Abstract: An apparatus as method for identifying, locating, and retrieving a downhole tool from a borehole. A controller is lowered into the borehole and is capable of detecting a signal from the tool. The signal can be broadcast from the tool, can be generated in response to a signal from the controller, or can be reflected from a controller signal. The controller processes the signal to identify the location and heading of the controller from the tool, and to guide the controller toward the tool. When the controller is moved proximate to the tool, a catch mechanism can be activated to connect the tool and controller housing. The tool is then dislodged for further operation, or is retrieved to the borehole surface.

Abstract: A method for calculating the orientation of a geologic feature with respect to the axis of a wellbore drilled through earth formations. The method uses finely detailed measurements of a selected property of the earth formations made along the wall of the wellbore. The method includes the steps of segregating the finely detailed measurements by an angle subtended with respect to an arbitrary reference on the circumference of the wellbore. The measurements are further segregated into a selected axial interval along the wellbore. For each segment, for each subtended angle, the segregated measurements are spectrally analyzed with respect to spatial frequency. Coefficients of a best fit curve are determined for the phase components of the spectrally analyzed measurements with respect to the subtended angle. The orientation of the geologic feature is calculated from the best fit curve.

Abstract: A method for determining the fractional amounts of, and the thermal neutron capture cross-sections of, individual components which are included in the decay spectrum measured by a pulsed neutron well logging instrument. The instrument includes a pulsed high energy neutron source, and one or more gamma ray detectors spaced apart from the source. The method includes generating a data kernel which is made up of representors of decay components of the wellbore and of the earth formations in the vicinity of the instrument. The decay spectrum measured by the instrument is inverted to determine parameters by which the representors are scaled so that in combination the scaled representors most closely match the measured decay spectrum. The parameters represent the fractional amounts of each exponential decay component which makes up the measured exponential decay spectrum.

Abstract: A nuclear magnetic resonance sensing apparatus, including a magnet for inducing a static magnetic field within materials to be analyzed. The magnetic field is substantially coaxial with a longitudinal axis of the apparatus. The magnetic field is polarized substantially perpendicularly to the longitudinal axis and is symmetric about the axis. The static magnetic field has a maximum longitudinal gradient which is inversely related to a speed of motion of the apparatus along the longitudinal axis through the materials to be analyzed. The apparatus includes a transmitter for generating a radio frequency magnetic field in the materials for exciting nuclei in the materials. The radio frequency magnetic field is substantially orthogonal to the static magnetic field. The apparatus includes a receiver for detecting nuclear magnetic resonance signals from the excited nuclei in the materials. In a preferred embodiment, the magnet comprise magnetized cylinders stacked along the longitudinal axis.

Abstract: A method for determining a volume fraction of water moving in a predetermined direction along a highly inclined conduit. The method includes measuring a fractional volume of water occupying the conduit at a plurality of locations along the conduit. An oxygen activation velocity of the water flowing in the conduit is determined at a plurality of locations along the conduit. A counting rate of a gamma ray detector used to measure oxygen activation is normalized with respect to the measured fractional volume of water. The normalized count rates of the gamma ray detector are characterized with respect to a relative velocity between the water and the detector. The step of characterizing is performed in portions of the conduit which are sloped so that gravity acts on the water along the predetermined direction. A fraction of the characterized counting rate represented by the oxygen activation counting rates measured along the conduit is determined.

Abstract: A magnetic coupling for substantially synchronously transferring linear motion through a non magnetic barrier from a first movable element to a second movable element. The coupling comprises magnets disposed at spaced apart locations along the first element. The magnets each have a magnetization direction substantially perpendicular to a direction of motion of the first element along the non magnetic barrier. The coupling includes magnets disposed at spaced apart locations along the second element at locations corresponding to locations of the magnets op the first element. Each of the magnets on the second element has a magnetization direction inclined at an oblique angle with respect to the magnetization direction of the corresponding magnet so as to capture magnetic flux from the magnets on the first element when either of the elements is moved along the barrier.

