General information about SOCON sonar tools
Sonar tools for carrying out geophysical surveys to determine the
volume and shape of underground caverns and cavities are based on the
echo sounding principle. Sonar tools do not measure distances, instead
they record the time that an ultrasonic pulse takes to travel from the
survey tool to the cavern wall and back to the tool.
For this reason it is essential when surveying to
determine the acoustic velocity of the medium in which the survey is
being carried out. Other physical parameters important to a survey
include such quantities as the temperature and pressure etc, which not
only affect the sonar data measured, but can also contribute to
improving and verifying the results.
In order to be able to interpret sonar signals ...
- all signals and signal shapes must be included in the
interpretation. To perform qualitative surveys it is absolutely
necessary to correlate sonar signals and to include them in the
analysis during interpretation and reporting.
Only SOCON tools satisfy this requirement. |
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All the tools used by SOCON have been developed and manufactured in house. |
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The systems generally available on the market do not satisfy the SOCON standards and for instance...
- cannot determine the direction in every measuring
direction, but instead calculate the direction from a starting position
by means of a stepping motor and gearing
- cannot be stabilized. The survey heads rotate continuously. "Slurring" of the traveltime measurements is therefore unavoidable
- cannot enable the sonar head to be optimized to the varying local conditions because the survey head is continuously rotating
- cannot carry out any adjustments, correlations and local plausibility checks owing to the continuous rotation
- cannot use any log functions for physical parameters
- cannot transfer sonar signals from the tool to the survey
truck, measuring point for measuring point, direction for direction,
for documentation, interpretation and verification of the local
situation.
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SOCON ECHOGRAM
Sonar reflections at one survey depth with direction data
Nowadays sonar tools of the 5th and 6th generation are in operation;
these are the tools of type BSE (Borehole Sonar Generation "E") and BSF
(Borehole Sonar Generation "F"). The difference between the BSE and BSF
tools lies essentially in the different compass systems used and in the
electronics for drive control.
The BSF and BSE sonar tools can be applied for all operations in cavern
and cavity surveying. This means they can be operated in leaching
caverns as well as in storage caverns filled with any type of currently
known storage medium.
The tools are of modular design.
Fitted with just the standard equipment the systems can be applied in
almost all areas of operation. By replacing or adding modules it is
possible to optimize the system for any job that is to be carried out. |
Sonarsonden BSE und BSF
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Cable head (connection to the borehole cable):
- Supply and control unit
- Gyro-stabilizers for preventing tool movements during sonar data acquisition
- CCL for detecting the casing collars
- SuperCCL for detecting the outer casing collars
- Natural-gamma
- Acoustic velocity measuring length
- Temperature sensor
- Pressure sensor
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Rotary drive with pressure compensation and compass for moving to and fixing at each measuring direction:
- Tilt drive with pressure compensation
- Tilt joint 0 to 90 degrees
- Inclination sensor for determining the vertical position of
the tool in space and for controlling and operating the ultrasonic
survey head
- Exchangeable ultrasonic transducer carrier
- Horizontal transducer I
- Horizontal transducer II
- Vertical transducer
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| Technical specifications: |
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| Tool diameter: |
70 mm |
| Weight: |
xxx bis yyy kg |
| Temperature range: |
10 to 80 degs Celsius |
| Pressure: |
300 bar |
| Length: |
3,50 m bis 4,80 m |
| Azimuthal positioning: |
<= 1 deg |
| Deviation: |
compensated < 0.5 deg |
| Vertical positioning: |
<= 1 deg |
| Acoustic velocity: |
<= 0,2 m/sec |
| Sonar frequencies: |
variable, 6 combinations |
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Tool modules
All tool modules can be used during a survey run individually or in combination with all other sonar functions.
CCL and SuperCCL
| | | | CCL
and SuperCCL are used for tying in the tool depth and for controlling
the sonar tools as well as for locating the casing collars so as to be
able to prevent the collars interfering with the results when measuring
through the casing. |
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| CCL |
SuperCCL |
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Natural-gamma
Module for determining the highest leached out zone in
the cavern as well as for finding out geological information such as
the remaining salt thickness. |
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| NATURAL - GAMMA |
CCL |
TEMPERATUR |
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Acoustic velocity, temperature and pressure
Module for determining the prevailing acoustic velocity over the entire depth range to be surveyed in the cavity.
