3D BHR Information Syllabus
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Transcript of 3D BHR Information Syllabus
8/3/2019 3D BHR Information Syllabus
http://slidepdf.com/reader/full/3d-bhr-information-syllabus 1/21
T&A Survey B.V. Dynamostraat 481014 BK Amsterdam, The NetherlandsT/F: +31 20 6651368/[email protected] - www.ta-survey.nlU.S. agent: [email protected] - T: +1 720 261 4775
Product Information
System Configuration
Applications
Survey Data Sheets
Operational Information
33DD BBOOR R EEHHOOLLEE R R AADDAAR R
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3D Borehole Radar 2
Contents
3D Borehole Radar: A Breakthrough in Ground Penetrating Radar Survey ..................... 3
System Configuration ............................................................................................. 4
Application: Reservoir Characterization .................................................................... 6
Application: Mining Industry ................................................................................... 7
Application: Geothermal Energy Detection ................................................................ 8
Application: Geotechnical Survey ............................................................................. 9
Application: Determination of Jet Grout Column Diameter ........................................ 10
Application: Tunnel Track Exploration ..................................................................... 11
Application: Detection of Unexploded Ordnance (UXO) ............................................. 12Data Sheet 1: Water Test Case ............................................................................. 13
Data Sheet 2: Soil Test Case ................................................................................. 15
Data Sheet 3: Sheet Piling Wall ............................................................................. 17
Data Sheet 4: Object Classification ........................................................................ 18
Operational Information ....................................................................................... 19
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3D Borehole Radar 3
3D Borehole Radar: A Breakthrough in Ground
Penetrating Radar SurveyThe 3D Borehole Radar (3D BHR) is a geophysical technique for high-resolution 3D
mapping of borehole surroundings. It’ s a breakthrough technology with very high
accuracy as it allows, for the first time, radar survey at great depths and in difficult
circumstances. Applied in a single borehole, the 3D BHR combines all the advantages of
ground penetrating radar tools in one:
Directional information: 3D positioning of detected objects.
High-resolution data: exact positioning of detected objects.
Penetration range up to 15 meters.
T&A is responsible for the design, engineering, operating and processing software and
testing. Subcontractors TNO-FEL (Physical Electronic Laboratory) and NLR (Dutch
National Aerospace Laboratory) developed and built the mechanical and electronic
components of the down hole tool.
How does it work?
The 3D BHR emits radar waves into the subsurface by means of a transmitter antenna,
situated in the borehole. When a wave meets a contrast in material parameters (an
object or geological boundary), part of it is reflected and received by the receiver
antenna, situated in the same borehole. A continuous 3D image of the subsurface is
obtained by rotating the antenna system and moving the 3D Borehole Radar vertically in
the borehole.
Applications of the 3D
Borehole Radar:
• Oil and gas reservoir
characterization• Mining• Geothermal energy
detection• Geotechnical survey • Determination of jet
grout column diameter • Tunnel track
exploration• Object detection
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3D Borehole Radar 4
System Configuration
The 3D Borehole Radar system is pulled or pushed
through a non-metallic cased and water-filled borehole.
It consists of four main parts:
1. Positioning unit
The positioning unit contains a control unit, a motor to
rotate the radar unit and several sensors to determine
the position of the system in the borehole. The sensors
consist of magnetometers, accelerometers, FOG
gyroscopes sensors and an angle encoder. This unit is
the outer shell of the complete 3D BHR system as it has
a specially designed housing for the enclosed radar
unit, protecting it from mechanical and environmentalborehole conditions.
2. Radar unit
The radar unit is
enclosed and rotates inside the 3D BHR system. It
contains two directional antennas. The reflectors behind
the antennas provide the directional sensitivity and the
energy bundling of the antenna.
The control unit, transmitter electronics and receiver
electronics are also situated in the radar unit. The
recorded analogue data is digitized down hole by a veryfast A/D converter.
3. Cable
The 3D BHR is connected to the surface by a cable which
supplies power and allows high-speed data transmission.
