US4845433A — Apparatus for microinductive investigation of ear…

Claim 1

Independent Claim 135 words

A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; an antenna set mounted in said body, comprising: a conductive backplane member mounted in said body; a first antenna element having a location selected to couple image currents in said backplane; a second antenna element having a location to couple image currents in each backplane; and a third antenna element having a location selected to couple image currents in said backplane; wherein the locations of second and third antenna elements are further selected to place said second and third antenna elements in electromagnetic symmetry relative to said first antenna element; and; means for differentially coupling said second and third antenna elements.

Claim 2

Dependent Claim 135 words

A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; an antenna set mounted in said body, comprising: a conductive backplane member mounted in said body; a first antenna element having a location selected to couple image currents in said backplane; a second antenna element having a location to couple image currents in each backplane; and a third antenna element having a location selected to couple image currents in said backplane; wherein the locations of second and third antenna elements are further selected to place said second and third antenna elements in electromagnetic symmetry relative to said first antenna element; and; means for differentially coupling said second and third antenna elements.

Claim 3

Dependent Claim 61 words

An apparatus as in claim 1, wherein: 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 4

Dependent Claim 172 words

A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; an antenna set mounted in said body, including a conductive backplane member, a first antenna element, a second antenna element, and a third antenna element; the respective locations and orientations of said first, second and third antenna elements being selected to couple image currents in said backplane member and to place said second and third antenna elements in electromagnetic symmetry relative to said first antenna element; means for differentially coupling said second and third antenna elements; means for energizing a selected one of said first antenna element and said differentially-coupled second and third antenna elements within a frequency range of approximately 1 MHz to 300 MHz to induce currents in a formation engaged by said wall-engaging face; and receiver means coupled to the other one of said first antenna element and said differentially-coupled second and third antenna elements.

Claim 5

Dependent Claim 172 words

A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; an antenna set mounted in said body, including a conductive backplane member, a first antenna element, a second antenna element, and a third antenna element; the respective locations and orientations of said first, second and third antenna elements being selected to couple image currents in said backplane member and to place said second and third antenna elements in electromagnetic symmetry relative to said first antenna element; means for differentially coupling said second and third antenna elements; means for energizing a selected one of said first antenna element and said differentially-coupled second and third antenna elements within a frequency range of approximately 1 MHz to 300 MHz to induce currents in a formation engaged by said wall-engaging face; and receiver means coupled to the other one of said first antenna element and said differentially-coupled second and third antenna elements.

Claim 6

Dependent Claim 61 words

An apparatus as in claim 3, wherein: 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 7

Dependent Claim 142 words

A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; transmitter antenna mounted in said body for coupling electromagnetic energy into a formation, said transmitter antenna having a conductive backplane member and a conductive antenna element located to couple image currents in said transmitter backplane member; a receiver antenna mounted in said body and having differentially coupled antenna elements and respective backplane elements located in electromagnetic symmetry relative to said transmitter means, said receiver elements being located to couple image currents in said respective receiver backplane elements; means for energizing said transmitter antenna in the frequency range of approximately 1 MHz to 300 MHz; and means coupled to said receiver antenna for obtaining an indication of said characteristic.

Claim 8

Dependent Claim 142 words

A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; transmitter antenna mounted in said body for coupling electromagnetic energy into a formation, said transmitter antenna having a conductive backplane member and a conductive antenna element located to couple image currents in said transmitter backplane member; a receiver antenna mounted in said body and having differentially coupled antenna elements and respective backplane elements located in electromagnetic symmetry relative to said transmitter means, said receiver elements being located to couple image currents in said respective receiver backplane elements; means for energizing said transmitter antenna in the frequency range of approximately 1 MHz to 300 MHz; and means coupled to said receiver antenna for obtaining an indication of said characteristic.

