3dbhr eage 2013

3D Borehole Radar™

Product Information

System Configuration

Applications

Survey Data Sheets

Operational Infomation

T&A Survey B.V.Dynamostraat 481014 BK AmsterdamThe NetherlandsT: +31 20 [email protected] www.ta-survey.nl

U.S. Agent:[email protected]: +1 720 2614775

York

打字机

EPC Patrick: 3965 4802

本页已使用福昕阅读器进行编辑。福昕软件(C)2005-2009，版权所有，仅供试用。ഀ

Contents

3D Borehole Radar: A Breakthrough in Ground Penetrating Radar Survey ..................... 2

System Configuration Prototype .............................................................................. 4

3D BHR Next Generation Tool: Technical Plan Summary ............................................. 6

Application: Oil and Gas Exploration ......................................................................... 7

Application: Mining Industry ................................................................................... 8

Application: Geothermal Energy Detection ................................................................ 9

Application: Geotechnical Survey ........................................................................... 10

Application: Determination of Jet Grout Column Diameter ........................................ 11

Application: Tunnel Track Exploration ..................................................................... 12

Application: Detection of Unexploded Ordnance (UXO) ............................................. 13

Data Sheet 1: Water Test Case ............................................................................. 14

Data Sheet 2: Soil Test Case ................................................................................. 16

Data Sheet 3: Sheet Piling Wall ............................................................................. 18

Data Sheet 4: Object Classification ........................................................................ 19

Operational Information ....................................................................................... 20

3D Borehole Radar 2

3D Borehole Radar: A Breakthrough in Ground

Penetrating Radar Survey

About T&A Survey

T&A Survey is an experienced and technologically advanced subsurface research company

founded in 1992 in Amsterdam, The Netherlands. T&A specializes in geological and

geophysical studies of the deep underground and the development of geophysical

hardware and software. Our customers include all major Dutch engineering

companies, building contractors, oil and gas companies as well as regional and national

authorities. Interest in T&A Survey from large, multi-national oil and gas companies

continues to increase as T&A has demonstrated its continued development with proven

technology.

Robert van Ingen is the single shareholder and Managing Director. He holds an MSc in

Geology and has 25 years of experience in geophysics with Atlas Wireline Services and

Jason (Fugro). T&A employs highly qualified engineers from the Universities of Zürich,

Utrecht, Delft and Amsterdam, ensuring optimum performance in projects undertaken.

The Technology

T&A Survey was founded on the principal and Robert’s personal belief that the success of

the company would be in direct response to its commitment to investing in research and

development. These R&D efforts have resulted in the patented 3D Borehole Radar (3D BHR)

technique. Applications for this technique include oil and gas exploration, mining and

geothermal applications.

As a non-seismic tool, it can add useful information to existing logging techniques. Due

to the unprecedented penetration of the directional radar signal, combined with its

typical high resolution, it is able to investigate the first few meters of the reservoir

formation and build up a fully detailed 3D image of the surrounding borehole. This is the

first time that it is possible to obtain high-resolution information from the borehole

surroundings and not only from the borehole wall.

3D Borehole Radar applications for oil and gas are as a wireline logging, measurement

while drilling (MWD), and a geosteering tool especially in thin pay zones. This facilitates

the 3D positioning of the drill bit, reservoir characterization, fracture detection and 3D

monitoring of the steam/waterfront. T&A Survey believes the technology is uniquely

effective and profitable with other multiple applications such as SAGD and as a fishing

tool.

3D Borehole Radar 3

In order to use the 3D BHR in the oil & gas exploration and production industry it needs

to be adapted to function in the high temperature and high pressure conditions which

commonly occur in deep-lying reservoirs. Furthermore, it needs to be adapted to the

data communications and drill pipe industry standards. The first step in this R&D process

is the proof of concept for geological applications of the tool, for which a “next

generation” 3D BHR tool is required.

Applications of the 3D BHR:

• Oil and gas reservoir

characterization

• Mining

• Geothermal energy detection

• Geotechnical survey

• Determination of jet grout

column diameter

• Tunnel track exploration • Object detection

3D Borehole Radar 4

System Configuration Prototype

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

environmental borehole 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 very

fast 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, computer

and 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.

and power supply during

rotation.

3D Borehole Radar 5

Technical Specifications

Length 4.2 meters

Diameter 16 centimeters

Weight 250 kg

Source 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 lower

Antenna 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 boreholes

3D BHR Vertical Only to be used in vertical boreholes.

