Indications of gas are found accompanying seepages of oil, at the surface, from an area south of the Rio Soto la Marina to the vicinity of the Rio Cazones. Combustible gas is found, accompanying oil, in wells in the Northern and Southern fields of the Tampico Embayment. In a large part of the Northern fields the gas is non-inflammable, due to an excess proportion of carbon dioxide. Natural gas is found in wells in association with oil in the fields of the Isthmus of Tehuantepec and Tabasco.
The writer is indebted to E. DeGolyer for the notes on the Tanhuijo well. Acknowledgments are due to the following for most of the gas analyses and other data: S. A. Grogan, chief geologist of the Mexican Gulf Oil Company, E. H. Ritter, chief geologist of Compania Mexicana de Petroleo “El Aguila,” and to D. Trumpy, former chief geologist of the same company. Sam Katz, of Compania Explotadora “La Imperial,” and P. J. Reilly, of Carbonic Products Corporation, supplied the gas analyses and some of the data concerning the Quebrache field. A. H. Seabrook of the Kern Mex Oilfields, Ltd., supplied the gas analyses from the fields of La Palma and Salinas. Paul Weaver reviewed the original manuscript and made several suggestions which have been included in the text. W. L. Steed, formerly general superintendent of the Mexican Petroleum Company at Ebano, drew the writer's attention to the occurrence of gas associated with salt water in the Ebano field.