Giant Fields of the Southern Zone—Mexico<xref ref-type="fn" rid="ch17fn1"><sup>1</sup></xref>

Countries and geological basins may hold hundreds or thousands of producing oil and gas fields, but the production is almost invariably dominated by a small number of giant fields. Giant structural traps are commonly found during early stages of exploration, while stratigraphic and unconformity traps sometimes linger for decades before discovery. For purposes of this book, a giant field is defined by an ultimate recovery of 500 million barrels of oil or 3 TCF of gas in the Middle East, North Africa and Asiatic Russia, and 100 million barrels of oil or 1 TCF of gas elsewhere. An international symposium on Giant Discoveries of the Past Decade was held at the 1979 annual AAPG meeting of AAPG in Houston. During the 1968-1978 decade 288 giant fields were found worldwide in a wide variety of geographic areas and geological settings. The combined estimate of more than 50 billion barrels of oil and 100 trillion cubic feet of gas represent the majority of new worldwide reserves found during this time period. Thirty papers describe new giant fields or the geological regions in which they were found. Most of these are in-depth field studies, which after several decades continue to be among the best sources of published information for the given fields. The largest concentration of eight papers refers to developments in the North Sea, which became a major producing region for the first time during the subject decade.