Saudi Arabian Oil Co., aka Aramco, on Tuesday agreed to take $15.5 billion for a 49% interest  in its natural gas pipeline infrastructure to a consortium led by BlackRock Inc.

Saudi Aramco

In the transaction, newly formed Aramco Gas Pipelines Co. would have lease and leaseback usage rights of the network over a 20-year period. BlackRock clinched the deal with partner Hassana Investment Co., the investment management arm of Saudi Arabia’s General Organization for Social Insurance (GOSI).

Aramco has “reached yet another major milestone in our portfolio optimization program as we build toward a bigger and stronger gas business,” said CEO Amin H. Nasser. “It further underscores our commitment to long-term value creation for our shareholders, while bringing in BlackRock and Hassana as...