Abstract: An apparatus is disclosed for measuring formation resistivity through a conductive pipe in a wellbore. The apparatus includes a sonde adapted to be moved through the wellbore, and a plurality of voltage measurement electrodes are disposed on the sonde at spaced apart locations. At least one current source electrode is disposed on the sonde. All the electrodes are adapted to make electrical contact with the pipe. The apparatus includes a digital voltage measuring circuit controllably coupled to selected ones of the voltage measurement electrodes.

Abstract: A method is disclosed for determining a direction of a target formation with respect to an instrument in a wellbore. The target has an electrical conductivity different than earth formations surrounding the wellbore. The method includes inducing time varying electromagnetic fields in the formations surrounding the wellbore. The electromagnetic fields have at least some components along mutually orthogonal directions. Voltages induced by the time varying electromagnetic fields are detected. The detecting is performed to have at least some component along mutually orthogonal directions. The direction of the target is calculated from the detected voltages.

Abstract: A method is disclosed for calculating the quality factor Q from a seismic data trace. The method includes calculating a first and a second minimum phase inverse wavelet at a first and a second time interval along the seismic data trace, synthetically dividing the first wavelet by the second wavelet, Fourier transforming the result of the synthetic division, calculating the logarithm of this quotient of Fourier transforms and determining the slope of a best fit line to the logarithm of the quotient.

Abstract: An electromagnetic induction logging method is disclosed. The method includes measuring electromagnetic induction response in earth formations surrounding a wellbore. The measuring is performed on an electrically conductive sonde support. The measured response is deconvolved with respect to a response of an instrument not having an electrically conductive sonde support.

Abstract: A connector is disclosed for joining two cable ends. The connector includes a load transfer plug adapted to couple to a strength member in each end of the cable. A connector insert assembly is coupled to an inner portion of each load transfer plug. Conductor terminals are disposed in corresponding openings of the insert. The terminals protrude from the insert. An alignment sleeve holder is coupled to one of the insert assemblies. The alignment sleeve holder includes alignment sleeves for receiving the protruding terminals. A housing element is sealingly coupled to an exterior of each of the plugs. The housing elements are adapted to coupled to each other and to urge the connector insert assemblies into contact with each other, and to transfer axial load between the plug coupled to each end of the cable. The housing elements have rotational and axial alignment features on corresponding surfaces. The housing elements are adapted to be removed from the plugs without uncoupling the cable from the plug.

Abstract: A method is disclosed for attenuating noise from marine seismic signals caused by a noise in the water. The method includes determining an arrival time of a noise event at each of a plurality of seismic sensors, estimating a position of the noise source from the arrival times, and attenuating the noise event from the signals detected by the seismic sensors.

Abstract: A method is disclosed for monitoring a reservoir. The method includes making a first set of electromagnetic measurements at locations along the Earth's surface, making a first measurement from at least one sensor disposed proximate the reservoir in a wellbore and determining an initial Earth model from the first electromagnetic and first sensor measurements. The initial Earth model include a fluid contact. At selected times, the sensor and electromagnetic measurements are repeated and a spatial distribution of the fluid contact is determined from the repeated measurements.

Abstract: A method is disclosed for generating an image of earth formations penetrated by a wellbore. The method includes generating an initial model of the earth formations using formation resistivity measured by a direct current signal. A response to the initial model of an instrument used to make the direct current resistivity measurements is calculated. The calculated response is compared to the measurements of resistivity. The model is adjusted, and the calculating and comparing are repeated until a difference between the calculated response and measurements reaches a minimum. The adjusted model is refined based on resistivity measurements made using an electromagnetic measuring instrument, and the refined model is constrained using acoustic velocity measurements.

