Abu Dhabi National Oil Co is preparing a shortlist of companies that will be invited to bid for onshore oil concessions as shareholders such as ExxonMobil Corp may face competition from new entrants. ExxonMobil, Royal Dutch Shell, BP, Total and Partex Oil and Gas have been shareholders in onshore reserves under a concession agreement that dates back to 1939. The fields began commercial production in 1960. Adnoc, as the state-run explorer is known, joined as a partner in the 1970s, forming Abu Dhabi Co for Onshore Oil Operations, which holds the rights for six main onshore deposits until 2014. \"We are now in the selection process of the bidders and we have not come up with the final list of bidders,\" Abdullah Nasser Al Suwaidi, director general of Adnoc, said yesterday in Abu Dhabi. \"A lot of oil companies are being considered. Definitely our current partners are important.\" Oil companies are waiting for the tender to bid for Abu Dhabi\'s 1.4 million barrel-a-day onshore oil rights as the current contracts expire. Abu Dhabi holds more than 90 per cent of the crude in the UAE, one of the few countries in the Middle East that allow overseas companies to explore for and produce oil within its borders. Adnoc is currently setting up the tendering process to accept bids for the reserves, Al Suwaidi said. The company has time to finalise the tender since concessions don\'t expire until 2014, he said. ExxonMobil expects Abu Dhabi to change the terms for the main oil-producing concession when the current agreement expires in 2014, chief executive officer Rex Tillerson said in Dec-ember. Total expects to remain a partner, chief executive officer Christophe de Margerie also said. Shell is \"very interested\" in renewing its rights, John Barry, the company\'s country chairman, said in October, while Partex is in discussions about renewing its stake in the partnership, said Antonio Costa Silva, chairman of the company\'s management commission.