Abstract: A method for measuring the velocity of shear waves in a formation beneath a body of water. The shear wave velocity is derived from the parameters of water density, water-bottom reflection coefficient, formation compressional wave, velocity and the propagation velocity of a submarine ground-roll wave front.

Abstract: A production logging tool for use in deviated wellbores is provided having an elongate tool body and an elongate sensor probe that is capable of lateral movement relative to the tool body. The sensor probe is connected to the tool body by a mechanism serving to deploy the sensor probe such that it is oriented across the wellbore. The tool body has a defined weight and the probe has a weight less than the defined weight, thus causing gravity induced orientation of the sensor probe so as to extend from top to bottom of the fluid passage for sensing all phases of the fluid present therein. The sensor probe is typically of elongate configuration and may support a single elongate sensor or a plurality of independent similar or dissimilar sensors arranged in spaced relation along the length of the probe. Orientation of the sensor probe across the borehole is accomplished mechanically by coil or leaf springs or by a hydraulically or pneumatically powered mechanism or by an electric motor driven mechanism.

Abstract: A method of reducing effects of noise in seismic signals generated by a plurality of seismic sensors at spaced apart locations from a seismic source is disclosed. Each of the signals is represented by a signal trace in a record section. The method includes the steps of isolating noise in the signal traces, time aligning corresponding portions of the noise in the traces thereby generating time-aligned noise traces, stacking the time-aligned noise trace to generate a stacked noise trace, replicating the stacked noise trace at each corresponding trace position in the record section, restoring the replicated traces to the original trace time positions by reversing the step of time-aligning to generate noise signature traces, comparing the noise signature traces to corresponding signal traces to generate filters which substantially minimize a measure of the difference between the noise signature traces and the signal traces.

Abstract: A liner for a shaped charge formed from a mixture of powdered tungsten and powdered metal binder. The liner is formed by compression of the mixture into a substantially conically shaped solid body. In a preferred embodiment of the invention, the mixture comprises approximately 80 percent by weight of tungsten and 20 percent of the powdered metal binder. In a specific embodiment of the invention, graphite powder is intermixed with the powdered metal binder and tungsten to act as a lubricant. The powdered metal binder preferably comprises a malleable, ductile metal such as lead, bismuth, tin, zinc, silver, antimony, cobalt, nickel or uranium.

Abstract: An improved shaped charge for generating a jet. A lens shaped waveshaper is positioned within the explosive material of a shaped charge to modify the shape of the divergent detonation wave into a planar wave or a converging wave. The waveshaper is formed with a low sound speed material having a high index of refraction. By reshaping the detonation wave, the acceleration of the shaped charge liner is increased, and the penetration depth and hole size of the jet can be increased. The shaped charge operates more efficiently, thereby requiring less explosive material than a conventional shaped charge.

Abstract: The invention is a method of determining the flow regime of fluid having more than one phase flowing in a conduit. The method includes the step of positioning a sensor in the conduit, the sensor generating measurements capable of discriminating more than one phase in the fluids, generating measurements from the sensor for a period of time, characterizing the measurements with respect to changes in magnitude of the measurements occurring during the period of time, and comparing the characterized measurements to similarly characterized measurements of a similar sensor positioned within flow streams having known flow regimes.In a preferred embodiment of the invention, the characterization of the measurements includes performing a variability analysis of the measurements.

Abstract: The amplitude spectrum is generated within a selected time window of a seismic time scale recording. The rate of change, Q, of the natural logarithm of the signal amplitude is measured with respect to frequency. A Q-derived static time shift is computed and applied to the selected seismic time scale trace to correct the raw seismic times for dispersion-induced time distortion. Amplitude-correction and phase-correction filters are applied to the static-corrected trace to provide a new time scale trace corrected for velocity dispersion which is processed to provide a physical model of the subsurface of the earth.

Abstract: The invention is a system for conducting a geophysical survey in a wellbore, comprising a battery-powered, self-contained borehole seismic receiver which internally digitizes and records an electrical signal generated by a transducer in the receiver, and a surface control unit which records the acoustic signature of the seismic energy source deployed at the earth's surface, controls the firing of the seismic source, and correlates the recording in the receiver to the recording of the source to determine the travel time of the seismic energy through the earth.

