The notion of linking natural gas to crude oil is a funny one for the uninitiated in North America, where an abundance of supplies and a robust wholesale market reign. However, nearly three-quarters of all the world’s liquefied natural gas (LNG) trade is tied to oil prices.

Unlike oil, the global gas trade has no single benchmark to unify it like Brent. The market has grown more liquid over the last decade as more LNG producers, particularly those in the United States, and large commodity traders have gotten more involved. While that has led to more short-term and spot buying with gas hub-linked prices across the world, more traditional long-term, oil-indexed contracts remain dominant.

Oil-indexed contracts accounted for about a quarter of gas purchases in Europe in 2018,...