Class 324/374 - Including a pad member

Subclass of Class 324 - Electricity: measuring and testing
Definition: Subject matter in which the electrodes are mounted on the
No. of patents: 36
Last issue date: 06/28/2011

Number	Title	Issue Date
RE42493	Apparatus and method for wellbore resistivity measurements in oil-based muds using capacitive coupling A resistivity device for downhole use with a nonconducting mud injects a current at a frequency sufficiently high to pass capacitively through the mud and a mud cake into the formation. The frequency is further selected so that the impedance due to the dielectric co...	06/28/2011
7382136	Shielded apparatus for reducing an electrical field generated by a pad during electrically exploring geological formations An apparatus for investigating the wall of a borehole in a geological formation. The pad having shielding means which are arranged between a source electrode and a set of measurement electrodes and between the measurement electrodes and a return electrode. The shiel...	06/03/2008
7365545	Two-axial pad formation resistivity imager A resistivity imaging device injects currents in two orthogonal directions using two pairs of return electrodes and performing impedance measurements of the buttons placed between the returns. ...	04/29/2008
7301345	While-drilling methodology for estimating formation pressure based upon streaming potential measurements Logging-while-drilling apparatus and methodologies for measuring streaming potential in an earth formation are provided. The apparatus and methodologies can be utilized to find information relevant to the drilling operations. In particular, since the streaming poten...	11/27/2007
7265553	Method and apparatus for imaging earth formation The invention concerns an apparatus for investigating the wall of a borehole tilled with non-conductive mud, said apparatus comprising: a pad having an inside face and an outside face for pressing against the wall of the borehole; a set of measurement electrodes mou...	09/04/2007
7256582	Method and apparatus for improved current focusing in galvanic resistivity measurement tools for wireline and measurement-while-drilling applications A galvanic resistivity tool with one or more measurement electrodes and guard electrodes, and one or more shielding electrodes. The potential difference between the measurement electrodes and the guard electrodes is controlled to minimize current flow between the me...	08/14/2007
7242194	Formation imaging while drilling in non-conductive fluids A resistivity tool for investigating a wall of a borehole drilled with a non-conductive mud includes a tool body adapted to be incorporated in a logging-while-drilling tool assembly; a resistivity sensor disposed on the tool body, wherein the resistivity sensor comp...	07/10/2007
7228903	Apparatus and method for wireline imaging in nonconductive muds A pad mounted resistivity imaging device includes at least one transmitter and two or more arrays of receivers. Analysis of the received signals is done using either amplitude and phase differences between the arrays of receivers, or by analyzing amplitude and phase...	06/12/2007
7119544	Method and a tool for electrically investigating a wall of a borehole in a geologic formation A method for electrically investigating a wall of a borehole in a geologic formation including injecting a current into the formation at a first position along the wall and returning the current at a second position along the wall, the formation current having a fre...	10/10/2006
7109719	Method and apparatus for azimuthal resistivity measurements in a borehole An azimuthal resistivity logging tool includes one or more pads for making azimuthal resistivity measurements of earth formation. Current from the pads, guard electrodes and a measure electrode are measured while monitoring the voltage difference between pairs of mo...	09/19/2006
7098664	Multi-mode oil base mud imager A multi-mode oil base mud imager for use in non-conductive drilling fluid includes at least one current source—a current return pair, and one or more monitor electrodes not located between the current source and the current return of the current source-current ret...	08/29/2006
7066282	Apparatus and methods for measuring formation characteristics in presence of conductive and non-conductive muds Tools for investigating an earth formation in the presence of either oil-base or water-base mud include a circuit which induces current into the formation in a focused manner, and a sensor electrode which is isolated from the circuit, at least partially surrounded b...	06/27/2006
7046010	Multi-mode microresistivity tool in boreholes drilled with conductive mud A multi-mode resistivity tool measures at multiple depths into the near-borehole formation. By use of a four mode tool, measuring to four depths at the formation, a more accurate invasion zone resistivity measurement may be made than previously known. The tool itsel...	05/16/2006
6978672	Wireline apparatus for measuring steaming potentials and determining earth formation characteristics Earth formations are characterized by using an array of electrodes which can measure streaming potentials in the formation, and by interpreting the data obtained by the electrodes. The electrodes are placed on a wireline tool, a LWD tool, or in a fixed manner about ...	12/27/2005
6891377	Conductive pad around electrodes for investigating the wall of a borehole in a geological formation The present invention relates to apparatus for a tool for investigating the wall of a borehole in a geological formation, the apparatus comprising: a non-conductive pad having an inside face and an outside face for pressing against the wall; a set of measurement ele...	05/10/2005
6809521	Apparatus and method for wellbore resistivity measurements in oil-based muds using capacitive coupling A resistivity device for downhole use with a nonconducting mud injects a current at a frequency sufficiently high to pass capacitively through the mud and a mud cake into the formation. The frequency is further selected so that the impedance due to the dielectric co...	10/26/2004
6714014	Apparatus and method for wellbore resistivity imaging using capacitive coupling An apparatus for obtaining resistivity images of a borehole includes an array of measure electrodes separated from a pad or the body of the instrument by a focusing electrode. The focusing electrode is maintained at a slightly higher potential than the measure elect...	03/30/2004
6348796	Image focusing method and apparatus for wellbore resistivity imaging An apparatus for obtaining resistivity images of a borehole includes an array of measure electrodes separated from a pad or the body of the instrument by a guard electrode. The guard electrode is maintained at a slightly lower potential than the pad and t...	02/19/2002
