko Island and 10 km south of the Benita discovery, which is also on block I. It was drilled to TD of 2,890metres.
It just got better…
Results of the ‘I-5’ well on the Benita structure were announced in June 2008. The well encountered approximately 13 meters of net oil pay, defined the water-oil contact, and moved the lowest known oil down structure approximately nine (9) meters. Test results from this high-quality Miocene reservoir yielded flow rates of 6,250 barrels of oil per day and 5.4 MMscf/d of natural gas, with production rates limited by test equipment. Noble declared that, based on test information gathered, “the Benita development wells are anticipated to produce approximately 10 thousand barrels of oil per day”. Samples taken indicated a crude oil gravity of 300. This time, the company talked of a Field Development Plan. “We are moving forward with the engineering and production studies to submit a plan of development by the end of 2008, with hopes to sanction the project in 2009. Our target for first production from Benita remains 2012”, Charles D. Davidson, Noble Energy’s Chairman, President and CEO, said
..But the best was yet to come
By late August 2008, Noble Energy had tested a commercial pool of oil and gas in a prospect entirely different from the Benita structure. Diega 1 (which was drilled on , the last remaining Miocene channel prospect identified on the block by AVO response), encountered approximately 38 feet of net gas-condensate pay in the primary target, as well as an additional 30 feet of net gas-condensate pay underlain by 37 feet of net oil pay in a previously untested feature. Tests yielded a flow rate of 2,700BOPD of oil and 2.7 million cubic feet per day of natural gas. Fluid samples taken during the test indicated similar crude oil characteristics to Benita, which it complements. Noble Energy did not say whether the two would be jointly developed. The company, however, stretched interpretation rather far when it declared that “the development well completions in Benita can be designed to achieve production rates of approximately 10,000 BOPD of oil plus associated natural gas”. This is curious; Benita had only tested 6,500BOPD of oil 1-5, the fourth of the four wells announced on the Benita Field. No other well on the structure had flowed oil. So how would the company produce 10,000BOPD from the field when it hadn’t even flowed 10,000BOPD in the field? Perhaps there are some other tests that Noble Energy hasn’t announced.
Noble Energy operates in Block 1 in partnership with PA Resources (6%), Atlas Petroleum International (29%) and Glencore (25%). GEPetrol (the national oil company of the Republic of Equatorial Guinea) will have a 5% carried interest once commerciality has been determined.
Noble Energy is working to further define the development and production scenarios to commercialize its discoveries in Equatorial Guinea. The company is focused on accelerating the Benita development with a targeted project sanction in 2009 and first oil production in 2012. The Belinda gas-condensate development will come Benita and will then be followed b addition of Yolanda and YoYo.