“Nodal” seismic is just the latest step in a continuing evolution of this ground-shaking industry.
By Hanaba Munn Welch
Survey the world of seismic, and nodal systems emerge as trendsetters.
Also called “blind” systems, cable-free nodal technology depends on the collection of data via autonomous nodes—small compact cable-less battery powered devices containing all equipment required to record seismic data. Some nodes, depending on their design, also contain global positioning devices.
Mounted on small spikes or otherwise staked in place, the nodes are easily deployed to record data.
Nodes tread lightly, leaving little evidence of their presence in an area—a particular advantage when urban or otherwise sensitive terrain is at issue.
Some manufacturers of nodal systems are Geospace, INOVA, AutoSeis, and FairfieldNodal.
In the Permian Basin, FairfieldNodal is involved in an ongoing multiple-county seismic survey.
“We’re seeing this resurgence in the Permian,” said Joe Dryer, vice president of FairfieldNodal’s data licensing division. “Our goal is to build up this large contiguous database. We’re trying to develop a large regional data set—a premiere data set for the Permian.”
Houston-based FairfieldNodal is working with TRNCO and Dawson Geophysical to gather data across several counties.
Originally, FairfieldNodal’s focus was offshore seismic.
“We started out developing a deep water node, cable-free,” Dryer said.
The need to gather seismic data on land without cables prompted the development of an onshore nodal system.
“Initially, our system was used in the urban environments where you couldn’t have a cable exposed on the surface,” Dryer said.
FairfieldNodal’s system for seismic surveys on land is called ZLand.
TRNCO Petroleum Corp., based in Midland, is led by Thomas Nickoloff, president and chief geophysicist.
“We are a geophysical project management company,” Nickoloff said. “We manage 3D seismic projects for individual companies as well as oil companies small and large. In 2010, we partnered and joint-ventured with Fairfield to do onshore spec seismic.”
TRNCO often works with Dawson Geophysical, also Midland-based.
“Dawson is our major subcontractor,” Nickoloff said.
Ownership of seismic data varies from project to project, with companies like TRNCO sometimes serving only as managers for proprietary surveys and at other times taking risks to record data with the presumption that it somehow will be of marketable value or, no doubt more often, something in-between—a situation where at least part of a venture is underwritten by one or more interested parties.
“We do group projects where several companies are in the same area and are interested,” Nickoloff said. “FairfieldNodal, they joint-ventured with my company. We find companies that want seismic data in the area. We shoot and own the data. We license it to who wants it.”
The licensing system offers a pricing advantage to users.
“They get the seismic data generally cheaper than they could do it by themselves,” Nickoloff said. “We take a certain amount of risk.”
Nickoloff and FairfieldNodal are now working in the Delaware Basin. Counties involved include Culberson, Reeves, and Loving in Texas and Lea and Eddy in New Mexico.
“Those are all in the Delaware Basin,” Nickoloff said. “We have so far acquired about 1,100 square miles of spec data with an additional 600 to 700 square miles we’re expecting to shoot within the next year.”
It’s an ambitious enterprise—lots of nodes recording lots of data.
“It’s wireless,” Nickoloff said. “I think that’s probably where everything is going. When I first started in the business 30 years ago, the largest number of channels or sensor stations we could put out there in the field was generally 24 channels. Now, with hardware and digital technology, in the Delaware Basin we’re routinely recording 6,000 to 7,000 stations simultaneously. We’re getting higher and higher spatial resolution.”
Powerful computer technology has allowed seismic techniques to improve in practice.
“The concept of 3D seismic is nothing new,” he said. “People were predicting it 30 to 40 years ago.”
Instead of invention, evolution has been the rule in seismic, Nickoloff would say.
“When I started in the business, all seismic was plotted on paper,” he said. “You’d write on paper and put it on the map.”
Now all the data is loaded into a computer workstation instead.
“Everybody can have one sitting on their desk,” he said.
The same way medical technology has changed, so has seismic. The comparison is clear.
“Oil companies can slice through the earth much like a doctor can slice through someone’s brain with an MRI,” Nickoloff said. “We are shooting 3D seismic. Oil companies are interpreting these data.”
