MARTYN MNDERHOUD LOOKED up briefly from the presentation and faced the audience. “Somebody said that Zabazaba was a discovery”, he said. “Well, I don’t know”.
Then almost immediately Shell’s Vice President for Exploration and Production in Africa put up a series of slides, indicating that Shell considers Nigeria the best place to look in its deepwater portfolio worldwide. The scene was the banquet hail of the Sheraton Hotel in Abuja, at the conference of the Nigerian Association of Petroleum Explorationists(NAPE) in November 2006.
In the last three years (2003-2006) almost everyone has lamented the lack of success in ultradeepwater Nigeria. But not Shell. The Anglo Dutch giant has always had a successful story. Shell reported in 2006 that Bobo -l in OPL 322, encountered some 120m of hydrocarbon. Indeed, in his paper, (See illustration) Minderhoud declared Bobo-1 as a “fat cat” discovery. Bobo is located squarely in the ultradeepwater, outboard of 1 ,700m water depth, and its location is not in the Outer Toe Thrust(OTT)Belt area, which has proven quite problematic in terms of structuration for holding hydrocarbon. But if the general rule has been that the farther and deeper from 1 ,600metre water depth you get, the less likely you are to find a significant hydrocarbon tank, then Shell has proven an exception to the rule. Agip’s Dou-1 and Emein-1, OPL 244, both drilled in 2,000m of water encountered marginal gas. Chevron’s Iroko- l(in 2000m WD) in OPL 250, was as much a disappointing story as Phillips Onigun- l (2,200mWD) in OPL 318, Petrobras’s Erinmi-1(2,300mWD) in OPL 324 and Ocean Energy’s Pina-l (in 2,500mWD), which encountered some gas and Tan-1 (2,000m WD) in OPL 256.
While Minderhoud abstained from outright declaration of Zabazaba-l ( 2,000metre water depth) as a discovery, the company has gone ahead to drill Zabazaba 2, an indication that the first well, at least, opened doors to possibilities. Outside the rank wildcat area, Shell is proving up more oil in fields already established.
The January 2007 edition of AAPG Explorer, the influential in house magazine of the largest grouping of earth scientists on the globe, cites Bonga North 2X, as one of the four major discoveries in subsaharan Africa in 2006. Bonga North 2 X is the dual leg appraisal to the Bonga North 11X discovery in OML 118, where the Bonga main, (the main field of the Bonga structure) is producing over 200,000BOPD, or at least 8% of Nigeria’s entire production, today.
AAPG Explorer says that “Shell is trying to prove up enough reserves (500MMBO+) that could lead to Bonga North being developed separately from Bonga”. But Shell sources say that the Bonga North field will be tied to the FPSO of the Bonga main.
Meanwhile, plans have progressed with Chevron to develop Bonga South-West/ Aparo (Chevron’s Aparo wells probed the same sands as Bonga South West, hence a unitization proposal). This means two projects of some 1 50,000B0PD each, at peak, apart from Bonga. Translation; on the Bonga structure and its satellites alone, the company is going to be exploiting, by 2015, three fields delivering a total of at least 500,000BOPD.
One key beneficiary of this is ExxonMobil, who holds 43.7% interest in OML 118. The company will be rewarded whenever these fields come on stream; and it doesn’t even have to lift a finger. Shell itself has 43.7% in ExxonMobil’s OML 133, which hosts the Erha and Erha North fields, producing 230,000BOPD today. The two largest oil producers in Nigeria thus currently deliver close to 500,000BOPD, roughly one fifth of the country’s total production, from deepwater. ExxonMobil’s rich pickings apart, Nigeria has made a rebound in exploration effort in deepwater, an indication that the overall pessimism that hung over the terrain two years ago, is wearing off. Eleven wildcats were spudded in deepwater Nigeria in 2006, a figure which is higher than all the exploratory wells drilled in both shallow water and land last year.
Chevron’s Obo 1 is one play that may put to lie the perception that the outer toe thrust belt is a no no. AAPG Explorer reports that the first deepwater well in the Joint Development Zione (JDZ0 between Nigeria and Sao Tome et Principe, “encountered a cumulative 45 metres of net hydrocarbon pay in multiple reservoirs”.
The magazine said: “Reserves are runmoured to be not as large as expected, leading to speculation that the well was not sited at the most prospective location but rather on the edges of a major structure to check its extent”. As new discoveries show up with less and less reserves than the first set of discoveries, in just 10 years of exploration, there is a spirited debate on the knowledge base regarding the thrust belt features in the Niger Delta deepwater.