wireless geophones
TRANSCRIPT
Wireless Geophones
Chapter 1
Introduction
1.1. Definition of wireless geophones:
- Wireless: no lines (network or power).
- Wireless Sensor Network: network of individual sensors connected to transmit data.
through nodes, or motes, which function as tiny radio transmission devices.
- Practical application, however requires a low power, low complexity, low data rate
compliant RF device.
1.2. What is a Wireless Sensor Network?
- Wireless communication is becoming a very important aspect of modern day
networking and in deploying practical solutions for the real world.
- A wireless sensor network consists of a base station and numerous wireless sensors
(motes) that can transmit and receive data. The wireless sensors establish a
connection via an ad-hoc infrastructure to the base station, which serves as the
gateway for outputting the data from the network.
- This type of infrastructure allows for an extended coverage range.
1.3. Wireless Sensor Networks:
- Consist of a set of small devices with sensing and wireless communication
capabilities.
- Those small devices are named sensor nodes, and are deployed within a special
area to monitor a physical phenomenon.
1.4. Wireless seismic system:
Wireless Seismic is pleased to introduce an exploration seismograph that operates
without cables. Small modules operate as independent seismic data acquisition units.
The seismic data is sent by radio to your computer in real time for instant display and
storage, just as in a conventional wired seismograph.
1
Wireless Geophones
Working with seismic cables is painful. Now you can eliminate them by replacing
these cables with a wireless mesh network. This seismic system will cost less to buy,
but more important, it will greatly reduce the logistics effort, and manpower required to
conduct a seismic survey. Lowering the environmental impact will open new areas to
exploration.
The RF transceivers are low power, so the range is limited, but each unit acts as
a radio relay so that data from distant modules is handed across the network until it
reaches the base station. Normal geophone spacings are well within the range of
transmission, but the total areal extent of the array can be theoretically unlimited.
Since the data is digital, there is no degradation in data quality as the information is
passed from station to station.
Of course the system meets the requirements of an exploration seismograph: 24-
bit data conversion, stacking, fast and slow sample rates, synchronized timing,
correlation for swept sources, true amplitude recovery, and self-test functions. Data
may be displayed and stored on industry-standard notebook computers or tape drives
in SEG standard formats.
Control and display software for Windows-compatible computers is provided with
the system. An interface unit, called a base station, acts as the radio communication
link between the computer and the individual modules. TTie base station has an
Ethernet interface which connects to the computer. A built-in Ethernet hub allows
additional base stations to be connected for system expansion. Each base station can
accommodate multiple remote units for system expansion where the base stations are
arranged in a line and the remote units in cross lines to make large arrays of sensor
stations.
Because of the short cables, electrical interference is kept to a minimum.
Different surveys call for different geometries. A wireless system frees you to locate
your geophones where they ought to be instead of being constrained by your spread
cables.
2
Wireless Geophones
Fig1.1: Distribution of wireless geophones
Fig1.2: Wireless geophone
3
Wireless Geophones
Chapter 2Wireless procedures
2.1. Networked Sensing Enabler
Small (coin, matchbox sized) nodes with
- Processor
8-bit processors to x86 class processors
Memory
Kbytes – Mbytes range
- Radio
20-100 Kbps initially
- Battery powered
- Built-in sensors!
Fig2.1: Sensing components
2.2 .Sensor Nodes
Fig2.2: Types
of Sens
or Nodes
2.3.
Motes:
- Motes are used as the building blocks of wireless sensor networks:
- Small
4
Wireless Geophones
- Low Cost
- Monitor Sensor Data
- Components on the MICAz mote: Fig2.3: Motes figure
- In Crossbow’s MICAz, it uses ATmel ATmega 128L processor running at
4MHZ
- Communicates using a MIB510 at its base node to link with a computer
- Has 10-bit A/D Converter so sensor data can be digitized
- Limited Range (10 to 200 feet) due to power consumption
Istrumentation: 2.4.
2.4.1 .Existing Instrumentation:
- Sensors connected by cables to data logger
- Data logger wirelessly transmits sensor
readings to base station
Fig2.4: Wired geophones array
2.4.2 .Our Experiment:
- Sensor nodes with
- On-board computation
- Wireless communication
5
Sensor
Data Logger
Sensor
Data Logger
Wireless Geophones
- Can we build a (possibly multi-hop)
wireless seismic sensor array?
- Can greatly simplify deployment
Fig2.5: Wireless geophones array
2.4.3 .Experiment Design:
- Deploy wireless array beside wired array
- Goals
- Understand systems design issues
- Validate by comparing data
obtained using wired
infrastructure
Fig2.6: Wireless beside wired array
2.5 .The Technology:
- Mica-2 motes from Crossbow
- Atmel processor
- Chipcon CC1000 transceiver
6
Sensor
Data Logger
Wireless Geophones
- Vibration daughter card (under development)
-16-bit, up to 100 Ksps, on board processor and sample memory
Fig2.7: The technology in motes
2.6 .Rockwell WINS & Hidra Nodes:
- Consists of 2”x2” boards in a 3.5”x3.5”x3”
enclosure
- StrongARM 1100 processor @ 133 MHz
- 4MB Flash, 1MB SRAM
- Various sensors
- Seismic (geophone)
- Acoustic
- magnetometer
- accelerometer, temperature, pressure
- RF communications
- Connexant’s RDSSS9M Radio
@ 100 kbps, 1-100 --mW, 40 channels
- eCos RTOS
- Commercial version: Hidra
- mC/OS-II
- TDMA MACwith multihop routing
Fig2.8: Rockwell WINS &Hidra Nodes
2.7 .Sensoria WINS NG 2.0, sGate, and WINS Tactical Sensor:
- WINS NG 2.0
- Development platform used in
DARPA SensIT
- SH-4 processor @ 167 MHz
7
Wireless Geophones
- DSP with 4-channel 16-bit ADC
- GPS
- Imaging
- Dual 2.4 GHz FH radios
- Linux 2.4 + Sensoria APIs
- Commercial version: sGate
- WINS Tactical Sensor Node
- Geo-location by acoustic ranging and angle
- Time synchronization to 5 ms
- Cooperative distributed event processing
Fig2.9: Types of Wins & its configuration
Fig2.10: The diameter & height of Wins
2.8. Sensoria Node Hardware Architecture:
8
Wireless Geophones
Fig2.11: Sensoria Nodes Hardware
Geophone Operating Conditions: .2.9
- Wide temperature range (-40 to +85°C)
Humidity 0 – 100%-
- Robust
- 2000g shock survivability Fig2.12: Geophones in water
- Altitude: -100 to +5500m
- Exposure to water, dirt, sand, animal attacks
- Transportation by truck, helicopter, boats, divers, etc.
