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Nodal land seismic acquisition: The next generation
Article in First Break · February 2018
DOI: 10.3997/1365-2397.n0061
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2. SPECIAL TOPIC: LAND SEISMIC
F I R S T B R E A K I V O L U M E 3 6 I J A N U A R Y 2 0 1 8 4 7
systems, based on sonobuoys developed during the Second World
War, were actually introduced in the early 1970s and the use of
cableless recording was first patented in 1941 (Figure 1). These
systems were designed for shallow marine or transition-zone (TZ)
acquisition, with the unit mounted on a small float (Figure 2a)
although they could also be deployed on land (Figure 2b).
A reduction in the amount of line cables (typically associated
with a land recording system) brought several advantages to the
shallow water TZ environment, namely:
a.
Reduction in recording downtime – cables could be eaten by
water rodents and marine life, swept away by strong currents,
wave action or even just a log floating down a river. Typically
a cable break would bring down a complete line of channels,
whereas if a node was swept away it would be limited to just
the few channels of sensors connected to it and recording
could continue.
b.
Reduction in personnel and equipment – fewer cables to deploy
and pick-up requires fewer people. It also reduces the need to
fix the spread, a particular problem when boats are involved.
Data was stored within the node before being transmitted sequen-
tially back to a central system over radio (many units allowed
processing such as stacking to be applied prior to transmission
to reduce the amount of data). Such systems included the Telseis
series from Aquatronics (acquired by Fairfield in 1976), the
OpSeis 5500 from Applied Automation (acquired by CGG),
Myriaseis from CGG/IFP, Digibuoy from Ref-Tek (acquired by
Trimble) and early Digiseis systems from Terra-Marine (acquired
by Geco-Prakla in 1991).
The units were heavy and had limited battery life, for example
the OpSeis 5500 weighed 17 kg (Myriaseis weighed 10 kg but
recorded only 1 trace vs. 4 for OpSeis) but had only 72 hours of
battery life (Aldridge, 1983). Sequential data transmission also
resulted in significant transmission times. The OpSeis 5500 took
Nodal land seismic acquisition:
The next generation
Tim Dean1*
, John Tulett2
and Richard Barnwell3
discuss new systems and make some
suggestions about where future developments should lie.
Introduction
Within the last two years six new land seismic nodal acquisition
systems have been launched, a pace unmatched even during the
oil boom of the late 2000s/early 2010s. Any acquisition system
that utilizes recording instrumentation that does not incorporate
cables is often referred to as a nodal system. Some instruments,
however, are beginning to blur what initially appears to be a clear
boundary. For example, the U-Node system from Seismic Instru-
ments utilizes a node that records data from up to 24 different
channels that can then be stored locally or transmitted via Wi-Fi
to a central system. The reduction in cabling, which is usually
cited as the core advantage of nodal recording, is therefore limited
to the backbone connecting the central recording system to the
field recording units. In this paper we will concentrate on nodes
that are designed to record data from a single point and are thus
typically limited to six or fewer channels.
Over the history of nodes there have been six major catego-
ries developed (listed roughly in the order of their introduction):
1.
Delayed data – Data is stored on the node and then transmitted
after each shot, or stacked series of shots, is completed.
2.
Remote-controlled – data is recorded internally but recording
is initiated via radio messages.
3.
Remote-synchronized – data is recorded continuously but the
timing signal is issued via radio.
4. Real-time data – Data is transmitted in real-time.
5.
Real-time QC – Status and or quality control data is transmit-
ted in real-time.
6.
Blind – the node records data internally and does not provide
status or QC information in real-time.
In this article we look at how nodal systems have evolved over
the last 50 years. We begin with a historical overview starting
from the early 1970s finishing in 2015. We then introduce the
latest nodal systems and look at the implications of their use for
seismic survey acquisition logistics. Finally, we will discuss the
implications of these new systems and make some suggestions
about where future developments should lie.
The rise and fall of the radio frequency systems
Owing to the publicity associated with a boom in the number
of systems available and their use, nodal seismic acquisition
is often thought of as a recent innovation. However, the first
1
Curtin University | 2
Schlumberger | 3
Terrex Seismic
*
Corresponding author, E-mail: tim.dean@curtin.edu.au
Figure 1 Diagram of a nodal acquisition system from a patent granted in 1941
(adapted from Burg (1941)).

