In closely examining the many discoveries made in the Gulf of Mexico over the last century, it quickly becomes evident that evolving geophysical technology has played a major role in developing this super basin.
Tracing the first major offshore discoveries to present day, Bill Langin, senior vice president for exploration at Shell US, highlighted not just the innovative technology, but the ingenious ideas of explorers that ultimately made successful plays possible. Langin’s insights paid tribute to the late Michel T. Halbouty – credited for his creative thinking that led to the discovery of more than 50 oil and gas fields – at the annual International Meeting for Applied Geoscience and Energy in Houston in August.
Historically, a competitive spirit has been the driver for advancements in the Gulf of Mexico, as companies competed against each other for larger and larger discoveries. Yet, Langin said, in today’s world where exploration has become more technical than ever, “ruthless competition” must become “ruthless collaboration” in order for exploration and development in the Gulf of Mexico to thrive.
Seismic in the Gulf
In search of Gulf of Mexico plays, Shell acquired the first offshore seismic data in the 1930s – well before drilling and development technology could act on that data. More extensive offshore seismic acquisition began in the 1940s, yet it was not until the late 1960s and early 1970s that computer-based seismic processing took off, churning out big datasets for the first time. From that data, the basin’s first large wave of offshore discoveries began. Around this time, companies began using amplitude anomalies as direct hydrocarbon indicators in piecing together this complex basin.
The 1980s saw advancements in computer modeling, followed by 3-D seismic interpretations a decade later. In the early 2000s, 3-D/4-D visualization was being used, and ocean bottom nodes made their debut in the 2010s.
The voluminous discoveries in the Gulf of Mexico tend to directly correlate with advances in seismic acquisition, imaging and interpreting techniques. “With each of these innovations comes another uptick in the creaming curve because we can see the plays, we can understand the traps, we can sharpshoot the risk elements, and we can turn that into valuable discovery wells that ultimately become valuable projects,” Langin explained.
Furthermore, such advancements in technology have also coincided with better well designs and projects in deeper waters. Langin pointed out that Shell’s Cognac discovery in 1978 occurred in water less than 400 meters deep. Yet its 2016 Stones play was drilled in 2,800 meters of water.
Not only is the Gulf of Mexico the birthplace of many innovations, Langin said it has enabled the new technology to successfully be applied to numerous basins around the world.
Ingenious Minds
In addition to Halbouty, a small group of people stand out in Langin’s mind for pushing exploration forward and delivering what he calls the “art of possible.”
He referenced the late John “Jack” Oliver, a seismologist and former chairman of the Geophysics Department at Cornell University, known as “a father of plate tectonics.” When Langin was a student and athlete at Cornell, Oliver once told him: “You know what? Geophysics can be a contact sport. It’s as competitive as any football game you’ve ever played in, and you have to treat discovery like a contact sport and have the mindset that you want to win. Then you will be outstanding in this field.’”
Langin took those words to heart as he began his career, as well as another adage from Oliver: “Never confuse sophistication with understanding.”
Having started at Shell in 2003 as an exploration geophysicist, Langin has learned over the years that the formula for discovery, as once stated by Oliver, is remarkably simple: “You find something you really want to focus on and devote yourself to it. Dive into it. Think deeply about it, reflect and come up with new thoughts. Test them with others and go after it.”
The late Sid Kaufman, a geophysicist at Shell from 1935 to 1973, also influenced Langin. Kaufman is remembered as the first explorer to acquire seismic data in the offshore Gulf of Mexico when he rented a shrimp boat, took some dynamite offshore and hung geophones over the side of his boat – insisting they would be able to communicate with onshore seismic reflectors. Just before proving he was right, Kaufman received a telegram from Shell asking what he was doing in 65 feet of water, as drilling there was deemed impossible at the time, Langin said.
“Don’t believe everything you read,” Kaufman advised. “Have an ever-curious mind.”
In today’s mindset of corporate efficiency and streamlining, preserving “out-of-the-box” thinkers is crucial, Langin said. “We need to preserve people like that who drive innovation and creative thinking and who ultimately change the game.”