Parts: Integrated positioning and radar unit (more robust)


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


3D Borehole Radar 6

3D BHR Next Generation Tool: Technical Plan Summary

The current first generation 3D Borehole Radar (3D BHR) tool was built based on the

following design criteria:

Application: detection of metal objects

Shallow boreholes, maximum depth 30 m, later on extended to 90 m

Rugged design

Because of continuous product development, the demand for new (geological)

applications and the major technical improvements in the hardware components and

operating and processing software for the tool, the need for a new tool has arisen. The

next generation 3D BHR should be applicable at greater depths up to 300 m.

Furthermore, the tool should be suitable for a wider range of applications, such as Oil &

Gas exploration and geothermal research. The new tool should be able to withstand the

following, still moderate, environmental circumstances: a temperature of 30 °C and a

borehole pressure of 35 bar.

Design Criteria

Based on the above information, including the accumulated experience to date with the

current tool, we propose the following changes with respect to the current system:

Adaption of the housing to 30 °C and 35 bar

Reduced overall diameter of the tool

Changes in antenna system configuration

Modified pulse generator pulse shape, improved matching to antenna system

Modified low noise front-end

Enlarged ADC (analogue to digital conversion) resolution

Light weight rotor and driving motor for power reduction

An option for down-hole data storage

Possibly a down-hole battery pack instead of on-line power

Fibre optic borehole data cable instead of metal coaxial cable

3D Borehole Radar 7

Application: Oil and Gas Exploration

The 3D Borehole Radar technology is a promising addition

to existing logging techniques used in oil and gas

exploration and production. The main benefit of the

3D BHR is the ability to see beyond the borehole.

Applications:

Monitor steam/water front

Fracture geometry (m to decametre scale)

Karst detection (m to decametre scale)

BHA

Measurement While Drilling

Geosteering

Steam-assisted gravity drainage (SAGD)

Very shallow oil reserves with horizontal wells

Monitor proppant placement

Time lapse measurement to image (saline) tracers

Penetration range

The 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

• 3D BHR detects the position of the oil-water contact zone in reservoirs

because the electromagnetic impedance contrast is higher than the contrast

in acoustic impedance.

• In SAGD, 3D BHR provides an accurate relative position of the two wells from

only one borehole without needing access to the producer well.

• In thin pay zones, 3D BHR provides the information to steer the drill bit. The

distance to the top and bottom of the reservoir can also be measured.

• In production phases, the 3D BHR monitors the movement of the

steam/water front in 3D.

• In an exploration environment, the 3D BHR can be used as an Electric

Propagation Tool to detect the electrical properties of the formation.

3D Borehole Radar 8

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 provides a useful

addition to existing geophysical techniques in

recognizing geology for mining. It can be applied

in both exploration and production phases.

In an exploration environment, the 3D Borehole

Radar 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 around

the 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

to 20 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 mine

development.

3D Borehole Radar 9

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 formation to

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.

3D Borehole Radar 10

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 location

of the object in the subsurface.

• No overburden effects.

• Much higher resolution with the acquired

images.

• No site constraints with surface structures

as boreholes can be drilled at any angle or even horizontally.


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 3D Borehole Radar method.


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°, it

gathers 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.


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 be located 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

the magnetometer method.

Very high location accuracy due

to the nature of the radar

method and the directional

radiation pattern that is transmitted by the 3D BHR.


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 is

transmitted 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 small

radial distance from the antennas.

Detection cone

Detected object

70-90°

Horizontal plane

Transmitting antenna

10-15°

Detection cone

Receiving antenna

Rays that hit the receiver

Detected object

Side view Top view

Rays that miss the receiver


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 a

horizontal 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.


Data Sheet 2: Soil Test Case


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) from

transmitter to receiver antenna. The object cannot be seen in this unprocessed data.




cylinder after processing. The

direct wave has been

suppressed and the reflection

from 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!


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 relation

to 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 30

degrees. 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.


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



measurement. All data in this

a 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 same

measurement 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.


Data Sheet 4: Object Classification


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 survey

was 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.


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 the

direct wave between

transmitter and receiver

antenna.


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.


Connection

The cable can be connected

in multiple ways, using hooks

or pulleys as indicated in the

pictures. The inner diameter

of 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 will

cause 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.


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 us

Power cables nearby Contact us

Weather condition Minimum temperature –5 °C

3dbhr eage 2013

Documents