Claim 9

Dependent Claim 61 words

An apparatus as in claim 5, wherein: 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 10

Dependent Claim 149 words

A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; a receiver antenna mounted in said body, said receiver antenna having a conductive backplane member and a conductive antenna element located to couple image currents in said receiver backplane member; a transmitter antenna mounted in said body for coupling electromagnetic energy into a formation adjacent said wall-engaging face, said transmitter antenna having differentially coupled antenna elements and respective backplane elements located in electromagnetic symmetry relative to said receiver antenna, said transmitter elements being located to couple image currents in said respective transmitter backplane member; means for energizing said transmitter antenna in the frequency range for approximately 1 MHz to 300 MHz; and means coupled to said receiver antenna for obtaining an indication of said characteristic.

Claim 11

Dependent Claim 149 words

A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; a receiver antenna mounted in said body, said receiver antenna having a conductive backplane member and a conductive antenna element located to couple image currents in said receiver backplane member; a transmitter antenna mounted in said body for coupling electromagnetic energy into a formation adjacent said wall-engaging face, said transmitter antenna having differentially coupled antenna elements and respective backplane elements located in electromagnetic symmetry relative to said receiver antenna, said transmitter elements being located to couple image currents in said respective transmitter backplane member; means for energizing said transmitter antenna in the frequency range for approximately 1 MHz to 300 MHz; and means coupled to said receiver antenna for obtaining an indication of said characteristic.

Claim 12

Dependent Claim 61 words

An apparatus as in claim 7, wherein: 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 13

Dependent Claim 20 words

An apparatus as in claim 1 wherein said first, second and third antenna elements each comprises a conductive wire element.

Claim 14

Dependent Claim 43 words

An apparatus as in claim 9 wherein said antenna set further comprises conductive side walls adjacent and transverse to said conductive backplane, said side walls being dimensioned and positioned in said body to focus electromagnetic energy into a formation adjacent said wall-engaging face.

Claim 15

Dependent Claim 44 words

An apparatus as in claim 9 wherein said first conductive wire element comprises a semi-circularly shaped antenna wire element, and said second and third conductive wire elements comprise semi-circularly shaped antenna wire elements positioned parallel to and symmetric about said first conductive wire element.

Claim 16

Dependent Claim 19 words

An apparatus as in claim 11 wherein the ends of said semi-circularly shaped antenna elements originate in said backplane.

Claim 17

Dependent Claim 16 words

An apparatus as in claim 10 wherein said wall-engaging face further comprises a substantially conductive face.

Claim 18

Independent Claim 136 words

An apparatus for microinductively determining the conductivity of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; antenna means mounted in said body for focusing electromagnetic energy into a formation engaged by said wall-engaging face, and for obtaining an indication of induced currents therein, said antenna means including a conductive cavity, and first, second and third wire antenna elements which are positioned to couple image currents in said conductive cavity, said second and third antenna elements being positioned in electromagnetic symmetry about said first antenna element; means for differentially coupling said second and third antenna elements; receiver means coupled to said antenna means for obtaining an indication of induced currents in the selected formation, and thereby determining the conductivity thereof.

Claim 19

Independent Claim 136 words

An apparatus for microinductively determining the conductivity of earth formations traversed by a borehole, comprising: a body adapted for sliding engagement with the wall of said borehole, said body having a wall-engaging face; antenna means mounted in said body for focusing electromagnetic energy into a formation engaged by said wall-engaging face, and for obtaining an indication of induced currents therein, said antenna means including a conductive cavity, and first, second and third wire antenna elements which are positioned to couple image currents in said conductive cavity, said second and third antenna elements being positioned in electromagnetic symmetry about said first antenna element; means for differentially coupling said second and third antenna elements; receiver means coupled to said antenna means for obtaining an indication of induced currents in the selected formation, and thereby determining the conductivity thereof.

Claim 20

Dependent Claim 25 words

An apparatus as in claim 14 wherein said wire antenna elements each comprises a half loop with the ends thereof originating in said conductive cavity.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-07-03	1993-01-02	1993-07-04	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-07-03	1997-01-02	1997-07-04	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-07-03	2001-01-02	2001-07-04	$7700.00	Window Closed / Lapsed

Apparatus for microinductive investigation of earth formations

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