MADRID (AP) — Spanish energy company Repsol and London-based BP say they have found a gas field in the Caribbean containing an estimated two trillion cubic feet of natural gas — equivalent to two years of Spanish demand.

Repsol says it is the largest volume of gas it has discovered in the last five years and the most significant in a decade for Trinidad and Tobago. Repsol holds a 30 percent stake in the exploration consortium, with the rest held by BP.

A Repsol statement Monday says drilling is expected to begin in the second half of next year.

The company says about 65 percent of its production and 75 percent of its reserves are gas, a key fuel in the transition to a low-carbon economy.