CA1244881A - Electrode and assembly for induced-polarization prospecting - Google Patents
Electrode and assembly for induced-polarization prospectingInfo
- Publication number
- CA1244881A CA1244881A CA000543208A CA543208A CA1244881A CA 1244881 A CA1244881 A CA 1244881A CA 000543208 A CA000543208 A CA 000543208A CA 543208 A CA543208 A CA 543208A CA 1244881 A CA1244881 A CA 1244881A
- Authority
- CA
- Canada
- Prior art keywords
- electrode
- adapter
- keying means
- prospecting
- bedrock
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/18—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging
- G01V3/26—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device
- G01V3/265—Operating with fields produced by spontaneous potentials, e.g. electrochemicals or produced by telluric currents
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/02—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with propagation of electric current
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Remote Sensing (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Geophysics (AREA)
- Electrochemistry (AREA)
- Electromagnetism (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
ABSTRACT
An electrode for induced-prospecting has an elongated cylindrical body of electricity conductive mate-rial provided with a leading end for contact with a con-ductive surface and a trailing end, an axial channel extends within the body from the trailing end, the electrode is pro-vided with keying means to cooperate with keying means on an adapter to prevent relative rotation, but to allow axial movement of the adapter relative to the electrode to permit its withdrawal therefrom, the body has a cavity opening onto its surface near its upper end for receiving the end of the insulated conductor for engaging the electrode; the electrode is employed in a geophysical prospecting method and apparatus especially suitable for measuring the metal content of the bedrock and over-comes disadvantages associated with the existance of a substantial, electrically conductive overburden or of non-conductive overburdens of significant depth.
An electrode for induced-prospecting has an elongated cylindrical body of electricity conductive mate-rial provided with a leading end for contact with a con-ductive surface and a trailing end, an axial channel extends within the body from the trailing end, the electrode is pro-vided with keying means to cooperate with keying means on an adapter to prevent relative rotation, but to allow axial movement of the adapter relative to the electrode to permit its withdrawal therefrom, the body has a cavity opening onto its surface near its upper end for receiving the end of the insulated conductor for engaging the electrode; the electrode is employed in a geophysical prospecting method and apparatus especially suitable for measuring the metal content of the bedrock and over-comes disadvantages associated with the existance of a substantial, electrically conductive overburden or of non-conductive overburdens of significant depth.
Description
This invention relates to a geophysical prospect-ing method and apparatus, more especially to an electrode for IP prospecting and a prospecting installation.
This Applica-tion is a Divisional of Canadian Patent Application, Serial No. 503,220, filed March 4, 1986.
Today's induced-polarization (IP) method of pros-pecting involves inserting electrodes into the ground and inducing a current through the overburden if such exists, shutting off the current, and then measuring the time of lQ decay of the charge as an index of mineral content in the bedrock. Where the overburden is thick, say 300 feet or more, or is too conductive, the reading is likely not to be a true reflection of the conductivity of the bedrock. An example of the induced polarization method is shown in U.S. Patent 1,808,397, Billotte et al (1931). The induced-polarization exploration method is described in more detail in an article of this title by John S. Sumner which appeared in Geophysics and Geochemistry in the Search for Metallic Ores, Geological Survey of Canada, Economic_Geology Report 31, p 123-133 (1979).
One attempt to overcome the problem has been to employ a powerful generator so as to induce a heavy current in the electrodes. There is no certainty, however, even with a high current that it will penetrate to bedrock.
Further, the use of high currents introduces safety problems.
There is now provided a method and apparatus which overcomes the disadvantages of prior prospecting procedures as described above, and more especially an electrode and prospecting installation for use in such method and apparatus.
-` ~.2~
In accordance with one aspect of the invention there is provided an electrode for IP prospecting, com-prising, an elongated cylindrical body of electrically con-ductive material provided with a leadiny end for contact with a conductive surface and a trailing end, said body being provided with an axial channel extending therewithin from the said trailing end, said electrode being provided with keying means to cooperate with keying means on an adapter to prevent relatlve rotation, but to allow axial movement of the adapter relative to the electrode to permit its withdrawal therefrom, said body having a cavity opening onto its surface near its upper end for receiving the end of an insulated conductor for engaging the electrode.
