For decades the oil and gas industry had relied upon a tried-and-true method to find reserves. It used seismic technology to assess the composition of rock formations, but not their age. This made sense, since certain porous rocks are indicators of potential oil and gas deposits.
Dr. Vail was a great integrator, learning from colleagues with different expertise and applying that knowledge in new ways to solve challenging problems. In 1961, Dr. Vail faced one such problem. Exxon had just drilled three wells off West Africa that puzzled the explorers. Based on seismic imaging data, they expected to find hydrocarbon-filled sand at a predicted depth. What they found instead was the sand in progressively deeper depths that was water-filled.
Dr. Vail had learned from his professors and other company experts that geologic age, or time lines, followed surfaces in the rocks, not their compositional formation. The observation he made on seismic data through these three wells was that the sand occurred at different seismic reflections. The intuitive leap he made was that seismic reflections follow geologic time lines, and thus was born seismic stratigraphy, as the practice is now called.
Knowing the age of the layers made it easier to interpret the arrangement of the sand, shale and carbonate layers, so explorers could be steered toward prospective hydrocarbon reserves that otherwise would have been missed. It also made a tremendous impact in field production, where seismic data could better define connected reservoirs for more efficient development.
This new interpretation was such a departure from the traditional method of seismic interpretation that many in the field opposed Dr. Vail when he first began presenting his findings. “One senior geologist accused me of proposing that the reflections were bouncing off the backs of fossils,” he recalled in a 1983 talk.
Despite the opposition, Dr. Vail persevered and evolved his concepts through discussion with colleagues and application around the world. The success of the method in predicting geology from seismic data made it a breakthrough in earth science. Dr. Vail and his team went on to literally rewrite the book on how seismic data is interpreted. His seminal 1977 publication, Seismic Stratigraphy: Applications to Hydrocarbon Exploration, has been used by generations of geoscientists to study his methodology.
Enter the Vail curve
Dr. Vail’s work didn’t end there, nor did his collaborative style.
As a scientist with a passion for big challenges, Dr. Vail had a long fascination with global sea level changes like those caused by periodic ice ages through time. In 1959, shortly after he joined Exxon, Dr. Vail made his first chart of global sea level changes over the past 600 million years based on studies he made from well logs around the world. With the discovery of seismic stratigraphy, he now had a tool to investigate even further. Seismic stratigraphy allowed geoscientists to map the position of coastlines through time as sea levels rose and fell. Dr. Vail and his team documented these events and published a curve of sea level highs and lows through time – now referred to as the Vail curve.
Changes in sea level are directly related to major geologic events, so the ability to recognize and date sea level change events gives geologists a greater understanding of the Earth’s geologic history. After his first curve was published, Dr. Vail worked throughout his career with many hundreds of earth scientists around the world to improve on this effort and refine his concepts.
Paying it forward
After his 30-year tenure at ExxonMobil, Dr. Vail entered academia, where he trained the next generation of geologists as a professor at Houston’s Rice University, and in seminars and schools around the world.
For his contributions to the field of geology and the energy industry, Dr. Vail has been recognized with many awards, including the Geological Society of America’s Penrose Medal, their top honor.
Thanks to his determination and his fresh interpretation of seismic data, we now have a better understanding of our energy-rich planet, and that’s a pretty big deal.