Read an Excerpt
Deep Life
The Hunt for the Hidden Biology of Earth, Mars, and Beyond
By Tullis C. Onstott PRINCETON UNIVERSITY PRESS
Copyright © 2017 Princeton University Press
All rights reserved.
ISBN: 978-1-4008-8424-7
CHAPTER 1
TRIASSIC PARK
It would seem probable that any waters entombed in the rocks as long ago as Pennsylvanian times must have undergone repeated changes in concentration and at least minor changes in composition by contact with other waters and with the rocks. Whether the bacteria found in these waters today are lineal descendants of forms living on the sea-bottom at the time the sediments were laid down or have been introduced later by ground waters descending from the surface to the oil-bearing horizons is an interesting question that may never be possible to answer.
— Bastin et al. 1926
MARCH 12, 1992, THORN HILL FARM, KING GEORGE COUNTY, VIRGINIA
The cerulean blue Schlumberger vans were lined up beneath a Texaco Murco 54 drilling rig on the fields of Thorn Hill Farm, Virginia (figure 1.1). After having punched through the gas-rich target zone at 9,100 to 9,200 feet, Texaco's drillers had been the first to reach a total depth of 10,213 feet and the bottom of the hidden Taylorsville Triassic basin. They continued to circulate the drilling mud to clean out and smooth the borehole wall in preparation for the insertion of Schlumberger's logging and sidewall coring tools. The roughnecks then began the tedious task of hauling out the drilling rods, or drill string, a hundred feet at a time. Hours later, they finally yanked the drill bit out of the one-foot-wide borehole. The roughnecks then raised the string of long and shiny, cylindrical Schlumberger logging tools on a steel cable, the wireline; centered them over the hot, roiling, mud-filled borehole; and slowly lowered them to begin imaging the layers of rock in the gas-rich zone deep below.
Back in their vans filled with the smell of burnt coffee and stale cigarette butts the Schlumberger field engineers began probing the rock around the borehole with low-energy neutrons, electrons, seismic waves, and gamma rays emitted by their logging tools. As the two-dimensional images of the rock at 9,000 feet came into focus, the engineers conferred with the Texaco geologists and a representative of the DOE's SSP, Tim Griffin, all of whom were peering down at the paper logs strung out on the table. Based on the Schlumberger logs, what the Texaco geologists had seen in the drill cuttings, and the gas plays detected by the gas chromatographs hidden in the Exploration Logging Company (EXLOG) trailer, the choice targets for the microbial sampling appeared to be alternating sandstone and shale of a paleo-lake sequence at a depth of 8,900 to 9,200 feet.
Tim could only hope they were right, because at 9,000 feet beneath the surface, they were exploring for life at a depth ten times greater than anyone else had done before them and no one, including Schlumberger, had a logging tool for detecting deeply dwelling bacteria. The DOE team had arrived at the site resolved to collect pristine cores from different sedimentary facies, sedimentary rock that is visibly distinguishable and represents specific depositional environments. In the case of these Triassic lake beds, they wanted some cores from the dark, organic-rich shale, some cores from the reddish silts and sands, and some cores from the interfaces between these two facies. These sediments had been quickly buried in a fault-bound basin as North America struggled to tectonically disengage itself from Africa and the rest of Gondwanaland. Then as Pangaea split asunder and the mid-Atlantic ridge started pouring basalt into the new seafloor, the basin became buried by an Early Cretaceous, newly formed Atlantic Ocean. The lake sediments and the bacteria that were trapped within them had been completely hidden from the surface for 230 million years, until today. If the bacteria or their descendants were still alive, they could be living fossils from the dawn of the age of the dinosaurs.
The caliper logs indicated that there had been few washouts in these zones, that is, the hole gauge was uniform and ideal for coring into the side of the borehole wall. This meant that the sidewall core tool could be rammed tightly against the borehole wall with few gaps. The engineer reassured Tim that recovery of the core would probably be pretty good. That was an encouraging thought given all the challenges they had faced to get this far. The gas logs revealed minor gas plays, which disappointed the Texaco geologists, who were looking for natural gas, not deep-dwelling bacteria. The data analyses had suggested that they had a "dry" hole, that is, one that was not a commercially viable source of natural gas. The Texaco geologists were already receiving instructions from Houston to wrap it up and demobilize the rig as soon as they had finished their deal with the U.S. DOE.
