U.S. patent number 3,831,138 [Application Number 05/232,799] was granted by the patent office on 1974-08-20 for apparatus for transmitting data from a hole drilled in the earth.
Invention is credited to Rudolf Rammner.
United States Patent |
3,831,138 |
Rammner |
August 20, 1974 |
APPARATUS FOR TRANSMITTING DATA FROM A HOLE DRILLED IN THE
EARTH
Abstract
An arrangement for measuring and transmitting geological,
physical, geometrical or chemical data of soil strata penetrated by
a drilling hole, comprising a signal generator located inside the
drilling hole and including a converter which produces signals
corresponding to the measured data and a transmitter controlled by
the converter and which emits modulated output signals. A receiver
is located in the region of the open upper end of the drilling hole
for demodulating the received signals and producing a visual
display thereof in an indicator. The output of the transmitter of
the signal generator and the input of the receiver are connected to
conductive dipoles which are in electrically conductive connection
with the soil such that the electrical signals are wirelessly
transmitted through the soil in accordance with the electrical
conductivity of the soil.
Inventors: |
Rammner; Rudolf (D 6472
Altenstadt 2, DT) |
Family
ID: |
25760765 |
Appl.
No.: |
05/232,799 |
Filed: |
March 8, 1972 |
Foreign Application Priority Data
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|
|
|
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Mar 9, 1971 [DT] |
|
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2111046 |
Feb 8, 1972 [DT] |
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2205837 |
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Current U.S.
Class: |
367/81; 324/323;
324/369 |
Current CPC
Class: |
E21B
47/125 (20200501); G01V 9/00 (20130101); G01V
3/34 (20130101); E21B 47/06 (20130101); H04B
13/02 (20130101) |
Current International
Class: |
E21B
47/12 (20060101); G01V 3/34 (20060101); H04B
13/00 (20060101); G01V 9/00 (20060101); E21B
47/06 (20060101); G01V 3/18 (20060101); H04B
13/02 (20060101); G01v 001/40 () |
Field of
Search: |
;340/18NC,18FM,18LD
;324/1,5,10 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hubler; Malcolm F.
Assistant Examiner: Birmiel; H. A.
Attorney, Agent or Firm: Waters, Roditi, Schwartz &
Nissen
Claims
What is claimed is:
1. An arrangement for measuring and transmitting geological,
physical, geometrical, or chemical data of soil strata penetrated
by a drilling hole, comprising a battery, a signal generator
producing an alternating current having a low frequency, said
battery and said signal generator being located inside the drilling
hole, a pair of mutually insulated transmitter contacts coupled
with the signal generator, said pair of transmitter contacts being
in electrically conductive connection with the soil surrounding the
drilling hole to facilitate electrical signals from said
transmitter contacts to be wirelessly transmitted through the soil
in accordance with the electrical conductivity thereof, a pair of
mutually insulated measuring contacts on a drill stem within the
drilling hole for measuring the voltage drop of said electrical
signals, said signal generator including a converter coupled with
said measuring contacts and modulating said alternating current
corresponding to said voltage drop, receiver means located in the
region of the open upper end of the drilling hole, a pair of
receiver contacts coupling said receiver means with the bottom of
said drilling hole for demodulating the receiver signals, and
indicator means connected to said receiver means.
2. An arrangement according to claim 1, comprising two pairs of
metallic segments being provided on said drill stem and forming,
respectively, said transmitting and measuring contacts, said
battery supplying a current with constant intensity to the
transmitter contacts, the signal generator being controllable by a
voltage drop at the measuring contacts.
3. An arrangement according to claim 2, said signal generator
producing oscillations which are modulated pursuant to a
predetermined modulation factor, said modulation factor being a
function of the detected data which is changed into said electrical
signals.
4. An arrangement according to claim 3, only one half-wave of the
oscillations being modulated, the ratio of the modulated half-wave
to the unmodulated one being a function of the detected data.
5. An arrangement according to claim 3, said oscillations
comprising a series of pulses.
6. An arrangement according to claim 1, said signal generator
having a self-oscillating frequency dependent upon the input
voltage, and having an input circuit including at least one
thermistor.
7. An arrangement according to claim 5, said signal generator
producing a pulse series modulated in accordance with the voltage
of the measuring contacts, the thus modulated signals
simultaneously serving as a transmission current at the transmitter
contacts.