The ability to image the earth via seismic keeps growing more precise, but interpretation remains key.
“Just like any two doctors may not give you the exact same interpretation, they [the geologists and geophysicists who interpret seismic data] may not come up with the same interpretation. It’s still subjective…. Science, engineering, math—it’s also an art form.”
Nickoloff himself has mastered the art of explaining the intricacies of seismic surveys and equipment in ways that simplify the subject.
“I try to talk to people about our business,” he said. “I try to explain it.”
He compares the Fairfield ZLand nodes to vintage quart-size oil cans, albeit with spikes on the bottom.
“In that node is the geophone that we’ve always had,” he said. “It continuously records. All that information, instead of being sent down by wires to a truck, is all contained in that individual node.”
When the nodes are retrieved, they’re taken to the truck and put in a charging rack to renew the batteries. At the same time, the data is reaped—offloaded onto a hard drive.
Not that TRNCO has switched completely to nodal systems. But Nickoloff believes it’s the direction things are going in the business of seismic surveys.
In Denver, Colo., geophysicist Phyllis Spear of Anschutz Exploration would agree.
“This is probably the thing that the industry is going towards,” said Spear. “It leaves less of an environmental footprint because you’ve got less equipment to put on the ground.”
Anschutz, however, didn’t utilize the new nodal technology for its latest 3D project in Wilbarger County, Texas, opting instead for an RSR telemetry system. The RSR seismic equipment is categorized as “cable-less” because cables aren’t used to connect the geophones to the central recording truck.
“Nodal systems aren’t as available as other systems,” Spear said, citing one factor in the process of choosing a seismic system for any survey.
Nor is Spear inclined always to be the first to cast the old aside.
“I see one of the downsides of the nodal systems is that there is only one geophone per receiver location,” she said. “Six geophones per station (like in the system used in the Wilbarger survey) helps to cancel out the noise.”
Geokinetics, a global geophysical services company headquartered in Houston, shot the 109-square-mile proprietary survey for Anschutz.
Why the survey?
“It’s been announced, we are exploring for Barnett Shale in the Hardeman Basin, and we’re looking for oil,” Spear said. “We’re cautiously optimistic.”
Anschutz already has begun drilling in the area.
“The reason for shooting the 3D is so we can have better well locations,” Spear said. “There are some faults we want to avoid. We’re still early in this project. We want to design the wells as best we can. After you’ve gotten the initial learning down, you can go on to locations that are more challenging.”
Besides the Barnett, the Chapel and Atoka formations are of interest to Anschutz.
“The Chapel has been a target for a long time,” Spear said. “Most of those wells are vertical. The Atoka is another formation of interest. Those wells would probably be vertical and possibly horizontal. There are shallower targets also. Those are generally vertical wells.”
The 109 square miles surveyed by Anschutz represent a significant undertaking for the company.
“I think it’s the largest proprietary survey that Anschutz has shot recently,” Spear said.
Geokinetics started the survey in October. Crews battled early-season cold weather—blue northers, ice, and snow.
“It took just almost 60 days to shoot,” Spear said. “It is extremely hard labor, and technology-intensive work.”
Seismic surveys, whether nodal or more conventional, are groundwork in the fullest sense of the word. In the hands of the right interpreter, the products of the surveys are like maps that, ideally, can point the way to treasure. Beyond “X marks the spot,” seismic imaging facilitates horizontal drilling and fracturing to optimize production of oil and natural gas.
Worth noting, seismic systems that allow real time analysis offer an advantage over nodal systems that do not—which explains why the nodal approach is also called “blind.”
“Real time is the ability to view the data as it is being gathered—just like with a cabled system,” said Patricia Jonesi, a representative of Wireless Seismic, Inc.
The “RT” in Wireless Seismic’s RT System 2 stands for Real Time. The company touts the system as the best of both worlds—a cable-less system that also produces real time data, transmitting the information by radio.
Sercel is another seismic equipment company that offers a system that uses radio in a similar way.
Engineers and geophysicists utilize real time seismic data to monitor fracturing.
In the “what’s happening now” world of seismic, all sorts of systems have their strong points and their downsides. If anything is riding a technological wave into the future, it’s human ingenuity.