In another aspect there is provided a prospecting installation which comprises the electrode and an adapter, said adapter having a stem adapted to be received within said axial channel of the electrode, said adapter having a head attached to the stem provided with an internal axially extending threaded cavity for engaging the threaded end of a drill string.
There is also disclosed an installation for prospecting by induced polar zation in terrain made up of a bedrock beneath a substantial overburden comprising at least two spaced-apart passages, in particular elongated passages, leading from the surface of the overburden at least substantially to the bedrock surface, a current electrode in effective electrical contact with said bedrock surface at a lower end of each passage, an insulated con-ductor leading from each electrode through its passage to a generator means which is adapted to apply a current to charge 8~
the bedrock and which has means for turning current on and off, and means for measuring electrical characteristics of the charged bedrock as an index of the metal content of the bedrock.
Still further there is disclosed a method of prospecting by induced polarization in terrain made up of bedrock beneath a substantial overburden in which current is effectively applied to bedrock at spaced-apart sites to charge the bedrock, while substantially insulating the current from the overburden, and electrical characteristics of the charged bedrock are measured subsequently to deter-mine the metal content of the bedrock.
In particular, the overburden is a substantial conductive overburden which is effective to dissipate electric current conducted thereinto and typically has a depth of at least 20 feet and often more than 100 feet.
The overburden may also be an essentially non-conductive overburden of substantial depth typically at least 100 feet.
In particular, at least two spaced-apart drill holes are made through the overburden to the bedrock. A
current electrode on the end of a drill string is passed down through each drill hole until it is in actual contact with or effective eIectrical contact with the bedrock. An insulated conductive wire is connected to each electrode and is carried with it down through the drill hole. The upper end of the conductive wire above the surface leads to a generator or any other type of induced polarization unit.
The drill string is then separated from the electrode and withdrawn from the drill hole, leaving the electrode in contact with the bedrock or efEectively in electrical contact therewith and the insulated wire extending from it to the generator.
As in conventional practice potentiating electrodes are installed at ground level between the respective current electrodes so as to measure electrical characteristics of the bedrock resulting from applying a charge to i-t as well understood in the art.
In one prospecting method employing the invention, power is supplied from the generator through the conductive wires to the electrodes for long enough to energize the bed-rock to a given degree. Then, the power is cut off and the rate of decay of the charge is measured by the potentiating electrodes and observed. The rate of decay of the charge supplies information as to the metal content of the bedrock.
~aving thus generally described the invention, it will be referred to in more detail by reference to the accompanying drawings, illustrating preferred embodiments, and in which:
FIG. 1 is a diagram showing a general installation employing the electrode of the invention;
FIGS. 2 and 3 are fragmentary side elevations partly in section of the electrode adapter, and the end of the drill striny in active position in a drill hole;
FIG. 4 is an enlarged perspective view showing in detail the construction of the electrode and the adapter, in accordance with the invention, and illustrating the relation-ship between these parts and the end of the drill string.
~2~
Referring more particularly to Fig. 1 of the drawings, 11 and 12 represent spaced-apart drill holes extending through a bed of conductive clay B, from the surface ~ of the overburden to the surface of the bedrock .
An electrode D is shown in contact with the bedrock C and an insulated wire 19 exténding up through the drill hole 12 and to a generator G. Likewise, an electrode Dl is in contact with the bedrock C at the foot of a drill hole 11 and insulated wire 21 extends from the electrode Dl to a generator Gl.
Ideally, the electrodes D and Dl should be in actual contact with the surface of the bedrock C. However, effective electrical contact may be made on occasion, where the electrode D or Dl is as much as two feet or even rnore from C, although the invention embraces a procedure where the electrode is in effective electrical contact with the bedrock C, so that the proportivn of the current dissipated into the overburden is at a minimum. The invention is particularly applicable to overburdens of conductive clay which cause dissipation of the current prior to reaching the bedrock C.