6025722	Azimuthally segmented resistivity measuring apparatus and method An instrument for measuring resistivity of earth formations within azimuthal segments. The instrument includes azimuthally separated measure electrodes placed in contact with the wall of a wellbore penetrating the earth formations. The electrodes are plac...	02/15/2000
5596142	Well logging apparatus comprising a measuring pad and a combinaton device including such apparatus A well logging apparatus adapted to be moved inside a borehole includes an elongate body, a measuring pad adapted to contact the wall of the borehole, a support device for the pad mounted pivotally on one side of the body, and a counter arm which causes t...	01/21/1997
5198770	Logging apparatus having a wall engaging pad with longitudinally aligned detecting devices The apparatus includes a pad (20) pressed against the wall of a borehole (12), the pad comprising a plurality of detecting devices (42, 43, 44, 45) disposed in alignment along the longitudinal direction of the borehole. Each detecting device includes a ho...	03/30/1993
5191290	Logging apparatus for measurement of earth formation resistivity A logging apparatus for measurement of earth formation resistivity is disclosed. The apparatus includes an elongated sonde having an insulated section and an electrically isolated conductive pad mounted for lateral extension into contact with a borehole w...	03/02/1993
5049822	Method of and apparatus for carrying out measurements on open and closed fractures in a hard rock formation pierced by a borehole A microelectric method and apparatus for recording and differentiating between open and closed fractures along the walls of boreholes is disclosed. A main current and a controlled opposing or bucking current are fed into a hard rock formation in a measure...	09/17/1991
5036283	Method and apparatus for measuring the resistivity of earth formations using anti-parallel active and passive focussing electrodes The invention relates to a logging method and apparatus for determining the electrical resistivity of an earth formation traversed by a borehole. The resistivity is determined using a measuring pad which has a central electrode operable to deliver a measu...	07/30/1991
5012193	Method and apparatus for filtering data signals produced by exploration of earth formations A filter removes certain noise-induced artifacts from a two-dimensional image of a bore-hole wall, this image being formed by signals from a two-dimensional array of staggered electrodes pulled along the bore-hole wall. The noise artifacts are due to a ty...	04/30/1991
4742303	Depth and refocusing pulses for use with inhomogeneous radiofrequency coils in nuclear magnetic resonance spectroscopy In a pulsed nuclear magnetic resonance method of analysis, a series of phase cycled radiofrequency pulses of the form 2θ; θ[&#b1;x]; (2θ[&#b1;,&#b1;y])4, called a depth pulse scheme, may be applied using an irradiation coil which provides an...	05/03/1988
4692707	Method and apparatus for measuring the earth formation resistivity of a plurality of radial regions around a borehole A wall engaging pad for well logging comprises a face portion of electrically conductive material within which are disposed three or more current electrodes. The survey current emitted from the current electrodes is differently focussed. A suitable curren...	09/08/1987
4594552	Logging method and apparatus for measuring earth formation resistivity as well as arm mechanism for the same In a well logging sonde having a sonde body and wall engaging pad, the sonde body comprises two conductive sections spaced from one another by an insulating section. The pad and sonde are maintained in a relative longitudinal position such that the focuss...	06/10/1986
4588951	Arm apparatus for pad-type logging devices An apparatus is described for urging the measuring pad of a well logging sonde into engagement with the wall of a borehole. A relatively long primary arm on which the pad is mounted includes an actuator, and is pivotally connected to the body of the well ...	05/13/1986
4468623	Method and apparatus using pad carrying electrodes for electrically investigating a borehole Methods and apparatuses for electrically investigating a borehole are described. Tool mounted pads are provided, each with a plurality of small measure electrodes from which individually measurable survey currents are injected toward the wall of the boreh...	08/28/1984
4251773	Method and apparatus for exploration of geological formation tilt in boreholes Method and apparatus are disclosed for investigating lateral characteristics of an earth formation penetrated by a borehole. Substantially identical measurement transducers are mounted in a fixed separation, side-by-side relationship on a pad adapted for ...	02/17/1981
4117394	Well logging apparatus with pad-mounted vertical electrode array for measuring the resistivity of the flushed zone In accordance with an illustrative embodiment of the present invention, a well logging apparatus uses a narrow wall-engaging pad equipped with an array of long vertical electrodes. The width of the pad is between 2 and 4 inches, and the length-to-width ra...	09/26/1978
4087739	Earth formation permeability determining technique using synthetic resistivity parameters A pad mounted well logging measuring device provides a determination of permeable and impermeable zones in a subsurface earth formation....	05/02/1978
4019125	Well logging pad devices having selective differential relief A well logging instrument comprises a focus section having a focus upper guard, a center electrode and lower focus guard. The bottom section of the instrument includes a pad device having electrodes on its borehole wall-engaging surface and adapted to be ...	04/19/1977
4015197	Method and apparatus for determining permeable zones in subsurface earth formations In accordance with an illustrative embodiment of the present invention, a method and apparatus for logging an earth formation of interest is disclosed that provides an indication of the presence of permeable and impermeable zones in the earth formation....	03/29/1977
3973188	Method and apparatus for the determination of the thickness of a mudcake layer on a borehole wall traversing a subsurface earth formation An electrical well logging apparatus of the spherical focusing type is suspended in a borehole drilled into an earth formation and is utilized to provide information regarding the thickness of the mudcake formed on the borehole wall....	08/03/1976

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Class 324/374 - Including a pad member