8. An arrangement according to claim 7, said signal generator
including a time-base circuit for production of pulses having
constant charge, said circuit having an output connected to the
transmitter contacts, a control circuit connected to the output of
the time-base circuit, the input of the control circuit being a
control switch connected with the measuring contacts for
controlling the frequency of the time-base circuit in dependence of
the voltage at the measuring contacts.
Description
BACKGROUND
A. Field of the Invention
The invention relates to apparatus for measuring and transmitting
data from soil strata penetrated by a drilling hole. Such data may
include information of a geological, physical, geometrical or
chemical nature.
B. Prior Art
According to known geophysical drilling hole measuring techniques,
measuring probes are sunk into the drilling hole, in order to
measure geological, physical, geometrical or chemical data of soil
strata penetrated by a drilling hole. The probes can be inserted
only after the mechanical drilling operations have been completed.
The transmission of the data, which is detected by means of probes
or transducers and converted into electric signals, to the surface
of the earth is usually accomplished by means of cables. Inasmuch
as the probes or transducers need electric energy, this must be
supplied to them from the surface of the earth by the cable.
It is disadvantageous in the measuring methods that they cannot be
applied simultaneously with the drilling operation. On the
contrary, it is necessary that the drilling tube be pulled out of
the hole for measuring purposes. Without regard of the fact that
this additional working operation is very time consuming, there
exists a danger that the walls of the drilling hole may collapse
during this procedure. Moreover, such processes do not permit
simultaneous monitoring, i.e., a continuous and simultaneous
observation during the drilling operation, so that technical
drilling decisions cannot be made before the drilling tube is
pulled out of the drilling hole.
Since the conventional measuring probes must be connected with a
receiver located on the surface of the earth in the proximity of
the drilling hole by means of insulated electric lines, it is
difficult for technical reasons to attach the measuring probes or
transducers directly to the drilling tube in order to enable
measurements to be taken in the course of the drilling
operation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an arrangement,
by means of which the data measured in the drilling hole can be
transmitted to the receiver during the measuring operation without
using the cable connection.
The invention contemplates an arrangement including a signal
generator located inside the drilling hole and a receiver arranged
in the neighborhood of the drilling hole collar. The signal
generator consists of a converter which generates the electric
signal corresponding to the measured values, and a transmitter
controlled by the converter for transmitting modulated signals. The
receiver demodulates the received signals and provides a visual
indication thereof by means of a measuring or plotting
instrument.
The arrangement according to the invention is based on the concept
of using the electrical conductivity properties of the soil for
transmission of the signals. For this purpose, it is proposed in
accordance with the invention that the transmitting output of the
signal generator and the receiving input of the receiver are each
connected to a conductive dipole, which is in electrically
conductive connection, in such a manner that the electric signals
are wirelessly transmitted by the electrically conductive soil.
Advantageously, the transmission current is fed into the soil by
means of a dipole which extends parallel to the axis of the
drilling hole, and is received by a dipole which extends parallel
to the surface of the earth. This method is already known per se in
geoelectrics as a dipole method for measuring the electric
resistance of soil strata. However, it has not been heretofore used
for transmission of electric data. According to this method,
electric current is supplied to the soil by means of a transmitting
dipole, the current propagating in the form of a current field.
This current field causes a current drop at the electrodes of the
receiving dipole, from which the transmitted data can be derived
after demodulation.
Since no wire connections are needed between the transmitter and
the receiver, the transmitter can be accommodated to advantage in a
closed container, together with an independent source of energy,
for instance a dry battery or an accumulator battery, and located
directly at the lower end of the tube line. If higher transmission
outputs are required, for instance in the course of measurements at
greater depths, the battery or accumulator battery voltage can be
transformed upwardly by means of a chopper and subsequent rectifier
circuit.
The transmitter dipole can consist of two metallic segments which
are arranged above one another at the drilling tube and which are
mutually insulated, and which preferably have an annular or tubular
shape. It is even more advantageous if one of the segments of the
transmitter dipole is formed by the metallic drilling tube itself.
If such is the case, then the transmitting dipole approximately
consists of a point-like and of a line-shaped current source. Since
the line-shaped current source having the form of the drilling tube
extends up to the surface of the earth, the magnitude of the
current field in the region of the receiving dipole is consequently
substantially increased. Herein, a more or less large portion of
the entire transmission output is transmitted upwardly also by
means of the drilling tube.
The arrangement according to the invention can be used for
transmission of all possible geological, physical, geometrical or
chemical data, as, for instance, of the electric conductivity, of
the temperature, the salt content or similar data.
