US5138263A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electromagnetic formation evaluation tool
Assignee: Baker Hughes Oilfield Operations LLC
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Filing: 1991-01-16
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Granted: 1992-08-11
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Expires: 2011-01-16
Abstract
Abstract A tool for evaluating electrical properties of an earth formation surrounding a borehole while drilling the borehole is disclosed. The tool includes a housing for connecting upper and lower portions of a drillstring, a transmit antenna for generating electromagnetic waves at least two receiving antennas for receiving electromagnetic waves and magnetic elements associated with each of the antennas for electromagnetically coupling each of the antennas with the formation. The tool provides improved transmit efficiency and improved receiving sensitivity.
Inventors
- 👤 Jonathan Towle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:50
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/30
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
64 words
A measurement-while-drilling tool for evaluating electrical properties of an earth formation surrounding a borehole, comprising: a housing, said housing connecting upper and lower portions of a drillstring; antenna means, associated with said housing, for electromagnetically interacting with the earth formation; magnetic means for electromagnetically coupling said antenna means and the earth formation, said magnetic means being disposed between said antenna means and said housing.
Claim 2
Dependent Claim
64 words
A measurement-while-drilling tool for evaluating electrical properties of an earth formation surrounding a borehole, comprising: a housing, said housing connecting upper and lower portions of a drillstring; antenna means, associated with said housing, for electromagnetically interacting with the earth formation; magnetic means for electromagnetically coupling said antenna means and the earth formation, said magnetic means being disposed between said antenna means and said housing.
Claim 3
Dependent Claim
17 words
The tool of claim 1 wherein the antenna means comprises transmitting antenna means for generating electromagnetic waves.
Claim 4
Dependent Claim
22 words
The tool of claim 2, wherein the magnetic means directs the electromagnetic waves outwardly from the housing means and into the formation.
Claim 5
Dependent Claim
17 words
The tool of claim 1, wherein the antenna means comprises receiving antenna means for receiving electromagnetic waves.
Claim 6
Dependent Claim
21 words
The tool of claim 4, wherein the magnetic means directs the electromagnetic waves between said antenna means and said housing means.
Claim 7
Dependent Claim
28 words
The tool of claim 2, wherein the housing means comprises a cylindrical housing having an outer diametral surface and a circumferential groove defined in the outer diametral surface.
Claim 8
Dependent Claim
24 words
The tool of claim 6, wherein the antenna means comprises an antenna loop circumferentially surrounding said cylindrical housing and secured within said circumferential groove.
Claim 9
Dependent Claim
30 words
The tool of claim 7, wherein the magnetic means comprises a plurality of circumferentially spaced apart magnetic elements disposed within said groove between said antenna loop and said circumferential housing.
Claim 10
Dependent Claim
43 words
The tool of claim 8, wherein each of the magnetic elements comprises a "C"-shaped magnetic element having a curvilinear body extending from a first end to a second end and wherein said first and second ends are oriented radially outwardly from said groove.
Claim 11
Dependent Claim
18 words
The tool of claim 8, wherein the magnetic elements comprise powdered iron magnetic elements or ferrite magnetic elements.
Claim 12
Dependent Claim
25 words
The tool of claim 8, wherein each of the magnetic elements comprises a magnetic material having a relative magnetic permeability of about 10 or greater.
Claim 13
Dependent Claim
24 words
The tool of claim 11, wherein the magnetic material comprises a magnetic material having a relative magnetic permeability between about 10 and about 20.
Claim 14
Dependent Claim
25 words
The tool of claim 9, further comprising elastomeric means, bonded within said groove, for protecting the antenna loop and magnetic elements from impact and moisture.
Claim 15
Dependent Claim
27 words
The tool of claim 13, further comprising: shell means, circumferentially surrounding said elastomeric means and secured to said cylindrical housing, for protecting said elastomeric means from abrasion.
Claim 16
Dependent Claim
24 words
The tool of claim 14, wherein the shell means comprises a metal, and the shell means provides an electrostatic shield for the antenna means.
Claim 17
Dependent Claim
36 words
The tool of claim 15, wherein the shell means defines a plurality of circumferentially spaced apart longitudinally extending slots and wherein each of the slots is radially and longitudinally aligned with one of the magnetic elements.
Claim 18
Dependent Claim
34 words
The tool of claim 1, wherein the housing means comprises a cylindrical housing having an outer diametral surface and having a plurality of circumferentially spaced apart longitudinally extending slots defined in the outer surface.
Claim 19
Dependent Claim
45 words
The tool of claim 17, wherein the antenna means comprises a plurality of antenna elements, wherein the magnetic means comprises a plurality of magnetic elements and wherein one of the antenna elements and one of the magnetic elements are disposed in each of the slots.
Claim 20
Dependent Claim
50 words
The tool of claim 18, wherein each of the magnetic elements comprises a "C"-shaped magnetic element having a curvilinear body extending from a first end to a second end and wherein said first and second ends are longitudinally aligned within the slot and are oriented radially outwardly from said slot.
Claim 21
Dependent Claim
18 words
The tool of claim 18, wherein the magnetic elements comprise powdered iron magnetic elements or ferrite magnetic elements.
Claim 22
Dependent Claim
25 words
The tool of claim 19, wherein each of the magnetic elements comprises a magnetic material having a relative magnetic permeability of about 10 or greater.
Claim 23
Dependent Claim
25 words
The tool of claim 18, further comprising elastomeric means, bonded within said slot, for protecting the antenna loop and magnetic elements from impact and moisture.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-08-11 | 1996-02-10 | 1996-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-08-11 | 2000-02-10 | 2000-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-08-11 | 2004-02-10 | 2004-08-11 | $7700.00 | Window Closed / Lapsed |