Fig2.14: Geophone connected Fig2.13: Transportation by truck
2.10 .Complex deployment logistics:
9
ProcessorRAMFlash
GPS
Address/Data Bus
DSPPreprocessor
Multi-lennahC
rosneSecafretnI
golanAtnorF
dnE
rossecorperPecafretnI
regamIecafretnI
regamIeludoM
raludoMsecafretnI latigiD dna sseleriW
FRmedoM
1
FRmedoM
2
latigiDO/I
001/01nrehtE
te
Wireless Geophones
Fig2.15: Complex deployment lo
gistics
2.11 .Seismic Imaging: Analog to Digital Transitions:
Fig2.16: Analog to digital transitions
Energy Management .2.12
10
?
Tx Rx
?
Wireless Geophones
Radio Energy Management 2.12.1.
Fig2.17: Radio energy management
- During operation, the required performance is often less than the peak performance
the radio is designed for.
- How do we take advantage of this observation, in both the sender and the receiver?
2.12.2 .Energy in Radio: the Deeper Story.…
Fig2.18: Energy in radio
- Wireless communication subsystem consists of three components with substantially
different characteristics.
- Their relative importance depends on the transmission range of the radio.
Chapter 3Applications of wireless geophones
11
Tx: SenderRx: Receiver
ChannelIncominginformation
Outgoinginformation
TxelecE Rx
elecERFE
Transmit electronics
Receive electronics
Power amplifier
time
Wireless Geophones
3.1 .Environmental Potential of ENS Technology (Applications being
pursued at CENS):
Fig3.4:Marine Microorganisms
Fig3.3: Contaminant Transport
- Micro-sensors, on-board processing, wireless interfaces feasible at very small scale
can monitor phenomena “up close”.
- Enables spatially and temporally dense environmental monitoring.
3.1.1 .Example Application: Seismic:
12
Wireless Geophones
- Interaction between ground motions and structure/foundation response not well
understood.
- Current seismic networks not spatially dense enough
to monitor structure deformation in response to
ground motion, to sample wavefield without spatial
aliasing.
- Science
- Understand response of buildings and
underlying soil to ground shaking.
- Develop models to predict structure response
for earthquake scenarios.
- Technology/Applications
Fig3.5: Building damage
- Identification of seismic events that cause significant structure shaking.
- local, at-node processing of waveforms.
- Dense structure monitoring systems.
Fig3.6: Bridge damage Fig3.7: Building damage
Field Experiment: 3.1.2.
- 38 strong-motion seismometers in 17-story steel-frame Factor Building.
- 100 free-field seismometers in UCLA campus ground at 100-m spacing.
13
Wireless Geophones
Fig3.8: Seismometers in building
- A Wireless Seismic Array:
- Use motes for seismic data collection
- Small scale (10 or so)
- Opportunity: validate with existing wired
infrastructure
- Two on-going experiments
- Factor building
- Four Seasons building
Fig3.9: Wireless array in building
3.1.3 .Contaminant Transport:
-Science
- Understand intermedia contaminant transport and fate in real systems.
14
Wireless Geophones
- Identify risky situations before they become exposures , Subterranean
deployment.
- Multiple modalities (e.g., pH, redox
conditions, etc.).
- Micro sizes for some applications (e.g.,
pesticide transport in plant roots).
- Tracking contaminant “fronts”.
- At-node interpretation of potential for risk
(in field deployment).
- marine contaminants.
- Dispersal enormously can be damage to
the environment.
- Groundwater contaminants. Fig3.10: Subsurface contamination
- Study of contaminant transport involves.
- Understanding the physical (soil structure), chemical (interaction with and impact on
nutrients), and biological (effect on plants and marine life) aspects of contaminants.
- Modeling their transports.
- Mature field!
- Fine-grain sensing can help.
3.1.4. Field-Level Experiments:
- Nitrates in groundwater.
- Application
- Wastewater used for irrigating alfalfa.
15
Wireless Geophones
- Wastewater has nitrates, nutrients for alfalfa.
- Over-irrigation can lead to nitrates in ground-water.
- Need monitoring system, wells can be expensive.
- Pilot study of sensor network to monitoring nitrate levels.
Fig3.11: Wastewater detection
Fig3.12: Sensor network
3.1.5 .Marine Micro-organism Monitoring:
- Algal Blooms (red, brown, green tides) impact.
- Human life.
- Industries (fisheries and tourism).
- Causes poorly understood, mostly because.
- Measurement of these phenomena can be complex and time consuming.
16
Tethered-robot
sample collectors
Wireless Geophones
- Sensor networks can help.
- Measure, predict, mitigate.
Fig3.14: Marine Fig3.13: Algal Blooms
-Lab-Scale Experimentation:
- Build a tank testbed in which to study the factors that affect micro-organism growth.
- Actuation is a central part of this.
- Can’t expect to deploy at density we need.
- Mobile sensors can help sample at high frequency
Initial study:
- Thermocline detection
Fig3.15: Marine micro-organism
Fig3.16: Experimentation
3.1.6 .Application Scenario:
17
Wireless Geophones
Fig3.17: Sensors distribution in application scenario
Ecological / Health
Contaminant monitoring / mapping
Agricultural
Precision farming
ENS Research Implications:-
- Environmental Micro-Sensors. Fig3.18: Groundwater detection
- Sensors capable of recognizing phases in air/water/soil mixtures.
- Sensors that withstand physically and chemically harsh conditions.
- Microsensors.
- Signal Processing.
- Nodes capable of real-time analysis of
signals.
- Collaborative signal processing to expend
energy only where there is risk.
Fig3.19: Contamination detection
3.2 .Ecosystem Monitoring:
Science- Remote sensing can enable global assessment of ecosystem.
- Understand response of wild populations (plants and animals) to habitats over time.
- Develop in situ observation of species and ecosystem dynamics.
Techniques
18
Wireless Geophones
- Data acquisition of physical and chemical properties, at various spatial and temporal
scales, appropriate to the ecosystem, species and habitat.
- Automatic identification of organisms (current techniques involve close-range human
observation).
- Measurements over long period of time, taken in-situ.
- Harsh environments with extremes in temperature, moisture, obstructions, ...