At the surface, the data is stored and can then be
processed to provide a 3D image of the borehole
surroundings.
4. Software
The 3D BHR is supplied with custom designed operating
and processing software, called Dafos, which can also be
used by other geophysical equipment containing multiple
sensors.
Accessories
Depending on the application, the following accessories
are required to operate the 3D BHR:
Tripod
Winch
Surface equipment (DC power supply, computerand housing)
15.9 cm
A specially designed connection between the positioning unit and radar unit allows high-speed data
communication and power supply during rotation.
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3D Borehole Radar 5
Technical Specifications
Length 4.2 meters
Diameter 16 centimeters
Weight 250 kgSource signal impulse (up to 850 V)
Centre frequency 100 MHz
Sample frequency 600 MHz
Bandwidth 100 MHz
Dynamic range between
transmitter/receiver
120 dB
Avg. penetration 5 – 15 meters
Avg. angle accuracy 1– 30 degrees
Avg. axial accuracy 1 – 30 centimeters
Conductivity range 20 mS/m @ 100MHz and lowerAntenna set-up bistatic (two antennas)
Antenna type shielded dipole (directional)
Temperature rage 0 C - 60 C
Max. pressure 15 bar (150 meters in vertical water-
filled borehole)
Avg. power consumption 60 Watts
Material RVS 316 (non-magnetic) and
composite materials
T&A operates on a policy of continuous product improvement. Future series of the 3D
BHR will be smaller and possess extended temperature and pressure ranges.
Versions
The 3D BHR is available in different versions, from a full-service modular geophysical tool
to a stand-alone radar module.
3D BHR Omni To be used in cased boreholes (in every position)
Parts: positioning and radar unit, housing and cable
Length: 4.2 meters, Weight: 250 kg
Extras: centralizers for open boreholes3D BHR Vertical Only to be used in vertical boreholes.
Parts: Integrated positioning and radar unit (more robust)
Length: 3.2 meters, Weight: 200 kg
Parts: 1 (integrated rotor/stator and cable)
3D BHR Probe A system of a separate radar unit (with embedded software)
To be integrated in other equipment
Length: 1.50 meters, Weight: 65 kg
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3D Borehole Radar 6
Application: Reservoir Characterization
The 3D Borehole Radar technology is a
promising addition to existing loggingtechniques in oil and gas exploration
and production.
Main applications
• Logging tool: In an exploration environment, the 3D BHR can be used as an ElectricPropagation Tool to detect the electrical properties of the formation.
• Geosteering: In thin pay zones, where it is crucial to follow a specific drilling path,the 3D BHR can provide the information to steer the drill bit. The distance to the topand bottom of the reservoir can also be measured.
• Monitoring: In production phases, where water or steam drives are used, the 3DBHR is well suited to monitor the movement of the steam/water front in 3D.
Penetration rangeThe penetration range of the 3D Borehole Radar system in reservoirs is 5 to 10 meters,
based on average reservoir properties (see table). Penetration range increases with
increasing resistivity. In ideal situations, a penetration range of 15 meters can be
obtained.
Reservoir Permittivity Resistivity [Ohm-m]
Oil-bearing 10 50
Water-bearing 20 2
T = 120º C and p = 300,000 hPa
Main advantages
• A more complete picture of the reservoir. The 3D BHR can detect the position
of the oil-water contact zone in reservoirs because, between the two layers,the electromagnetic impedance contrast is higher than the contrast in acoustic
impedance.• A detailed 3D image of the borehole surroundings is achieved by using high
frequency, high resolution electro-magnetic waves resulting in unprecedented penetration depth.
• Only one borehole is needed in SAGD. In the drilling stage, 3D BHR providesan accurate relative position of the two wells from only one borehole, without needing access to the producer well.
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3D Borehole Radar 7
Application: Mining Industry
The mining industry is all about knowing what's going on in the underground. Without
subsurface testing, it is impossible to locate an ore body, to define exploitable reserves
or to design a mine plan.
