Potential buyers are expected to submit bids at the end of October, said one of the sources. Earlier this year Aramco, similar to Abu Dhabi National Oil Co (ADNOC), used a lease-back agreement to sell a 49 per cent stake of newly formed Aramco Oil Pipelines Co to the buyer and rights to 25 years of tariff payments for oil carried on its pipelines. It plans to use a similar structure for its gas pipelines.