Fig3.20: Ecosystem monitoring
3.2.1. Monitoring ecosystem processe:
- Imaging, ecophysiology, and environmental sensors.
- Study vegetation response to climatic trends and diseases.
Fig3.21: Stress physiology
19
Wireless Geophones
3.2.2. Species Monitoring
- Visual identification, tracking, and population measurement of birds and other
vertebrates.
- Acoustical sensing for identification , spatial position, population estimation.
3.2.3 .Education outreach
-Bird studies by High School Science classes (New Roads and Buckley Schools).
Fig3.22: Virtual field observations Fig3.23: Avian monitoring
Fig3.24: Vegetation change detection
20
Wireless Geophones
3.3 .CENS Habitat Monitoring Network@ James Reserve:
- Microclimate and ecophysiological studies.
- Continuous Monitoring System-deployed.
- ~ 20-30 nodes.
- Exetensible Sensing System – in development.
- > ~ 100 nodes.
- Hierarchical architecture.
- Weather boards + MICA.
- IPaqs/802.11 as cluser heads.
- Mote and iPaq software stack.
- Directed diffusion routing (Tiny-
diffusion).
- Sampling management.
- Neighbor discovery , link quality
management, etc.
- Sensor device drivers.
Fig3.25: Habitat monitoring network
- Backend server software.
- Transport an recording of sensor data from remote sensor nets.
- Storage schemas.
- Internet-based publish-subscribe bus.
Fig3.26: Clustered architecture Fig3.27: Housing design
Clustered architecture.- -Weather-resistant housing design.
Sensors: Light, temperature, pressure, humidity.-
21
Wireless Geophones
Landslides: 3.4.
- A landslide is an event where a block of earthen mass slides downhill covering the
area underneath with dirt and debris.
- Landslides are a major geologic hazard.
Fig3.28: Side effect of land slides
Fig3.29: House damage by land slide
22
Wireless Geophones
3.4.1 .Slip surface localization:• While overall physics of landslides is understood prediction is complicated since:
– Geologic materials are
highly heterogeneous with spatially
distributed properties.
– Temporal variation of driving and
resisting forces dictates landslide potential
but is difficult to forecast.
Fig3.30: Slip surface lacalization
3.4.2 .System Architecture:
23
Wireless Geophones
Fig3.31: System architecture
– Sensor columns detect movements.
– Determine columns that moved.
– Estimate new locations of dislocated columns.
– Estimate location of slip surface.
– Transfer selected measurements to analysis station.
3.4.3. Detection of slip surface:
- Uses strain gages on each sensor column.
- Can measure changes in their length due to
deformation.
- Conserves power.
- Two-tier detection algorithm.
1. Detect statistically significant
changes in length of individual columns.
2. Check that number of false positives
along potential slip plane is below
threshold.
Fig3.32: Detection of slip surface
3.4.4 .Classification of slip surface:
- Determine which sensors are above and below the slip surface.
24
Wireless Geophones
Fig3.33: Determine sensors movements
3.4.5 .Slip surface estimation:
– Find surface that maximizes distance
between static and moved nodes
Based on constraints.
– Surface separates static and displaced
nodes.
– Slip surface is consistent with set of
displacements.
Fig3.34: Slip surface estimation
Leak detection: 3.5.
Water transmission and distribution pipes deteriorate naturally with time and
eventually develop leaks. The amount of lost water due to leakage can be significant,
reaching levels as high as 50% of production for some systems.
Leaks waste both money and a precious natural resource, and they create a
public health risk. Water system operators invest significantly in finding and fixing
leaks. Unfortunately,significant resources are wasted when leaks are not found
25
Wireless Geophones
or inaccurately located.
Fig3.35: Leak detection
Fig3.36: Wireless se
nsors uses in leak detection
3.6 .Overview of Oil & Gas Seismic Imaging
3.6.1 .Much like medical ultrasound imaging:
- Sound waves are sent into the earth, then reflect off various
geological structures. Signals come from miles below.
- Sound source is dynamite, vibrator trucks, or air guns
- Geophones record the reflected sound waves to create
seismic images.
Fig3.37: Seismic imaging
26
Wireless Geophones
Fig3.38: Geophones record the reflected sound
3.6.2 .Improved Seismic imaging:
27
Wireless Geophones
Fig3.39: Improved Seismic imaging
Fig3.40: Conventional geophone image Fig3.41: MEMS-based VectorSeis image
3.7 .Others Applications of Sensor Networks :
3.7.1 .Applications of Sensor Networks(1)
Fig3.42: Battlefield application
28
Wireless Geophones
3.7.2 .Applications of Sensor Networks (2)
Fig3.43: Weather application
3.7.3 .Applications of Sensor Networks (3)
Fig3.44: Habitat monitoring application
29
Wireless Geophones
3.7.4 .Applications of Sensor Networks (4)
Fig3.45: Different
application
3.8 .Monitoring Volcanic Eruptions:
Wireless sensor networks have the potential to greatly benefit studies of
volcanic activity. Volcanologists currently use wired arrays of sensors, such as
seismometers and acoustic microphones, to monitor volcanic eruptions. These
sensor arrays are used to determine the source mechanism and location of an
earthquake or explosion, study the interior structure of the volcano, and differentiate
30
Wireless Geophones
true eruptions from noise or other signals (e.g., mining activity) not of volcanological
interest. A typical campaign-type study will involve placement of one or more
stations on various sites around a volcano. Each station typically consists of a few
(less than five) wired sensors distributed over a relatively small area (less than 100
m2), and records data locally to a hard drive or flash card. The data must be
manually retrieved from the station, which may be inconveniently located. Power
consumption of these systems is very high, requiring large batteries and solar panels
for long deployments.
Fig3.46: Sensor arrays for volcanic monitoring
Wireless sensor networks, comprised of many resource-limited nodes linked
by low-bandwidth wireless radios, have been the focus of intense research over the
last few years. Since their conception, wireless sensor networks have excited other
scientific communities because of their potential for facilitating data collection and
monitoring. Collaborations between computer scientists and other domain
scientists have produced networks capable of recording data at a scale and
resolution not previously possible. Wireless sensor networks have the potential to
greatly advance the pursuit of scientific knowledge across a wide variety of
disciplines.
Fig3.47: Schematic representation of our sensor network architecture
31
Wireless Geophones
Fig3.48: One of our two-component stations. The blue Pelican Case contains the wireless sensor network node and hardware interface board. The external antenna is mounted on the PVC pole to reduce ground effects. A microphone is taped to the PVC pole and a single seismometer is buried nearby.