Evolving Geophysics
Valuing such mindsets helped place many operators on the map. In the 1970s, Shell developed a methodology to predict the sand thickness of hydrocarbon plays on seismic sections in the Gulf of Mexico. This “bright spot” technology unlocked an advantage for the company, leading to a discovery at Eugene Island that produced 150 million barrels of oil equivalent that same decade. This technology ultimately led to the discovery of 1.5 to 2 billion barrels of oil on the shelf and 4 billion barrels in deep water. “For decades this has sustained the company,” Langin said.
Yet in the mid-2000s, Shell’s amplitude portfolio was in distress. Its sub-salt prospects in the Gulf’s Miocene and Paleogene formations were poorly imaged, making accurate mapping challenging. “We were struggling with the first few sub-salt Miocene wells we drilled,” Langin explained. “But we heard that BP was doing well with a new acquisition technique, wide azimuth towed streamer, in some of its developments (notably Atlantis).”
A geoscientist at Shell suggested using wide-azimuth seismic for exploration purposes – an idea that was initially shot down because of cost. Yet, a team was pulled together to make the economics work. In 2006, they piloted a project to use WATS data on a prospect called Friesian in Green Canyon. Shell and Western GECO, now SLB, acquired and processed the first exploration-scale WATS survey, which after several iterations, was “absolutely there,” Langin said.
In 2009, this technology led to the Vito discovery that began production in 2023 with an estimated peak production at 100,000 barrels of oil equivalent per day.
By the mid-2010s, wide-azimuth data covered most prospective areas of the entire Gulf of Mexico. This unilaterally led to more successful Miocene discoveries, Langin said.
“The ability to create an idea, get it going, have it take off, and then ultimately be the new standard for how we acquire seismic … this was probably one of the best experiences I ever had to see how you lead through change, and changing people’s mindsets on what’s possible.”
Today, node-based acquisition on an exploration scale has become a “monumental advancement” in seismic acquisition and processing, Langin said, adding that the advantages of this acquisition methodology for exploration are “enormous.”
What’s Next?
Geophysics in the Gulf of Mexico continues to evolve. The ability to deliver higher frequency elastic full waveform inversion data has helped overcome challenges and uncertainties with Shell’s Sparta development, Langin said. With reverse time migration data, the eFWI data has improved structural imaging for development well placement to maximize recovery. It has also improved the signal-to-noise ratio and relative amplitude character and fault imaging to properly assess reservoir compartmentalization, he added.
Langin is pushing this technology in the exploration realm as well. “Why do we just have to use OBN and FWI for what we have already found? The new plays are getting harder and harder to find. How do we make this cost effective in pushing the exploration domain?” he asked. “I don’t really drill things for structural failure anymore, so we need to get this kind of character, this type of geological understanding to help us unlock the next wave of plays.”
His team is also working to make exploration-scale long offset, low frequency technology cost-effective for exploration. LOLF is enabling large-scale model updates, quicker conversions of FWIs on velocity models, and reducing the source output of energy in acquisition.
Referring to an area north of Sparta called Momentum, located in Paleogene play fairway, “We are getting usable frequencies down to 1 hertz, a half a hertz … and we are seeing a significant improvement in the output data quality versus the conventional source,” he said.
In this area, they were able to reveal the subsalt with a sparsely shot tuned pulse source, OBN and FWI surveys. The images reveal deep crustal architecture and sub-salt sediment sections. “You can begin to map sub-salt sediment fairways more confidently, and you can begin to sweet spot where the channel systems might have gone, and we can really begin to build the Gulf of Mexico basin from the bottom up for the first time ever,” Langin said. The project is seen as a successful “proof of concept” test of LOLF seismic for exploration, with a major impact on subsalt and deep image quality.
“I think this will ultimately be game changing for the Gulf of Mexico sub-salt basins,” Langin said.
And, he believes the data will continue to improve, especially if companies embrace a creative mindset. “We have created value from seismic in the Gulf for decades and turned that into some really strong producing assets. But ultimately, I think most importantly, we must preserve the innovation mindset, the behaviors that ultimately enable these types of discoveries to happen, both geophysical discoveries but also the exploration discoveries,” he said. “It’s preserving that mindset and that creativity in a world that is ever-focused on efficiency and cost…and finding the right balance to do those things.”