* Governance bill concerns state oil company
* Part of broader oil bill discussed for over a decade
* Governance bill needs lower house and presidency approval (Adds analyst quotes, details, background and bullet points)
By Camillus Eboh
ABUJA, May 25 (Reuters) - Nigeria's Senate passed a long-awaited oil governance bill on Thursday which the president of parliament's upper chamber said would improve transparency in the OPEC member's energy industry and stimulate growth in the sector.
The Petroleum Industry Governance Bill is one part of proposed reforms that make up the sprawling Petroleum Industry Bill (PIB), aimed at overhauling Nigeria's energy sector which has been hobbled by corruption and mismanagement for decades.
The PIB, which has been discussed for over a decade following several redrafts, is central to President Muhammadu Buhari's reform plans because oil sales provide 70 percent of government revenue in Africa's biggest economy.
"I believe not only Nigerians but investors in the petroleum sector are looking forward to ensure accountability and transparency," said Senate President Bukola Saraki after announcing that the governance portion of the bill was passed after its third reading.
He said it would "create the enabling environment for the petroleum sector that would be necessary to further stimulate growth", adding that he hoped it would attract investment.
The PIB, which covers an overhaul of the state oil company to taxes on upstream projects, was broken up into separate parts including governance and fiscal issues to help speed up debate.
The governance part deals with management of the Nigerian National Petroleum Corporation (NNPC). The bill's backers have said Nigeria's oil sector is in dire need of change, with power currently concentrated in NNPC and the petroleum ministry.
The passed bill would create four new entities whose various powers would include the ability to conduct bid rounds, award exploration licences and make recommendations to the oil minister on upstream licences.
It must be passed by the House of Representatives and the lower chamber of parliament, and needs the approval of the president before becoming law. Buhari is on medical leave in Britain and has handed over power to his deputy, Yemi Osinbajo.
Uncertainty over fiscal terms in the industry have held back billions of dollars of investment.
Rolake Akinkugbe, head of energy and natural resources at FBN Merchant Bank, said changes at the state oil company gave a "signal" regarding the investment climate in the oil sector.
"NNPC has an extensive network of energy infrastructure that needs to be rehabilitated, providing an entry platform for private investors. The private sector will want to see how these reforms are implemented on a day-to-day basis," she said.
Aaron Sayne of the Natural Resource Governance Institute, a non-profit group that advises nations on how to manage natural resources, said the bill was very broad.
"A lot of the big decisions, especially on the national oil company, are to be determined," he said. (Additional reporting by Alexis Akwagyiram and Libby George in London; editing by Susan Thomas and David Evans)