President’s Column – June 2002

Title: A Gas Farmer in Mexico

Author: John Robinson

Publication: The Outcrop, June 2002, p. 3

Last month I was sitting on the beach in Cabo San Lucas trying to think of a new gas play. Cabo is a wonderful place to conjure up such thoughts. My mind wandered and I got to thinking how much the place had changed since my last visit in 1973. Back then there were no hotels, no golf courses, no glitzy restaurants and bars. Just a little fishing village with a dusty main street. Back then, I camped alone on the beach where the Westin Hotel now sits.

In 1973 I took a side trip to La Paz and then to Cabo during a break in the mapping project I was working on for PEMEX. PEMEX hired Gordon Gastil to coordinate a petroleum geology assessment of the southern half of the Baja California peninsula — in one summer. Gordon was a professor at San Diego State University and co-author of GSA Memoir 140 — Reconnaissance Geology of the State of Baja California. The only previous work in southern Baja was completed in 1957 and PEMEX wanted a fresh look at the rocks. I spent the entire summer in southern Baja mapping, measuring sections and collecting samples for porosity, permeability, and source rock analysis. The study area was the Vizcaino Basin, located about midway down the west coast of Baja California. The west side of the basin is somewhat mountainous and contains well-exposed Jurassic and Cretaceous strata. The east side of the basin onlaps the granitic core of the Peninsular Ranges. The basin is asymmetric to the southwest and some parts of the west side of the basin have been transported northward by strike-slip motion of the Pacific Plate. Briefly, the geologic section consists of Jurassic “Franciscan” ophiolites and breccias, overlain by 7600 feet of late Jurassic (Kimmeridgian) turbidites, and about 25,000 feet of “middle” Cretaceous (Aptian-Albian) turbidites. A thin veneer of Miocene strata, equivalent to the Monterey Formation in California, was deposited on the Jurassic-Cretaceous section. I was fortunate to have the “type sections” for these units in the area I was mapping. During the summer of 1973, I mapped about 100 sq. mi., measured over 20,000 feet of section, and fixed many flat tires. I was able to turn the work into a MS thesis and graduate from SDSU.

The onshore portion of the greater Vizcaino-Magdalena basin extends for 330 miles along the west side of southern Baja and is about 200 miles wide. It resembles, in virtually every aspect, the Great Valley of California, except for one thing. It’s never been explored for its hydrocarbon potential. Picture the Sacramento basin without any wells!

So there’s a new gas play. It just happens to be in another country, but it’s 500 miles of San Diego and the greater Los Angeles metroplex. It’s a huge potential energy supply for the power-starved west. In this day and time, the existence of an unexplored region of this magnitude is nothing short of remarkable.