3.9 .Wireless underground sensor networks (WUSN):
Sensor networks are currently a very active area of research. The richness of
existing and potential applications from commercial agriculture and geology to
security and navigation has stimulated significant attention to their capabilities for
monitoring various underground conditions. In particular, agriculture uses
underground sensors to monitor soil conditions such as water and mineral content
Sensors are also successfully used to monitor the integrity of belowground
infrastructures such as plumbing and landslide and earthquake monitoring are
accomplished using buried seismometers.
32
Wireless Geophones
3.9.1 .Environmental monitoring:
Sensor is being used in agriculture to monitor underground soil conditions,
such as water and mineral content, and to provide data for appropriate irrigation
and fertilization. A wireless underground system, however, can provide a
significant refinement to the current approach for more targeted and efficient soil
care. For example, since installation of WUSNs is easier than existing wired
solutions, sensors can be more densely deployed to provide local detailed data.
Rather than irrigating an entire field in response to broad sensor data, individual
sprinklers could be activated based on local sensors. In a greenhouse setting,
sensors could even be deployed within the pot of each individual plant.
The concealment offered by a WUSN also makes it a more attractive and
broadly viable solution than the current terrestrial agricultural WSNs. Visible and
physically prominent equipment such as surface WSN devices or dataloggers
would most likely be unacceptable for applications such as lawn and garden or
sports field monitoring. WUSNs are particularly applicable to sports field
monitoring, where they can be used to monitor soil conditions at golf courses,
soccer fields, baseball fields, and grass tennis courts. For all of these sports, poor
turf conditions generally create an unfavorable playing experience, so soil
maintenance is especially important to ensure healthy grass. An additional
practical feature of underground sensors is that they are protected from equipment
such as tractors and lawnmowers.
Monitoring the presence and concentration of various toxic substances is
another important application. This is especially important for soil near rivers and
aquifers, where chemical runoff could contaminate drinking water supplies. In
these cases, it may be desirable to utilize a hybrid network of underground and
underwater sensors.
In addition to monitoring soil properties, WUSNs can be used for landslide
prediction by monitoring soil movement.
Current methods of predicting landslides are costly and time-consuming to
deploy, preventing their use in the poorer regions that stand to benefit the most
from such technology. Like terrestrial WSN devices, WUSN devices should be
inexpensive, and deployment is as simple as burying each device. WUSN
33
Wireless Geophones
technology will allow for a much denser deployment of sensors so that landslides
can be better predicted and residents of affected areas can be warned sufficiently
early to evacuate.
Another possible application is monitoring air quality in underground coal
mines. Buildup of methane and carbon monoxide is a dangerous problem that can
lead to explosions or signify a fire in the mine, and the presence of these gasses
must be continually monitored. This application would necessitate a hybrid
architecture of underground open-air sensors and underground embedded sensors
deployed between the surface of the ground and the roof of the mine tunnel. This
would allow data from sensors in the mine to be quickly routed to surface stations
vertically, rather than through the long distances of the mine tunnels.
Another mining application would include an audio sensor (i.e., a powerful,
high-sensitivity and low-power microphone suitable to underground environments)
attached to the distributed underground sensor nodes to assist in location and
rescue of trapped miners. WUSN devices with microphones would also be useful
for other applications, such as studying the noises of underground animals in their
natural habitats.
Fig3.49: A WUSN deployed for monitoring a golf course. Underground sensors can be used to monitor soil salinity, water content, and temperature. Surface relays and sinks, which can be placed away from playing areas, are used to forward WUSN sensor data to a central receiving point (in this case, the golf course maintenance building).
34
Wireless Geophones
Fig3.50: Underground topology
Fig3.51: Hybrid topology
3.10 .Monitoring of Bridges:
Innovative scenario-based post-event response and crisis management, if
coordinated with pre-event measures, plays a crucial role in cost-effectively
mitigating the consequences of a sudden disaster. Given a scenario, the extent of
damage, casualty and disruption can be rapidly assessed by real time acquisition
of data from dense array of sensors, strategically placed advanced SCADA
devices, remote sensing, human sensors and possible other instrumentations,
through reliable and large capacity telecommunication capability. In the risk
assessment context, this exercise provides conditional estimation of economic
losses given the scenario, and somewhat simplistically put, the risk is then
35
Wireless Geophones
estimated as the sum of the products of conditional economic losses and
occurrence probability of each scenario over the number of scenarios envisioned
for a particular system, or by extension, for a combination of systems in principle.
From this and other points of view, real-time health monitoring technology is of
great importance to the broader study of societal risk associated with civil
infrastructure systems.
Fig3.53: Sensor and data acquisition system
Fig3.52: MEMS Sensors with Transmitters and Receiver
36
Wireless Geophones
Fig3.54: Bridge tested
Fig3.55: Instrumentation
Fig3.56: General schematic of the seismic monitoring system using Data acquisition Blocks
1 and 2 at the Piers 1 and 2, off-structure Central Recording System and wireless communication technology (Wireless IP Cloud)
Chapter 4
37
Wireless Geophones
The Future of Land Seismic
Imagining a World Without Cables: 4.1.
Since the end of World War II, oil & gas companies, equipment
manufacturers, and acquisition contractors have made continuous progress in
developing new and improved land seismic imaging tools and methods. While
these have improved exploration success rates and reduced the risks and costs of
fnding and developing hydrocarbons, our industry’s ability to continue the pace of
technology advancement is impeded by a single, highly restrictive constraint –
cables.
The vast majority of land acquisition systems rely on cable-based
architectures. Unfortunately, cables impact land imaging in several unfavorable
ways. Some of these impacts are operational in nature and are directly related to
the costs to deploy, repair and roll cable-based sensor grids in the field. Other
impacts adversely affect the acquired seismic image. These include an inability to
cost-effectively sample the subsurface with a very high coverage of single-point
sensors.
If we can eliminate cables for onshore acquisition, our industry stands poised
to unlock the Holy Grail of land seismic imaging – cost-effective, fully sampled, full-
wave surveys. The opportunities and challenges that exist onshore require a
fundamental rethink to land imaging. In this article, we explore the limitations of
today’s cable-based recording systems and hypothesize the benefts that might
result if a new generation of cableless imaging systems were available to the
industry.
