Mapping as Mexico Opens for Exploration
MEXICO CITY — Now that Mexico’s potential oil and gas riches are open to outside investment, how does the industry figure out what’s there?
North of an east-west line across the Gulf of Mexico are United States waters, where the bedrock deep below the ocean floor has proved to hold vast reservoirs of oil and gas. But south of that line, there is very little information.
Geologists suspect that Mexico’s Gulf waters hold similar resources, but they lack the crucial first step in oil exploration, the seismic data that allows them to develop a picture of what lies beneath.
Until now, whatever seismic data existed was closely held by Pemex, the state-owned oil company, which commissioned the studies for itself. But that is all starting to change.
Not only did Mexico’s 2013 energy reform end Pemex’s monopoly on exploration and production, it also ended its monopoly on information.
In April, Mexico’s regulator, the National Hydrocarbons Commission, began issuing licenses — 18 so far — to specialized geophysical companies that gather and analyze seismic data, to survey vast stretches of the Gulf of Mexico, areas that had not been studied independently since the 1970s. And on Sept. 23, the commission, known by its Spanish initials as the CNH, made all of Pemex’s seismic data available to any company for a fee.
“The information belongs to the country,” said Juan Carlos Zepeda, the president of the CNH. “Our responsibility is to manage and trigger the development of new information.”
Mr. Zepeda estimates that the companies that have sought licenses will invest about $2 billion to survey the Mexican Gulf and process the data.
The relative smoothness with which the seismic licenses are being granted are a bright spot in what is proving to be a rocky start for Mexico’s energy reform, as falling oil prices have dampened enthusiasm.
Where the interest is still high is for the deepwater lease blocks, defined as depths below 1,000 feet. On the United States side of the Gulf, Shell, Chevron and BP are working together in an area called the Perdido Fold Belt, producing oil from a reservoir below the sea bed at depths of about 8,000 feet.
The Perdido Fold Belt extends 30 to 60 miles south into Mexican waters, where Pemex made its first deepwater discoveries. But Pemex does not have the capital to invest in expensive deepwater production and discovery, and many outside oil companies are eager to explore there.
Before doing that, though, they will need the seismic data. To collect the data, geophysical companies send out boats dragging long cables known as streamers, which emit low-frequency sound waves that travel deep through the water and through the geological layers below the seabed.
The velocity of the sound waves as they travel and reflect back gives geophysicists insight into the kind of rock lying below and an indication of structures that may contain oil and gas.
“Seismic data can be thought of as roughly analogous to a sonogram that would be performed on a pregnant woman, except on a much larger scale,” Matthew Bognar, a senior vice president based in Houston for the French company CGG, wrote in an email. “It is similar in that we use sound waves to make an image of something we cannot see.”
The lowest-level survey, known as 2-D seismic, involves dragging the streamers in parallel lines six to 12 miles apart to get a broad sense of the geology below the sea floor. Then companies go back and do more detailed 3-D seismic studies of areas that appear to have potential, this time drawing a tight grid of lines just tens of yards apart or less, or dragging them in a spiderweb pattern.
“We’re trying to find a string of fields, a whole play, a string of successes,” said Mark J. Gresko, director of geology and geophysics at ION Geophysical Corp. in Houston.
In the United States, this geophysical data can also be interpreted along with results from wells because the logs become public after two years. “There is a lot of competitive intelligence that goes on among companies,” said John Snedden, a senior research scientist at the Institute for Geophysics at the University of Texas at Austin.
“When failures are transparent everybody learns. When successes are announced, everybody learns. With just one company in the south,” he said, referring to Pemex, “the learning curve is pretty flat.”
Under the CNH rules, companies that perform the seismic surveys must share them with the agency, but they keep exclusive rights to sell the information for 12 years.
The agency has also released Pemex well log information, along with the seismic data.
Although most of the attention in the energy reform has focused on deep water, geologists say all of the Gulf offers potential, and a number of companies are preparing surveys in other areas.
After the data is compiled, oil companies may want to nominate promising blocks for future auctions, Mr. Zepeda said. “It’s a crowd-sourcing. You are asking the industry to tell you what they think.”
The Gulf of Mexico is a basin that began to form about 180 million years ago as the ancient supercontinent Pangea split apart.
Conditions were perfect for the formation of hydrocarbons and for a thick layer of salt that acts as a trap, said Mr. Snedden. “The Gulf is such a great endowment,” he said. “There are six billion, 10 billion barrels. It depends on who you talk to.”
“The geology does not stop at the border between the United States and Mexico,” he said. “The geology is very similar, with similar reservoirs, similar structures.”
Geophysical companies are planning 2-D surveys all over the Mexican Gulf, including shallow waters. Oil companies that want a closer look can commission their own, more expensive 3-D surveys.
Geophysical companies are also taking old data and reinterpreting it, using new techniques.
In the 1970s, the University of Texas Institute for Geophysics did a survey of the Mexican side of the Gulf — the only one not commissioned and owned by Pemex.
As the possibility of the energy reform grew more likely a couple of years ago, ION used the old magnetic tapes and logs and new technology to put together a seismic survey called YucatanSPAN that it released in stages in 2013 and 2014.
“I would say it was very popular,” Mr. Gresko said. “It was the only data out there.” ION has new licenses to acquire data, using techniques that will produce images as deep as 25 miles below the surface, he said. “We think it’s important to know what’s down there deeper than where you are going to drill,” he said.
Another company that has moved quickly to map the southern Gulf is the Oslo-based Petroleum Geo-Services, or PGS, which began work in May, said a spokesman, Bard Stenberg.
PGS soon signed with Schlumberger and Spectrum Geo to expand the project, which is intended to map 31,000 to 39,000 square miles. The joint venture is supposed to “get the data as quickly to the market as possible,” Mr. Stenberg said.
CGG has planned surveys to review data in two areas that Pemex has already mapped — one of them is Perdido — and a third to acquire new data in the southern Gulf.
“We’re all convinced there is a prize there in Mexico,” Mr. Snedden said.
A version of this special report appears in print on October 7, 2015, in The International New York Times. Order Reprints| Today's Paper|Subscribe