Oil industry shakeup initiated by the Buhari administration could results in billions of fines for oil majors.

Shell and Eni have long been under scrutiny for playing by the Nigerian rules of the day. The only question now is if the supermajors lose this key offshore block.

Supermajors Royal Dutch Shell (RDS.A, RDS.B) and Italian Eni (NYSE:E) could be facing the loss of one of the biggest offshore oil exploration blocks in Nigeria, putting an estimated 9 billion barrels of crude oil at risk.

As the new Nigerian government launches a rampaging anticorruption campaign, local media are reporting government recommendations to reclaim block OPL 245 from oil giants Shell and Eni.

Nigerian Justice Minister and Attorney General Abubakar Malami is behind the recommendation, and is a key figure advising the government on the case.

At issue is how Shell and Eni landed the block in the first place-a controversial deal that is now being investigated in the UK, Italy and Nigeria.

If newly elected Nigerian President Muhammadu Buhari agrees with Malami's recommendation, not only could Shell and Eni lose the block, but they could also face billions of dollars in fines for allegedly bribing corrupt public officials and private citizens.

According to Global Witness, Shell's and Eni's Nigerian subsidiaries had agreed to pay the government $1.1 billion to acquire the offshore block. The watchdog also said that an investigation revealed that at the same time, the same amount was offered to Malabu Oil and Gas, a company widely reported to be controlled by former oil minister Dan Etete. Etete was convicted of money-laundering in France in 2007.

There has been a lot of talk about going on the offensive against corruption in the Nigerian oil industry for years, but it's mostly been the empty talk of campaign promises. This time around, the new president, elected in March 2015, has shown a drive that threatens to bring down anyone connected to the oil business under the previous government. So far, he's made good on his campaign promises, much to the demise of the industry.

Nigeria is Africa's biggest economy, and it relies on oil exports for 58 percent of the government's revenue. When Buhari officially took office in May, he said the coffers were empty and massive amounts of oil money had been embezzled-upwards of $150 billion. Now the country is facing a harrowing economic crisis.

Buhari appears to be serious about shaking up the industry. He's already split up the state-owned NNPC oil company into two entities. He also fired the former oil minister, Diezani Alison-Madueke, and had her arrested in London for allegedly facilitating the embezzlement of a whopping $20 billion. New investigations into former officials are being launched at breakneck speed.

Things aren't looking good for Shell and Eni. On top of the reclamation recommendation that would lose them one of the most lucrative plays in the country, both, along with French oil and gas giant Total SA (NYSE:TOT) are now being accused of getting a $3.3 billion extraordinary tax break from the previous government in relation to the Nigeria Liquefied Natural Gas (NLNG) consortium set up in 1999.

The industry as a whole will balk at Buhari's brazen moves, and criticize the new government for destroying the investment climate and putting the last nail on the coffin of Nigerian oil. But the Nigerian oil industry is already in crisis, and a major overhaul was the only inevitability outside of a complete meltdown.

The abysmally opaque NNPC needed to be split and reformed. Oil corruption needed to be addressed before the country disintegrated. Shell and Eni have long been under scrutiny for playing by the Nigerian rules of the day. The only question now is if the supermajors lose this key offshore block, who will get it.

At the end of the day, Nigeria is Nigeria, and this oil powerhouse can get away with a great deal of house-cleaning without scaring away investors. Anyone who hasn't already been scared away by the industrial-scale oil theft and world class corruption won't do more than bat an eye at the latest developments.