Oil development in Mexico commenced with the early years of the present century, but detailed exploration was concentrated in the Tampico embayment, the Isthmian saline basin and, in lesser degree, in the belts of Cretaceous and Eocene rocks in northeast Mexico as a logical extension of the Gulf Coast Province of Texas. These regions are not the only possible oil provinces in Mexico, but are the regions where surface geology could be mapped and, in the Tampico embayment and the Isthmian saline basin, where numerous oil seepages attracted the attention of oil geologists.
When geophysical methods were first used in the search for oil they were naturally applied to the main oil provinces of Tampico and the Isthmus, which were being developed, and only in comparatively recent years have they been applied to new regions where surface geology could not be used to the best advantage.
In this paper, seven possible future oil provinces or extensions of present oil provinces are described: the Burgos basin, the San José de las Rusias region, the Veracruz embayment, the Tabasco re-entrant, and three regions in Lower California. The Burgos basin (Rio Grande embayment) has been known as a gas province for years, but the first oil field was not discovered until 1948. It must be borne in mind, however, that only one hundred exploratory and development wells have been drilled in the basin.
The Tabasco re-entrant may be divided into five regions corresponding with four major structural units. The first structural unit is