* Shell wants to force a partnership with producer Seplat
* Glencore has dropped out of the race
* Aliko Dangote, Sahara finalising deal on other blocks
* Oil major divestments fraught with pitfalls
By Tim Cocks and Ron Bousso
ABUJA/LONDON, March 28 (Reuters) - Nigerian firms Taleverasand Aiteo have made the highest bid of $2.85 billion for thebiggest of four Shell assets up for sale, but the oilmajor is holding out while it tries to persuade them to team upwith Seplat, an existing operator.
Several oil industry sources told Reuters that, althoughthere is little doubt the duo can raise cash for the block,Shell is concerned about the reputational risk of selling it totwo exporters of crude and importers of gasoline that have noprevious experience in running producing oil assets.
Shell is divesting its 30 percent stake in four Nigerian oilblocks, with France's Total and Italy's Eni also set to profit from their 10 percent and 5 percent shares.The Nigerian National Petroleum Corporation (NNPC) owns theremaining 55 percent.
As well as being an existing operator, Seplat is set to listits shares in London and Lagos next month.
Shell declined to comment. Taleveras, Aiteo and Seplat didnot respond to requests for comment. Bidders are bound by confidentiality clauses.
Winners are expected to be announced next month.
Choosing the right buyer, rather than the highest bidder,can be crucial to securing sales, in a country where politicalinfluence can decide deals and legal disputes or financialproblems can scupper them.
"Taleveras is resisting because it wants the block foritself, not in partnership with Seplat," one source said.
The sources also said Africa's richest man Aliko Dangote,with a personal fortune of $20 billion, and local firm SaharaEnergy, had bid for the other three blocks, OMLs 18, 24 and 25,and were in late-stage talks for at least one of them.
TROUBLE DIVESTING
Neither Dangote nor Sahara responded to requests forcomment. Dangote, who owns two power plants and several cementfactories, is more interested in the gas, two sources said. Theblocks between them have more than 1.5 trillion standard cubicfeet (scf) of gas, they said.
The Nigerian sales are part of a wider plan by Shell todispose of $15 billion of assets this year and next, in order toslim down operations after a profit warning.
Commodity trader Glencore said this month it wasinterested in the assets. Sources said it hadsince backed away. Glencore officials declined to comment.
Shell faces a dilemma: sit tight and try to force a marriagebetween Seplat and the other two, or dispose of the block andface the criticism that it did not do so to a proper operator.
There is high demand for assets in the Niger Delta, whichholds a large portion of Nigeria's 37 billion barrels of oilreserves. The oil is high-quality, relatively easy to drill, andsome Nigerian companies have said they can better handle thesecurity challenges faced by oil majors.
Consensus estimates of the value of the combined 45 percentstake in all four blocks are around $3 billion, showing howasset values are being inflated by a scramble among Nigeria'sincreasingly wealthy elites, analysts say.
But deals are fraught with pitfalls. U.S. energy companyChevron is embroiled in a legal battle over its own saleof three Niger Delta blocks. ConocoPhillips has beentrying to close a $1.79 billion deal for over a year withNigerian buyer Oando, although Oando says it has nowraised the finance. (Additional reporting by Joe Brock in Johannesburg; Writing byTim Cocks; Editing by Dale Hudson)