3. SPECIAL TOPIC: LAND SEISMIC
4 8 F I R S T B R E A K I V O L U M E 3 6 I J A N U A R Y 2 0 1 8
Figure 3b) system, first introduced in 1995 was a 6-channel radio
QC system that stored data using flash memory. Improvements
in electronics resulted in the weight of nodes decreasing but the
RSR was still a hefty 6.8 kg (excluding the battery). A smaller,
radio-controlled recording system, was introduced by Ascend
Geo (a subsidiary of Aspect Energy) who launched the G5
(Figure 3c) in 2005. This system differed from previous systems
as it recorded data continuously using a timing signal transmitted
over radio by a central unit.
A new real-time radio data transmission system was launched
by Wireless Seismic in 2009 (Figure 4a). The system was con-
siderably smaller and lighter than previous systems and ran off
2 D-cell batteries (giving ~100 hours of life). Wireless Seismic
continue to make real-time radio systems releasing the RT System
2 (Figure 4b) in 2012 and the System 3 (Figure 4c) in 2017. The
System 3 differs from previous versions in that each recording
unit sends data to a relay unit which then transmits it to a central
system. Radio QC systems, in contrast, have all but disappeared,
the most recently introduced being the FireFly (Figure 4d) back
in 2006 by Input/Output (now Inova).
VibTech (acquired by Sercel in 2006) created the Unite sys-
tem that utilised WiFi to send data/QC information in real-time.
The Unite system can be used both as an entirely nodal system or
incorporated with a cabled system for use in areas with restricted
5 minutes to receive data from 95 channels (Bays, 1984), the
Telseis II 48 s to download 96 traces (6 s length, 2 ms sample
interval) and Myriaseis 3 min 12 s to download 256 channels (also
6 s @ 2 ms) (Ray and McDavid, 1979). Although improvements
in download speed were made by increasing the number of trans-
mittal frequencies, real-time data transmittal was not achieved
until the introduction of the TelSeis RtDt by Fairfield in 1988
(other real-time data systems included the Digiseis FLX and the
TelSeis STAR).
The idea of recording data within a node and then down-
loading after acquisition was complete, was first implemented in
the Seismic Group Recorded (SGR) system introduced by GUS
manufacturing (acquired by Grant Geophysical) in 1979. Syn-
chronization between the recording units was achieved via radio
messaging with data being recorded on tapes. The removal of the
need for data transmittal reduced the weight of the node to around
9 kg, making it suitable for land surveys (Shave, 1982). Although
successful for its time (Shave, 1982) states there were 20 crews
with 200 units each in operation in 1984), blind recording (i.e. no
real-time status or QC reporting) was difficult to accept for many
clients and development of real-time or delayed transmission
radio systems continued. Such systems included the Fairfield
BOX (Figure 3a), the Sercel Eagle/SU6-R and the Syntron
PolySeis. The I/O (now Inova) remote seismic recorder (RSR,
Figure 2 (a) Digiseis nodes being prepared for
deployment (image courtesy of Schlumberger).
(b) Myriaseis telemetry unit (reproduced from
Lavergne (1989)). (c) Opseis 5500 (reproduced from
Angrove (1985)).
Figure 3 (a) Fairfield BOX, (b) I/O RSR, (c) Ultra G5.
Figure 4 (a) Wireless seismic Mk2., (b) RT System 2, (c) RT System 3, (d) Inova Firefly.

4. SPECIAL TOPIC: LAND SEISMIC
F I R S T B R E A K I V O L U M E 3 6 I J A N U A R Y 2 0 1 8 4 9
differs from other systems in that it can be used in a number
of different configurations: blind recording, radio-controlled,
real-time data via WiFi, cellular controlled and even cabled. The
latest version, the Sigma4, continues to offer a wide variety of
operating modes but also incorporates internal 2 Hz geophones
for passive seismic acquisition.
Recently introduced systems
Six new acquisition systems aimed at large channel count seismic
crews have been released in the last two years. Five of these
systems have an integrated battery and sensor, four are blind
(Figure 7a-d, Figure 8) and one is real-time radio data (Fig-
ure 4c). The remaining system, the Sercel WTU-508 (Figure 7f),
offers real-time QC functionality via a low-power proprietary
wireless transmission technology, but with a larger (34-cm tall)
and heavier (2.1 kg) unit (although battery life is still 30 days in
autonomous mode).
