Talos Energy spudded the Zama-1 exploration well in the Sureste Basin offshore the state of Tabasco in Mexico on 23 May. The prospect is estimated to hold from 100 million to 500 million bbl of oil, according to project partner Premier Oil. The drilling effort marks the first well to be spudded on a block awarded in Mexico’s first acreage tender in July 2015, following the country’s historic energy reform that opened oil and gas projects to foreign investors. An offshore well operated by Eni—which resulted in a discovery announced on 23 March—was drilled before Zama-1 on acreage awarded in the second tender in September 2015. Talos, the operator, holds a 35% interest in the Zama well, with the remaining stakes held by Sierra Oil & Gas (40%) and Premier (25%).