Geophysical tools used in the oil industry
(such as 3D seismic techniques) have been
adapted and applied in mining industry,
resulting in great benefits for the exploration
of mines. However useful these tools may be,
none of them can compete with the 3D
Borehole Radar’s capacity to reveal a high-
resolution contrast between different
materials in the underground.
Main applications
The 3D Borehole Radar (3D BHR) provides a
useful addition to existing geophysicaltechniques in recognizing geology for mining. Itcan be applied in both exploration andproduction phases.
In an exploration environment, the 3D BoreholeRadar can be applied in horizontal and vertical
drillings into e.g. coal, ore and salt bodies.
Depending on the resistivity of the formation,
the signals penetrate up to 20 meters aroundthe borehole. It can be used for detecting:
• Lateral and vertical inhomogeneities
• Cavities • Faults • Fracture zones: length, dip and distance
Other possible applications are:
• Locating an ore body
• Defining exploitable reserves • Designing a mine plan • Detecting pot holes
Main advantages
In an exploration environment:
• High-resolution data:transitions can be detected with great accuracy.
• Directional data: a 3D image
of geological situation around the borehole is obtained
• High penetration range up to20 meters.
In a production environment:
• monitoring and locating potential mining problems.
• finding zones of potential danger due to caving and
shock bumps.• finding hazardous structures
like water bearing fissures
ahead of planned minedevelopment.
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3D Borehole Radar 8
Application: Geothermal Energy Detection
Due to increasing scarcity in oil and gas resources, energy
costs are rising and so is the demand for alternative
resources. Deep geothermal energy is an alternative
energy source with great advantages, which could become
more and more important.
Geothermal Energy is generated by pumping up deep
groundwater from a depth of 1.5 to 4.0 kilometers with a
temperature of 70 to 100 degrees Celsius, in order to heat
houses and/or horticulture greenhouses. After releasing its
heat, the groundwater is pumped back into the
groundwater reservoir. This energy source is almost
inexhaustible.
Mapping deep groundwater reservoirs
In order for a geothermal project to be successful, it is
important to study the geological structure and
stratigraphy of the subsurface of the planned location. The
research target of a geological study is to map deep
groundwater reservoirs. The results of the study include a
detailed description of, for example, the geometry and
other properties of the reservoir. The completed study is
comprised with other drillings, wire line logs and cores.
Main applications
The groundwater reservoir needs to be estimated very accurately prior to making the
decision whether a geothermal system can be successfully and economically exploited.
Additional information, next to the wire line logs, can be obtained by 3D Borehole radar
measurements. 3D Borehole Radar data can be used to delineate the location and
dimensions of the reservoir and
to determine the presence of
impermeable cap rock on top of
the groundwater reservoir. Faults
and fractures can be detected,
including dip measurements.
Main advantages
• 3D BHR can be applied in vertical and horizontal drillings into the formationto detect transitions between different rock types and to detect and delineate
cavities, faults and fractures.• 3D BHR provides 3D positioning of
interesting features.• 3D BHR provides high accuracy data.• 3D BHR provides a high penetration
range compared to other geophysical survey methods.
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3D Borehole Radar 9
Application: Geotechnical Survey
Measurement of underground structures (concrete piles, sheet piles and foundations) are
important in order to verify their exact location and dimensions and to check possible
damage or degradation. After many years, the
exact location of structures is often unknown
and needs to be determined again.
Measurement of underground structures with
conventional surface measurement techniques
are operationally difficult and tend to be
unreliable for several reasons:
• The structures are positioned too deep for
conventional measuring.• The current surface techniques prevents
conducting overburden.
• The current techniques do not provide
enough resolution.
• The existing above ground structures
makes measuring difficult.
Steered Drilling
Steered drilling is a new technique for laying underground cables. As an alternative to
digging trenches, it is a cost-effective method that causes fewer disturbances to the
environment. As the number of cables and other objects in the shallow subsurface
increases, there is more need for exploration of the drilling path. As an alternative to
measurements from the surface, the high-resolution directional borehole radar can be
integrated in the drilling process to explore the drilling path in advance.
Main advantages
• The radar is brought down to the locationof the object in the subsurface.