If temperature measurements are conducted, a thermistor can be used
in a conventional manner as a converter, or another similar element
depending on the temperature, in which a temperature change induces
a change of its characteristic properties, for instance, a change
of resistivity.
The four-point method as mentioned above can also be used for
determination of the electric resistance of the soil strata
penetrated by the drilling hole, according to which method the soil
is supplied by an electrical current by means of a pair of metallic
segments which serve as emission electrodes, wherein said electric
current influences a further pair of metallic segments serving as
measuring electrodes, and causes a voltage drop thereon. In order
to keep the number of bits of data to be transmitted as low as
possible, it is proposed according to a further feature of the
invention to either supply the emission electrodes with a current
having a constant intensity, or to supply them intermittently with
a constant charge. If the intensity of the electric current or the
intermittently supplied charge is kept constant, it is sufficient
for the determination of the change of resistance to transmit the
voltage drop at the measuring electrodes. Thus, the receiver is to
be controlled by this voltage.
If modulated oscillations, for example, amplitude modulated,
frequency-modulated or phase-modulated oscillations, are used in
accordance with a further feature of the invention, the modulation
factor or the frequency or phase shift can be a function of the
detected data, i.e., the changed electric signals.
In particular, frequency modulation or phase modulation seem to be
most advantageous, as the frequency shift or the phase shift are
independent of losses.
A signal which is also independent of the losses can be achieved if
the amplitude modulation is used in such a manner that only one
half-wave of the transmitted oscillation is modulated, while the
other half-wave remains intact, wherein the relation of the
modulated half-wave to the unmodulated half-wave is a function of
the detected data which has been changed in electric signals.
In an embodiment according to the invention, frequency-modulated
pulse series are used for transmission of the signals. In addition,
amplitude-modulated, wavelength-modulated or phase-modulated pulse
series are suitable. Even herein, the modulation factor,
respectively the phase of frequency shift or the pulse duty ratio
is a function of the detected data, which has been changed in
electric signals.
The details of the circuitry of the arrangement of the invention
will next be described with reference to an embodiment of the
invention with reference to the attached drawings.
Particular importance is given to an arrangement for measuring and
transmitting the specific electric resistance of the soil strata
penetrated by the drilling hole, according to the invention. It is
characteristic for this arrangement that an alternate current
having a low frequency, or a pulse series is supplied to the
emission electrodes, said alternate current or pulse series being
modulated in dependence of the voltage at the measuring electrode,
the emission current modulated in this manner simultaneously
serving as a transmission current. In this arrangement,
consequently, the emission electrodes simultaneously form the
transmission dipole, by which the construction becomes greatly
simplified. The electronic device for production of the emission
current can also be combined in a very simple manner with the
chopping circuit which effects the modulation of the emission
current.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic illustration of the arrangement according to
the invention showing equipotential and current lines;
FIG. 2 is a diagrammatic view of the lower end of the tube line
with a built-in electronic device for temperature measurements;
FIG. 3 is a block diagram of the electronic circuit with a
voltage-frequency converter for the arrangement according to FIG.
2;
FIG. 4 is a more detailed circuit diagram of the electronic device
for the arrangement according to FIG. 2;
FIG. 5 is a view of the lower end of the tube line with the
electronic device according to a second embodiment to the invention
for measuring the specific electrical resistance;
FIG. 6 is a block diagram of the electronic circuitry in the
arrangement according to FIG. 5; and
FIG. 7 is a circuit diagram of the electronic device of FIG. 6.
DETAILED DESCRIPTION
The mode of operation of the arrangement according to the invention
is schematically illustrated in FIG. 1. Therein is seen a drilling
tube 2 which is driven into the soil 1 in order to produce a
drilling hole 3. Near the front end of the tube line, there are
provided emission electrodes 4 and 5, as well as measuring
electrodes 6 and 7. The outer surface of the jacket of the tube 2
serves herein as an emission electrode. The current field produced
by both the electrodes 4 and 5 is illustrated by current lines i.
Furthermore, the equipotential lines e corresponding to electrodes
4 and 5 are illustrated in dotted lines.
At the surface of the earth, there is provided a receiver 8 in
proximity of the drilling hole collar 3a, the input of said
receiver being connected to probes 9 which are driven into the
soil, and which form a conductive receiving dipole. The signals
received by this dipole are amplified in the receiver 8 and
demodulated or decoded therein, and visually indicated on an
indicator or plotting device 10.
