Nigeria sold 16 oil licences on Friday in return for promises by mostly Asian investors of $20 billion in new infrastructure, in a public sale that raised questions about transparency.
Chinese and Indian companies dominated the winners' list, but several Nigerian firms also secured drilling rights in the deep water areas, many of which are close to big oilfields.
On top of bids totalling $500 million, which should be paid when the contracts are signed, the winners promised to invest about $20 billion in oil refining, power generation, agriculture and railways in the impoverished African oil giant.
The appearance of several unknown or inexperienced Nigerian companies among the winners, and some questionable bidding, raised concerns over the transparency of the process.
Transcorp, a new Nigerian company set up last year by a group of corporate moguls with the blessing of President Olusegun Obasanjo, bid on four blocks but failed to produce a supporting bank draft.
"419!" shouted several assembled executives, referring to a section of the Nigerian criminal code on fraud.
The licensing comes at a time of heightened political uncertainty in Nigeria with landmark elections due next year when Obasanjo must step down.
"In the same way that Obasanjo had a long hard look at the deals made at the tail end of the previous military administration, there is every reason to think that a new government next year would look at these if there is any controversy associated with this process," said Anthony Goldman, an independent risk analyst based in London.
Most of the blocks were unused portions of earlier licenses which were relinquished by major oil companies, some of which have seen billion-barrel oil finds.
India's ONGC exercised its right of first refusal over a hotly contested block 279, taken from an area where ExxonMobil found the giant Erha oilfield, and matched a contested Transcorp bid of $75 million. They also bagged block 285, a relinquished part of Shell's Bonga oilfield licence.
ONGC in consortium with Mittal Steel has agreed to spend $6 billion on building a new 180,000-barrel-a-day oil refinery, 2,000 megawatts of power generation, and a railway running East-West across Nigeria.
State-run China National Petroleum Corp walked away with four licences for a total of $16 million in bids. The Chinese government has committed to investing $2 billion in a refinery in the northern state of Kaduna.
Britain's BG Group and Sahara Energy secured rights to block 286, a discarded part of the licence where Chevron co-discovered the Bonga Southwest/Aparo oilfield.
Transcorp was named the winner of two blocks despite not having the required bank draft.
The government also used the licensing to address civil unrest in its oil heartland by reserving one block for a collection of "youth groups" - a local term for militants - who would reinvest any of their profits into local development.
"We decided it was right for us to give them rights on blocks that are relatively easy to exploit. We as the government are going to help them," said Tony Chukwueke, head of Department of Petroleum Resources,
Militants demanding more control over their resources have attacked the oil industry in the Niger Delta, cutting the Opec nation's exports by a quarter since February.
Another in-house deal was the award of block 289 to Clearwater, owned by the southern state of Rivers, in return for a promise to invest $1.5 billion in power in its own state.
A joint-venture of Nigeria's Jigawa state government and an unnamed Canadian investor secured two blocks including 292, taken from a licence containing Chevron's giant Agbami oilfield. They pledged investment of $4 billion in an ethanol project based on a 300-hectare sugar plantation in northern Nigeria.
Analysts said it was questionable whether these Nigerian companies had the financial or technical ability to explore for and produce oil in deep water.