Discovery of the World Class Petroleum Province Reforma-Akal, Southeast Basin, Mexico

Abstract

Abstract

The history behind the discovery of the Reforma-Akal trend exemplifies the geological imagination and supporting technological ingenuity that can come together when the needs are critical. Faced with growing domestic demand and decreasing reserves and consequently importing oil, PEMEX in the 1960s undertook a major effort over the whole country to explore for major new oil provinces with no initial success. In the area of Villahermosa, new techniques in processing recently developed CDP reflection seismic data identified a deep high velocity layer not seen on earlier seismic data. Some thought this layer to be Eocene sandstones and conglomerates that are seen in nearby wells and exposed in the Chiapas Mountains. Others thought this layer could correspond to Upper Cretaceous evaporates seen in a few wells in Chiapas to the south. Field mapping had identified porous Upper to Middle Cretaceous rudist-bearing limestones and dolomites which showed numerous oil seeps in the crests of thrust faulted anticlines plunging to the northwest. Three on-trend thrust faulted anticlines were seismically mapped in the subsurface beneath a section of sealing shales. Well engineering had by now progressed to be able to drill deep wells and to control the well while drilling through the geopressured basal Tertiary shale. The resulting wildcats discovered high production rates of oil and gas from Upper Cretaceous carbonates in two out of three of the prospects, Sitio Grande and Cactus. Further wildcats on structures to the north were equally successful in discovering pools in a complex later named Bermudez. These results onshore encouraged offshore seismic surveys in waters where oil slicks had been previously reported. The offshore wells found thick, porous and very permeable pay in Upper Cretaceous breccias that flowed at rates up to 33,000 bopd. Adjacent pools were later combined becoming the largest offshore oil field in the world, the Cantarell complex.

Both the onshore and offshore successes were followed up with a vigorous exploration and development drilling campaign. By 1974, production from this new trend had increased sufficiently for Mexico to renew exports, thus becoming a key player on the international oil scene once again. Base on this geological success, the Mexican economy grew to the status that it enjoys today.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016