In FIG. 2 of the drawing, there is shown the lower end of the tube
line according to the invention, in a partial cross-sectional view.
Above the boring bit 2a, the drilling tube is formed with annular
segments 11 and 12, which are electrically insulated from each
other and the remainder of the drilling tube 2 by means of
insulation rings 13. The illustration of the segments 11 and 12 and
rings 13 of the boring tube 2 is purely schematic. It is preferred
for reasons of strength to use a continuous, uninterrupted tube,
the segments 11 and 12 either being provided on the surface of the
tube or embedded in the tube, and simultaneously separated from
each other and from the remainder of the tube by insulating
elements.
The segments 11 and 12 form a vertical, conductive transmitting
dipole, and the segments are connected to the output of a signal
generator 14. A thermistor 15 is connected in the input circuit of
the signal generator 14, the resistance of said thermistor changing
in dependence on the temperature. Thus, the thermistor serves as a
converter for production of signals corresponding to the
temperature of the surroundings, which signals are demodulated or
decorded in the receiver 8 and visually displayed by the device
10.
As shown in FIG. 2, the entire electronic device is accommodated in
a closed container 16, which is fastened in the inside of the tube
line 2 in such a manner that the thermistor 15 is in thermal
contact with the drilling tube 2 and, consequently, with the earth
surrounding the drilling hole.
One embodiment of the circuitry of the signal generator 14 is shown
in the block circuit diagram according to FIG. 3. In the input
circuit of the transmitter 14a, which is not shown in a greater
detail and which simultaneously serves as a
current-frequency-converter and which is supplied with power from
the battery 14b, there is provided the thermistor 15. Current is
supplied from the battery 14c through a resistor 17 to the
thermistor 15, and the output voltage at the thermistor 15 is
designated as U.sub.VAR. Since the resistance of the thermistor 15
varies with temperature, the voltage U.sub.VAR correspondingly
varies. The transmitter 14a is constructed in such a manner that
the frequency of the output voltage u varies as a function of the
input voltage, so that frequency modulated signals are transmitted
by the transmitting dipole whose annular elements 11 and 12 are
connected to the output of the transmitter 14a, the frequency of
these signals being a function of the temperature of the material
surrounding the drilling hole. Since the sources of voltage 14b and
14c form a signal generator together with the transmitter 14a, and
are commonly accommodated in the container 16, the arrangement
according to the invention does not need any special electrical
supply lines.
In FIG. 4, there is shown in greater detail a circuit diagram for
the electronic device according to FIG. 2 for conducting
temperature measurements. Herein, the transmitter consists of a
conventional Wien generator, whose input circuit is formed as a
Wien bridge. The Wien bridge is composed of an RC-series connection
18, 19 and an RC-parallel connection 20, 21. In series with the
resistors 18 or 20 respectively of both RC-connections, there is
always provided one thermistor 15a or 15b respectively. When the
temperature changes, the ohmic resistance of both RC members vary,
which causes variation of the natural frequency of the generator
which is constructed in a conventional manner, consisting of
transistors 22, 23 and 24. Both thermistors 15a and 15b are in
thermal contact with the drilling tube under equal conditions so
that they always have the same temperature.
Instead of the annular segment 11 according to FIG. 2, the entire
upper part of the drilling tube 2, which is electrically insulated
in respect to the segment 12, can serve as an emission electrode of
the vertical transmission dipole. If such is the case, a current
field will be created corresponding to that shown in FIG. 1 between
the annular electrode 12 and the upper portion of the drilling tube
2, wherein the upper end of the drilling tube emits a long line
source.
The arrangement illustrated in FIGS. 5 to 7 serves the purpose of
measuring the electrical resistance of the soil surrounding the
drilling tube in the vicinity of metallic segments 25, 26 and 27,
which are the transmitting, or measuring electrodes, respectively.
The signal generator feeds a pulse current to the soil by means of
the upper line of the drilling tube 2' serving as a line source and
the segment 25 which approximately serves as a point source. The
specific electrical resistance .rho. of the earth surrounding the
drilling hole can be computed from the pulse current detected by
the measuring electrodes 26 and 27 in accordance with the
conventional dipole-method, using the following equation:
.rho. = u.sub.M .sup.. F/i.sub.E
wherein:
u.sub.M = voltage between the measuring probes 26 and 27;
i.sub.E = emission current fed into the soil by means of the
drilling tube 2' and the segment 25; and
F = geometric factor, which depends on the size and the mutual
distance of the segments, as well as the arrangement of further
metallic masses, for instance, the lower part of the drilling tube,
which may be provided and which have short circuit properties.