Abstract: The invention is a shaped charge comprising a housing, a liner, a quantity of explosive inside the housing between the housing and the liner, and a retaining spring in contact with the liner and the housing. The retaining spring is positioned to retain the liner substantially immovably inside the housing and has compressed external dimensions to enable locking engagement with the housing. The retaining spring provides axial force against the liner to compress the explosive and prevent shifting and settling of the explosive. The retaining spring also exerts laterally outward force against the circumference of the liner to reduce effects of thermal contraction on the liner. In the preferred embodiment, the retaining spring comprises a bellville spring. The bellville spring has an internal diameter substantially the same as the maximum diameter of the liner to prevent interference with discharge of the detonating shaped charge.

Abstract: A system has been invented for producing a final earth model of part of an earth formation having N (one or more) layers, the method including, in one aspect, generating an initial earth model based on raw data produced by a wellbore logging tool at a location in a borehole through the earth, performing 2-D forward modeling on the initial earth model to produce an interim earth model that includes a set of synthetic tool responses data for the wellbore logging tool, comparing the synthetic tool response data to the raw data to determine whether there is misfit between them; if misfit between the synthetic tool response data and the raw data is acceptable, saving and storing the interim earth model as the final earth model; if misfit between the synthetic tool response data and the raw data is unacceptable, performing 1-D forward modeling N times on the interim earth model, producing a secondary earth model; performing 1-D inversion on the secondary earth model; and either saving the secondary earth model as t

Abstract: A method of adjusting induction receiver signals for skin effect in an induction logging instrument including a plurality of spaced apart receivers and a transmitter generating alternating magnetic fields at a plurality of frequencies. The method includes the steps of extrapolating magnitudes of the receiver signals at the plurality of frequencies, detected in response to alternating magnetic fields induced in media surrounding the instrument, to a response which would obtain at zero frequency. A model of conductivity distribution of the media surrounding the instrument is generated by inversion processing the extrapolated magnitudes. Magnitudes of the receiver responses at the plurality of frequencies are synthesized based on the model of conductivity distribution.

Abstract: A method of determining a plurality of formation models each of which will simulate the response of a well logging instrument. A measured response of the well logging instrument is used to generate an initial model using inversion processing. A response of the instrument to the initial model is synthesized. A singular value decomposition is performed on the synthetic response to generate eigenparameters of the initial model. Eigenparameters having the least significant overall contribution to the synthetic response are sequentially substituted with linear equations representing prior constraints on the initial earth model. A linear system, including the remaining ones of the eigenparameters and the linear equations is solved so that the eigenparameters are preserved exactly and the linear equations satisfy a least squares fit. An additional synthetic instrument response is generated for each solution to the linear system which falls below a predetermined error threshold.

Abstract: A method of joint inversion processing acoustic velocity and electrical resistivity well log data. The method includes generating an initial model of earth formations over an interval of interest. The initial model corresponds to earth formations for which the acoustic velocity and resistivity well log data have been measured. The initial model includes layers each having a geometry, a value of resistivity and a value of acoustic velocity. Acoustic velocity and resistivity data are synthesized based on the initial model. Differences are determined between the synthesized data and the measured data. The initial model is adjusted and the steps of synthesizing the log data and determining the differences are repeated until the differences reach a minimum, thereby generating a final model of the earth formations.

Abstract: A method for producing synthetic tool responses for a well logging tool for an earth formation, the method including, in one aspect, generating wellbore logging data for a particular part of an earth formation with a wellbore logging system with a wellbore logging tool, the earth formation having at least one layer, producing an input earth model of the particular part of the earth formation based on the wellbore logging data, inputting the input earth model to a trained artificial neural network, e.g. resident in a computer, the computer with the trained artificial neural network processing the input earth model and producing synthetic tool responses for the wellbore logging tool for one point or for a plurality of points in the earth formation.

Abstract: A method for determining the 2-dimensional distribution of horizontal and vertical electrical conductivities of earth formations surrounding a wellbore using measurements made by a transverse electromagnetic induction well logging instrument. A model is generated of the axial distribution of the horizontal and vertical conductivities, from induction signals acquired by the instrument using two-frequency alternating current. The model is generated by calculating an initial estimate of the conductivity distribution and axially inverting the estimate with respect to the measurements made using the two-frequency alternating current. Shoulder correction is applied to measurements made by the instrument using single-frequency alternating current. An estimate of the radial distribution of the conductivities is generated from the shoulder corrected induction signals acquired using the single-frequency alternating current.