4.2 .THE ONSHORE IMPERATIVE:
38
Wireless Geophones
In today’s search for onshore hydrocarbons, the challenges are both varied and
daunting. Some are related to imaging the target itself. Diffcult near-surface conditions,
complex structures, subtle stratigraphic traps, fractured reservoirs, and the need to
illuminate deeper targets all require operators to use the latest seismic tools and
methods, like three-component (3-C) digital sensors and processing to account for
anisotropy. Other challenges are operational. The general pressures to reduce acquisition
costs and field downtime, shorten cycle times, and mitigate HSE (Health, Safety and
Environmental) are signifcant.
Overcoming these challenges requires a revolution in land seismic imaging. The
linchpin to our industry’s collective success involves rethinking land recording platforms
so that cables disappear. If successful, we would enable a variety of additional imaging
benefts, including the ability to design customized, wide-azimuth, long-offset surveys as
well as to fully sample the entire seismic wavefeld using single-point 3-C sensors.
4.3 .CABLE-BASED ARCHITECTURE LIMITATIONS:
Cables serve multiple purposes, though the primary one is to transmit data on a
real-time basis from the sensors to the central recording system. While the ability to view
all shot records in real time may provide some comfort in quality-controlling the
acquisition process, the cost to provide this capability is signifcant in terms of operational
effciency, HSE and image quality. At least six major downsides result from the use of
cable-based recording systems.
Signifcant system weight. On today’s standard seismic survey, cables and
miscellaneous ground equipment supporting cable-based data transmission weigh 25 tons
or more. Because weight directly contributes to the costs of transporting gear and
mobilizing a seismic crew, the cables themselves increase the cost of acquisition. The
economic modeling work we have completed suggests that the excess weight introduced
by cables accounts for up to 20% of the operational cost of a “typical” survey onshore in
North America.
Manpower and logistics intensity. Deploying, rolling, troubleshooting and repairing a
cable-based system is a manpower-intensive operation. It is estimated that 25-50% of the
39
Wireless Geophones
individuals tasked with spread deploymentand retrieval are involved in cable-based
activity. Additionally, 50-75% of troubleshooting personnel are focused on cable problems.
This manpower intensity has other second-order cost impacts. For instance, as the
number of feld personnel goes up, the costs to train, mobilize, feed and shelter them goes
up as well.
Increased HSE risk. Every individual in the feld represents a potential health and
safety liability for both the contractor and the oil & gas company. So, cables also drive up
health and safety risks. Moreover, the process of moving heavy cables, especially in
mountainous areas or other diffcult terrain, is a hazardous operation.
Cable repair and maintenance downtime. In our recent work with seismic contractors,
we have discovered that up to 50% of operational time is spent on cable troubleshooting.
This has a direct impact on costs (one of the seismic crews we studied spent nearly US
$1,000 a day repairing cables). The even bigger impact is on productivity, with only 50%
of the time spent on actual acquisition. In effect, the cables can cause any seismic survey
to be only about half as effcient as it could be.
Complex network architectures. As the number of stations increase, there is simply
more opportunity for line failures. Troubleshooting often involves time-consuming,
sequential, trial-and-error approaches. And although modern cable systems with
redundant data paths improve reliability, it comes at the cost of adding even more cables.
Undersampling the subsurface. Cable-based architectures impose constraints on
how surveys are designed. For instance, sensors are required to be spaced in gridded
geometries at intervals that approximate the length of individual cable takeouts. This
prevents a survey from being tailored to unique surface, near surface and subsurface
challenges. Moreover, cable-based architectures make increasing station density
prohibitively costly. As shown in Figure4.1 the operational cost to acquire a fully sampled,
high station count survey increases with a cableless system, but not nearly at the rate as the
same survey acquired with cables.
40
Wireless Geophones
While many geophysicists we’ve interviewed see the ideal survey design as having
upwards of 50,000 stations, cable-based systems make this goal operationally
impractical. As a result, cables force compromises in fnal image quality.
Fig4.1: Typical acquisition cost of cable-based and cableless surveys
4.4. FULL SAMPLING VERSUS PARTIAL SAMPLING:
Contemporary 3-D seismic acquisition techniques are not meeting the industry’s
imperative need to rapidly and cost-effectively identify new drilling opportunities nor to
reduce prospect risk. With traditional cable-based recording systems, we simply cannot
cost-effectively deploy enough stations to fully sample the reflected seismic energy nor
properly image prospective targets at all depths in the geologic section.
With the advent of higher station count recording systems and improved acquisition
economics in the late 1990s, many basins were re-shot with wider azimuths and longer
offsets. Stations were often added, but line intervals were also spread out. Sometimes the
group interval was reduced, but this did not significantly help to improve the spatial
resolution of the primary objective. The problem of effectively imaging only a narrow time
window in the seismic section was not solved.
41
Wireless Geophones
Our analysis of velocity error profiles in many imaging settings indicates that errors
can often be substantial in deeper sections because there is not enough offset available
while, in the shallow section, errors can be highly variable since there often is
inconsistent offset coverage from bin to bin. Interpreting in the deep or shallow sections
using legacy data often means the geophysicist is relying on potentially poor-quality
amplitudes. Amplitudes showing up on the seismic data may have nothing to do with the
reservoir and everything to do with artifacts of how the data was acquired and
processed.
None of this addresses the other aspect of undersampling, which is that we have
not effectively reduced the bin size; therefore, subtle features in the reservoir are not
imaged any better than with the previous generation of seismic except for the noise
reduction higher fold provides and for the upside delivered by wide-azimuth attributes.
To properly image all horizons in this basin, the geophysicist needs a new
generation of seismic data with full-sampling of the subsurface. Delivering this requires
dramatically higher station counts and a land acquisition system that removes cable-
based spacing constraints.
4.5. EARLY ATTEMPTS TO ADDRESS THE CABLE CHALLENGE:
Over the past several decades, wireless technology has been applied to seismic
acquisition systems in different ways to accomplish different objectives. Unfortunately,
none have produced productivity breakthroughs that make high station count surveys
practical.
There are three radio implementations of modern land acquisition systems. The
first uses multiple receiver channels which are connected to a common field acquisition
unit. Each field acquisition unit utilizes radio telemetry to communicate to a recording
truck. The radio link provides command and control from the central station to the field
units, while the data is stored locally.
The second utilizes point-to-point radio connections to extend cable telemetry
spreads, ultimately connecting all stations to a common central recorder. This type of
implementation has been used to extend cable-based systems where environmental
conditions, permitting issues or other obstructions restrict access.
42
Wireless Geophones
A third implementation of radio telemetry involves multi-channel acquisition units
that use wireless telemetry to connect to a central node. The nodes interconnect by
cable to each other and to the central station, creating a combination radio/cable
telemetry system. Depending on the type of wireless protocol that is implemented, there
can be severe bandwidth limitations, limiting its practical use in large-scale acquisition
projects.
