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Class Information
Number: 324/373
Name: Electricity: measuring and testing > Of geophysical surface or subsurface in situ > Using electrode arrays, circuits, structure, or supports > Coupled to artificial current source > Including separate pickup of generated fields or potentials > For well logging > Using current focussing means
Description: Subject matter in which main survey current and auxiliary guard current electrodes are provided so as to confine or "focus" the survey current to a thin horizontal path into the formations.
Sub-classes under this class:
Patents under this class:
| Patent Number |
Title Of Patent |
Date Issued |
| 7436185 |
Highly integrated logging tool |
Oct. 14, 2008 |
| 7256582 |
Method and apparatus for improved current focusing in galvanic resistivity measurement tools for wireline and measurement-while-drilling applications |
Aug. 14, 2007 |
| 7151377 |
Permanent apparatus for monitoring a well by injecting current through the casing into the formations |
Dec. 19, 2006 |
| 7109719 |
Method and apparatus for azimuthal resistivity measurements in a borehole |
Sep. 19, 2006 |
| 7042225 |
Apparatus and methods for induction-SFL logging |
May. 9, 2006 |
| 6801039 |
Apparatus and method for measuring mud resistivity using a defocused electrode system |
Oct. 5, 2004 |
| 6667621 |
Method and apparatus for determining the resistivity of a formation surrounding a cased well |
Dec. 23, 2003 |
| 6633164 |
Measuring focused through-casing resistivity using induction chokes and also using well casing as the formation contact electrodes |
Oct. 14, 2003 |
| 6426625 |
Apparatus for logging the resistivity of a geological rock formation |
Jul. 30, 2002 |
| 6373254 |
Method and apparatus for controlling the effect of contact impedance on a galvanic tool in a logging-while-drilling application |
Apr. 16, 2002 |
| 6369575 |
Methods and apparatuses for measuring the resistivity of drilling mud in a borehole |
Apr. 9, 2002 |
| 6060886 |
Radial sounding electrical well logging instrument |
May. 9, 2000 |
| 6046593 |
Method/apparatus for measuring mud resistivity using a focused-electrode system |
Apr. 4, 2000 |
| 6025722 |
Azimuthally segmented resistivity measuring apparatus and method |
Feb. 15, 2000 |
| 6023168 |
Apparatus and method for measuring the resistivity of underground formations |
Feb. 8, 2000 |
| 5883515 |
Method of determining formation resistivity utilizing combined measurements of inductive and galvanic logging instruments |
Mar. 16, 1999 |
| 5852363 |
Methods and apparatus for measuring characteristics of a formation around a borehole using computed focusing |
Dec. 22, 1998 |
| 5721492 |
Electrical logging sensor having conductive and insulating portions formed by layer deposition of hard materials and its method of manufacture |
Feb. 24, 1998 |
| 5708369 |
Capacitive measuring device |
Jan. 13, 1998 |
| 5426368 |
Logging method and apparatus for investigating geometrical characteristics of a borehole and for investigating formation resistivity |
Jun. 20, 1995 |
| 5399971 |
Method and apparatus for evaluating formation resistivity using focused annular and azimuthal electrodes |
Mar. 21, 1995 |
| 5396175 |
Method and apparatus for evaluating formation resistivity using focused annular and azimuthal electrodes |
Mar. 7, 1995 |
| 5343153 |
Well logging method and apparatus using passive azimuthal electrodes |
Aug. 30, 1994 |
| 5268641 |
Logging method and apparatus for measuring the Grondingen effect-corrected resistivity of earth formations |
Dec. 7, 1993 |
| 4786874 |
Resistivity sensor for generating asymmetrical current field and method of using the same |
Nov. 22, 1988 |
| 4743854 |
In-situ induced polarization method for determining formation permeability |
May. 10, 1988 |
| 4730162 |
Time-domain induced polarization logging method and apparatus with gated amplification level |
Mar. 8, 1988 |
| RE32564 |
Apparatus for determining the resistivity of a subsurface earth formation at different lateral distances from a bore hole wall |
Dec. 15, 1987 |
| 4697150 |
Two electrode well logging system for measuring resistivity of subsurface formations |
Sep. 29, 1987 |
| 4658215 |
Method for induced polarization logging |
Apr. 14, 1987 |
| 4646026 |
Method and apparatus for measuring resistivity of an earth formation |
Feb. 24, 1987 |
| 4583046 |
Apparatus for focused electrode induced polarization logging |
Apr. 15, 1986 |
| 4471307 |
Amplitude modulated resistivity logging system |
Sep. 11, 1984 |
| 4412180 |
Method and device with adjustable focusing for measuring the electric resistivity of geological formations |
Oct. 25, 1983 |
| 4335353 |
Method and apparatus for detecting an anomaly in a resistivity measurement of an earth formation |
Jun. 15, 1982 |
| 4286217 |
Device for electrode-type electrical logging tools and tool incorporating said device |
Aug. 25, 1981 |
| 4087740 |
Spherical focusing method and apparatus for determining the thickness of a zone in an earth formation traversed by a borehole |
May. 2, 1978 |
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