Production has been decreasing in Mexico since 2007, in recent years by almost 9% annually, primarily due to the decline of mature fields and lack of new startups to compensate. The biggest discoveries in Mexico were made in 2008, the most successful year in the last decade, but that was followed by a sharp drop. Since 2012, when Pemex discovered the deepwater Trion field, an average of 400 MMboe resources have been discovered per year. Shallow water discoveries in the mature areas have taken an average of six to nine years to start up and recent finds are not substantial enough to reverse this declining trend. To counter this, Mexico introduced new reforms, opening conventional and unconventional exploration opportunities to international companies, which has successfully generated a lot of interest in the country.
The first successful impact of this reform was the recent Zama discovery by Talos Energy. In-place volumes are ~1.4 Bbo, and Rystad Energy estimates that the recoverable reserves are 511 MMboe. This discovery has highlighted the still sizeable unexplored possibilities in the Sureste Basin, which has been Mexico’s main producing area. In the recent License Round 2.1, 10 out of the 15 blocks awarded are in this basin.
Sureste consists of three main sub-basins: Villahermosa Uplift, Saline- Comalcalco, and Macuspana. Rystad’s creaming curves highlight that Villahermosa has had the most exploration activity, dating back to 1949, with more than 350 wells. The largest oil discovery in the basin, Cantarell, was made in 1976, followed by other major discoveries, including Ku (1979) and Maloob (1985). This Mesozoic sub-basin is light-oil-bearing to the south and has heavy oil towards the north-east. The Macuspana Sub-basin, in the south-western tip of the Sureste Basin, produces non-associated shallow gas and the offshore region is underexplored. Saline-Comalcalco has had little exploration since major discoveries such as onshore Cinco-Presidentes (1958) and the offshore Yakaan field (1984). The Zama discovery in this sub-basin has caused the creaming curve to spike again, with a new Miocene play that Pemex previously missed.
Until recently, most of the discoveries in Mexico were onshore and in shallow waters, and deepwater, despite some discoveries, is still considered frontier. In Licensing Round 2.4 the government has announced 30 mostly deepwater blocks. According to Rystad Energy estimates, Mexico offshore still has around 36 Bb of undiscovered resources, with around 24 Bb in Campeche and Perdido belts, and 5 Bb in the Saline Sub-basin. There is also potential for about 1.5 Bboe in the Tampico Misantla Basin. Further successful exploration in these regions has potential to upturn production by 2024.