Cable-free node deployed near Pecos in the Permian Basin in west Texas. Photos courtesy of FairfieldNodal
Seismic data acquisition systems dubbed cableless, wireless, cable-free, no-cable, etc. were viewed as a kind of novelty in the industry only a few years ago.
That has changed dramatically as the success stories emanating from increased numbers of field applications are being reported evermore often.
It had to happen, not just offshore but also on land in particular.
Think about seismic crew members traipsing around rugged, inhospitable terrain lugging the heavy, cumbersome cables and accompanying equipment required by cable systems, the longtime industry stalwart.
Then consider the cost and time to load and move all of this weight via helicopter – a transport frequently necessary to reach the often-inaccessible areas where data must be acquired.
There are other issues.
Besides the potential to leave an undesirable environmental footprint using cable systems, gnawing sharp-teeth varmints feast on these wires wherever possible – troubleshooting, anyone?
Even ordinary thunderstorms pose a risk.
“A lot of wire on the ground is a big problem where you have thunderstorm activity because of the static it generates into the cable,” said Darin Silvernagle, vice president of technology at SAExploration, or SAE, (nee NES LLC). “When you have 400 miles of wire laid out on the ground, static can be a big problem.”
The available cableless, i.e. nodal, land systems include the FairfieldNodal ZLand® system and its transition zone, shallow water counterpart Z700, INNOVA HAWK®, Sercel UNITE and OYO GSR, among others.
Nodal systems are designed to meet a number of industry needs:
- More flexible acquisition geometries, e.g. wide and full azimuth for land surveys.
- Reduced downtime and maintenance.
- Increased productivity.
- Improved health, safety and environment conditions (HSE).
- Enhanced access to challenging locales.
Today’s high-tech nodal systems are being purchased and/or leased by data acquisition companies as well as oil companies.
Selecting the best available product for the job at hand is a far more complex process than perusing a group of display shelves with credit card in hand and zeroing in on which system captures your fancy at the moment.
First there’s the field trial, such as the one conducted recently by SAE for Apache Corp. The trial took place over a part of Apache’s sizeable lease position at Alaska’s Cook Inlet, which the company views as an exploration play.
The 2-D program tested a variety of seismic recording and source systems to determine which would best meet the demands of exploration across the area. Both nodes and traditional cable digital telemetry seismic technology were put through their paces.
The end result: The continuously recording, totally cable-free self-contained systems were selected by Apache for its multi-year 3-D seismic program in the area. This marks the first time that both the onshore and offshore versions of the equipment are being used in combination.
The program is designed to include marine, transition zone and land environments. The water depth at Cook Inlet at high tide doesn’t exceed 100 feet, according to Silvernagle.
Actually experiencing the ease of operations and the resulting high quality seismic data using the nodal system in Alaska’s unpredictable pack ice and ground conditions can be mighty convincing.
SAE not only purchased the equipment for the trial shoot at Cook Inlet, it also leased 6,000 nodes for a program it operated for 120 days in southern Alberta in Canada this past winter. Afterward, it shipped that equipment to New Zealand, Silvernagle noted, where it will be deployed on a 3-D program until July, when SAE will bring it back to North America.
SAE also runs a crew for Brisbane-headquartered Linc Energy, which purchased a ZLand system to deal with upcoming projects that harbor some unique challenges, according to Keith Matthews, systems division sales director at FairfieldNodal.
“In the node world, the weight per channel is down to about five to seven pounds, which is a big advantage for us, compared to about 20 pounds for wireless,” Silvernagle said. “There are operational advantages in how quickly you can move the equipment, and you can move it with fewer people. The HSE advantages speak for themselves.”
Ice-covered ground appears to be no deterrent to nodal system application.
Besides the Cook Inlet test, a couple of successful comparison demos were implemented recently under Arctic conditions in two densely forested areas in frigid Siberia.
Comesa (Compania Mexicana de Exploraciones S.A. de C.V.) crew member positions cable-free nodal seismic unit in sugar cane field in Tabasco, Mexico, prior to field burnoff that left all nodes intact and unharmed.