Potentiating electrodes 17 are in contact with the overburden B at the sur~ace A between the respective electrodes D and Dl. The potentiating electrodes are such that they can be moved anywhere between the drill holes, as is normal in any IP survey.
With further reference to Fig. 2, there is shown an electrode D being lowered in drill hole 12 in bed B of overburden towards bedrock C (not shown).
, ~ ~448~
Electrode D is mounted on an adapter E which is threadedly attached to a drill string M. :[nsulated wire 19 is connected to electrode D.
With further reference to Fig. 3, electrode D is shown in direct contact with bedrock C, drill string M and adapter E having been withdrawn from drill hole 12.
Fig. 4 shows a typical electrode D, provided with a cylindrical body having a pointed tip and an internal cylindrical cavity 23 extending axially and adapted to receive a stem 25 of an adapter E. A key 30 on the inside of the cavity 23 rides in a keyway 29 in the stem 25. The head 34 of the adapter E is threaded in-ternally at 24 and threadably connected to a threaded end 35 of a drill string M. The adapter E slides out of electrode D when the drill string M is pulled out of the drill hole. The electrode D
is retained on the adapter E during the downward passage through the drill hole, by tension on the wire 19. The diameter of the adapter E and of the electrode D can be varied according to the size of the drill stem.
~0 The electrode D has a small cavity 37 receiving the end of the electric cable 19 in electrical contact and suitably secured therein, for example, by welding or soldering. The key 30 has been shown on the electrode and the keyway 29 on the adapter stem 25. This could be reversed.
The depth to which the electrode D and Dl are sunk depends on a number of factors. For example, if the overburden B is highly conductive and the bedrock C not too far below the surface A, say 20 feet or less, the invention is useful. As the depth of the overburden B increases, the invention becomes more and more useful. The invention contemplates, therefore, operating at 20 fee-t or more, and up to the capability of a drill, say 300 feet or even more.
The least distance at which the current electrodes D, Dl would be placed apart would probably be not less than 400 feet, and could be spaced-apart up to a couple of thousand feet.
The invention is especially applicable for use in sites where the bedrock is particularly deep, say 100 feet or more, even though not conductive or where the overburden B is conductive at levels as little as 20 or 30 feet.
This Applica-tion is a Divisional of Canadian Patent Application, Serial No. 503,220, filed March 4, 1986.
Today's induced-polarization (IP) method of pros-pecting involves inserting electrodes into the ground and inducing a current through the overburden if such exists, shutting off the current, and then measuring the time of lQ decay of the charge as an index of mineral content in the bedrock. Where the overburden is thick, say 300 feet or more, or is too conductive, the reading is likely not to be a true reflection of the conductivity of the bedrock. An example of the induced polarization method is shown in U.S. Patent 1,808,397, Billotte et al (1931). The induced-polarization exploration method is described in more detail in an article of this title by John S. Sumner which appeared in Geophysics and Geochemistry in the Search for Metallic Ores, Geological Survey of Canada, Economic_Geology Report 31, p 123-133 (1979).
One attempt to overcome the problem has been to employ a powerful generator so as to induce a heavy current in the electrodes. There is no certainty, however, even with a high current that it will penetrate to bedrock.
Further, the use of high currents introduces safety problems.
There is now provided a method and apparatus which overcomes the disadvantages of prior prospecting procedures as described above, and more especially an electrode and prospecting installation for use in such method and apparatus.
-` ~.2~
In accordance with one aspect of the invention there is provided an electrode for IP prospecting, com-prising, an elongated cylindrical body of electrically con-ductive material provided with a leadiny end for contact with a conductive surface and a trailing end, said body being provided with an axial channel extending therewithin from the said trailing end, said electrode being provided with keying means to cooperate with keying means on an adapter to prevent relatlve rotation, but to allow axial movement of the adapter relative to the electrode to permit its withdrawal therefrom, said body having a cavity opening onto its surface near its upper end for receiving the end of an insulated conductor for engaging the electrode.
