+

WO1993019388A1 - Dispositif de diagraphie de sondage par induction electromagnetique - Google Patents

Dispositif de diagraphie de sondage par induction electromagnetique Download PDF

Info

Publication number
WO1993019388A1
WO1993019388A1 PCT/US1992/008021 US9208021W WO9319388A1 WO 1993019388 A1 WO1993019388 A1 WO 1993019388A1 US 9208021 W US9208021 W US 9208021W WO 9319388 A1 WO9319388 A1 WO 9319388A1
Authority
WO
WIPO (PCT)
Prior art keywords
electromagnetic induction
coil
receiving coil
logging system
induction well
Prior art date
Application number
PCT/US1992/008021
Other languages
English (en)
Original Assignee
Inco Limited
J.W. Fishers Mfg., Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Inco Limited, J.W. Fishers Mfg., Inc. filed Critical Inco Limited
Publication of WO1993019388A1 publication Critical patent/WO1993019388A1/fr

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
    • G01V3/28—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 using induction coils

Definitions

  • This invention relates to geophysical exploration within a borehole, wherein induced currents are measured to reveal the electrical conductivity and magnetic susceptibility of the surrounding formations. The conductivity and susceptibility data are then used to determine the composition of the orebody along the length of the borehole.
  • Measurement devices generally consist of a transmitting antenna coil and a receiving antenna coil.
  • the coils are contained within a probe which is lowered into the borehole and connected to the surface by a cable. Electrical currents flowing in the transmitting coil create a primary magnetic field around the coil.
  • the magnetic field around the coil changes in strength. This changing magnetic field induces voltages, causing secondary current flow in the surrounding rock.
  • the secondary current in turn, generates a secondary magnetic field which is sensed at the receiving coil as induced voltage signals.
  • the secondary currents, secondary magnetic field, and induced voltage signals are proportional to the conductivity and susceptibility of the rock. Systems using these principles are described in U.S. Patent N ⁇ 3,090,910 to Moran.
  • the secondary magnetic field due to induced current flow is entirely out-of-phase with respect to the primary magnetic field and thus provides a proportional measurement standard for conductivity of the material.
  • the magnetic susceptibility of the material produces a secondary magnetic field in response to the primary magnetic field, which is entirely in-phase with the primary field.
  • the conductivity and susceptibility may be distinguished as separate components, albeit through the use of complex systems and analysis. These measurements can be used to distinguish ore from surrounding rock, as well as different types of ore. However, this complex wave separation need not be done for certain orebodies, which exhibit high conductivity accompanied by high magnetic susceptibility.
  • the present invention provides a simple, inexpensive borehole probe which provides immediate, usable data to an operator working in the mine. These parameters are critical, for instance, for a blasting engineer working by himself in a production hole who needs immediate data as to ore-rock contacts to minimize dilution in the mined ore.
  • the invention has accomplished the above in a borehole probe which utilizes a simple three pulse time domain system to provide a combined induced voltage signal resulting from both the conductivity and susceptibility of the ore.
  • a system is especially advantageous in ore bodies which have both high conductivity and high susceptibility, such as in nickel-copper sulfide ores.
  • the initial transmit pulse T induces eddy currents, which in turn induce voltage signals in the receiver.
  • the voltage signals are then sent to the sampling circuit.
  • a short timing pulse Gl is sent to the sampling circuit at the precise time at which the eddy currents would be affecting the analyzed wave shape of the induced voltage signal.
  • a second short timing pulse G2 is sent to the sampling circuit after the effects of the eddy currents have dissipated, but before the next transmit pulse is sent.
  • the magnitude of the wave induced is then compared to the off-time response of the instances marked by pulses Gl and G2 to give a precise voltage measurement, which can then be translated to conductivity plus susceptibility, and eventually to the ore make-up by calibration with known assays.
  • the transmitted pulse is nominally a square wave, but the self- induction of d e coil produces significant oscillation in the turn-off.
  • the transmitted waveform will vary with changes in host rock conductivity and/or susceptibility. This variability in the transmitted waveform may complicate the problem of quantitatively calibrating the system.
  • the response can be approximated by the step-function transit response of a small coil in a uniform half-space of conductivity ⁇ and susceptibility ⁇ .
  • the voltage induced in a coincident receiving coil is given approximately by
  • the present system measures the difference in voltages between readings at t lf and j (i.e., Gl and G2). This difference is directly proportional to o 3 ' 2 and ⁇ 12 . This system, therefore, even at low induction numbers, responds to both ⁇ and ⁇ . In general, however, the conductivity response will dominate because the range of conductivity between ore and non-ore will be greater.
  • the voltage measurements may be revealed on a meter located near the operator to provide immediate and meaningful data and may be set to eliminate all but the most intense responses.
  • One embodiment of the invention which has been found to give superior results when used with a nickel-copper sulfide system comprises a transmit pulse of 120 ⁇ sec duration at 100 msec intervals, and two timing 20 ⁇ sec timing pulses. It is contemplated that similar pulsing arrangements will be effective with similarly conductive and magnetic ore bodies and such arrangements are within the purview of this invention.
