Abstract: A method of correcting accelerometer and magnetometer measurements made in a well, comprising: making a series of triaxial measurements with magnetometers and accelerometers in an interval of the well to derive measured values of gravitational acceleration g, magnetic filed intensity B and the sine of the magnetic inclination sinl; obtaining known values of g, B and sinl for the interval; determining values of a correction to be applied to the measured values by simultaneously minimising the difference between the measured values and the known values of g, B and sinl for the interval; and applying the correction to the measured values to obtain in situ corrected values for g, B and sinl.

Abstract: A method of measuring depth and/or azimuth of logging data, the logging data being related to at least one property of a zone GF, CS, CA surrounding a wellbore and being measured by at least a sensor array SA1D, SA2D, the method comprising the steps of: acquiring and storing a first logging data frame F11, F21 corresponding to a first position of the sensor array, acquiring and storing a second logging data frame F12, F22 corresponding to a second position of the sensor array, the first and second position are such that the second logging data frame F12, F22 overlaps at least partially the first logging data frame F11, F21, comparing the first F11, F21 and second F12, F22 logging data frame, and calculating a relative change in the depth ?DP and/or azimuth ?AZ of logging data measured by the sensor array SA1D, SA2D between the first F11, F21 and second F12, F22 logging data frame.

Abstract: A method for depth matching borehole images and/or core section images is disclosed wherein signals from sensors at different levels on a logging tool are converted into an averaged signal representing the average bed signal at the center of the borehole at each of the different levels. A depth matching technique is applied to the averaged signals from the sensors at different levels on the logging tool to determine the optimum depth offset necessary for matching two sets of signals from sensors at the different levels of the logging tool. In an alternative embodiment of the invention a Hough transform is utilized to process the well log images and generate three-dimensional images in Hough space. The three dimensional images are converted into two-dimensional extremum curves. Depth matching is performed on the two dimensional extremum curves to calculate an offset to match the two dimensional extremum curves. The calculated offset is then applied to the well log images to depth match them.

Abstract: Apparatus for obtaining images of the wall of a borehole, comprises a tool body; a light source mounted on the tool body and arranged to illuminate the borehole wall; a camera mounted in the tool body; and a mirror moveably mounted on the tool body and spaced axially from the camera and arranged to reflect an image of the borehole wall at the camera, wherein the movement of the mirror allows images of different parts of the borehole wall to be reflected at the camera.

Abstract: Apparatus for imaging the wall of a borehole drilled through an underground formation, comprising: a light source; an optical detector device such as a CCD camera; a sensor head including a window for application against the wall of the borehole, the light source being connected to the sensor head so as to illuminate the region of the borehole wall when the sensor head is applied to the wall; and an optical fibre bundle connecting the window to the optical detector device so as to pass optical signals from the wall to the optical detector device; wherein the optical fibre bundle comprises a coherent bundle, each fibre of the coherent bundle providing one pixel of a two-dimensional, multi-pixel image of the borehole wall.

Abstract: 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 mounted on the outside face of the pad, potentials differences being measured between said measurement electrodes in order to provide measured points representative of the resistivity of the formation; both a source electrode and a return electrode adapted to inject current into the formation, the set of measurement electrodes being situated between the source electrode and the return electrode.

Abstract: 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 comprises a sensor pad supporting a current injector electrode, a current return electrode, and an array of measurement electrodes, and a circuitry for controlling current injection from the current injector electrode and for measuring voltage difference between electrodes in the array of measurement electrodes, wherein the current injector electrode and the current return electrode are disposed near opposite ends of the sensor pad and the array of measurement electrodes is disposed between the current injector electrode and the current return electrode, wherein the sensor pad is constructed of an insulating material and includes a conductive shielding member, or wherein the sensor pad is constructed of a conducting material and includes insulating sec

Abstract: The invention concerns an apparatus for investigating the wall of a borehole filled 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 mounted on the outside face of the pad, potentials differences being measured between said measurement electrodes in order to provide measured points representative of the resistivity of the formation; both a source electrode and a return electrode adapted to inject current into the formation, the set of measurement electrodes being situated between the source electrode and the return electrode.

Abstract: In general, the invention is directed to integration of passive radio frequency (RF) structures with at least one integrated circuit in a single integrated circuit (IC) package. An IC package in accordance with the invention may include, for example, a radio IC, a digital IC, a passive radio frequency balun as well as additional passive RF structures or ICs. Additionally, passive electronic components may further be incorporated in the IC package. For example, the IC package may include a resistor, capacitor, inductor or the like. The components of the IC package may be distributed throughout layers of a multi-layer IC package, such as a multi-layer ceramic package. The different ICs and the passive RF structures may be electrically coupled via conductive traces, which may be varied in thickness and length in order to match input and output impedances of the different ICs and passive RF structures.

Abstract: 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 frequency below about 100 kHz, measuring a voltage in the formation between a third position and a fourth position along the wall, the third and fourth positions being located between the first and second positions, and determining an amplitude of a component of the voltage in phase with the current.

Abstract: A method for depth matching borehole images and/or core section images is disclosed wherein signals from sensors at different levels on a logging tool are converted into an averaged signal representing the average bed signal at the center of the borehole at each of the different levels. A depth matching technique is applied to the averaged signals from the sensors at different levels on the logging tool to determine the optimum depth offset necessary for matching two sets of signals from sensors at the different levels of the logging tool. In an alternative embodiment of the invention a Hough transform is utilized to process the well log images and generate three-dimensional images in Hough space. The three dimensional images are converted into two-dimensional extremum curves. Depth matching is performed on the two dimensional extremum curves to calculate an offset to match the two dimensional extremum curves. The calculated offset is then applied to the well log images to depth match them.