The technical improvements possible can be seen from
comparing the specifications of the first Zland node (released
in 2008, Figure 6c) with the latest model (released in 2013,
Figure 7e). Battery life improved from 12 days to 40 days while
access. It also offers wireless data harvesting from a vehicle or
aircraft (a technique that was first patented in 1962 (Figure 5) and
used to record data from a Telseis system in 1981).
The more recent (post-2007) boom in nodal systems was
enabled by a single key technology, GPS, allowing the introduc-
tion of truly blind continuously recording systems. Previously,
even systems that continuously recorded needed their timing
maintained by a radio signal (e.g. the Ultra G5) but GPS timing
allows an unlimited number of remote acquisition units to record
synchronised data (assuming they have a clear view of the sky).
Removing the requirement to transmit and receive radio signals
reduced the power consumption and size of the units and also
saved the operator the often complex issue of obtaining the
appropriate radio licences.
The first truly blind nodal system, the Geospace GSR was
introduced in 2007. The system consisted of a recording unit with
an external battery and sensor (Figure 6a). Other manufacturers
also followed this concept, Global Geophysics with the AutoSeis
HDR in 2010, and Inova with the Hawk in 2011 (Figure 6b).
Fairfield, however, decided to incorporate the battery and sensor
producing a single unit, ZLand, introduced in 2008 (Figure 6c).
The iSeis Sigma system (Figure 6d) was launched in 2010 and
Figure 5 Diagram from Herzog (1962) showing an RF acquisition system being
controlled from a helicopter.
Figure 6 (a) Geospace GSR, (b) Inova Hawk, (c) Fairfield Z-Land GEN1, (d) iSeis
Sigma, (e) iSeis Sigma4 with a WiFi antenna attached.
Figure 7 (a) Innoseis Tremornet/Inova Quantum , (b) Geospace GCL (c) DTCC
SmartSolo, (d) GTI NRU 1C, (e) Fairfield ZLand generation 2 (f) Sercel WTU-508.
Note that these are not shown to scale.
Figure 8 Graphical summary of the battery and sensor configuration for nodal
systems released since 2006.

5. SPECIAL TOPIC: LAND SEISMIC
5 0 F I R S T B R E A K I V O L U M E 3 6 I J A N U A R Y 2 0 1 8
The NRU 1C differs from the other nodes in its shape, instead
of using a spike the node is inserted into the ground. This results
in excellent coupling but makes deployment more complex as a
tool often has to be used to create a hole to insert the node into.
Where required, for example in areas with hard ground, the
bottom section of the node, which houses the geophone, can be
replaced by a takeout and an external sensor used.
Logistics
An oft-stated advantage of nodal systems is their lower weight
and the logistical advantages this offers. Prior to the release of
the latest nodal systems, cabled systems were often lighter unless
the receiver interval was large (Figure 10). The lighter weight of
the latest nodal systems, however, suggests that this advantage
no longer exists.
As well as the weight of the equipment, laying a cabled
system needs to be done with care, cables can easily become
tangled and multiple line boxes have to be correctly placed.
The number of personnel required to lay out the spread has led
to a significant body of work aimed at developing automated
deployment systems. The earliest reference we found is a patent
issued in 1961 that involves the use of what would now be
called a land-streamer (Figure 11a). The problem with automat-
ed deployment of cable-based systems is that the sensors are
generally not attached to the line cable but instead connected
to a take-out by a shorter cable. An added level of complexity
can also be added through the use geophone arrays. The use
of nodes, however, allows for easier mechanical deployment.
Figure 11b shows the GTI ‘Automated Deployment System’
(ADS), consisting of a tracked trailer that can be towed behind
a vehicle to deploy nodes. The system can deploy more than
400 nodes per day with a single operator (averaging around
25 s per node).
weight dropped from 2.2 kg to 1.8 kg. Quality also improved
with distortion and the noise level dropping by a factor of three.
Such improvements are typical of all the newly introduced
nodes.
A major difference between the systems is the manner in
which they are charged and the data downloaded. The Tremor-
net/Quantum, NRU 1C, and ZLand are charged/downloaded
via surface mount pins on the side/top of the units. The GCL,
however, is cable-free (charging time is seven hours and
download time is ~11 minutes) and the SmartSolo splits into
two parts, the lower section contains the battery which goes to
be recharged while data is downloaded from the top part. As the
data download is much faster (~10 s) than the battery charging
(~three hours), by having a larger number of batteries you can
cycle the nodes more rapidly, although at the cost of the time
spent disassembling the nodes (~five seconds/node using the
device shown in Figure 9). The extended battery life of some of
the nodes (up to 50 days in continuous operation) means, how-
ever, that they may not need recharging during the survey at all.