In another aspect there is provided a prospecting installation which comprises the electrode and an adapter, said adapter having a stem adapted to be received within said axial channel of the electrode, said adapter having a head attached to the stem provided with an internal axially extending threaded cavity for engaging the threaded end of a drill string.
There is also disclosed an installation for prospecting by induced polar zation in terrain made up of a bedrock beneath a substantial overburden comprising at least two spaced-apart passages, in particular elongated passages, leading from the surface of the overburden at least substantially to the bedrock surface, a current electrode in effective electrical contact with said bedrock surface at a lower end of each passage, an insulated con-ductor leading from each electrode through its passage to a generator means which is adapted to apply a current to charge 8~
the bedrock and which has means for turning current on and off, and means for measuring electrical characteristics of the charged bedrock as an index of the metal content of the bedrock.
Still further there is disclosed a method of prospecting by induced polarization in terrain made up of bedrock beneath a substantial overburden in which current is effectively applied to bedrock at spaced-apart sites to charge the bedrock, while substantially insulating the current from the overburden, and electrical characteristics of the charged bedrock are measured subsequently to deter-mine the metal content of the bedrock.
In particular, the overburden is a substantial conductive overburden which is effective to dissipate electric current conducted thereinto and typically has a depth of at least 20 feet and often more than 100 feet.
The overburden may also be an essentially non-conductive overburden of substantial depth typically at least 100 feet.
In particular, at least two spaced-apart drill holes are made through the overburden to the bedrock. A
current electrode on the end of a drill string is passed down through each drill hole until it is in actual contact with or effective eIectrical contact with the bedrock. An insulated conductive wire is connected to each electrode and is carried with it down through the drill hole. The upper end of the conductive wire above the surface leads to a generator or any other type of induced polarization unit.
The drill string is then separated from the electrode and withdrawn from the drill hole, leaving the electrode in contact with the bedrock or efEectively in electrical contact therewith and the insulated wire extending from it to the generator.
As in conventional practice potentiating electrodes are installed at ground level between the respective current electrodes so as to measure electrical characteristics of the bedrock resulting from applying a charge to i-t as well understood in the art.
In one prospecting method employing the invention, power is supplied from the generator through the conductive wires to the electrodes for long enough to energize the bed-rock to a given degree. Then, the power is cut off and the rate of decay of the charge is measured by the potentiating electrodes and observed. The rate of decay of the charge supplies information as to the metal content of the bedrock.
~aving thus generally described the invention, it will be referred to in more detail by reference to the accompanying drawings, illustrating preferred embodiments, and in which:
FIG. 1 is a diagram showing a general installation employing the electrode of the invention;
FIGS. 2 and 3 are fragmentary side elevations partly in section of the electrode adapter, and the end of the drill striny in active position in a drill hole;
FIG. 4 is an enlarged perspective view showing in detail the construction of the electrode and the adapter, in accordance with the invention, and illustrating the relation-ship between these parts and the end of the drill string.
~2~
Referring more particularly to Fig. 1 of the drawings, 11 and 12 represent spaced-apart drill holes extending through a bed of conductive clay B, from the surface ~ of the overburden to the surface of the bedrock .
An electrode D is shown in contact with the bedrock C and an insulated wire 19 exténding up through the drill hole 12 and to a generator G. Likewise, an electrode Dl is in contact with the bedrock C at the foot of a drill hole 11 and insulated wire 21 extends from the electrode Dl to a generator Gl.
Ideally, the electrodes D and Dl should be in actual contact with the surface of the bedrock C. However, effective electrical contact may be made on occasion, where the electrode D or Dl is as much as two feet or even rnore from C, although the invention embraces a procedure where the electrode is in effective electrical contact with the bedrock C, so that the proportivn of the current dissipated into the overburden is at a minimum. The invention is particularly applicable to overburdens of conductive clay which cause dissipation of the current prior to reaching the bedrock C.
