In reality, though, foreign firms such as Royal Dutch Shell <RDSa.L>, Chevron (>> Chevron Corporation), Eni (>> Eni SpA) and Total (>> TOTAL) are here to stay, industry sources say.
The majors are likely to sell only small blocks that are not worth their while -- those assets worst affected by theft and sabotage or fields that risk expropriation in a government push to promote local ownership.
Meanwhile, the large oil producing blocks, huge gas deposits, key pipelines and the export terminals that control the passage of onshore oil to international markets will most likely stay in their hands -- enabling them to retain infrastructure for which they can charge rent to other users.
Complaints by oil majors that Nigeria has done little to combat oil theft or end uncertainty over changes to the fiscal regime by passing the Petroleum Industry Bill (PIB) are genuine, but they won't drive the firms away from the country.
"Nigeria's 'difficult' operating environment, security concerns and the non-passage of the PIB all provide useful cover for what may essentially be a portfolio optimisation process," said Razia Khan, Head of Africa Research at Standard Chartered.
The global shale oil and gas boom means there are more exploration opportunities, so it makes financial sense to keep only the most profitable businesses in Nigeria, like gas for LNG export, and expand deep offshore where there is no oil theft.
If anything, they will use their grievances as leverage in negotiations with government over licenses and taxes.
OIL THEFT HEADACHES
Nigeria's oil production, which fluctuates between 2-2.5 million barrels per day (bpd), is unlikely to be hugely affected by any oil block sales in the short-term and could get an uplift in the future if smaller local companies work harder to exploit reserves or can better stem insecurity with local communities.
Tycoons Tony Elumelu and Wale Tinubu, the Oando (>> Oando Plc) CEO, both of them negotiating to buy oil blocks off majors, told Reuters in recent interviews they thought it would be easier for Nigerian companies with a better understanding of local issues to manage often fraught community relations.
But ending oil theft -- officially estimated at 250,000 bpd -- is a massive undertaking. It is often associated with criminal gangs who tap crude from pipelines for local refining, but most stolen crude leaves the country in large tankers, which could not happen without the complicity of top officials.
Shell, the largest producer in Nigeria, said last week it took a $700 million (451 million pounds) hit from theft and other issues in Nigeria with its share of output falling to 158,000 bpd in the second quarter, down from 260,000 bpd in 2012.
Shell CEO Peter Voser nevertheless told Reuters this month the company was not seeking to leave Nigeria.
Eni said it had lost 30,000 bpd of output in the first half of the year due to theft and CEO Paolo Scaroni said the company was "reviewing its position" in Nigeria.
Total declined to comment on its plans.
Shell, which has already sold eight blocks in the Niger Delta for around $1.8 billion since 2010, announced it will sell more fields amounting to 80,000-100,000 bpd, although it is not clear if this level of output is yet being produced.
Chevron (>> Chevron Corporation) is also selling five shallow water blocks, but would not comment further on its plans for Nigeria, while fellow U.S. firm ConocoPhillips (>> ConocoPhillips) is selling its Nigerian businesses to Oando for about $1.79 billion.
Theft may not be the only reason for selling down.
The PIB, although still in a political deadlock that has lasted five years, could change the terms for foreign companies in Nigeria and will promote local ownership of onshore blocks.
Shell, Chevron, Eni and Total have been in failed negotiations with the Nigerian government for several years to renew expired licences on many onshore and shallow water blocks.
"Perhaps they would rather sell licences while they still can rather than having to relinquish them for nothing," said Antony Goldman, head of Africa-focused PM Consulting.
Yet Shell recently announced it would spend $3.9 billion on a gas project and a reconstruction of a better protected Trans Niger pipeline, one of the country's most important crude oil routes and often hit by outages caused by theft or sabotage. That suggests it still sees value working onshore in Nigeria.
Shell may even buy one of Chevron's blocks, two sources told Reuters, which would provide the perfect route from one of Nigeria's largest gas fields to its LNG export terminal.
Nigeria holds the world's ninth largest gas reserves, most of which are untapped. Energy majors are increasingly moving towards gas production instead of oil in the Niger Delta.
Majors such as Shell will likely keep large pipelines and export terminals, so even if local firms are getting the oil out of the ground, where the risks of insecurity are highest, the majors can make a cut from taking oil to international markets.
"Oil majors want to keep control of this infrastructure as it means they will have a large degree of control of onshore assets and derive revenue from transportation," said Kayode Akindele, partner at Lagos-based investment firm 46 Parallels.
There is no guarantee that deals on assets that majors do want to sell can be easily or quickly completed -- Nigeria has one of the world's slowest oil contract approval times, experts say.
Some of Shell's previous divestments took years to negotiate. Buyers will also be wary of the state oil company's production arm NPDC taking over the operating rights -- as it has on previous Shell field sales where the private buyers were expecting to operate them.
Yet for the all the pitfalls, Nigeria will be keen to close the deals, which please the political elite and public alike.
"The divestment is a positive step for all the major players involved ... (it) will have a positive knock-on impact on production longer-term," said Martin Kelly, Wood Mackenzie's Lead Analyst for Sub-Saharan Africa Upstream Research.
"But ... in order to make a noticeable difference other challenges need to be addressed -- like the PIB and security."
(Editing by Tim Cocks and Giles Elgood)
By Joe Brock