Abstract: A light path extending between first and second zones that are sealed relative to each other by a sealing gasket is provided. The light path includes at least one optical fiber. The optical fiber is provided with a metal coating and passes through the sealing gasket.

Abstract: A method for determining mud slowness of a mud in a borehole includes determining slowness as a function of frequency for at least one fluid mode from a set of measurements acquired with a sonic tool in the borehole; and determining the mud slowness from the slowness as a function of frequency for the at least one fluid mode. A downhole sonic tool includes a transmitter capable of generating signals covering a frequency range, a high end of which is more than 30 KHz; and a receiver array comprising a plurality of receivers, which are responsive to the frequency range of the transmitter, wherein the transmitter and the receiver array are spaced apart on a tool body at a selected TR spacing.

Abstract: A device for determining the mean resistivity of a multiphase fluid having a continuous conductive phase, includes a pipe segment (4) of insulating material and a oil (6) for generating an electric current in the fluid flowing along the pipe. The device has two measurement electrodes (10, 11) spaced apart in the axial direction of the insulating segment to measure the electrical resistance between said two electrodes, the measurement electrodes being applied to the outside of the wall of the segment to perform measurement by capacitive coupling. The voltage between the measurement electrodes is measured. The device is particularly useful for determining the volume fraction (“holdup”) of water in a mixture of water and hydrocarbons.

Abstract: Techniques for determining a formation property by simplifying various two-geological-layer or multi-geological-layer models into a multi-electrical-layer model. A volume fraction of a layer in a multi-electrical-layer model is determined for an anisotropic region (sliding window) of the formation. The multi-electrical-layer electrical model includes a relative-lower-resistivity layer and a relative-higher-resistivity layer. A high-resolution resistivity measurement is used in the determination and resistivities for the relative-lower-resistivity layer and for the relative-higher-resistivity layer based on the volume fraction and bulk resistivity measure ments of the anisotropic region are determined. The formation property is based on the volume fraction, the resistivity of the relative-lower-resistivity layer, the resistivity of the relative-higher-resistivity layer, a total porosity of the anisotropic region, and bulk resistivity measurements of the region.

Abstract: A method for formation logging includes acquiring measurements of neutron-induced signals having azimuthal information using a neutron tool; processing the measurements into a plurality of azimuthal sector data for each acquisition interval; and deriving a selected parameter from the plurality of azimuthal sector data. A logging tool includes a housing adapted to move in a borehole; a circuitry having memories for storing neutron-induced measurements; a neutron source disposed in the housing; and at least one detector bank disposed in the housing spaced apart from the neutron source, wherein each of the at least one detector bank comprises at least one detector disposed around a periphery of the housing such that the at least one detector is more sensitive to signals from an azimuthal direction, and wherein count rates detected by each of the at least one detector are separately stored in the memories.

Abstract: The invention relates to a system and methods for locating a fracture in an earth formation. A method for detecting a fracture in an earth formation using an induction tool includes inducing electromagnetic fields using a set of transmitters on the induction tool. A plurality of the transmitters being arranged such that their magnetic moments are transverse or tilted with respect to the tool axis. Voltages induced in a set of receivers on the induction tool are measured, the voltages being induced by eddy currents that result from the electromagnetic fields. A plurality of receivers being arranged such that their axes are transverse or tilted with respect to the tool axis. The transmitters and receivers are spaced apart along the tool axis. The presence of the fracture is determined based on the measured voltages.

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 invention relates to a tool holder serving to receive measurement means (9, 10, 13) for characterizing a multi-phase fluid coming from a deposit (17) through which at least one well (16) passes, and flowing inside said tool holder. According to the invention, the tool holder is provided with an axial cavity (3) and with a first radial opening (4) which opens out in the inside wall of said tool holder and intercepts said axial cavity, said cavity and said opening serving to receive said measurement means. The invention also relates to a device for characterizing a multi-phase fluid coming from a deposit (17) through which at least one well (16) passes, said device comprising: a source unit (9) for emitting gamma rays through said multi-phase fluid, and a detector unit (10) having a scintillator crystal (10a) receiving said gamma rays after they have passed through the fluid.

Abstract: Techniques for labeling a two-dimensional image of a multi-dimensional object include displaying the two-dimensional image of the multi-dimensional object. A plurality of label regions are calculated in the two-dimensional image, the plurality of label regions being substantially evenly spatially distributed along the two-dimensional image. A data value having a round number is determining within each of the label regions and a label point corresponding to the data value within each of the label regions is determined. The label point within each of the label regions in the two-dimensional image is displayed along with the data value adjacent the label point within each of the label regions in the two-dimensional image.

