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Houston Chronicle : For oil paleontologists, it’s layer upon layer of work: Looking at the fossils helps tell where crude is in the Gulf

By KRISTEN HAYS
Copyright 2007 Houston Chronicle
Oct. 19, 2007, 11:58PM: Energy

As oil and gas companies push into deeper ocean waters and more remote areas to find their bounty, a branch of science that conjures images of digging for bones of dinosaurs and human ancestors is becoming more integral in the search.

Paleontologists — scientists who study the history of life on Earth — are increasingly joining engineers and roughnecks on drillships, though they’re usually hunched over a microscope.

“It’s a cool job, to say the least,” said Mitch Covington, a Tallahassee, Fla.-based paleontologist under contract with Chevron Corp. for its drilling operation in the Bob North oil field in the Gulf of Mexico about 130 miles southeast of New Orleans.

Paleontology has had a role in finding oil and natural gas for decades. The scientists examine the tiniest of fossils found in “cuttings,” pieces of rock that break away as a well is drilled.

The fossils, often bits of plants or single-cell organisms like amoebas, don’t reveal oil reservoirs. But as a drill bit bores through layer after layer of rock, fossils help determine the age of each layer and during what periods sands were deposited in great abundance.

“That’s what we want, because that’s where the oil is,” Chevron geologist Bob Davis said.

Paleontology isn’t as critical onshore or in some areas where seismic imaging provides clear views of what lies underground. But in the Gulf of Mexico, where seismic technology is less of a sure thing because it cannot clearly see through canopies of salt that stretch underneath the ocean floor, paleontologists can help fill the information gap.

They go to the drilling site, set up shop on a drillship or rig, and examine fossils in cuttings as the drill brings them up. That on-site participation saves the time of taking samples ashore for study.

“They see the microfossils, tell us what age of rocks we’re drilling in, what we pass through, and what’s ahead of us,” Davis said. “The fossils are so small, they don’t get damaged by the drill bit.”

Also, deep-water wells can cost $100 million each, so the more information companies have about whether they’re on the right track, the better, said Ed Ringer, a lead biostratigrapher for Royal Dutch Shell who oversees a staff of 12.

Biostratigraphy is a form of paleontology that focuses on use of fossils to date rock layers. Ringer is in his 29th year in that role for Shell and he says he’s as busy as ever with operations in the Gulf, offshore Brazil, off northern Alaska and onshore operations around the world.

“They use us a lot more,” he said. “This is a true science in that we can help predict where to place wells based on our understanding of the region.”

Similar rock layers

In addition to revealing the age of a rock layer, fossils also help scientists “correlate” wells, or determine whether location and age of rock layers of a new well are similar to those in another well. If the existing well revealed oil, correlations give added assurance that companies are on the right path when drilling a new one.

“The fossils don’t tell you whether or not there’s oil there. They help you find the layer you’re looking for,” said Covington, whose company, Bugware, offers on-site paleontology services as well as software to help company scientists track fossil findings.

The fossils also can help signal when the drill has gone too far.

“If you get to one with fossils that come from layers lacking hydrocarbons, we can say you’re past the right age layer, so stop drilling,” Covington said.

He said fossils he typically examines are way too tiny to see with the naked eye. They are viewed under a microscope among shavings that can look like coarse ground pepper and emerge upon washing down and refining several pounds of cuttings.

They have myriad shapes, like a rose rock, a molar or even coiled rope.

“It’s amazing that they’re so intricate and delicate, yet they survive hundreds of millions of years of deposition and redeposition, and at the pressure they’re subjected to,” he said.

No set schedules

Covington said he and his five colleagues don’t have set schedules and often don’t know how long they’ll be offshore when called out on a job. Last year he was out for 39 days on one of multiple trips, almost quadruple the typical 10-day stretch.

But a Gulf storm that temporarily shuts down operations usually means it’s a good time for a vacation.

“Sometimes we do sit around for a month or two, especially right after a storm or a hurricane,” Covington said.

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http://www.chron.com/disp/story.mpl/business/energy/5230347.html

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