Figure 9 The ‘Automatic assembly/disassembly’ machine used to split a SmartSolo
node into two sections (image courtesy of Terrex).
Figure 10 Weight/channel of cabled and node systems for different receiver
intervals. The red and green lines show the data given in Lansley et al. (2008).
The weight of the new nodal systems is shown in blue, the UniQ cabled acquisition
system (fixed receiver interval) by the magenta point, and the Sercel 508XT cabled
system by the cyan line.
Figure 11 (a) Design for an automated seismic deployment system (adapted from
Hawkins and Wilcox (1961)) (b) Automated Deployment System.

6. SPECIAL TOPIC: LAND SEISMIC
F I R S T B R E A K I V O L U M E 3 6 I J A N U A R Y 2 0 1 8 5 1
offer smart data rerouting to overcome cable breakages (a
significant source of downtime), and lower power consumption,
increasing the number of channels supported by each line-box
and reducing the number of batteries required. Although nodes
can be particularly handy in areas with significant infrastructure,
cables can have their advantages, particularly in the desert where
sand storms can bury equipment. If used in urban areas then GPS
receiver sensitivity is important as ideally the sensors should be
buried out of sight.
A degree of real-time noise monitoring (or the use of real-time
data/QC nodes) is also essential as short period noise, such as that
from vehicles or aircraft, can contaminate a significant number of
records. The ability to use an external sensor (something that is
generally not offered by the newer systems) can be advantageous,
enabling use in areas covered by water.
Although the use of nodes is often thought to result in cheaper
surveys, the number of personnel removed from the line crews is
balanced to some extent by an increase in the number of technical
staff. The use of nodes, however, does enable a greater trace
density (when compared with a cabled system using small arrays)
and increased productivity (Terrex found on average more than an
hour each day of additional acquisition time) enabling a greater
source density. These two factors result in an increase in imaging
quality. The use of nodes also enables more imaginative spread
configurations, including the use of pseudorandom positioning
for surveys employing compressive sampling techniques. Finally,
there is an impact on safety as the number of vehicles required
on the line to troubleshoot and transport equipment is lower
The use of a nodal system also removes the need for a
large central recording truck. The only functionality required is
source control and this can be incorporated into a small vehicle
(Figure 12).
The advantages of having no cables is somewhat offset,
however, by the need to download data and recharge batteries.
Recharge times for the latest systems are relatively low, typically
around 3-4 hours with data download being even faster (typically
less than 10 s). Nodal systems, however, require the nodes to be
manually loaded into racks (with the SmartSolo nodes requiring
disassembling as well). The capacity of these racks is typically
quite limited, the rack shown in Figure 13a holds only 96 nodes
thus large channel count surveys need large numbers of racks.
For example, the 20,000 node system employed by Terrex has a
64-node download rack and 480 node recharge rack (Figure 13b).
This is sufficient to enable the rotation of 5000 nodes/day. Given
that data is continuously recorded the amount of data storage
required is also considerable (Terrex had ~200 TB of storage for
harvesting and ~240 TB for QC). Reductions in the number of
line personnel are therefore somewhat offset by an increase in
the number of (generally more expensive) technical personnel
in camp. The added complexity of correctly combing individual
records from the data and quality control may also increase the
number of technical staff required (although there is a decrease in
the number of cable repair and maintenance personnel required).
Discussion
The original nodal acquisition systems transmitted data over radio
after acquisition was complete, often taking several minutes for
even small channel counts. Such an approach is unthinkable now,
when high productivity using large numbers of channels is craved
and even a few minutes of delay is often unacceptable. Current
developments suggest that the future of nodal acquisition systems
is small, light-weight, and blind (Figure 8).
The total replacement of cabled systems by nodal systems in
the near future is, however, unlikely. This is partially owing to the
need for acceptance of the replacement of geophones in arrays by
a smaller number of single nodes, albeit at a closer spacing than
the array centres. Although this transition is happening, in areas
where large areal geophone arrays are preferred the use of cabled
systems makes more sense, particularly for very large-channel
count crews in open areas. The use of blind nodes also requires
a degree of confidence in their reliability, although this has been
clearly demonstrated. For example, in more than 170,000 deploy-
ments spread over 12 surveys, Terrex has had only nine failures,
two of which were a result of the nodes being run over. In all
these cases data recorded up to the point of failure was recovered.