Abstract: Techniques are presented for determining the drift of a clock adapted for subsurface disposal. Seismic signals are transmitted through the subsurface medium from an uphole location at selected times, acoustic signals associated with the transmitted seismic signals are received with acoustic sensors at identified downhole locations. First and second transit times for acoustic signals received at an identified downhole reference location are determined using the clock. A time difference between the first and second signal transit times at the reference point is calculated to determine the clock drift.

Abstract: Techniques for calibrating well-logging sensors comprising emitting a first signal into a first calibration substance disposed proximate to the sensor, measuring a first sensor response from the first signal, emitting a second signal into a second calibration substance disposed proximate to the sensor, measuring a second sensor response from the second signal, and determining a sensor response function from the first sensor response and the second sensor response. One embodiment includes providing a well-logging sensor having a known response function, determining an expected range of a quality check response of the sensor using a quality-check substance with known properties, emitting a quality check signal into the quality-check substance, measuring the quality check response from the quality check signal, and comparing the expected range with the quality check response.

Abstract: Systems and methods for determining a formation property related to formation strength and stresses are disclosed. A method for determining a formation strength includes obtaining radial formation property measurements at different wellbore pressures; generating a radial stress profile based on a formation model; generating a radial stress function from the radial stress profile; and comparing the radial formation property measurements with the radial stress function to determine the formation strength. A method for determining a formation stress profile includes deriving formation parameters from a formation radial profiling; obtaining formation log data that comprise formation density data; estimating formation stresses from the formation log data; and deriving a radial stress profile based on a formation model, the derived formation parameters, and the estimated formation stresses.

Abstract: An apparatus for stripping an insulated wire includes a resistive heater element having a first end, a second end, and a coil formed between the first end and the second end. The coil has an inner diameter that is large enough to receive a section of the insulated wire. The apparatus further includes an electronic circuit connected to the first and second ends to deliver power to the resistive heater element such that the coil uniformly distributes heat about the section of the insulated wire to thermally decompose insulation on the section of insulated wire.

Abstract: Apparatus for measuring the resistivity of a formation surrounding a borehole having a conductive casing comprises a tool body; first and second current injectors spaced apart on the tool body for injecting current into the casing; and an insulating body portion disposed between the current injectors, at least three ring electrodes being mounted on the insulating body portion between the current injectors.

Abstract: A connection for tubulars includes an outer housing, an inner housing receivable in the outer housing, a retainer member coupled to and axially restrained with respect to the inner housing, and a slidable member mounted on the inner housing and movable between an engaged position and a disengaged position. The slidable member carries a plurality of engagement elements that form an interlocking joint between the retainer member and the outer housing when the slidable member is in the engaged position.

Abstract: Methods for processing ultrasonic signal data to evaluate subsurface properties and tool orientation. Acoustic signals are transmitted into a plurality of azimuthal borehole positions. Formation echo signal transit time distributions are then determined in a plurality of azimuthal sectors for the acoustic signals. Front face echo signal transit times are also measured and farther-mode and closer-mode transit times are determined for the distribution of formation echo signals. Farther and closer tool standoffs are determined for the azimuthal sectors and a borehole diameter is determined from a summation including standoffs in opposing sectors. The standoffs are also used to determine a preferential tool position.

Abstract: The invention relates to a gravity separator for an effluent made up of a multi-phase fluid mixture comprising at least a heavy first phase and a supernatant second phase. According to the invention, said separator includes adjustment means for adjusting its geometrical separation characteristics.

Abstract: Techniques for measuring a displacement include generating a magnetic field using a magnetic field source; measuring a first magnitude of a component of the magnetic field using a sensor disposed within the magnetic field; displacing the magnetic field source; measuring a second magnitude of the component of the magnetic field using the sensor; determining a distance that the magnetic field source is displaced using the first magnitude and the second magnitude. An apparatus for measuring a radius of a hole includes a support member having at least one arm, each having a first end and a second end, the first end attached to the support member; a magnet moveably attached to the support member via the second end of the each of the at least one arm; and a first magnetic sensor fixed to the support member. An apparatus of the invention may further include a second and third sensors.

Abstract: Tubulars for monitoring subsurface reservoir characteristics in directed orientations. Elongated tubulars for permanent subsurface disposal are equipped with antennas adapted to transmit or receive electromagnetic energy. A tilted antenna is disposed within a groove on the tubular exterior. The groove includes a sealed opening to allow for passage of electromagnetic energy therethrough and the antenna is disposed within the groove in alignment with the opening such that the antenna is substantially perpendicular to the opening at the intersection. Methods for subsurface reservoir monitoring using the tubulars are also presented.

Abstract: The invention relates to an optical feedthrough including an optical fiber (11) and a protective tube (10) surrounding said fiber. In the invention, a seal (6) extends inside the annular space between the protective tube and the optical fiber, the length of said seal being greater than 50 mm.