US4651101A
Expired / Lapsed
US
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Induction logging sonde with metallic support
Assignee: Schlumberger Technology Corp
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Filing: 1985-04-03
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Granted: 1987-03-17
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Expires: 2005-04-03
Abstract
Abstract Induction logging sonde including transmitter and receiver solenoid coils mounted on a support and axially separated from each other. The support is made of conductive material and comprises at least one first longitudinal portion for mounting the coils and second longitudinal portions on each side of the first portion. At least the first portion has a substantially continuous and axisymmetric outer surface so as to favor the flow of eddy currents around the surface, whereby the electric field on that surface is substantially cancelled.
Inventors
- 👤 Thomas D. Barber
- 👤 Richard N. Chandler
- 👤 John F. Hunka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:33
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/26; G01V3/28; E; E21; E21B; E21B17/00; E21B17/003; E21B47/00; E21B47/01; E21B47/017
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
159 words
Induction logging sonde adapted for displacement in a fluidfilled borehole for investigating the formations traversed by the borehole, comprising: at least one transmitting solenoid coil transmitting at a frequency between about 10-400 KHz for generating an electromagnetic field substantially free from dielectric effects, which field induces currents in the formation, at least one receiving solenoid coil axially spaced from the transmitting coil for producing in response to the field induced by these currents a signal indicative of the conductivity of the formation, an elongate support having at least one first longitudinal portion mounting said coils in coaxial and spaced relationship thereto and second longitudinal portions on both sides of said first portion, said support being made of electrically conductive metal, at least said first portion having a substantially continuous outer surface to favor the flow of eddy currents resulting from said electromagnetic field circularly around said surface, the second portions being exposed to the pressure of the borehole fluid.
Claim 2
Dependent Claim
159 words
Induction logging sonde adapted for displacement in a fluidfilled borehole for investigating the formations traversed by the borehole, comprising: at least one transmitting solenoid coil transmitting at a frequency between about 10-400 KHz for generating an electromagnetic field substantially free from dielectric effects, which field induces currents in the formation, at least one receiving solenoid coil axially spaced from the transmitting coil for producing in response to the field induced by these currents a signal indicative of the conductivity of the formation, an elongate support having at least one first longitudinal portion mounting said coils in coaxial and spaced relationship thereto and second longitudinal portions on both sides of said first portion, said support being made of electrically conductive metal, at least said first portion having a substantially continuous outer surface to favor the flow of eddy currents resulting from said electromagnetic field circularly around said surface, the second portions being exposed to the pressure of the borehole fluid.
Claim 3
Dependent Claim
24 words
A sonde according to claim 1, wherein said second portions of the support have an outer diameter larger than that of said first portion.
Claim 4
Dependent Claim
41 words
A sonde according to claim 2, wherein the first and the second portions of the support are connected by transverse portions spaced from the end of the adjacent coil by a distance equal to at least the diameter of the coil.
Claim 5
Dependent Claim
24 words
A sonde according to claim 2, wherein the second portions of the support have an inner diameter larger than that of the first portions.
Claim 6
Dependent Claim
16 words
A sonde according to claim 1, wherein the support is made of copper or copper alloy.
Claim 7
Dependent Claim
141 words
Measurement-while-drilling sonde adapted for connection to a drill string, for providing signals indicative of the conductivity of formations traversed by a borehole being drilled, comprising at least one transmitting solenoid coil transmitting at a frequency between about 10-400 KHz for generating an electromagnetic field substantially free from dielectric effects, which field induces currents in the formation, at least one receiving solenoid coil axially spaced from the transmitting coil for producing in response to the field induced by these currents a signal indicative of the conductivity of the formation, a generally tubular elongate support of electrically conductive metal adapted for connection to a drill string, said support having portions mounting said coils in coaxial and spaced relationship thereto, said portions having a substantially continuous outer surface to favor the flow of eddy currents resulting from said electromagnetic field circularly around said surface.
