Mexico's state-run oil company Pemex will launch a $6 billion investment in 2017 aimed at maintaining current levels of production at its once-supergiant Cantarell field over the next decade, a Pemex official said on Tuesday. Discovered in 1976, output from the offshore Cantarell field once supplied over 2 million barrels per day (bpd), or more than half of Mexico's total crude production. But output at the field has fallen more than 80 percent since 2004 to hover around 340,000 barrels per day (bpd). The investment will counteract the natural decline of Cantarell by squeezing out an additional 100,000 bpd per...