Nodal acquisition is well suited to more complex, and even
random, geometries as the layout is not restrained by cable
lengths and avoids the need to use jumper cables. Cabled system
geometries are somewhat pre-defined by the existing cable length
between take-outs. Changing the length of the cables is expen-
sive, and, although the receiver spacing can be significantly less
than take-out spacing if required, this results in weighty sections
of coiled cable.
The development of cabled systems has not stopped because
of the apparent emphasis on nodal systems, the latest systems
Figure 13 (a) Tremornet/Quantum docking station holding 96 nodes, multiple racks
can be combined as shown in (b) SmartSolo recharge (left) and download (right)
racks.
Figure 12 Cabled acquisition system recording truck (left) and nodal system source
control vehicle (right). Images courtesy of Terrex.

7. SPECIAL TOPIC: LAND SEISMIC
5 2 F I R S T B R E A K I V O L U M E 3 6 I J A N U A R Y 2 0 1 8
(Figure 15), has also been suggested. These would be particularly
useful for use in areas where access is an issue. Efficient data
harvesting depends on leveraging the difference between the
short time required to harvest data and the significant battery life.
The ability to harvest data (and possibly recharge) while moving
the nodes in the field, i.e. without returning the nodes to camp,
would be hugely advantageous.
The impact of data processing should also not be ignored.
Future developments in processing, particularly improving our
ability to remove ground roll, will enable a reduction in the
number of sensors required in the field and make more nodes
more attractive, particularly if large areal arrays can be replaced
by single sensors.
Acknowledgements
The authors would like thank those who shared their knowledge
and experiences including Mark Beker, Florten Bertini, James
Blattman, Andrew Clark, Jason Criss, Richard Degner, John
Giles, Jose Medina, Phil Richards, Sean Siegfried, Jorgen Skjott,
Nicholas Tellier, Gary Wu, and Dave Yacco. Unless otherwise
acknowledged, all photos are courtesy of the manufacturer.
References
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Angrove, R. [1985]. The Point Torment seismic survey: A semi-portable
seismic operation. the APPEA Journal, 25, 248-352.
Bays, A.R. [1984]. The impact of microelectronic technology on seismic
data acquisition. The Leading Edge, 54-57.
Burg, K.E. [1941]. Prospecting method and apparatus, patent, 2265513 A.
Hawkins, J.E. and Wilcox, S.W. [1961]. Method and apparatus for
continuous geophysical exploration. Patent US 2990904 A.
Herzog, G. [1962]. Radio-link system of seismic exploration. (Ed. US). US.
Lansley, M., Laurin, M. and Ronen, S. [2008]. Modern land recording
systems: How do they weigh up? The Leading Edge, 888-894.
Lavergne, M. [1989]. Seismic Methods. Institut Francais du Petrole.
Ray, C.H. and McDavid, W.T. [1979]. Telseis II: An expanded capability
in radio telemetry seismic data acquisition. Geophysics, 44, 391.
Shave, D.G. Seismic group recorder system. Conference Seismic group
recorder system, 45-46.
Stewart, R.R., Chang, L., Sudarshan, S.K.V., Becker, A.T. and Li Huang.
[2016]. An unmanned aerial vehicle with vibration sensing ability
(seismic drone). SEG Annual Conference, Extended Abstracts.
(for example, one vehicle can carry 240 nodes but two are
required for 100 cabled channels).
Given the dramatic drop in seismic equipment sales (Fig-
ure 14) it seems unlikely that all the systems currently available
can survive. In our opinion, the key to their success is improving
efficiency – in particular, the time taken to deploy and harvest the
nodes. As discussed, the use of nodes allows the introduction of
automated deployment equipment (e.g. Figure 11b) but their util-
ity in the challenging terrain where the use of nodes is particularly
advantageous is yet to be established. The use of nodes attached
to drones (Stewart et al., 2016), or nodes dropped from drones
Figure 14 Quarterly revenue reported by Sercel. Where possible the result has been
divided into land and marine sales. The peak in Q4 2013 was owing to a seasonal
peak in land equipment sales.
Figure 15 Drone developed to drop nodes from the air (image courtesy of
Florent Bertini).
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