In each of the above implementations, a significant amount of cable remains both
for telemetry and for connecting sensors to the acquisition units. The potential benefit
from incorporating wireless is minimized unless a significant reduction in the amount of
cable can be achieved.
4.6. RE-THINKING THE IDEAL LAND ACQUISITION SYSTEM:
Next-generation acquisition systems should be able to leverage numerous
advances in wireless transmission, power and data storage from other industries.
Figure4.2 shows the form such a system might take. Each data acquisition station
would have an independent, bi-directional communication path to the recording truck.
There would be no telemetry cables interconnecting stations, allowing receivers to be
deployed without the constraints of a grid infrastructure.
Fig4.2: An example layout of the ideal land data acquisition system
43
Wireless Geophones
In the diagram, a single data acquisition station is connected to a single 3-C digital
MEMS sensor. The digital MEMS sensors would measure true 3-D particle motion and
record the full seismic wavefield with unsurpassed vector fidelity. As single-point
receivers, they would be less susceptible to the intra-array statics problems of
geophones and record the broadest bandwidth that the Earth returns. In addition, they
would allow additional cables associated with receiver arrays to be removed from the
system.
Data recording would occur at the station level, with local storage in solid state
memory. Intelligent QC features would automatically notify the operator of trace
problems and when the condition of feld electronics exceeds user-defined limits. The
QC system would send back key attributes of selected traces to ensure the spread was
functioning as planned. By eliminating the need to transmit all data in nearly real time,
power requirements and bandwidth constraints are greatly reduced.
Each field acquisition unit would operate autonomously, thereby eliminating single
points of failure that are present in cable-based systems and allowing stations to be
undisturbed once deployed until they are moved to the next stage of the survey. The field
acquisition units would also have embedded GPS (global positioning system) features to
determine their position with a high degree of accuracy and with a reduced need for
surveying expenditures and cycle time.
Lastly, this next-generation land acquisition system would be supported by the
latest in command and control software. Key features would include the ability to rapidly
determine the actual spread configuration vs. the original survey plan, testing availability
of all the stations in the spread, advanced troubleshooting and QC protocols, and the
ability to record “processing-ready” seismic data without geometry and header errors.
4.7. POTENTIAL SYSTEM BENEFITS
This ideal land system could deliver significant benefits to the oil & gas companies
and contractors, including:
• Improved seismic image quality.
• Increased operational productivity.
• Enhanced HSE performance.
44
Wireless Geophones
Seismic image quality would increase since geophysicists would be able to
randomize station placement and customize survey designs for specific subsurface
imaging objectives, including imaging shallow, intermediate and deep reservoir targets
simultaneously. Station density would be increased dramatically, improving spatial
resolution and fold, and reducing effective bin size. In addition, surveys could be more
cost-effectively designed for wide-azimuth, long-offset acquisition to help with AVO
analysis, cope with anisotropy and model reservoir fracture networks.
Image quality could be further enhanced if 3-C digital sensors were used to
acquire a broader frequency spectrum of refected seismic energy, record both
compressional (P) wave and shear (S) wave data, and mitigate intra-array statics issues
associated with traditional geophone receiver arrays.
A key beneft of a cableless architecture is operational productivity. Once the cables
are gone, the weight of the entire system goes down dramatically. Our best estimate is
that the weight could be reduced by 80%. In addition, eliminating the cables would mean
greater reliability of the entire land acquisition network and less downtime for
troubleshooting and cable repair. Detailed models that we have developed of the
conventional operational process suggest that a typical 3,000-station survey could be
performed at approximately 80-85% of the operational cost if an ideal cableless system
was used. The improvements with a cableless system are even more dramatic as
station counts increase. Compared to conventional recording systems, a cableless
system could acquire 12,500 stations worth of data at approximately 50-60% of the
operational cost.
Finally, HSE performance should improve. Once the cables are gone, we would
expect fewer incidents during deployment. Total weight is substantially decreased. The
need to move heavy cables is reduced. And fewer personnel are needed to troubleshoot
and repair cables. In addition, less acquisition equipment results in a reduced
environmental footprint. Cable lines wouldn’t need to be cut, nor would surface ground
cover be subject to cable deployment operations. Lastly, the number of support vehicles
could possibly be reduced, resulting in fewer emissions, fuel spills and collateral
damage in the areas adjacent to the acquisition operations.
45
Wireless Geophones
4.8. Other applications:
The seismic method is of course not confined to the exploration for hydrocarbons.
The seismic technique has long been used in the geotechnical and engineering
industries to study the near subsurface. To date, these seismic reflection and refraction
surveys have been conducted using specialist small systems rather than large-scale
seismic reflection instruments. Users wishing to conduct both types of survey currently
require two systems.
In order that users can use a single system for both geotechnical/engineering and
large-scale reflection surveys, Vibtech has launched the Min-it System, which is based
upon a hand-held CCU developed for the NASA evaluations. This scaleable system
enables existing users to conduct small channel surveys using their it System and for
new users to have a low barrier entry system which can be expanded to a full reflection
system without having to purchase a new system.
Fig4.3: NASA tests it System in Mars analogue dry valley in Antarctica
Fig4.4: Vibtech has carried out tests with NASA in the USA and in Antarctica
46
Wireless Geophones
Fig4.5: System stand-al
one RAU Fig4.6: Acquisition in the Australian bush
Fig4.7: The Min-it System uses a highly portable cable-free CCU
Fig4.8: Unite with integrated antennae and battery
Chapter 5Advantages & disadvantages of wireless geophones
47
Wireless Geophones
5.1 Advantages:
5.1.1 .Going Wireless
One of the biggest technological shifts is moving to high-channel count wireless
platforms that eliminate cables and hardwired connectors while significantly in-
creasing data density and resolution.
Wireless will be in high demand, because both operators and contractors will see
the benefits,” he predicts.
Wireless systems dramatically decrease the amount of people and equipment
on location, environmental impact, system weight, exposure to accidents, etc. In fact,
there are so many technical, operational and logistical benefits that it is difficult to
see significant adoption barriers to cableless land acquisition systems.
We anticipate high channel count cableless recording systems will enable
dramatic gains in image quality and productivit over traditional systems, Although we
anticipate broad acceptance of these systems, we expect to deploy them in parts of
the world with sensitive acquisition conditions.
