Editor’s Note: NGI’s Mexico Gas Price Index, a leader tracking Mexico natural gas market reform, is offering the following column by Eduardo Prud’homme as part of a regular series on understanding this process.

Almost 10 years have passed since the formation of Cenagas, the operator of Mexico’s Sistrangas natural gas pipeline network. The first open season in the network occurred seven years ago. Today, large- and medium-sized users of natural gas often lament their difficulties in accessing capacity and greater natural gas volumes. This situation is intriguing, given that a second open season has just concluded at Sistrangas amid record high imports from the United States.

Natural gas imports hit 6.9 Bcf/d last summer. In August 2014, the month Cenagas was created, Mexico...