Potentiating electrodes 17 are in contact with the overburden B at the sur~ace A between the respective electrodes D and Dl. The potentiating electrodes are such that they can be moved anywhere between the drill holes, as is normal in any IP survey.
With further reference to Fig. 2, there is shown an electrode D being lowered in drill hole 12 in bed B of overburden towards bedrock C (not shown).
, ~ ~448~
Electrode D is mounted on an adapter E which is threadedly attached to a drill string M. :[nsulated wire 19 is connected to electrode D.
With further reference to Fig. 3, electrode D is shown in direct contact with bedrock C, drill string M and adapter E having been withdrawn from drill hole 12.
Fig. 4 shows a typical electrode D, provided with a cylindrical body having a pointed tip and an internal cylindrical cavity 23 extending axially and adapted to receive a stem 25 of an adapter E. A key 30 on the inside of the cavity 23 rides in a keyway 29 in the stem 25. The head 34 of the adapter E is threaded in-ternally at 24 and threadably connected to a threaded end 35 of a drill string M. The adapter E slides out of electrode D when the drill string M is pulled out of the drill hole. The electrode D
is retained on the adapter E during the downward passage through the drill hole, by tension on the wire 19. The diameter of the adapter E and of the electrode D can be varied according to the size of the drill stem.
~0 The electrode D has a small cavity 37 receiving the end of the electric cable 19 in electrical contact and suitably secured therein, for example, by welding or soldering. The key 30 has been shown on the electrode and the keyway 29 on the adapter stem 25. This could be reversed.
The depth to which the electrode D and Dl are sunk depends on a number of factors. For example, if the overburden B is highly conductive and the bedrock C not too far below the surface A, say 20 feet or less, the invention is useful. As the depth of the overburden B increases, the invention becomes more and more useful. The invention contemplates, therefore, operating at 20 fee-t or more, and up to the capability of a drill, say 300 feet or even more.
The least distance at which the current electrodes D, Dl would be placed apart would probably be not less than 400 feet, and could be spaced-apart up to a couple of thousand feet.
The invention is especially applicable for use in sites where the bedrock is particularly deep, say 100 feet or more, even though not conductive or where the overburden B is conductive at levels as little as 20 or 30 feet.
Claims (4)
1. An electrode for IP prospecting, comprising, an elongated cylindrical body of electrically conductive material provided with a leading end for contact with a conductive surface and a trailing end, said body being provided with an axial channel extending therewithin from the said trailing end, said electrode being provided with keying means to cooperate with keying means on an adapter to prevent relative rotation, but to allow axial movement of the adapter relative to the electrode to permit its withdrawal therefrom, said body having a cavity opening onto its sur-face near its upper end for receiving the end of an insulated conductor for engaging the electrode.
2. An electrode as defined in claim 1, in which said keying means comprises a projection of the body extending inwardly from the axial channel to engage an axially extending slot in said adapter.
3. A prospecting installation comprising:
an electrode for IP prospecting and an adapter, said electrode comprising:
an elongated cylindrical body of electrically conductive material provided with a leading end for contact with a conductive surface, and a trailing end, said body being provided with an axial channel extending therewithin from the said trailing end, said electrode being provided with keying means to cooperate with keying means on said adapter to prevent relative rotation, but to allow axial movement of the adapter relative to the electrode to permit its withdrawal therefrom, said body having a cavity opening onto its sur-face near its upper end for receiving the end of the insulated conductor for engaging the electrode, said adapter having a stem adapted to be received within said axial channel to the electrode, said adapter having a head attached to the stem provided with an internal axially extending threaded cavity for engaging the threaded end of a drill string.
an electrode for IP prospecting and an adapter, said electrode comprising:
an elongated cylindrical body of electrically conductive material provided with a leading end for contact with a conductive surface, and a trailing end, said body being provided with an axial channel extending therewithin from the said trailing end, said electrode being provided with keying means to cooperate with keying means on said adapter to prevent relative rotation, but to allow axial movement of the adapter relative to the electrode to permit its withdrawal therefrom, said body having a cavity opening onto its sur-face near its upper end for receiving the end of the insulated conductor for engaging the electrode, said adapter having a stem adapted to be received within said axial channel to the electrode, said adapter having a head attached to the stem provided with an internal axially extending threaded cavity for engaging the threaded end of a drill string.