It was twilight on Friday, March 13, 1992, when Tim stepped outside to start pumping the perfluorocarbon tracer (PFT) into the drilling mud and help prepare the sidewall coring tool as the roughnecks finished hauling the Schlumberger logging tools up and out of the two-mile-deep borehole. An hour later the rotary sidewall corer, along with its gamma and caliper logging tools, started sliding down the steaming hole to the target depth. It wasn't long before the Schlumberger team stopped the corer's descent. They then started the coring into the side of the borehole at the deepest shale/sand transition. At 11 p.m. the coring tool returned to the surface with a disappointing eight of the twenty-five attempted core samples. At 3 a.m., as the tool started back down to collect the DOE microbial cores, Tim called Tommy Phelps at the Hampton Inn in nearby Fredericksburg, who then woke Rick Colwell and Todd Stevens. They quickly drove out to the drill site. In the dark, the site was easily visible from miles away because the Murco 54 was lit up like the shuttle launch pad at Kennedy Space Center. They had prepped the argon-filled glove bag before dinner that evening in anticipation of getting cores during the night. When they pulled onto the drill site, Tim was out with the Schlumberger engineers on the rig deck breaking down the corer beneath the floodlights of the rig. They went to work with sterile gloves, scooping out the samples and the drilling mud from the collection baskets and placing them in sterile Whirl-Pak bags. The cores were still warm to the touch, which meant that they were hot in their center, holding on to their primal heat against the frosty night air. The microbiologists dashed back to their trailer with their cherished loot, where they quickly transferred the cores into the glove bag. Rick and Todd photographed and logged them. They had only three short cores out of twenty-five core attempts and a lot of worthless mud-cake samples.
Meanwhile the post mortem on the drill deck by the Schlumberger engineers indicated that shale fragments had lodged in the rotating drilling mechanism, making it difficult for the tiny bit to rotate fully to the proper drilling angle. The samples that had been collected were also highly fractured, increasing the likelihood of contamination from the drilling mud. The third coring run returned to the surface at 9:30 a.m. with a few more cores than the second run, but again the core quality was very poor, with a high risk of contamination from the drilling fluids. The fourth coring run returned empty, this time due to an electrical short. Bad luck for Texaco. The fifth and final run began at 11:30 a.m., and Tim was informed by the Texaco site manager that they would be allowed only six of the twenty-five, with Texaco insisting that they keep to a fifty-fifty split deal even though they had only nineteen successful attempts so far at coring. Tim wondered how a fifty-cores-apiece deal turned into 50% of what cores you could get. At 12:40 p.m. the coring tool was pulled back out of the hole because the gamma logger had failed and needed to be repaired. Tommy, Rick, and Todd continued working on mud samples, and by 2 p.m. the coring tool was sliding back down the borehole for the final attempt. At 3 p.m. the rotary sidewall corer was pulled out of the borehole, and upon examination had collected only one core, at 9,161 feet deep.
The drill manager told the DOE research team that that was their last run. Tim expressed their dismay at getting only twenty attempts and recovering only ten cores, half of which were of marginal quality, leaving only five intact samples after the blood, sweat, and money they had shed over the past six weeks. Tim made a request for one last core run, but the request fell on what he thought were deaf ears. About an hour later, the Texaco geologist returned to their trailer after talking to the drill manager, who had contacted Texaco in Houston. He offered an opportunity to attempt a coring run with the percussion sidewall corer, the tool that literally shoots the core barrels into the rock. If the researchers were interested, they could keep all the samples.
The sun was setting outside, the Schlumberger crew members were beyond fatigue, and the rest were strung out on caffeine. Although the chances of successfully collecting microbial samples by the percussion method were slim, they all felt that having come this far, they must exhaust all of the options. Texaco was gracious enough to offer the percussion tool, and they took them up on their offer without hesitation. While Schlumberger prepped the percussion tool for the final coring attempt, they picked their five target depths. By 7:40 p.m. the core gun was sliding down the Thorn Hill no. 1 borehole to 9,188 feet.
A HIDDEN BASIN? OCTOBER 1991, LEWES, DELAWARE
The idea of looking for bacteria 9,000 feet beneath the surface in Virginia had begun six months earlier, when Dr. Frank J. Wobber sat down to work on a crossword puzzle at his shore home near Lewes, Delaware, decompressing from the intense schedule of the past four months. Although he was pleased with the progress made in the four field programs that he had been supporting — at the Pacific Northwest Laboratory (PNL), Idaho National Engineering Laboratory (INEL), the Savannah River Plant (SRP), and the Nevada Test Site (NTS) — he was frustrated with not being able to constrain the ages of the various novel microorganisms being grown from the rock cores at these locations. But as he opened up his Washington Post, he noticed near the bottom of the front page a small footnote of an article, no more than six or seven lines — one of those column fillers, local fluff — saying that Texaco was drilling natural-gas exploration wells into a completely buried Triassic-age basin, the Taylorsville Basin, starting in Virginia, then moving to Maryland, and then into Delaware.