Matthews pointed out the self-contained battery-equipped nodes, even though buried under two feet of snow, functioned perfectly, generating significant interest among the Russians for a true cableless kit.
A world removed from ice and snow, the company’s nodal land system was put through a 3-D seismic acquisition test in a jungle area in Uganda, reportedly in preparation for an upcoming program in an environmentally sensitive game preserve. The ability to bury the individual nodes under topsoil is a considerable advantage.
Regarding the test, Matthews noted the nodes performed as they envisioned.
The World Wildlife Fund announced recently that Total E&P is preparing for a nine-month seismic study in Uganda’s Murchison Falls national park beginning in September.
Aside from the “real” jungle, the urban jungle is equally challenging for data acquisition.
Entirely cable-free nodes are ideally suited for application in densely populated cities. This was demonstrated with the successful implementation of a 3-D ZLand survey at the old Long Beach oilfield sitting right smack in the middle of suburbia.
The unobtrusive nodes left essentially no footprint, and the vibrator trucks followed a schedule designed for the least impact on the citizens and businesses.
The same type nodal system then was used by NodalSeismic to acquire data in California’s Santa Maria Basin. The survey entailed a couple of two-and-a-half-D swaths, or what can be called a wide bin 3-D, of about 20 miles each, according to Dan Hollis, managing partner at NodalSeismic.
Proving a Point
Henri Houllevigue, vice president of geophysics, Total E&P Research and Technology, USA, and experienced in the world of nodal technology, said there are values of degree in cableless, with some systems having cables between phones, sensors or whatever.
“Today, the offerings are diverse, but for me, there’s a difference between cableless and nodal,” he said. With entirely cable-free nodes, you put them in the ground and then just forget about it until you come back to pick them up.
“For the oil company, there’s a full range of systems available, from the complete nodal system to the real time system,” he said. “They can choose depending on their needs.
“For the acquisition company, it’s more difficult because you must choose one system,” he continued. “If you want to purchase a system, you must make a choice and, depending on the oil company’s problem, that choice might not completely fulfill what the oil company is requiring.”
Compare and contrast is the operative phrase.
“We’re hearing from many of the leading seismic acquisition companies who want to see how our systems can improve their performance in terms of productivity, HSE and cost effectiveness,” Matthews said.
“We’re currently involved in a major spec project in West Texas where Dawson Geophysical is the contractor,” he continued. “Our goal is to demonstrate the superior performance of 10,500 of our land nodes when compared to a cable system, or the OYO GSR system.”
An Evolutionary Curve
It’s not a stretch to say that the industry is in a transitional phase.
“We believe wireless technology is functional anywhere,” Silvernagle emphasized. “Each system has its own nuances.
“But there are still a lot of areas where cable has its place and works fine,” he stressed. “We do still employ cable systems and own the equipment.
“There are some technical things that need to be worked out with all of the nodal systems that allow us to employ different techniques,” he added. “The technology is evolving and will continue to evolve.”
Many in the industry likely recall that nodal technology was all about development early on, especially in the marine environment.
What a difference a few years – and plenty of R&D – can make.
“In terms of exploration, sales on this type equipment are really beginning to take off,” Silvernagle said.
Noting that the technology is gaining significant momentum, he predicted that its evolution will happen at a much faster rate.
“It’s been there, kind of laying low for probably the last five years as it began coming online,” he commented. “Now that nodes have arrived, the evolution won’t be a linear deal anymore – it’s going to curve.
“This will happen rapidly as the exploration contractors become more involved and start getting features added to the systems,” he added.
Despite the array of providers of cableless systems in general, Houllevigue commented that it’s not known if all of the present systems will be available a few years hence or whether there will be some consolidation.
“Cableless technology is still a younger market in terms of technology choice,” he said. “There will be expansion.
“In the past two years, I’m seeing more cable crews going to full cableless crews,” he added.
“There will always be cable systems,” said Roger Keyte, director of marketing and strategy at FairfieldNodal. “But we think that relatively soon, perhaps in a decade, the majority of land seismic data will be collected with nodal systems.”