• No overburden effects.• Much higher resolution with the acquired
images.
• No site constraints with surface structuresas boreholes can be drilled at any angle or even horizontally.
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3D Borehole Radar 10
Application: Determination of Jet Grout Column Diameter
Measuring jet grout columns
Concrete foundations are used for an increasing number of underground infrastructure
projects. Various jet grout injections consolidate the soil and decrease the risks of
subsidence from large surface structures.
Jet grout columns vary in diameter, depending upon the injection pressure and the soil
conditions. The diameter is an important property that should be quantified, especially
when several grout columns are connected to form an underground concrete floor.
Until now, no proven or tested techniques existed to calculate the diameter of
injected columns. Until now, it has been almost impossible to conclude whether the
jetgrout foundations provide enough stability, especially in underpinning applications.
Main applications
By integrating the 3D Borehole
Radar technology into the
injection lance, the diameter of
the column can be determined
on site. The boundary between
grout column and hosting
medium is a sharp edge and,
therefore, a good
reflector for incident radar
waves.
There are two ways to apply the 3D BHR in the jet grouting process. In both cases, the
diameter can be measured very precisely because of the resolution of the 3D Borehole
Radar method:
Integrating the 3D BHR in the jet grouting system. During construction of
the column, the radar is located just below the injection point and the grout
column diameter is measured from within the column. The injection pressure can
be adjusted while the column is being made.
Drilling a borehole near the grout
column allows the 3D BHR to measure the
distance from this borehole to the edge of
the column.
Main advantages
The diameter of a jet grout
column can be measured
very precisely, because of the resolution of the 3DBorehole Radar method.
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3D Borehole Radar 11
Application: Tunnel Track Exploration
It is essential that any tunnel project starts with a comprehensive investigation of ground
conditions. In addition, encountering unforeseen ground conditions, objects or anomalies
can be costly in terms of time and materials. The 3D Borehole Radar technique
continuously gathers detailed information about obstacles and geological transition
zones.
Main applications
The 3D BHR is positioned in a
horizontal borehole with a diameter
of about 20 centimeters, and drilled
along the planned trajectory. It
measures the complete surroundings
of the borehole. Rotating 360°, itgathers and processes data from all
angles with special proprietary
software. After processing, the raw
ground penetrating radar data is
combined with simultaneously
collected positioning data, providing
meaningful operating data.
T&A is the first geophysical survey company to successfully integrate radar electronics
into a geophysical tool. It is capable of surveying the surrounding soil construction and
simultaneously determining the exact position of objects from within one borehole.
Main advantages
• Better analysis: The complete tunnel track can be explored in advance,
identifying the exact location of fault zones.• More efficient use of TBM’s: As more relevant information is available
during drilling, it allows for more precise decision-making.• Substantial technical and financial risks can be avoided.• Enhanced safety during tunnel construction.
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3D Borehole Radar 12
Application: Detection of Unexploded Ordnance (UXO)
Unexploded ordnance, such as aircraft bombs and
artillery shells from for example World War II still
can be found in the subsurface throughout Europe.
These explosives are especially dangerous when
touched or moved during digging, dredging or piling
activities.
Detection from the surface is often not feasible,
since the explosives are buried too deep. When a
bomb dropped from an airplane doesn't explode
touching the surface, it penetrates the upper soft
peat and clay layer and stops at the first stable
sand layer. In the Netherlands, this layer can belocated at a depth of more than 10 meters below
the surface. Due to resolution problems, detection
from the surface is not an option in these cases.
Measurements from a borehole are needed to solve
the problem. Traditionally, these measurements are
done using a magnetometer.
The main drawbacks of the magnetometer method are:
Limited penetration range of 1 to 2 meters.
The measurements contain no directional information.
Main applications
For 3D Borehole Radar measurements, a
borehole is drilled in a safe zone, just
outside the investigation area. When it's
determined that the area around this
borehole is safe, the next measurement is
done in an adjacent position closer to the
area of investigation. This way the whole
area is searched for deep explosives.