A full-wave seismic recording platform that integrates the latest GPS, data
storage and power technologies into a cableless architecture that supports high-station
counts for enhanced spatial sampling.
FireFly will record data using three-component, full-wave VectorSeis® sensors
that are designed to measure true particle motion as a three-dimensional vector
rather than along a single dimension, as a conventional geophone does.
Fig5.1: The FireFly™ from I/O is a full-wave seismic recording platform that integrates the latest GPS, WiFi, data storage and power technologies into a ca-bleless architecture that supports high-station counts for enhanced spatial sampling. FireFly records data using three-component, full-wave VectorSeis® sensors designed to measure true particle motion as a three-dimensional vector.
Seismic energy propagates as a
three-dimensional wavefront. In the past, most of the information embedded in the
48
Wireless Geophones
wave-field was simply ignored, but measuring in three dimensions allows us to
record broadband data that is far richer in its spectral content. Higher-bandwidth data
deliver a higher-resolution image. By utilizing all the data in the wavefield, we can
better characterize the target reservoirs, including mapping lithology, fluid content
and fracture patterns. This is a major step forward.
We believe FireFly is a natural progression to obtaining high-resolution images,
since it supports the cost-effective recording of full-wave data with greater density,
FireFly uses flash memory without the need to move seismic data across cables or a
radio network. Flash memory systems are simple and easily scalable to tens of
thousands of channels without the complexity of keeping a network of tens of
thousands of geophones on a wire up all the time. This is a significant advantage over
cable systems.
The ability to record multicomponent data.
Fast And Flexible:
The system eases logistical and maintenance requirements, provides fast
deployment, reduces crew size, and lessens environmental and cultural footprints in
plays such as the Barnett Shale in the Fort Worth Basin.
The biggest advantage in the Barnett Shale is flexibility. The ability to move
around quickly and get in among subdivisions is key, that is our forte. We are the
niche specialty 3-D seismic shooter in the Barnett Shale play. The speed of
deployment, flexibility, scalability, fast data transfer and smaller crews add to
incredible flexibility and efficiency. Plus, we have the ability to see the system on
screen in a central control unit(CCU) to make sure everything is working properly and
QC data during acquisition. We can even change design configurations on the fly.
The scalability also allows denser channel configurations for cost-effectively
sampling of greater seismic frequency.
By working with the flexibility the system offers, we hope contractors and
operators can start thinking about data quality rather than survey logistics,” he
remarks. “It is ideal for high-channel count recording.
Increased Productivity:
49
Wireless Geophones
Ultra™ is a distributed cableless platform developed by Ascend Geo that uses
1.5-pound/channel continuous recording units equipped with GPS timing and pro-
grammable radio frequency receivers that plug into a dedicated offloading and
recharging rack.
It is about performance efficiencies, designed to increase crew productivity
and profitability through dramatically reduced weight and equipment requirements,
simplified operations, and fast and flexible deployment.
The reduced size and weight make the self-contained field units easy to
deploy in difficult environments. “The Ultra G4 system will record three channels
continuously for up to 80 hours, making it ideal for multicomponent reservoir mon-
itoring and well fracturing applications using both active and passive seismic ac-
quisition.
Fig5.2: Its IT 3-D recording system in 2002, followed up by the UnITe Cellular Seismic™ system this year based on the same wireless platform. IT is configured with a four-channel remote acquisition unit and hybrid radio/cable telemetry to create a data structure using miniature cell phone tower-like repeaters to transmit to a central control unit within the shot cycle, while UnITe uses a GPS-enabled single-channel base unit and real-time radio telemetry to eliminate cables.
Fig5.3: The Ultra™ distributed cableless platform developed by Ascend Geo uses this 1.5-pound/chan-nel continuous recording unit that is equipped with GPS timing and programmable radio frequency receivers that plug into a
dedicated offloading and recharging rack.
50
Wireless Geophones
Cost-Effective Option:
The system uses analog geophones, with the data signal digitized at the box
the recording truck. “For our customers’ bread and butter land geophysical appli-
cations, the newest and most advanced analog-to-digital ARIES system is the most
cost-effective option.
In fact, we can acquire 3-D today using ARIES at a lower delivered price than in
the past because the system is so user friendly and so much faster, especially in
shallower gas plays.
Improved cost efficiencies and operational productivity give the contractor
better margins and the operator lower costs. “The operator gets higher productivity
with ARIES, which translates into less cost per square mile of data acquired.
We are simply able to get more shots in a day using this system.
5.1.2 .Embedded Wireless Networked Sensing &Actuation:
– “Communication” between people and their physical environment.
– Allow users to query, sense, and manipulate the state of the physical world.
5.1.3. Technology enablers:
– Cheap, ubiquitous, high-performance, low-power embedded processing.
e.g. Low-power processor cores.
– Cheap, ubiquitous (wireless) networking.
e.g. Single-chip CMOS radios.
– Cheap, ubiquitous, high-performance sensors and actuators.
e.g. MEMS device.
51
Wireless Geophones
Fig5.4: “The N
etwork is the Sensor”
-Distributed and large-scale, connected to other networks such as like the Internet,But
different from previous networks.
– Physical instead of virtual.
– Resource constrained.
– Real-time control loops instead of interactive human loop.
5.1.4. State-of-the-art Wireless System and Sensors:
- Licence exempt RF transmission frequency.
- Low noise and high sensitivity.
- Small size and light weight for excellent portability.
- Low temperature rated sensor cable.
- Durable construction.
- Optional high-power licence band available.
- Signal-to-noise ratio equivalent to digital radio system without the cost.
5.1.5 .Challenges:
- Detection of damage (cracks) in structures.
- Analysis of stress histories for damage prediction.
- Applicable not just to buildings but else to Bridges, aircraft.
52
Wireless Geophones
5.1.6 .Future technology trends:
Power reduction
- State-of-the art electronics
Lower costs
- Wireless communication & data storage
- System in Package
Integrated GPS
Increased sensitivity
- Deeper, higher fidelity data
Smaller size
- Multilayer packaging
- Embedded electronics
Fig5.5: Wireless technology
5.1.7 .Expansion into new energy applications:
- Reservoir monitoring
- Tracking movement of oil during extraction
- Optimal drilling
- Increased extraction efficiency
- More sure auditing of ‘reserves’
- Directional drilling
- Inertial guidance of drill head
- Vibration & position sensing Fig5.6: Energy expansion
■ Health Monitoring of drill head
■ Pipe line monitoring (PIGs)
■ Pipe line integrity monitoring
53
Wireless Geophones
5.1.8. Overview of Seismic geophones:
‘Moving coil’ inductive geophones are a mature year old technology.