  • FIG. 1 is a schematic diagram of the well-logging device of the claimed invention
  • FIG. 2 is a longitudinal partial cross-sectional view of the probe of the claimed device
  • FIG. 3 is a schematic profile of the transmit and timing pulses of the claimed device.
  • FIG. 4 is a circuit diagram of an embodiment of the claimed device.
  • the well-logging device of the present invention comprises a cylindrical sensor probe 1 connected at its tail end by a cable 2 to a control box 3 which remains at the surface with the system operator.
  • the probe 1 shown in FIG. 2 should be a suitable diameter so as to comfortably house the necessary internal parts and to fit within operating distance of the borehole walls 4.
  • the probe In a preferred arrangement for a borehole of 5.1-21 cm diameter, the probe is 5.1 cm in diameter, with tube length of 61 cm and overall length of 68.5 cm.
  • the probe 1 houses a cylindrical combined transmitter and sensor (receiving) coil 6 disposed towards the nose end 9 of the probe 1 and oriented perpendicular to the length of the borehole 5.
  • the coil 6 is a simple 56-turn coil having 3.49 cm diameter.
  • the sensor coil 6, probe electronics board 7, and ballast weight 8 are located in the front section 10 of the probe 1.
  • the probe is waterproof and has double O-ring seals 11 at both ends 9, 12.
  • the rear compartment 13 houses the waterproof cable connectors 14.
  • the cable 2 is communicated to the electronics board 7 in the front section 10 through a waterproof feedthrough bolt 16 situated within a waterproof baffle 17, which functions to keep the front section 10 of the probe free of water.
  • the ballast 8 ensures that the probe has negative buoyancy and will sink nose down should water be encountered in the borehole.
  • the claimed device requires no physical connection to the tested wall surface. However, it is beneficial if the probe is kept accurately centered within the borehole, so as to take advantage of the 360° orientation of the coil. While readings may be taken with the probe close to or touching a wall, such readings may not be reproducible if the ore concentration does not exhibit radial symmetry.
  • the cable 2 transfers power and timing control from the control box 3 to the coil 6, and sends the amplified return signals from the coil 6 to the control box 3 for processing.
  • the cable 2 preferably has waterproof, four-pin staggered connectors at both ends to provide for ease of connection and interchangeability.
  • the cable is marked at regular intervals to provide the operator with data regarding the depth of the probe.
  • an automated cable length counter may be employed, with the data therefrom fed directly to the processor.
  • the control box 3 remains at the surface of the terrain and may be advantageously worn on a belt around the operator's waist.
  • the control box is waterproof and contains all the necessary controls, connectors and indicators for complete operation of the system.
  • a rechargeable battery pack within the control box provides for ease of operation in remote locales.
  • the meter is calibrated by standard methods using rock and ore samples of known composition.
  • the first pulse generated is the transmit pulse T, a 120 ⁇ sec pulse occurring every 100 msec.
  • the transmit pulse T goes directiy to the probe electronics and activates the pulse driver circuit 26.
  • the pulse driver circuit produces a 5 amp, 120 ⁇ sec wide pulse to the sensor coil 6.
  • the 5.1 cm diameter coil 6 produces an intense magnetic field which lasts for 120 ⁇ sec. During this pulse time, any metals or detectable minerals that are within the generated magnetic field have eddy currents induced in them as a result of this magnetic field.
  • the sensor coil 6 receives the kickback and damped wave signal from the collapsing field and sends it to the pre-amp/driver 28, where it is amplified and sent via the cable 2 to the control box 3.
  • the signal arrives at the sampling circuit 30 and is gated in by pulses Gl and G2 from the timing circuit 24.
  • a 20 ⁇ sec pulse Gl occurs precisely at the time that any eddy currents would be affecting the waveshape.
  • G2 also a 20 ⁇ sec pulse, occurs after eddy currents would affect the wave shape and before the commencement of the next transmit pulse T.
  • the specified pulsing pattern has been found to be especially effective when used in the exploration of nickel-copper sulfide ores. It is expected that the pattern may be adjusted to suit different types of orebodies.
  • the output of the sampling circuit 30 feeds a differential amp 32 which compares the signal at the times of the pulses Gl and G2. Without eddy currents, the signal would be basically d e same and the output of the differential amp would be zero. If eddy currents are present, the two signals would be different and the output of the differential amp would be positive. The differential amp output increases in relation to increasing eddy currents.
  • the differential signals received may be sent to a digital data logger 34, such as the DL55 by Geonics Limited of Canada, which stores the signals digitally for continuing depths of the borehole.
  • the data logger is connected to a computer which translates the stored data into ore composition, e.g., nickel concentration, by comparing the data with the conductivity or susceptibility of known assays.
  • the ore composition is then plotted against the borehole depth to generate a concentration profile.
  • a visual voltage meter 36 and/or an audio device 38 for providing immediately usable information during mining operations, such as placing charges for blasting.
  • the analog voltage meter 36 and audio device 38 may be advantageously set to give discernable readings for only the highest readings, which would provide accurate information as to the location of desirable ores.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