Abstract: A method of nuclear magnetic resonance (NMR) well log processing. A wavelet decomposition of an NMR echo train is preformed. The resulting small scale coefficients, which may be discretely or continuously indexed by scale, in alternative embodiments, are windowed, and a first reconstruction generated therefrom by inverse wavelet transformation. The reconstructed signal is inverted and fit to a multiexponential model. Further refinements may be generated by iteratively decomposing the fitted signal at a preselected maximum scale, increasing at each iteration, generating a new coefficient by replacing the corresponding portion of the previous coefficient with the coefficient at the current scale, reconstructing the signal with the new coefficient, and fitting the signal so reconstructed to the relaxation time distribution.

Abstract: The invention is a nuclear magnetic resonance sensing apparatus comprising a magnet for inducing a static magnetic field in a region containing materials to be analyzed. The static magnetic field is polarized generally along the axis of the apparatus. The static magnetic field has a predetermined maximum longitudinal and maximum radial amplitude gradient. The apparatus includes a transmitter antenna for generating a radio frequency magnetic field in the region for exciting nuclei of the materials to be analyzed by conducting a radio frequency current through the transmitter antenna. The apparatus includes a receiving antenna for detecting a nuclear magnetic resonance signal from the excited nuclei. In a particular embodiment, the transmitter antenna and receiver antenna consist of coil pairs, each coil in a pair separated from the other by 90 degrees, to generate a circularly polarized RF magnetic field and to perform quadrature detection of the NMR signals.

Abstract: A nuclear magnetic resonance apparatus including a magnet generating a static magnetic field in a first region containing materials to be analyzed. The magnet generates zero static magnetic field in a second region. The magnet has generally homogeneous magnetization along a longitudinal axis and is magnetized substantially perpendicular to the axis. The apparatus includes means for generating a radio frequency magnetic field in the first region for exciting nuclei of the materials. The means for generating the radio frequency magnetic field includes an antenna disposed within the second region. The apparatus includes means for receiving a nuclear magnetic resonance signal from the excited nuclei. In a preferred embodiment, the means for generating and means for receiving include an antenna at least partially disposed within the second region. In a specific embodiment, the antenna consists of wire coils wound in planes perpendicular to the longitudinal axis of the instrument.

Abstract: A method for determining intrinsic transverse relaxation time of a first mobile phase in a porous medium using nuclear magnetic resonance measurement sequences. The sequences are measured at first and second wait times. At least two different interecho spacing times are used for each wait time. The first and second wait time are selected to provide different magnetization recoveries of the first phase, and are selected to be longer than the longitudinal relaxation time of a second mobile phase. For the measurements made at the first interecho spacing time, components of signals in the measurements corresponding to the first phase are separated from components corresponding to the second mobile phase by determining differences between the signals measured at the first and at the second wait times. The step of separating is performed for each of the interecho spacing times.

Abstract: A method for enhancing the axial resolution of conductivity well log measurements of in earth formation zones radially distal from a wellbore. The method includes calculating differential axial resolution information present in measurements of the conductivity of a zone radially proximal to the wellbore by low pass filtering the proximal zone measurements so as to have the same axial resolution as the measurements of earth formations radially distal from the wellbore, and subtracting the low pass filtered measurements from the measurements of the proximal zone. The differential axial resolution information is projected to conductivity values which would obtain if the proximal zone conductivity were equal to the distal zone conductivity. The projection is calculated by determining a projection factor, which is related to a weighted average of a ratio of conductivity in the distal zone with respect to the conductivity in the proximal zone.

Abstract: A method for generating an improved estimate of horizontal conductivity, dip angle, azimuth and anisotropy parameter of an earth formation penetrated by a wellbore from dual-frequency transverse electromagnetic induction measurements, comprising generating an initial estimate of the horizontal conductivity, dip angle, azimuth and anisotropy parameter from the dual-frequency transverse induction measurements made at each one of a plurality of base frequencies. The initial estimates from each of the plurality of base frequencies are input into a primary trained neural network, and the improved estimate is calculated by the trained neural network. The network is trained by generating models of earth formations each having a known value of horizontal conductivity, anisotropy parameter, dip angle and azimuth. Voltages which would be measured by the transverse electromagnetic induction instrument in response to each model are synthesized.