Unexploded bombs with a large metal
content show a strong electrical contrast
with the surrounding soil. Therefore, these
objects are very good reflectors of radar
waves.
Main advantages
High penetration range of 5-15 metres reduces the number of boreholes considerably. Even
with a penetration range of only 5 meters, the number of required boreholes is reduced by
a factor of 25 compared to themagnetometer method.
Very high location accuracy dueto the nature of the radar method and the directional radiation pattern that istransmitted by the 3D BHR.
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3D Borehole Radar 13
Data Sheet 1: Water Test Case
Objective and circumstances
The first measurements in water were carried out to calibrate the
3D Borehole Radar. These measurements took place in a water
basin at the TNO Physics and Electronics Laboratory. An iron gas
cylinder was hung next to the 3D BHR at a distance of 1.5
meters from the 3D BHR, at a depth of 2 meters below water
level and at an angle of 270º.
Radiation pattern
The 3D BHR was positioned vertically in the water basin. This
way, the transmitted signal travels along a horizontal plane, as
shown in the figure below. The radar unit of the 3D BHR rotates,
so it is a directional device. This means that the signal that istransmitted has an angular movement in the horizontal plane. In
both vertical and angular (horizontal) direction, the signal is not
transmitted in a single direction but in a bundle of directions.
This bundle has a width of 10-15º in vertical direction and a
width of 70-90º in angular direction. The two bundles combined
form what we call a detection cone. The energy density of the
transmitted signal is strongest in the middle of the cone. Because
of this, in measured data, objects are visible within a certain
angle and depth range and not at one single angle/depth
position. Note also that, because a separate transmitting and
receiving antenna are used, the detection cone starts at a smallradial distance from the antennas.
Detection cone
Detected object
70-90°
Horizontal plane
Transmitting antenna
10-15°
Detection cone
Receiving antenna
Rays that hit thereceiver
Detected object
Side view Top view
Rays that miss thereceiver
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3D Borehole Radar 14
Measurement results
The figure to the left shows a
vertical angle scan of the
gas cylinder measurement.All data in a vertical angle
scan have the same
measurement angle. The x-
axis represents the radial
distance from the 3D BHR
and the y-axis the depth
below water surface. The
radial distance is converted
from measurement time,
using the relative permittivity
of water.
The figure shows the reflection of the cylinder at a depth of 2 meters below water surface
and at a radial distance of 1.5 meters from the 3D BHR. In the vertical direction, one can
see the same hyperbolic reflection pattern that is characteristic for surface ground
penetrating radar. This is because, as the 3D BHR is lifted vertically and ‘passes’ the
object, the distance between the object and the 3D BHR first decreases and subsequently
increases.
The figure to the right shows ahorizontal depth scan of the
same measurement. All data in a
horizontal depth scan have the
same measurement depth, in this
case, 2 meters below the water
surface. The radial axis is the
radial distance from the 3D BHR
and the angular axis is the angle in
relation to the magnetic North.
The figure shows the reflection
from the cylinder at an angle of 270º with respect to magnetic
North and at a radial distance of
1.5 meters from the 3D BHR, a
prove of the excellent directionality
of the system.
In a horizontal depth scan, one doesn’t see a hyperbolic reflection pattern. This is
because, as the 3D BHR rotates and horizontally passes the object, the distance between
the object and the 3D BHR remains constant. What does change, however, is the
intensity of the radiated wave. It increases and subsequently decreases as the antenna
radiation beam horizontally passes the object. This results in the kind of ‘banana’ pattern
that can be seen in the figure. The object is located in the middle of this pattern.
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3D Borehole Radar 15
Data Sheet 2: Soil Test Case
Objective and circumstances
The water test case was repeated under the real circumstances of the subsoil. In this
test, the 3D Borehole Radar (3D BHR) was placed in one borehole and an iron cylinder of 10 cm. in diameter and 30 cm. in height was placed in another.
The cylinder was placed at depth of 6
meters, at a radial distance of 9
meters and at an angle of 345 degrees
relating to the magnetic North from
the 3D BHR.