4. A prospecting installation as defined in claim 3, in which said keying means of the adapter is an axially extending slot opening onto its surface and said keying means of the electrode comprises a projection extending inwardly from the surface of the axial channel to be engaged within said slot of the adapter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000543208A CA1244881A (en) | 1987-07-28 | 1987-07-28 | Electrode and assembly for induced-polarization prospecting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000543208A CA1244881A (en) | 1987-07-28 | 1987-07-28 | Electrode and assembly for induced-polarization prospecting |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000503220A Division CA1228646A (en) | 1986-03-04 | 1986-03-04 | Prospecting method and apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1244881A true CA1244881A (en) | 1988-11-15 |
Family
ID=4136165
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000543208A Expired CA1244881A (en) | 1987-07-28 | 1987-07-28 | Electrode and assembly for induced-polarization prospecting |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1244881A (en) |
-
1987
- 1987-07-28 CA CA000543208A patent/CA1244881A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2250769A1 (en) | Downhole electrode for well guidance system | |
| CA1234870A (en) | Method for preventing the drilling of a new well into one of a plurality of production wells | |
| US4864293A (en) | Inground boring technique including real time transducer | |
| US5160925A (en) | Short hop communication link for downhole mwd system | |
| EP0916101B1 (en) | Combined electric-field telemetry and formation evaluation apparatus | |
| US6392317B1 (en) | Annular wire harness for use in drill pipe | |
| US5168942A (en) | Resistivity measurement system for drilling with casing | |
| US5642051A (en) | Method and apparatus for surveying and monitoring a reservoir penetrated by a well including fixing electrodes hydraulically isolated within a well | |
| RU2454524C2 (en) | Plant and method for electro-impulse drilling and logging and device for electro-impulse drilling (versions) | |
| RU2386810C2 (en) | Method and system for exact direction of drilling of double wells | |
| US6978833B2 (en) | Methods, apparatus, and systems for obtaining formation information utilizing sensors attached to a casing in a wellbore | |
| GB2384861A (en) | A logging sonde for electrically exploring geological formations through which a borehole passes | |
| GB2259832A (en) | Transmission of information from a borehole | |
| GB2355538A (en) | Device and method for measurement of resistivity outside of a wellpipe | |
| KR20090055553A (en) | Modular geosteering tool assembly | |
| CA2337221A1 (en) | Downhole well corrosion monitoring apparatus and method | |
| CA2165645C (en) | Resistivity antenna shield, wear band and stabilizer assembly for measuring-while-drilling tool | |
| US20110030946A1 (en) | Method and system of transmitting electromagnetic waves from a wellbore | |
| EP0712499A4 (en) | Improved slick line system with real-time surface display | |
| BR9911332B1 (en) | device and process for detecting resistivity changes or dielectric properties, and process for recording electrical properties probing in a geological formation while drilling a well. | |
| RU2005133001A (en) | METHOD FOR CONTROLLING A BREED COLLECTOR LAYER WITH HIGH SPECIFIC RESISTANCE | |
| MY140383A (en) | Method and apparatus for investigating earth formations | |
| US11965415B2 (en) | Method of extending a borehole of a relief well, bottomhole assembly, drill string, and other apparatus | |
| AU7327887A (en) | Current sensing alarm arrangement for monitoring the presence of high voltage | |
| CA1244881A (en) | Electrode and assembly for induced-polarization prospecting |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |