EP0163574A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Apparatus for microinductive investigation of earth formations
Assignee: SLB NV
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Filing: 1985-05-22
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Granted: —
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Expires: 2005-05-22
Abstract
Abstract A wall-engaging apparatus for microinductively investigating a characteristic of earth formation traversed by a borehole includes an antenna set mounted in a longitudinally elongated body adapted for a sliding engagement with the wall of the borehole. The antenna set includes a first antenna element, and second and third antenna elements, having locations and orientations to place them in electromagnetic symmetry relative to the first antenna element. Means are included for differentially coupling the second and third antenna elements. Either the first antenna element or the differentially-coupled second and third antenna elements may be energized to function as a transmitter, while the other functions as a receiver of signals indicative of the characteristic. Alternative variations include a conductive body for focussing electromagnetic energy, a coductive backplane which enables half-loop antenna elements and an electroquasistatic shield which improve the performance of the antenna set.
Inventors
- 👤 Robert L. Kleinberg
- 👤 Weng Cho Chew
- 👤 Brian Clark
- 👤 Douglas D. Griffin
- 👤 Donald G. Dudley
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:03
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/26; G01V3/28
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
130 words
A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a longitudinally elongated body adapted for a sliding engagement with the wall of said borehole; an antenna set mounted in said body, comprising: a first antenna element for coupling electromagnetic energy; a second antenna element having a first location selected with respect to said first antenna element, for coupling electromagnetic energy; and a third antenna element having a second location selected with respect to said first antenna element, for coupling electromagnetic energy; and means for differentially coupling said second and third antenna elements; characterized in that said first and second locations in said antenna set are selected to place said second and third antenna elements in electromagnetic symmetry relative to said first antenna element.
Claim 2
Dependent Claim
130 words
A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a longitudinally elongated body adapted for a sliding engagement with the wall of said borehole; an antenna set mounted in said body, comprising: a first antenna element for coupling electromagnetic energy; a second antenna element having a first location selected with respect to said first antenna element, for coupling electromagnetic energy; and a third antenna element having a second location selected with respect to said first antenna element, for coupling electromagnetic energy; and means for differentially coupling said second and third antenna elements; characterized in that said first and second locations in said antenna set are selected to place said second and third antenna elements in electromagnetic symmetry relative to said first antenna element.
Claim 3
Dependent Claim
38 words
An apparatus as in claim 1, further characterized by: means for energizing said first antenna element within a frequency range of 1 MHz and 300 MHz; and receiver means coupled to said differentially-coupled second and third antenna elements.
Claim 4
Dependent Claim
40 words
An apparatus as in claim 1, further characterized by including: means for energizing said differentially coupled second and third antenna elements within a frequency range of 1 MHz and 300 MHz; and receiver means coupled to said first antenna element.
Claim 5
Dependent Claim
70 words
An apparatus as in claim 1, further characterized in that: said first antenna element comprises a conductive member conformably mounted on a stable form member; said second antenna element comprises a conductive member conformably mounted on a stable form member; and said third antenna element comprises a conductive member conformably mounted on a stable form member; said first, second and third antenna elements being essentially scale-invariant relative to one another.
Claim 6
Dependent Claim
45 words
An apparatus as in claim 4, characterized in that: said first, second, and third antenna elements are essentially coplanar; and the axis of the conductive members of said first, second, and third antenna elements are coaxial and normal to the wall-engaging face of said body.
Claim 7
Dependent Claim
122 words
An apparatus as in claim 5, characterized in that: said form comprises a ceramic disk section coaxially integrated with a ceramic cylindrical section; the conductive member of said first antenna element comprises a first loop having a preselected diameter, and being conformably mounted on said disk section coaxially therewith; the conductive member of said second antenna element comprises a second loop having a preselected diameter different than the diameter of said first loop, and being conformably mounted on said disk section coaxially therewith; and the conductive member of said third antenna element comprises a coil having a diameter and number of turns selected to place said second and third antenna elements in electromagnetic symmetry, and being conformably mounted on said cylindrical section.
Claim 8
Dependent Claim
46 words
An apparatus as in claim 4, characterized in that: said first, second, and third antenna elements are essentially coplanar; and the axis of the conductive members of said first, second, and third antenna elements are coaxial and parallel to the wall engaging face of said body.
Claim 9
Dependent Claim
122 words
An apparatus as in claim 7, characterized in that: said form comprises a ceramic disk section coaxially integrated with a ceramic cylindrical section; the conductive member af said first antenna element comprises a first loop having a preselected diameter, and being conformably mounted on said disk section coaxially therewith; the conductive member of said second antenna element comprises a second loop having a preselected diameter different than the diameter of said first loop, and being conformably mounted on said disk section coaxially therewith; and the conductive member of said third antenna element comprises a coil having a diameter and number of turns selected to place said second and third antenna elements in electromagnetic symmetry, and being conformably mounted on said cylindrical section.
Claim 10
Dependent Claim
103 words
An apparatus as in claim 1, further characterized in that: said first antenna element comprises a conductive member conformably mounted on a stable form member; said second antenna element comprises a conductive member conformably mounted on a stable form member; and said third antenna element is essentially identical to said second antenna element; wherein said first, second and third antenna elements are scale invariant relative to one another and integrally assembled; and wherein the respective locations and orientations of said second and third antenna elements are selected to place said second and third antenna elements in electromagnetic symmetry about said first antenna element.
Claim 11
Dependent Claim
38 words
An apparatus as in claim 9, characterized in that the plane of symmetry of said second and third antenna elements is oriented normal to the wall-engaging face of said body for obtaining a differential measurement of said characteristic.
Claim 12
Dependent Claim
43 words
An apparatus as in claim 10, characterized in that said body comprises a conductive backplane member oriented parallel to the wall-engaging face thereof, said first, second and third antenna elements being located between said backplane member and the wall-engaging face of said body.
Claim 13
Dependent Claim
38 words
An apparatus as in claim 9, characterized in that the plane of symmetry of said second and third antenna elements is oriented parallel to the wall-engaging face of said body for obtaining an absolute measurement of said characteristic.
Claim 14
Dependent Claim
43 words
An apparatus as in claim 12, characterized in that said body comprises a conductive backplane member oriented parallel to the wall-engaging face thereof, said first, second and third antenna elements being located between said backplane member and the wall-engaging face of said body.
Claim 15
Dependent Claim
76 words
An apparatus as in claim 9, characterized in that: said first antenna element comprises a conductive loop of a selected diameter photolithographically fabricated on a ceramic substrate; said second antenna element comprises a conductive loop of a selected diameter photolithographically fabricated on a ceramic substrate; and said third antenna element comprises a conductive loop of a diameter equal to the diameter of the conductive loop of said second antenna element, photolithographically fabricated on a ceramic substrate.
Claim 16
Dependent Claim
45 words
An apparatus as in claim 9, characterized in that said first, second and third antenna elements are coaxial loop antennae, and wherein the loop antennae of said second and third antenna elements are located essentially symmetrically about the antenna loop of said first antenna element.
Claim 17
Dependent Claim
45 words
An apparatus as in claim 9, characterized in that said first, second and third antenna elements are coplanar loop antennae, and wherein the loop antennae of said second and third antenna elements are located essentially symmetrically about the antenna loop of said first antenna element.
Claim 18
Independent Claim
159 words
An apparatus as in any one of claims 1, 9, 14, 15, and 16, further characterized by: an electroquasistatic shield element mounted coaxially with a magnetic dipole axis of one of said antenna elements, comprising a sheet of conductive, non-magnetic material having: a conductive center; a first annular band of narrow ray-like conductive segments, each of the conductive segments thereof integrally extending radially from said conductive center and being spaced from adjacent conductive segments by respective narrow radially-extending spaces originating in and traversing said first annular band; and a second annular band of ray-like conductive segments, the conductive segments thereof integrally extending radially in pairs from a respective one of the conductive segment of said first annual band, and being spaced from adjacent pairs of conductive strips of said second annual band by respective longitudinal spaces originating in said first annular band and from one another by a narrow radially-extending space originating in and traversing said second annular band.
Claim 19
Dependent Claim
80 words
An apparatus as in claim 17 further characterized by a third annular band of ray-like conductive segments, the conductive segments thereof integrally extending radially in pairs from a respective one of the conductive segment of said second annual band, and being spaced from adjacent pairs of conductive strips of said third annual band by respective longitudinal spaces originating in said second annular band and from one another by a narrow radially-extending space originating in and traversing said third annular band.
Claim 20
Dependent Claim
64 words
An apparatus as in claim 1, further characterized by: a conductive backplane member mounted in said body; wherein said first antenna element has a location selected to couple image currents in said backplane; said second antenna element has a location selected to couple image currents in said backplane; and said third antenna element has a location selected to couple image currents in said backplane.
Claim 21
Dependent Claim
63 words
An apparatus as in claim 19, characterized in that: said backplane member is parallel to the wall-engaging face of said body; said first, second and third antenna elements are coaxial half-loop antennae having respective ends located at said backplane member; and the half-loop antennae of said second and third antenna elements are located essentially symmetrically about the half-loop of said first antenna element.
Claim 22
Dependent Claim
108 words
A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a longitudinally elongated conductive body adapted for a sliding engagement with the wall of said borehole; a transmitter antenna; means for energizing said transmitter antenna; and means for detecting a magnetic field from said engaged formation arising from the coupled electrornagnetic energy; characterized in that said transmitter antenna is mounted in said body within a volume bounded in part by an integral conductive backplane and conductive sidewall and opening to the wall-engaging face of said body, for coupling focussed electromagnetic energy into a formation engaged by the wall-engaging face of said body.
Claim 23
Dependent Claim
108 words
A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a longitudinally elongated conductive body adapted for a sliding engagement with the wall of said borehole; a transmitter antenna; means for energizing said transmitter antenna; and means for detecting a magnetic field from said engaged formation arising from the coupled electrornagnetic energy; characterized in that said transmitter antenna is mounted in said body within a volume bounded in part by an integral conductive backplane and conductive sidewall and opening to the wall-engaging face of said body, for coupling focussed electromagnetic energy into a formation engaged by the wall-engaging face of said body.
Claim 24
Dependent Claim
43 words
An apparatus as in claim 21, further characterized in that said detecting means comprises a receiver antenna, said receiver antenna being integrated with said transmitter antenna and mounted therewith in said volume, said volume being conformal with said integrated transmitter and receiver antennae.
Claim 25
Dependent Claim
39 words
An apparatus as in claim 22, further characterized in that said backplane is oriented parallel to the wall-engaging face of said body, said transmitter and receiver antenna being located between said backplane and the wall-engaging face of said body.
References Cited (Backward Citations)
No citation records indexed.
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