The soil was composed of
homogeneous sand and was water-
saturated to about half a meter below
the surface. Conductivity was low.
Measurement results
The figure below shows the measured raw data. No processing has been done yet. The
figure shows a vertical angle scan of the measurement data. All data in a vertical angle
scan have the same measurement angle. The x-axis is the radial distance from the 3D
BHR and the y-axis is the depth below surface. The radial distance is converted from
measurement time, using the relative permittivity of the soil.
The large amplitude at small distance, which corresponds with small amount of time, is
the direct wave. This is the signal that travels directly (without reflection) fromtransmitter to receiver antenna. The object cannot be seen in this unprocessed data.
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3D Borehole Radar 16
The figure to the left shows a
vertical angle scan of the
cylinder after processing. The
direct wave has been
suppressed and the reflectionfrom the cylinder now appears
at a depth of 6 meters below
surface and at a radial distance
of 9 meters from the 3D BHR,
the exact position of the object!
The figure to the right shows a
horizontal depth scan of the same
measurement. All data in a
horizontal depth scan have the
same measurement depth, in this
case 6 meters below the surface.
The radial axis is the radial
distance from the 3D BHR and the
angular axis is the angle in relationto the magnetic North.
The figure shows the reflection
from the cylinder at an angle of
345 degrees and at a radial
distance of 9 meters from the 3D
BHR, again the exact position of
the object!
Although the bottle object has a diameter of only 10 centimeters, the object appears in
the data not only at an angle of 345 degrees, but over an angle range of about 300 to 30degrees. This is because the 3D BHR transmits a bundle of signals with a width of 70 to
90 degrees. The energy density of the transmitted signal is the strongest in the middle of
this bundle.
This test case proved the excellent performance of the 3D BHR with regard to
directionality and accuracy, not only under laboratory circumstances, but also in a real-
life case of a subsoil survey. It shows the system is able to detect the exact position of
an object placed at 9 meters from a single borehole, which is an unprecedented result in
ground penetrating radar survey.
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3D Borehole Radar 17
Data Sheet 3: Sheet Piling Wall
Survey objective and circumstances
In this survey, the objective was to detect a sheet piling metal wall in the subsoil. The
measurements were carried out from a 15-metre deep, PVC-cased borehole. The local
subsoil consisted of peat material (from the surface until 6 meter depth) and below it
consisted of sand. The metal wall was located at 2.8 meters horizontally from the 3D
Borehole Radar (3D BHR) and had a depth of 10 meters. The subsoil water table was
very near to the surface. The conductivity of the water-saturated subsoil was rated fairly
high.
Measurement results
The figure to the right shows a
vertical angle scan of the
measurement. All data in thisa scan have the same
measurement angle. The x-
axis represents the radial
distance from the Borehole
and the y-axis the depth
below water surface. The
radial distance is converted
from measurement time, using
the relative permittivity of the
soil. The figure shows the
results after data processing.
One can see the reflection of
the metal wall up to a depth of
about 10 meters and at a
distance of 2.5 meters from
the 3D BHR.
The figure to the right shows a horizontal
depth scan of the same measurement. All
data in this scan has the samemeasurement depth, in this case 8 meters
below the surface. The radial axis is the
radial distance from the 3D BHR and the
angular axis is the angle in relation to the
magnetic North.
The figure shows the wave reflection from
the wall at an angle of 200 degrees and at
a radial distance of 2.5 meters from the 3D
BHR.
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3D Borehole Radar 18
Data Sheet 4: Object Classification
Objective and circumstances
The objective of the survey was to determine
whether objects encountered during drilling
could be World War II conventional explosives.
During drilling activities, an object was hit at 8
m depth, which caused the drill bar to break.
Because of the history of the area, the
presence of either explosives or a bunker in the
underground could not be excluded. To
minimize risks during further drilling activities,
a 3D BHR survey was carried out at the drill
hole location. The specific goal in this surveywas to determine the dimensions of the object and whether it was part of a larger structure
like a bunker.