Claim 8
Dependent Claim
141 words
Measurement-while-drilling sonde adapted for connection to a drill string, for providing signals indicative of the conductivity of formations traversed by a borehole being drilled, comprising at least one transmitting solenoid coil transmitting at a frequency between about 10-400 KHz for generating an electromagnetic field substantially free from dielectric effects, which field induces currents in the formation, at least one receiving solenoid coil axially spaced from the transmitting coil for producing in response to the field induced by these currents a signal indicative of the conductivity of the formation, a generally tubular elongate support of electrically conductive metal adapted for connection to a drill string, said support having portions mounting said coils in coaxial and spaced relationship thereto, said portions having a substantially continuous outer surface to favor the flow of eddy currents resulting from said electromagnetic field circularly around said surface.
Claim 9
Dependent Claim
23 words
A sonde according to claim 6, wherein said portions have a reduced outer diameter to define recesses in which the coils are received.
Claim 10
Dependent Claim
14 words
A sonde according to claim 7, wherein the coils are embedded in rubber-like material.
Claim 11
Dependent Claim
25 words
A sonde according to claim 7, wherein said portions have a surface layer of a metal having a higher conductivity than that of the support.
Claim 12
Dependent Claim
21 words
A sonde according to claim 9, wherein the support is made of stainless steel and said layer is made of copper.
Claim 13
Dependent Claim
133 words
Induction logging sonde adapted for displacement in a borehole for investigating the formations traversed by the borehole, comprising: at least one transmitting solenoid coil transmitting at a frequency between about 10-400 KHz for generating an electromagnetic field substantially free from dielectric effects, which field induces currents in the formation, at least one receiving solenoid coil axially spaced from the transmitting coil for producing in response to the field induced by these currents a signal indicative of the conductivity of the formation, an elongate support mounting said coils in coaxial and spaced relationship thereto, said support being made of electrically conductive material and having at least in the vicinity of the coils a substantially continuous and axisymmetrical outer surface to favor the flow of eddy currents resulting from said electromagnetic field around said surface.
Claim 14
Dependent Claim
133 words
Induction logging sonde adapted for displacement in a borehole for investigating the formations traversed by the borehole, comprising: at least one transmitting solenoid coil transmitting at a frequency between about 10-400 KHz for generating an electromagnetic field substantially free from dielectric effects, which field induces currents in the formation, at least one receiving solenoid coil axially spaced from the transmitting coil for producing in response to the field induced by these currents a signal indicative of the conductivity of the formation, an elongate support mounting said coils in coaxial and spaced relationship thereto, said support being made of electrically conductive material and having at least in the vicinity of the coils a substantially continuous and axisymmetrical outer surface to favor the flow of eddy currents resulting from said electromagnetic field around said surface.
Claim 15
Dependent Claim
40 words
The sonde of claim 11, wherein said substantially continuous and axisymmetrical outer surface extends beyond the end of the respective coil in the longitudinal direction by at least about one diameter of the coil on both sides of the coil.
Claim 16
Dependent Claim
53 words
A sonde according to claim 11, wherein the support comprises an outer sleeve of a first material of high conductivity and an inner core of a second material of higher mechanical resistance than said first material, the inner core having an outside diameter substantially equal to the inside diameter of the outer sleeve.
Claim 17
Dependent Claim
26 words
A sonde according to claim 13, wherein the outer sleeve is made of copper or copper alloy and the inner core is made of stainless steel.
Claim 18
Dependent Claim
38 words
A sonde according to claim 13, wherein the inner core has longitudinal grooves formed in its periphery, said grooves defining with the inner surface of the outer sleeve respective passages, whereby conductors can be routed through the support.
Claim 19
Dependent Claim
16 words
A sonde according to claim 15, wherein the inner core further defines a central longitudinal bore.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-03-16 | 1990-09-15 | 1991-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-16 | 1994-09-15 | 1995-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-16 | 1998-09-15 | 1999-03-17 | $7700.00 | Window Closed / Lapsed |