Un dispositif de diagraphie de sondage par induction électromagnétique permet de mesurer l'effet combiné de la conductivité électrique et de la sensibilité magnétique présentes dans un gisement très conducteur et fortement magnétique. Il comprend un bobinage émetteur-récepteur (6) placé dans une sonde de forage qui, combiné à un système de mesure temporelle, produit puis capte des courants turbulents dans le minerai environnant. Un circuit de synchronisation (24) engendre un groupe de deux impulsions de synchronisation identiques intercalé entre des impulsions électriques primaires successives provenant du système de mesure temporelle. Un discriminateur (32) recueille les signaux reçus du bobinage et du circuit de synchronisation et les compare pour fournir alors une mesure relative combinant la conductivité et la sensibilité du gisement.
PCT/US1992/008021 1992-03-23 1992-09-22 Dispositif de diagraphie de sondage par induction electromagnetique WO1993019388A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US85526792A 1992-03-23 1992-03-23
US07/855,267 1992-03-23

Publications (1)

Publication Number Publication Date
WO1993019388A1 true WO1993019388A1 (fr) 1993-09-30

Family

ID=25320800

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1992/008021 WO1993019388A1 (fr) 1992-03-23 1992-09-22 Dispositif de diagraphie de sondage par induction electromagnetique

Country Status (3)

Country Link
AU (1) AU2673492A (fr)
WO (1) WO1993019388A1 (fr)
ZA (1) ZA932022B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2758580C1 (ru) * 2020-12-02 2021-10-29 Федеральное государственное бюджетное учреждение науки Институт геофизики им. Ю.П. Булашевича Уральского отделения Российской академии наук Скважинное устройство для измерения электропроводности и магнитной восприимчивости горных пород
US11377946B2 (en) 2018-03-13 2022-07-05 Halliburton Energy Services, Inc. Borehole imaging tool