Measurement results
The results of the measurements indicated that the object was not part of a larger
structure. The survey also indicated that the object was located at a depth of 5 meters.
This conclusion was later confirmed by magnetometer measurements.
The figure to the left shows a
vertical cross-section of the
data at a single angle of 2.8º.
The absolute value of the
data is shown, the wave
pattern of the data has been
removed. The object is
represented by the yellow
color at 5 meters depth and
3.5 meters radial distance.
The red color at small radial
distances represents thedirect wave between
transmitter and receiver
antenna.
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3D Borehole Radar 19
Operational Information
Equipment
The field crew needs a flat surface of about 40 m² near the
borehole to unpack and mount the equipment. Computers
and monitors need to be protected from rain and dirt, either
by a shelter or by a van. Setting up the equipment takes
approximately 60 minutes for two operators.
Auxiliary equipment
Auxiliary equipment needed to operate the 3D BHR:
Crane, rig or tripod
Winch
Power supply
Water supply
The mounted 3D BHR is 4.4 meters long, has a diameter
of 16 centimeters and weighs approximately 250
kilograms, so it needs to be lifted by a crane or, when
using a tripod, by an electrical winch. The crane or tripod
must be able to lift the 3D BHR approximately 5.0 meters
above borehole casing level. The cable speed of the crane
or winch must be reducible
to 1 meter per minute.
Boreholes
Boreholes can have a maximum depth of 30 meter and need
to be cased using PVC pipes or any other non-metallic (non-
conductive) material. Preferably, they have a inner diameter
of approximately 20 cm, with a minimum inner diameter of
19 cm and a maximum inner diameter of 24 cm. During
measurements, these holes need to be filled with fresh
water up to the edge of the casing.
If the groundwater table is low, for example, a few
meters below the surface, it is recommended to plug the
bottom end of the casing using a lid or clay in order to
avoid losing borehole water during measurements. A
fresh water supply is needed to maintain a stable water
reference level at all times.
Right: Water fill and depth reference.
Left: Wheel blocks at top and bottom will centralize the 3D BHR. An
inner diameter of 20 cm is ideal.
8/3/2019 3D BHR Information Syllabus
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3D Borehole Radar 20
Connection
The cable can be connected
in multiple ways, using hooks
or pulleys as indicated in the
pictures. The inner diameterof the eye on top of the
upper wheel block is 34 mm.
Left: ribbon
Right: hook
Procedure
The 3D BHR is lowered into the borehole, followed by a heating up period of 15 minutes.After heating up, the 3D BHR is lifted slowly (1 meter per minute) while measuring.
When the 3D BHR is surfacing, the measurements are stopped.
Left:
Lowering
Middle:
Heating and
starting
Right:
Stopping
Power supply
230 V/50 Hz/200 W or 24 Vdc/8A
Objects on the site
Large objects at the surface of the site like steel pylons, metal plates, concrete walls willcause interference with the 3D BHR measurements. Please provide us all the information
to make sure that 3D BHR measurements can be performed under the given conditions.
The presence of power cables near a borehole should be avoided as much as possible.
Weather conditions
Weather conditions, except lightning, do not influence 3D BHR measurements. In the
case of lightning, measuring will stop until the weather improves.
The minimum temperature during operation is –5 °C as lower temperatures can damage
the water filled 3D BHR system.
8/3/2019 3D BHR Information Syllabus
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Summary
Crane, rig or tripod cable length Approximately 30 meters of free cable length
Crane, rig or tripod weight
lifting
Approximately 250 kg
Crane, rig or tripod cable
pulling velocity
Approximately 1.0 meter/minute during measuring
Boreholes Maximum depth 30 meter, PVC cased (or similar)
inner diameter 20 cm, closed at bottom end in
certain situations
Connection Eye in top wheel block 34 mm inner diameter
Power supply 230 V/50 Hz/200 W or 24 Vdc/8A
Water supply Fresh water, quantity depending on geology, water
table height and site.
Object on the site Contact usPower cables nearby Contact us
Weather condition Minimum temperature –5 °C