The meandering network of pipes, wells and tankers belonging to the gigantic state oil company Pemex has long been an easy target of crooks and drug traffickers who siphon off natural gas, gasoline and even crude, robbing the Mexican treasury of hundreds of millions of dollars annually. Now the prohibition-created drug traffickers have taken sabotage to a new level: They've hobbled key operations in parts of the Burgos Basin, home to Mexico's biggest natural-gas fields.