Abstract: 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 placed in contact with the wall by springs, hydraulics or similar mechanisms. A guard electrode surrounds each measure electrode. The instrument includes a booster current electrode axially spaced apart from the guard electrodes. An insulator axially separates the guard electrodes from the booster electrode. Monitor electrodes are disposed on the exterior of the insulator. A first bucking current circuit is connected to the guard electrodes. The first bucking current constrains the flow of measuring currents from each measure electrode to a path substantially perpendicular to the axis of the instrument. A booster current circuit is connected to the booster electrode.

Abstract: A nuclear magnetic resonance well logging apparatus including a magnet for inducing a static magnetic field in a substantially cylindrically shaped sector located in earth formations penetrated by a wellbore. The sector subtends an angle of about 60 degrees. The sector is located only on one side of the wellbore and has a longitudinal axis substantially parallel to the wellbore. The apparatus also includes a transmitter for generating a radio frequency magnetic field in the sector for exciting nuclei. The radio frequency magnetic field and the static magnetic field substantially satisfy nuclear magnetic resonance excitation conditions substantially exclusively within the sector. The apparatus includes a receiver for detecting nuclear magnetic resonance signals from the excited nuclei.

Abstract: A method of determining the continuity of earth formations between wellbores by analyzing seismic energy imparted to the formations. The energy is imparted to the formations at a plurality of depths in one wellbore and is received at a plurality of depths in another wellbore. Compressional and shear components of the seismic energy received in the other wellbore are separated. A frequency spectrum is determined for the compressional component and the shear component of the seismic energy at each selected depth. Common imparted depth stacks of the compressional components and shear components are assembled at the depths at which the seismic energy is imparted. Common received depth stacks of the compressional components and the shear components are assembled at the selected depths at which the energy is received.

Abstract: A method for estimating axial positions of formation layer boundaries from transverse electromagnetic induction signals. A first derivative is calculated with respect to depth of the induction signals. A second derivative of the signals is calculated. The second derivative is muted. Layer boundaries are selected at axial positions where the muted second derivative is non zero, and the first derivative changes sign. The selected boundaries are thickness filtered to eliminate boundaries which have the same axial spacing as the spacing between an induction transmitter and receiver used to measure the induction signals, and to eliminate boundaries having a spacing less than an axial resolution of the induction signals. In a preferred embodiment, the process is repeated using transverse induction measurements made at another alternating current frequency. Layer boundaries selected in both frequencies are determined to be the layer boundaries.

Abstract: A method for determining an initial estimate of the horizontal conductivity and the vertical conductivity of an anisotropic earth formation. Electromagnetic induction signals induced by induction transmitters oriented along three mutually orthogonal axes are measured. One of the mutually orthogonal axes is substantially parallel to a logging instrument axis. The electromagnetic induction signals are measured using first receivers each having a magnetic moment parallel to one of the orthogonal axes and using second receivers each having a magnetic moment perpendicular to a one of the orthogonal axes which is also perpendicular to the instrument axis. A relative angle of rotation of the perpendicular one of the orthogonal axes is calculated from the receiver signals measured perpendicular to the instrument axis. An intermediate measurement tensor is calculated by rotating magnitudes of the receiver signals through a negative of the angle of rotation.

Abstract: A system and method for identifying, locating and marking an underwater pipeline anomaly such as excessive pipe wall corrosion. An inspection tool is pulled through the pipeline with a cable. The cable length is precisely measured when a pipeline anomaly is detected, and a transmitter generates a signal representing the pipeline anomaly location. This measurement provides an accurate positioning system for deploying a mobile receiver, and the receiver identifies the transmitter signal for facilitating precise marking of the pipeline anomaly from the pipeline exterior. Accurate cable measurements are taken by a controller which monitors the magnitude and variations in cable tension and length.