The measuring length is open on one side so that the fluid in the cavern can optimally circulate through it.
The module has one channel for temperature measurement (BSE+BSF) and one channel for pressure measurement (BSE only). |
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Acoustic velocity measurement over three reference lengths, short - long - difference, with system as well as error analysis.
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Inclination
  All
SOCON tools are fitted with an inclination sensor in the ultrasonic
survey head for determining the position of the head and controlling it
to the required recording position.
By rotating the tool at a fixed measuring depth it is possible also to record the borehole inclination at that point.
Sonar tools of type BSF are fitted in addition with inclination sensors
for the x and y-direction. In combination with the fiber-optics gyro
module logs can be recorded for determining the borehole deviation. Ultraschallmesskopfes auf die
gewünschte Erfassungsposition.
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Slide-on and intermediate centralizers
Centralizers of different designs are available for
securing the tools in the casing during survey runs and measurements
through the casing.
Slide-on centralizer; centralizer that is pushed over the sonar tool
and increases the minimum diameter to 90 mm. The length of the tool is
not affected.
Intermediate centralizer; centralizer that is screwed between the
different modules. The tool diameter is unaffected, but the tool
becomes longer. |
Weight sections
Ultrasonic transducers
 To
optimally adapt the tool to special conditions, for example surveying
in heavy oil or gas under low pressure, there are available, in
addition to the standard ultrasonic survey head, various sonic heads
with different transducers, different transducer sizes and different
installation positions. Inclined transducers in the measuring head can
in addition, provided the general physical conditions are observed,
measure at an inclined angle through the casing. |
Laser module
A laser head is available for measuring in caverns or cavities filled
with air that cannot be surveyed using sonic means. The laser head (BSE
only) is fitted at the bottom end of the tool instead of the sonic
head. At present the diameter of the laser head is 160 mm.
Tool joints
 Jointed
modules are available for increasing safety when running through casing
in deviated boreholes or when there is little space to maneuver inside
the casing. |
Tool extensions
In caverns in which the end of the casing has been formed by exploding
the bottom part of it, it is not permitted to run the full length of
the tool through the bottom of the casing owing to the risk involved
when running the tool back into the casing.
To enable measurements to be made more than a tool length below the
bottom end of exploded casing, tool extension units (two meter lengths)
can be added to the tool.
Dewpoint
A dewpoint module is available for determining the humidity in gas storage caverns.
 The measuring range of the unit extends from dewpoint temperatures of -20 to +20 degrees Celsius.
To achieve as little "slurring" of the measured values as possible, the
module is fitted with an open circulation channel and a motor to
increase the circulation. Also included in the module is a pressure and
temperature sensor. |
Fiber-optics gyro
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When measuring through the casing there is no azimuthal north orientation of the surveyed sections.
So
when determining the shape of the cavern the surveyed sections can be
turned on top of each other to find the optimal agreement, but if this
proves to be inadequate a gyro compass is the only remaining option.
The fiber-optics gyro computer developed by SOCON calculates and
manages all the rotational movements of the sonar tool during a survey
run and establishes a fixed relationship between the direction of the
survey head and the fiber-optic gyro direction.
The high resolution fiber-optic gyro as well as the connected drift
computer optimize the application of this module and minimize the
time-dependent residual error to < 3 degrees per hour.
The fiber-optic gyro can be aligned either at the surface by taking a
bearing or in the cavern by running the tool at least two meters
outside the bottom of the casing.
The latter option of using the compass installed in the tool to find
the orientation is considerably easier and moreover allows regular
checking of the fiber-optic gyro during surveying.
Regardless of the procedure, the fiber-optic gyro must be oriented at
the beginning of a survey and this orientation checked at the end of
the survey. Any differences that may occur must be spread over the
survey time accordingly on the individual surveyed sections. All the
fiber-optic data are managed by the survey program so as to minimize
all error sources. |
Special modules
Further modules will be available from 2004. These modules
are based on the logging functionalities of the BSE and BSF sonar tools
and provide extra functions:
- Calliper module, with 4 or 6 arms or as a twin set with 8 or 12 arms
- Module for sampling fluids at any depth with a vessel holding up to 2 liters
- Photo and video module instead of the ultrasonic head, can be rotated and tilted.
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Sonar tools for special applications
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BCS Value microC (Generation 4)
In many parts of Europe underground cavities created by mining exist under surface areas that are now populated.