Abstract: A method for determining a profile of a wall of a wellbore drilled through earth formations. The earth formations are irradiated by a source of gamma rays. Scattered gamma rays are detected at axially spaced apart locations from the source. At least one of the axially spaced apart locations is positioned on an opposite side of the source from the other ones of the spaced apart locations. A function, related to a rate of detecting the scattered gamma rays at a first one of the spaced apart locations with respect the rate of detecting scattered gamma rays at the at least one spaced apart location positioned on the opposite side of the source is calculated. Density of the earth formations, density of the fluid in the wellbore, and a difference between the densities is determined. An area bounded by the function is determined. The area is scaled with respect to the difference between the densities, and the profile is calculated from the scaled area bounded by the function.

Abstract: A method of determining the conductivity of earth formations penetrated by a wellbore. The method includes inserting an induction well logging instrument into the wellbore. The instrument includes a transmitter, a source of alternating current connected to the transmitter, and a receiver. The transmitter is energized with the alternating current, voltages induced in the receiver are recorded, and area enclosed with respect to a baseline, by voltage peaks present in the recorded voltages is determined. The enclosed area corresponds to the conductivity.

Abstract: A method for estimating porosity of an earth formation from measurements of acoustic energy traversing the earth formation and from measurements of seismoelectric voltages generated in the formation in response to the acoustic energy. The method includes the steps of measuring the acoustic energy traversing the earth formation and measuring said seismoelectric voltages generated in response to the acoustic energy traversing the formation. A seismoelectric signal is synthesized from the measurements of the acoustic energy using an initial value of the porosity. A difference is determined between the synthesized seismoelectric voltages and the measured seismoelectric voltages. The initial value of porosity is adjusted, and the steps of synthesizing the seismoelectric voltages from the acoustic signal, determining the difference, and adjusting the value of porosity are repeated until the difference drops below a predetermined threshold or the difference reaches a minimum value.

Abstract: A nuclear magnetic resonance sensing apparatus, comprising a magnet for inducing a static magnetic field in a region containing materials to be analyzed. The magnet has a longitudinal axis and substantially uniform magnetization along the axis. The apparatus includes a system for generating a radio frequency magnetic field to excite nuclei of the materials to be analyzed, which includes a first antenna having an axial length shorter than a length along the axis over which the magnet has said substantially uniform magnetization. The axial length of the first antenna is shorter in a direction of motion of the apparatus so that the radio frequency magnetic field excites the nuclei where they are substantially prepolarized by the static magnetic field to an equilibrium state along the direction of motion. The apparatus includes a system for receiving nuclear magnetic resonance signals from the excited nuclei.

Abstract: An apparatus for measuring conductivity of earth formations penetrated by a wellbore including a magnet for inducing a static magnetic field in the earth formations penetrated by the wellbore. The apparatus includes means for generating a radio frequency magnetic field in the wellbore and the earth formations, means for selectively varying a frequency of the radio frequency magnetic field, and means for receiving a nuclear magnetic resonance signal from excited nuclei in the earth formations. The means for receiving includes means for measuring a difference in phase between the magnetic resonance signal and the radio frequency magnetic field. The phase difference measured is related to the conductivity of the earth formations.

Abstract: An apparatus for measuring induction resistivity and nuclear magnetic resonance properties of earth formations penetrated by a wellbore. The apparatus includes a magnet for inducing a static magnetic field in the formations, a transmitter antenna positioned proximal to the magnet and having a principal magnetic axis substantially perpendicular to the principal magnetic field direction of the magnet. The apparatus includes receiver antennas positioned at spaced apart locations from the transmitter antenna, a circuit for generating radio frequency power pulses which is selectively connected to the transmitter antenna, and circuits for measuring the voltages induced in both the transmitter antenna and induced in the receiver antennas. The measuring circuit is adapted to measure voltages in the receiver antennas during the radio frequency power pulses, when the voltages are induced in the receiver antennas by electromagnetic induction.

Abstract: A well logging instrument string including a first section adapted to be operated substantially in contact with a wall of a wellbore, a coupling connected at one end to one end of the first section. The coupling includes first and second flexible joints for enabling relative angular deflection between the first section and a second section. The coupling includes a biasing mechanism for urging at least one of either the first or the second flexible joints, or both, to assume their positions of maximum angular deflection. The instrument string includes a second section connected to the other end of the coupling. The second section is adapted to be operated spaced apart from the wellbore wall.