Shaking up the Oil Patch


Better oil exploration through geochemistry

Mark McCaffrey belongs to the rare breed of scientist who occasionally stops dead in his tracks and asks the hardest questions of all: Why am I doing this? Am I still having fun?

Since graduating from the Joint Program in 1990, he has made contributions to the field of geochemistry out of proportion to his youth: publishing 28 papers in nine years and pioneering geochemical methods to improve oil exploration and production at Chevron and ARCO. In 1996, he won the European Association of Organic Geochemists’ Pieter Schenck Award for outstanding contributions from a geochemist under age 35. Not exactly what you’d expect from a high school dropout.

Born in Larchmont, NY, Mark moved after his parents divorced to Charleston, SC, where he struggled to pay tuition for private high school. He tutored students in algebra, biology, and calculus, and bused tables at a restaurant in the summer. “I was so miserable working all the time to pay for school,” he said, “that I decided to drop out after my junior year—not a decision popular with my mother.”

Even without a high school diploma, his high grades and SAT scores got him into the College of Charleston that fall. There, his continued academic excellence won him a rare transfer to Harvard as a freshman in 1981. This began his most critical transition: a kid from the South, without the advantages of wealth, thrown into the intellectual cauldron of Cambridge.

“For the first time,” he said, “I saw that everything I had been taught about the Civil War was wrong. It was just one eye-opener after another.” At the end of his first semester he sought out the person who had handled his admissions application. “I showed her my report card, with three As and one B+, and said, ‘I just want you to know you made the right decision.’ ‘That’s good,’ she said, ‘because you were in and out of the acceptance pile several times.’”

During his freshman year, a creative fire ignited by Stephen Jay Gould’s course “History of Earth and Life” was fanned by his Harvard mentor, H.D. Holland, an inorganic geochemist, who suggested that McCaffrey investigate the minerals that precipitate from evaporating seawater. “I liked the topic because it was broad,” McCaffrey said, “but also because it had a field component”— to a sparsely inhabited island paradise in the Bahamas where Morton Salt makes road salt from seawater. His resulting bachelor’s thesis remains one of his most cited papers, drawing readership from both academic and commercial scientists interested in seawater-derived minerals.

While at Harvard, he landed a summer job at Union Texas Petroleum in Houston, where he cut slabs from rock cores extracted from oil wells to assess the petroleum potential of an area. The next summer he plotted acoustic reflections used to locate subsurface rock structures that might contain hydrocarbons. Those summers kindled a feeling that the chemistry of carbon—organic chemistry—might be the most fun and the most useful.

After he graduated from Harvard magna cum laude with highest honors in geological sciences, McCaffrey enrolled in the Joint Program, intending to stick to the more academic, noncarbon world of inorganic chemistry. But by the end of the first year, he kept thinking that the field offered limited opportunities to “make a difference in the world.”

“I was looking at trace elements in marine sediments, and I couldn’t see spending my days marching through the isotope alphabet, from boron to zirconium. I wasn’t happy and kept thinking I should have gone to med school. I kept thinking, ‘Why am I doing this?’”

McCaffrey met John Farrington, a chemical oceanographer and now Dean of Graduate Studies at WHOI. While at Harvard, McCaffrey had been impressed by one of Farrington’s papers on using seafloor sediments off Peru to reveal past El Niño events.

“I was casting around for something,” McCaffrey said. “The great thing about the Joint Program is that you are permitted, even encouraged, to explore in the first two years. For me, it was a lifesaver when John said, ‘Why don’t you come work in my lab?’”

McCaffrey had never taken organic chemistry, not even an introductory course. He began a crash tutorial guided one-on-one by WHOI scientist Jean Whelan. Working by day in Farrington’s lab, he studied late nights to pass Whelan’s once-a-week exams. “It was amazing that they allowed me to do that,” he said. “Once you see what your options are, the program has the resources and openness to allow you to seek what excites you.”

Passing organic chemistry, McCaffrey built on the work started by Farrington and a previous Joint Program student, Susan Henrichs. His doctoral dissertation showed that certain chemical compounds in seabed sediments could indeed flag certain depositional conditions, including those associated with El Niño events of the past 150 years.

From the Joint Program, he went to Chevron, then a mecca for pioneering geochemical applications for the oil industry. Oil is made from organic matter incorporated into sediments that are deposited and subsequently buried. The oil contains molecular fossils, called biomarkers, that can help identify the original organisms that contributed organic matter to the sediments. By identifying the organisms, scientists can date the oil.

Working on biomarkers, McCaffrey and colleagues identified an entirely new class of steroids and suggested that they were a previously unrecognized product of marine bacteria, which generally do not make steroids. The work resulted in a significant paper in Nature, co-authored with Jeremy Dahl and Michael Moldowan. McCaffrey had the thrill of extending the taxonomy of steroids—like a lepodopterist discovering a new species of butterfly. Though the discovery had no immediate application, his line of inquiry soon paid off.

In East Siberian oils, he linked certain unusual steroids in oil with 500- to 700-million-year-old sponges from the Cambrian and late Precambrian eras. At last, a chemical indicator could be used to date very old oils and accurately distinguish them from younger oils—an important tool for evaluating the petroleum potential of certain regions. He and co-workers subsequently developed methods using biomarker distributions in oils to predict petroleum potential in different regions. The method is now a widely used petroleum exploration tool. Organic chemistry, the chemistry of life, was delivering on the promise of “making a difference in the world.”

The work was fun, but research funds in the oil industry began to dry up in the mid-1990s, and McCaffrey’s research specialization put him at the mercy of a large company. He thought about pursuing an MBA. But after rejections from Stanford and Harvard, McCaffrey was back in the lab, wondering if the fun would disappear for good.

Then came a propitious phone call from Europe: He had won the second Pieter Schenck award for his application of biomarkers to petroleum exploration. It was an organic geochemist’s equivalent of winning a Pulitzer Prize. “It pulled me back to staying in the industry,” McCaffrey said.

Leaving an uncertain future at Chevron, he became principal geochemist with ARCO, where he has developed new ways to assess the potential of proposed petroleum exploration sites. On the production side, he has developed chemical methods to distinguish the contributions from separate zones of oil into a commingled flow—an approach that can save thousands of dollars per well.

In December, McCaffrey and his old Chevron colleague Jeremy Dahl launched their own company, OilTracers L.L.C. ( They apply their geochemical expertise to solve problems for clients throughout the petroleum industry, especially smaller companies that have no in-house geochemical capabilities.

“What I find exciting, and what I think every scientist wants,” McCaffrey said “is to somehow change the way people think or behave. You can do that through basic research, or in the academy. But in my work, I get an immediate rush when I see people using my methods to find more oil for less money and at less risk, and I think ‘Wow, I did this, and people are using it every day.’ I don’t think it gets any more fun than that.”

— James M. Kent