In order to detect the specific electric resistance by means of
measuring devices arranged on the surface of the earth, the current
intensity of the emission current as well as the voltage drop
between the measuring electrodes 26 and 27 have to be
transmitted.
The technical expenditure can be reduced in accordance with a
further feature of the invention, if either current having constant
intensity or current pulses having constant charge are supplied to
the electrodes. In this case, it is sufficient if the voltage drop
between the measuring electrodes 26 and 27 is transmitted. It has
been proved to be particularly advantageous to feed the emission
current to the electrodes in pulses, wherein the pulses have a
known and always constant charge, so that the integral with respect
to time of the voltage produced between the electrodes 26 and 27 is
a measure of the specific electrical resistance of the surrounding
soil stratum. By means of a converter 28a which is shown in FIG. 6,
a control value is derived from the detected measuring voltage,
which modulates the transmitter 28b of the signal generator 28,
(preferably by modulating its phase).
A particularly simple circuit results, if the pulse series
frequency of the emitted current is varied in dependence of the
probe voltage. If such is the case, the emission current can
simultaneously serve the function of the transmission current which
transmits the signals, as the information is contained in the
instantaneous frequency of the emitted pulse series.
As a result of these simple measures, three segments 25, 26 and 27,
which are electrically insulated from the drilling tube 2', are
sufficient for detection of the resistance and for transmission of
the detected data. Also in this arrangement, the energy source, for
instance, a dry battery 28c, is included in the signal generator
28, on the other hand, is accommodated in a protective container
16' which is attached to the drilling tube 2'. The container 16'
protects the electronic circuitry 28 as well as the supply lines 29
to the electrodes.
A very simple embodiment of the invention and of the circuitry
according to the invention to be used in the arrangement according
to FIGS. 5 and 6, is shown in the circuit diagram according to FIG.
7. The transmitter 28b substantially consists of a self-oscillating
time-base circuit with a glow-discharge lamp 30, a chargeable
condenser or capacitor 31 and two resistances 32 and 33 which are
connected in series. The energy source, preferably dry battery 28c
is connected in series with the capacitor 31 and the resistors 32
and 33. The glow-discharge lamp 30 is located in the circuit formed
by the chargeable capacitor 31, an inductance 34 and the soil
between the electrodes 2' and 25. This arrangement has the
following mode of operation:
The capacitor 31 is charged over the resistors 32 and 33 until it
reaches the ignition voltage of the glow-discharge lamp 30. When
the ignition voltage is reached, the capacitor 31 discharges itself
over the glow-discharge lamp and the soil located between the
electrodes 2' and 25, until the substantially lower extinction
voltage of the glow-discharge lamp is obtained. The spent amount of
charge is defined by the ignition voltage, extinction voltage and
capacity of the capacitor. The inductance has the influence that
the steep discharge pulses are changed so as to have approximately
sinusoidal character of oscillation.
The charge pulses which are emitted by the electrodes 2' and 25
produce approximately sinusoidal current pulses between the
measuring electrodes 26 and 27, which are stepped up by means of a
transformer 35, which simultaneously serves the purpose of galvanic
decoupling, and the pulses are rectified by means of a rectifier
circuit, consisting of a diode 36 and a capacitor 37. The electrode
of the diode 36 which is connected to the capacitor 37 is connected
by means of a resistor 38 with the base of a transistor 39. The
signals produced by the rectifier, which are negative in relation
to the emitter of the transistor 39, switch the transistor on for a
limited period of time corresponding to a pulse, wherein the
duration of the pulse varies in dependence on the magnitude of the
transmitted charge and, consequently, also in dependence on the
electrical resistance of the surrounding soil strata.
The switched-on transistor 39 bridges with its emitter-collector
line, which has a low ohmic resistance during this time period, the
resistance 32, so that the condenser or capacitor 31 of the
time-base circuit is charged more rapidly. The result of this is
that the series frequency of the pulses produced by the time-base
circuit increases. In this arrangement, the pulse series frequency
increases with increasing electrical resistance of the surrounding
soil, since the magnitude of the charge delivered to the capacitor
37 is larger the greater is the specific electrical resistance of
the soil.
A characteristic value for any specific resistance can be derived
from the current pulses received by the receiving dipole by
frequency modulation.
* * * * *