Frank was a geologist, a sedimentologist/stratigrapher by training. Supported by a Fulbright Scholarship in the early 1960s, he had mapped the rugged, windswept, wave-cut beach outcrops of the Bristol Channel. He had also spent a summer working for Texaco Oil Company after graduating from the University of Illinois. From this geological training and his past ten years of experience as a program manager at DOE working on groundwater contamination, he knew of only one type of "basin" that had features that might isolate deep, indigenous, subsurface bacteria for millions upon millions of years. That basin would have to be completely buried so that recent ground-water never penetrated its formations. Its porous sedimentary compartments would need to be sealed by low-permeability rock formations, perfect for trapping the natural gas being sought by Texaco.
Most important, he needed a basin that had never been drilled before so that there was no risk of drilling contamination from oil exploration. As an undergrad, Frank had heard of the geologist at the University of Chicago, Edson Sunderland Bastin, who back in the '20s had studied the source of HS and bicarbonate in water from oil fields. His colleague, Frank Greer, was aware that certain microorganisms, SRBs, could utilize sulfate for respiration in place of O in these anoxic environments. Bastin reasoned that the HS and bicarbonate were being produced by SRBs as they degraded organic components in oil. In an experiment reported in Science in 1926, Bastin and Greer cultured SRBs from groundwater samples collected from oil wells in the Waterloo oil field of Illinois that had been drilled to depths of 500 to 1,700 feet. One question asked by Bastin and Greer was whether those SRBs were descendants of those buried more than 340 million years ago, when the sediments were deposited, or whether they had been introduced during drilling. The latter explanation was favored by many scientists who viewed the existence of microorganisms deep beneath the surface with guarded skepticism, if not outright disbelief. After all, drilling an oil well was a filthy, dirty process that made it difficult to obtain samples that were uncontaminated by microorganisms from the surface, and Bastin had known this. Their results were ignored for two decades, until the late '40s and early '50s. A microbiologist by the name of Claude ZoBell began renewing interest in subsurface bacteria, this time in marine sediments, by claiming that they not only ate oil (figure 1.2), but also produced petroleum. But ZoBell failed to prove that the bacteria in oil wells were nothing more than contaminants from drilling or reservoir flooding, so the scientific community at large had dismissed the possibility of deep subsurface life again.
By 1991 the oil and gas wells in the United States numbered over two million. But the oil and gas companies had somehow missed Taylorsville Basin, which made it the one-of-its-kind basin that Frank had been seeking. Texaco would be drilling into sediments far older, 150 million years older, than the ones Frank's team of scientists had cored at the SRP four years earlier. The Taylorsville Basin sediments were Triassic in age, and the Texaco drilling campaign would offer a window into a previously hidden Triassic basin uncontaminated by the oil and gas industry.
Frank quickly contacted a geologist friend who worked for the Delaware Geological Survey, but his friend hadn't heard about any drilling by Texaco and had difficulty pinning down any details. Frank then phoned Tim Griffin and Brent Russell, Tim's boss, at Golder Associates in Richland, Washington, who quickly volunteered to make inquiries off the clock, so to speak. Tim contacted an old friend working at the New Orleans office of Texaco, who in turn directed Tim to a colleague in Texaco's exploration office in Houston. The Houston office told him that the Delaware drilling was a "no go." "We recently took a few shallow slim cores from the Triassic Taylorsville Basin on the Virginia side, but we gave those to Paul Olsen at Lamont-Doherty Geological Observatory. Would those be helpful? You should check with him," said the manager over the phone. Tim thought to himself, "Nope, those would be contaminated." The manager went on to say, "And we ARE drilling deeper in the Taylorsville Basin. Down near Fredericksburg, Virginia, at a place called Wilkins. Would you be interested in samples from that site?" Tim's ears perked up and he barely constrained his enthusiasm, "Sure we would be interested." The Houston exploration manager carried on, "In May we will be completing our final and deepest hole near Thorn Hill Farm. It is about an hour's drive south of D.C. We could talk to our management. Maybe we could get you folks a few core samples. We don't know about you coming on site though. We CANNOT guarantee you anything, of course." After he hung up the phone, Tim thought to himself, "We need to be on site to collect those samples, and we have a lot to do in a short time-frame."
Between January 14 and 16, 1992, Frank held a Deep Microbiology Investigators stocktaking meeting at the only non-gaming motel in Las Vegas, during which all his investigators were to report on the results of the analyses and experiments performed on the samples they had just collected months before from INEL, PNL, and NTS. They were also asked to present hypotheses concerning the origin of deep subsurface bacteria in different types of sedimentary formations (figure 1.3). How could they distinguish those bacteria that had been deposited with the sediment from those that might have migrated into the sediment with groundwater flow?
(Continues...)
Excerpted from Deep Life by Tullis C. Onstott. Copyright © 2017 Princeton University Press. Excerpted by permission of PRINCETON UNIVERSITY PRESS.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
