Tullow Oil is looking to exploit a huge oil prize within its West African portfolio, which could spell billions of dollars of profit.

The U.K. independent is talking up the potential of its fields offshore Ghana, where it expects to recover 1.4 Bbbl by increasing output from the producing Jubilee field and the TEN development, which is due onstream mid-2016.

But the reserves picture could more than double as the explorer sees nearly 4 Bbbl of total oil in the region, which it plans to go after in a big way. “Tullow has discovered world-class fields in Ghana and there is a little saying in the oil business that big fields get bigger over time. We certainly believe we have got some very big fields in Ghana, and that they will get bigger as we manage them over time,” said David Lawrie, vice president for the East and West African region.

Oil recovery from the Jubilee field, which spans the West Cape Three Points and Deepwater Tano licenses, is expected to be the region of 1 Bbbl. Recovery from the TEN fields (Tweneboa, Enyenra and Ntomme) is expected to be 440 MMbbl.

But Tullow expects actual recovery to be much higher—about 3.88 Bbbl of ultimately recoverable resources.

Putting that in context, Lawrie explained just how profitable more development could be. He said, “It is probably worth noting that we have produced about 100 MMbbl from Jubilee over 7 years, generating more than US $10 billion of revenue in that time.”

Signalling the size of the opportunities still to come, he continued, “But it is only 2.5% of what we believe could be the ultimate oil-in-place of what we have discovered in Ghana, and only about 7% of what we see as the potential recoverable oil resource,” he told the audience during a capital markets day presentation. “And we have only just started in this business. We are very much in a marathon, not a sprint.”

With the Jubilee FPSO in place Tullow is currently working to upgrade the capacity of that floater, and is thinking of the same for the TEN floater once it is onstream. “Once that initial infrastructure is in place we see high potential for incremental investment opportunities,” said Lawrie. “We also see potential to expand FPSO capacities in both Jubilee and TEN over time....through low-cost de-bottlenecking projects which can further enhance value by accelerating production.”

Improvements and cooling modifications are indicated for the Jubilee FPSO, while pumps and exchangers are the subject of further work to optimise oil production. Gas debottlenecking is planned; dehydration systems are to be optimised, while a power capacity upgrade is still to be done. This should take Jubilee oil production up from its nameplate capacity of 125,000 bbl/d to 140,000 bbl/d, and gas production from 160 MMcf/d to 180 MMcf/d. The field sustained production through the first half of this year at 100,000 bbl/d, with this level of output expected to continue throughout the rest of this year.

After pioneering 4-D seismic techniques at the Okume and Ceiba fields operated by Hess in Equatorial Guinea, which delivered incremental production opportunities, Tullow has more recently completed 4-D baseline surveys at Jubilee and TEN.

“We expect a number of as-yet unseen opportunities to emerge as the next survey is shot later this year or early next year,” said Lawrie.

For the TEN project, Modec is supplying the Centennial Jewel VLCC, now undergoing conversion by Jurong in Singapore, to provide plateau production of 80,000 bbl/d of oil, processing for 170 MMcf/d of gas and storage for 1.7 MMbbl for delivery in 2016 under a 10-year lease contract with another 10 years of options.

Modec will own and operate the TEN FPSO, which will be stationed in 1,500 m (4,920 ft) of water and moored via an external turret. All the key contracts for the project including the vessel conversion and subsea infrastructure are in place and work is underway.

Earlier this year Tullow participated in a global benchmarking study for the Jubilee FPSO with 33 other floating production units and found its costs were well below the industry average.

However, the news is not all good for Tullow in Ghana. “We are starting to see some growth in indirect costs to support the infrastructure organisation, which supports our offshore organisation.” Lawrie admitted.

Although costs are running at $9/boe in Ghana, he said this will reduce as production increases and as efficiency improvements are made, along with synergies with the TEN project being realised. “But this will come down again once TEN is onstream and our costs are spread over a wider production base,” he said.

Gas export from Jubilee remains constrained by government gas production facilities, which are due onstream in fourth-quarter 2014.

TEN was 30% complete at the end of June and Tullow expects that figure to reach 50% by the end of this year. With $4.9 billion of capex, TEN will have a total of 24 wells drilled. Ten are due onstream at first oil mid-2016, with seven so far drilled by the West Leo rig, and the reservoir penetrated by the eighth. “Information from those wells has helped to underpin our confidence in the resource base,” said Lawrie.

Elsewhere more frontier deepwater wells are also planned by Tullow offshore Equatorial Guinea, Gabon, and Namibia as it seeks to establish more reserves.

In Equatorial Guinea the company has pinpointed opportunities from shallow to deepwater. The Fatala deepwater prospect has been selected for drilling, with 373 MMbbl gross unrisked means resources and up to 974 MMboe on a P10 basis, with the chance of success (CoS) put at 20%.

Offshore Gabon, Tullow is planning to spud Sputnik-1 this month, a presalt prospect, with 206 MMbbl (gross unrisked mean), 427 MMbbl (P10), and a CoS of 27%.

Also this year Tullow will target the Albatross prospect offshore Namibia with 422 MMbbl gross unrisked mean), 1,093 MMbbl (P10), and with a CoS of 17%.

Off the coast of South America, meanwhile, in the Guyanas Margin (where Tullow hit 72 m [236 ft] of pay in the Zaedyus?1 well in 2012), the company was unsuccessful with follow-up appraisals. But Ian Cloke, Tullow’s vice president for exploration, said industry interest in the region has continued to ramp up, demonstrated by the recent decision by ExxonMobil and Total to enter ultradeepwater acreage downdip of the Zaedyus discovery.

Offshore