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2623923A (en) * 1951-04-23 1952-12-30 Schlumberger Well Surv Corp Electrostatically shielded magnetic well logging system
US3014177A (en) * 1957-06-24 1961-12-19 Shell Oil Co Electromagnetic earth surveying apparatus
US4314339A (en) * 1971-09-07 1982-02-02 Schlumberger Limited Method of generating subsurface characteristics models
US4327412A (en) * 1972-07-31 1982-04-27 Schlumberger Limited Well logging data processing technique
US4551681A (en) * 1983-05-02 1985-11-05 The United States Of America As Represented By The Secretary Of The Interior Magnetic susceptibility well-logging unit with single power supply thermoregulation system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2623923A (en) * 1951-04-23 1952-12-30 Schlumberger Well Surv Corp Electrostatically shielded magnetic well logging system
US3014177A (en) * 1957-06-24 1961-12-19 Shell Oil Co Electromagnetic earth surveying apparatus
US4314339A (en) * 1971-09-07 1982-02-02 Schlumberger Limited Method of generating subsurface characteristics models
US4327412A (en) * 1972-07-31 1982-04-27 Schlumberger Limited Well logging data processing technique
US4551681A (en) * 1983-05-02 1985-11-05 The United States Of America As Represented By The Secretary Of The Interior Magnetic susceptibility well-logging unit with single power supply thermoregulation system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11377946B2 (en) 2018-03-13 2022-07-05 Halliburton Energy Services, Inc. Borehole imaging tool
RU2758580C1 (ru) * 2020-12-02 2021-10-29 Федеральное государственное бюджетное учреждение науки Институт геофизики им. Ю.П. Булашевича Уральского отделения Российской академии наук Скважинное устройство для измерения электропроводности и магнитной восприимчивости горных пород

Also Published As

Publication number Publication date
ZA932022B (en) 1993-12-30
AU2673492A (en) 1993-10-21

Similar Documents

Publication Publication Date Title
Won et al. GEM-2: A new multifrequency electromagnetic sensor
EP0796446B1 (fr) Procede et dispositif de diagraphie de formations souterraines au moyen du radar
US4600356A (en) Underground pipeline and cable detector and process
US4845434A (en) Magnetometer circuitry for use in bore hole detection of AC magnetic fields
CA1284674C (fr) Dispositif d'enregistrement a induction par impulsion a portee etendue, et mode d'utilisation
US6313755B1 (en) Downhole buried utility sensing and data transmission system and method
CN1869400B (zh) 随钻双感应电阻率测量仪
Daniels et al. Borehole resistivity and electromagnetic methods applied to mineral exploration
US4422043A (en) Electromagnetic wave logging dipmeter
EP1242963B1 (fr) Procede de traitement interferometrique permettant d'identifier les limites de lit
US3978396A (en) Method and apparatus for measuring electromagnetic conductivity of a medium and for detecting anomalies therein
Annan et al. Resistive-limit, time-domain AEM apparent conductivity
Annan et al. An application of airborne GEOTEM in Australian conditions
King et al. Review of geophysical technology for Ni-Cu-PGE deposits
Ibrahim et al. Frequency-Domain Electromagnetic and VLF data with an application to modeling of basement structures: A case study within, Ibadan area, Southwestern Nigeria
WO1993019388A1 (fr) Dispositif de diagraphie de sondage par induction electromagnetique
US5208539A (en) Method for determining electromagnetically the locations of underground ore deposits
IE54890B1 (en) A method and apparatus for correcting the relative motion of a transmitter and a receiver in airborne electromagnetic prospecting
Macnae et al. Classification of sign changes in Borehole TEM decays
Stolz Electromagnetic methods applied to exploration for deep nickel sulphides in the Leinster area, Western Australia
RU2526520C2 (ru) Способ и устройство для измерения кажущегося электрического сопротивления пород в условиях обсаженных скважин
US4774469A (en) Method of determining the mineral composition of ore bodies in rock mass
Eadie The downhole EM response of the Hellyer ore deposit
Buselli Electrical geophysics in the USSR
GB2114752A (en) Method of determining the location of a deep-well casing by magnetic field sensing

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU CA DE FI NO RU SE

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

NENP Non-entry into the national phase

Ref country code: CA

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载