Abstract: 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 frequency below about 100 kHz, measuring a voltage in the formation between a third position and a fourth position along the wall, the third and fourth positions being located between the first and second positions, and determining an amplitude of a component of the voltage in phase with the current.

Abstract: The present invention relates to a method of investigating the wall (2) of a borehole in a geological formation by means of two injectors (4, 5) with a potential V being applied between them and in measuring the potential difference ?V between two electrically isolated measurement electrodes (6) situated between the two injectors (4, 5) and spaced apart from the formation by an insulating layer (1), in which the resistivity of the formation is obtained from the measured values of ?V, V and I, with corrections being made for the effects due to the nature and the thickness of the insulating layer (1). In a first variant these corrections are based on a correction factor obtained from curves of K=Rt.I/?V as a function of the impedance V/I of the injector. In a second variant these corrections are obtained by estimating the current IF actually injected into the formation while taking account of leakage current IL, and calculating the resistivity of the formation from the equation (I).

Abstract: 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 electrodes mounted on the outside face of the pad and means for measuring the potential difference between two measurement electrodes; and both a source electrode adapted to inject current into the geological formation and a return electrode, the set of measurement electrodes being situated between the source electrode and the return electrode for the current; the apparatus being characterized in that the pad comprises an electrically conductive portion covering the entire measurement electrode zone and electrically insulated from the measurement electrodes.

Abstract: 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 comprises a sensor pad supporting a current injector electrode, a current return electrode, and an array of measurement electrodes; and a circuitry for controlling current injection from the current injector electrode and for measuring voltage difference between electrodes in the array of measurement electrodes, wherein the current injector electrode and the current return electrode are disposed near opposite ends of the sensor pad and the array of measurement electrodes is disposed between the current injector electrode and the current return electrode, wherein the sensor pad is constructed of an insulating material and includes a conductive shielding member, or wherein the sensor pad is constructed of a conducting material and includes insulating sec

Abstract: The invention provides a balun for coupling an unbalanced device with a balanced device. The balun may, for example, comprise an unbalanced balun structure having a first unbalanced component and a second unbalanced component electrically coupled to one another and a balanced balun structure having a first balanced component and a second balanced component. The first balanced component electromagnetically couples more than one side of the first unbalanced component and the second balanced component electromagnetically couples more than one side of the second unbalanced component. The unbalanced and balanced components may comprise conducting strips, such as strip lines, disposed on a dielectric layer. The balun may be formed on multiple layers or only a single layer. The balun receives unbalanced signals and outputs balanced signals, i.e., signals with a 180-degree phase shift and vice versa.

Abstract: The invention provides a balun for coupling an unbalanced device with a balanced device. The balun may, for example, comprise an unbalanced balun structure having a first unbalanced component and a second unbalanced component electrically coupled to one another and a balanced balun structure having a first balanced component and a second balanced component. The first balanced component electromagnetically couples more than one side of the first unbalanced component and the second balanced component electromagnetically couples more than one side of the second unbalanced component. The unbalanced and balanced components may comprise conducting strips, such as strip lines, disposed on a dielectric layer. The balun may be formed on multiple layers or only a single layer. The balun receives unbalanced signals and outputs balanced signals, i.e., signals with a 180-degree phase shift and vice versa.

Abstract: In general, the invention is directed to integration of passive radio frequency (RF) structures with at least one integrated circuit in a single integrated circuit (IC) package. An IC package in accordance with the invention may include, for example, a radio IC, a digital IC, a passive radio frequency balun as well as additional passive RF structures or ICs. Additionally, passive electronic components may further be incorporated in the IC package. For example, the IC package may include a resistor, capacitor, inductor or the like. The components of the IC package may be distributed throughout layers of a multi-layer IC package, such as a multi-layer ceramic package. The different ICs and the passive RF structures may be electrically coupled via conductive traces, which may be varied in thickness and length in order to match input and output impedances of the different ICs and passive RF structures.

Abstract: The present invention relates to a method of investigating the wall (2) of a borehole in a geological formation by means of two injectors (4, 5) with a potential V being applied between them and in measuring the potential difference &dgr;V between two electrically isolated measurement electrodes (6) situated between the two injectors (4, 5) and spaced apart from the formation by an insulating layer (1), in which the resistivity of the formation is obtained from the measured values of &dgr;V, V and I, with corrections being made for the effects due to the nature and the thickness of the insulating layer (1). In a first variant these corrections are based on a correction factor obtained from curves of K=Rt.I/&dgr;V as a function of the impedance V/I of the injector. In a second variant these corrections are obtained by estimating the current IF actually injected into the formation while taking account of leakage current IL, and calculating the resistivity of the formation from the equation (I).

Abstract: 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 electrodes mounted on the outside face of the pad and means for measuring the potential difference between two measurement electrodes; and both a source electrode adapted to inject current into the geological formation and a return electrode, the set of measurement electrodes being situated between the source electrode and the return electrode for the current; the apparatus being characterized in that the pad comprises an electrically conductive portion covering the entire measurement electrode zone and electrically insulated from the measurement electrodes.