Saudi Aramco has agreed a $15.5 billion lease-and-leaseback deal for its gas pipeline network with a group of companies led by BlackRock Real Assets and state-backed Hassana Investment Company. As part of the deal, the world's largest exporting company's newly-formed unit, Aramco Gas Pipelines Company, will lease usage rights in the state energy firm's gas pipelines network and lease them back to Aramco for a 20-year period, the company said in a statement.