Geophones must be small, rugged, cost-effective, and high performance.
MEMS-based solution offers:
– Full wave: 3D imaging + 3 vector
- Pressure (z) + 2 shear waves
– Low-frequency response (<6Hz)
- Higher fidelity image
– Direct digital output
- Better signal integrity
– Auto tilt correction
- Easy deployment especially underwater
Fig5.7: Conventional coil-based geophones Fig5.8: VectorSeis® multi component
digital sensor
54
Wireless Geophones
5.1.9 .Structure of Oil & Gas Energy Market
• Exploration
– Improved seismic imaging for more reliable hydrocarbon identification and recovery.
– Reduced environmental impact from operations.
– Improved operational capability and efficiency, especially in remote or deep water
applications.
• Extraction & Recovery
– 4D reservoir monitoring during extraction.
– Improved down-hole sensing.
– Health Usuage Monitoring Systems.
Fig9: Extraction&Recovery
• Refining / Transport
Fig5.9: Extraction & Recovery
Fig5.10: Exploration site
5.2. Disadvantages:
1- Limited battery energy.
2- Limited wireless bandwidth.
3- Limited memory and communication capabilities.
4- Demanding deployment environments.
- Susceptible to physical attack, e.g., node capture.
- Posing new security problems.
55
Wireless Geophones
Conclusion
The flexibility now offered by cable free systems offers explo-rationists
unlimited scope to deploy sensors in an unrestrained manner, without the
need to consider the constraints of the traditional seismic grid. These
systems completely eliminate cables without compromising the real-time
recording of the data. This also brings a real advance in the logistics of land
and transition zone surveys, allowing system users to concentrate on data
quality, not logistics, whilst enjoying enormous HSE benefits, thus
improving the future prospects of our industry.
56
Wireless Geophones
REFERENCES
A. Sheth, K. Tejaswi, P. Mehta, C. Parekh, R. Bansal, S. Merchant, T.
Singh, U.B. Desai, C.A. Thekkath, K. Toyama, Senslide, 2005, a
sensor network based landslide prediction system, in:
SenSys’05: Proceedings of the 3rd international conference on
embedded networked sensor systems, pp. 280–281.
B. Chouet et al.,2003, “Source mechanisms of explosions at Strom-boli
Volcano, Italy, determined from moment-tensor inversions of very-
long-period data,” J. Geophys. Res., vol. 108, no. B7, p. 2331.
C. Dietel et al.,1989, “Data summary for dense GEOS array observations of
seismic activity associated with magma transport at Kilauea Volcano,
Hawaii,” U.S. Geological Survey, Tech. Rep. 89-113.
Chung, H-C, Enomoto, T. and Shinozuka, M., 2003, “MEMS-type
accelerometers and wireless communication for structural
monitoring”, the 2nd MIT Conferences on Fluid and Solid
Mechanics, Cambridge, MA, June 17-20,
http://shino8.eng.uci.edu/MEMS_ppt Feng, M. Q., and Bahng, E. Y.
(1999).
G. Werner-Allen, K. Lorincz, M. Welsh, O. Marcillo, J. Johnson, M. Ruiz,
J. Lees,2006, Deploying a wireless sensor network on an active
volcano.
Henry david Thoreau, , (1817-1862)."Leak Finder RT (PC Based Leak Noise
Correlator)", www.echologics.com
57
Wireless Geophones
Jason Hill, Robert Szewczyk, Alec Woo, Seth Hollar, David Culler, and
Kristofer Pister,2000, System architecture directions for networked
sensors. In ASPLOS.
J. Benz et al.,1996, “Three-dimensional P and S wave velocity structure of
Redoubt Volcano, Alaska,” J. Geophys. Res., vol. 101, pp. 8111–8128.
Jim Hollis and Marty Williams and Scott Hoenmans, June 2006. " The Future of
Land Seismic.
J. Lees , R. Crosson,1989, “Tomographic inversion for three-dimensional
velocity structure at Mount St. Helens using earthquake data,” J.
Geophys. Res., vol. 94, pp. 5716–5728.
J. Neuberg, R. Luckett, M. Ripepe, and T. Braun,1994,“Highlights from
a seismic broadband array on Stromboli volcano,” Geo-phys.
Res. Lett., vol. 21, no. 9, pp. 749–752.
John Flavell Smith, February 2006." How a new cable-less land seismic survey
acquisition system was born”.
K. Martinez, R. Ong, J. Hart, Glacsweb, 2004, a sensor network for
hostile environments.
Moteiv, Inc., Nov. 2000, , J. Hill, R. Szewczyk, A. Woo, S. Hollar, D. E. Culler,
and K. S. J. Pister, “System architecture directions for networked
sensors,” in Proc. the 9th International Conference on Architectural
Support for Programming Languages and Operating Systems, Boston,
MA, USA, pp. 93–104, http://www.moteiv.com .
58
Wireless Geophones
Robert, Szewczyk, J. Polastre, A. Mainwaring, D. Culler, January 2004,
“Lessons from a sensor network expedition,” in Proc. 1st European
Workshop on Wireless Sensor Networks (EWSN ’04).
S. McNutt,1996, “Seismic monitoring and eruption forecasting of volcanoes:
A review of the state of the art and case histories,” in Monitoring and
Mitigation of Volcano Hazards, Scarpa and Tilling, Eds. Springer-Verlag
Berlin Heidelberg, pp. 99– 146.
S. Moran, J. Lees, and S. Malone,1999, “P wave crustal velocity structure in
the greater Mount Rainier area from local earthquake tomography,” J.
Geophys. Res., vol. 104, no. B5, pp. 10 775–10 786.
T. Dubaniewicz, J. Chilton, H. Dobroski,1991, Fiber optics for
atmospheric mine monitoring, in: Industry Applications
Society Annual Meeting, pp. 1243–1249.
Tim Beims, JULY 2006. "THE AMERICAN OIL 8.GAS REPORTER(Array Of
New Technologies,Improved Business Conditions Transforming Land
Seismic)".
WEB SITES
http://cens.ucla.edu/
http://www.cens.ucla.edu
www.echologics.com
http://enl.usc.edu/
http://www.moteiv.com
http://nesl.ee.ucla.edu
http://shino8.eng.uci.edu/MEMS_ppt Feng
http://www.wirelessSeismic.com
59
Wireless Geophones
61