Abstract: The present invention is a differential pressure fluid density production logging tool. The tool comprises an elongated housing adapted to traverse a wellbore. The housing has ports in hydraulic communication with the wellbore at spaced apart locations. The tool also comprises a differential pressure transducer having two inputs, a selective valve, and a reference tube filled with a liquid having a known density. The valve is selectively operable to shunt the inputs of the transducer, to connect the reference tube across the inputs of the transducer to calibrate the transducer, and to connect the ports across the inputs of the transducer to enable measurement of the fluids in the wellbore.

Abstract: The invention is an apparatus for initiating a wellbore perforator comprising a first firing head for generating a first explosive signal when a first actuation signal is applied to the first firing head, a second firing head for generating a second explosive signal when a second actuation signal is applied to the second firing head, a first means for transferring the first explosive signal to shaped charges in the perforator including a first bulkhead interposed between the shaped charges and the first means for preventing transfer of low order initiation of the first means to the shaped charges, and a second means for transferring the second explosive signal to the shaped charges including a second bulkhead interposed between the shaped charges and the second means for preventing transfer of low order initiation of the second means to the shaped charges.

Abstract: An apparatus for withdrawing fluid from an earth formation comprising an elongated housing, a first inflatable elastomeric seal adapted to expansively fill an annular space between the housing and the wall of a wellbore. The seal includes axially spaced seal lips protruding from a surface of the seal. The seal lips circumscribe the seal and define a flow channel therebetween. The flow channel includes radially spaced filler blocks which divide the channel into radial segments. Each segment further includes a flow port. The apparatus includes means for inflating the seal. The apparatus includes valves connected to each of the flow ports for connecting selected flow ports to an intake of a fluid pump and connecting selected other flow ports to a discharge port of the pump. The pump is operable in conjunction with the valves to withdraw fluid from selected flow ports and to discharge fluid into other flow ports.

Abstract: The present invention is a sample tank for storing and transporting a fluid sample withdrawn from an earth formation by a formation fluid sampling tool. The sample tank includes a storage cylinder adapted to withstand high internal pressure. The storage cylinder is selectively hydraulically connected to the sampling tool for conducting the fluid sample into the storage cylinder. A fusible metal substantially surrounds the storage cylinder. The fusible metal has a melting temperature not more than the temperature of the fluid sample, so that solidification of the fusible metal maintains the fluid sample substantially at the melting temperature of the fusible metal during solidification of the fusible metal as the tool is withdrawn from the wellbore and cooled. The fusible metal is surrounded by an outer housing which contains the fusible metal when it is in a liquid state.

Abstract: A method of determining resistivity of an earth formation penetrated by a wellbore having conductive casing. The preferred embodiment includes inserting a sonde into the wellbore, the sonde having a plurality of electrodes at axially spaced apart locations adapted to electrically contact the casing, applying electrical current between a first and a second one of the electrodes and measuring the current, measuring a first voltage between a first pair of electrodes axially disposed between the first and second electrodes and measuring a second voltage between a second pair of electrodes also axially disposed between the first and second electrodes and disposed externally to the first pair to determine casing resistance in between the pairs of electrodes. A second difference between the first and second voltages is also measured.

Abstract: The signal-to-noise ratio of televiewer signals from a rotary sidewall acoustic-beam scanner is improved by replacing the volume of borehole drill fluid that lies in the path of the acoustic beam with a solid medium characterized by a lower coefficient of attenuation than that of the drill fluid.

Abstract: A method of determining the acoustic propagation velocity of an earth formation penetrated by a wellbore by processing signals from an array acoustic wellbore logging tool. The tool includes a transmitter and a plurality of receivers axially spaced apart from the transmitter. The method includes the steps of combining signals generated by ones of the receivers in response to acoustic energy propagated through the wellbore from the transmitter, to generate a synthesized signal corresponding to another one of the receivers. The step of combining includes time shifting signals from the ones of the receivers by an amount corresponding to a predetermined velocity for each propagation mode and the axial distance between the ones of receivers and the other receiver. The synthesized signal is compared to the signal generated at the other receiver in response to the acoustic energy to determine a degree of correspondence between the synthesized signal and the received signal.

Abstract: The present invention is a system for determining the depth of a logging tool attached to a cable extended into a wellbore penetrating an earth formation. In a preferred embodiment, the system includes a circuit for generating a measurement of phase shift in a sinusoidal electrical signal traversing the cable, the phase shift corresponding to a length of the cable. The system also comprises an accelerometer disposed within the tool and electrically connected to a bandpass filter and thence to a double integrator connected to the bandpass filter. The integrator calculates displacement of the tool coaxial with the wellbore. The phase shift measurement is filtered in a low pass filter. The low pass filter and the bandpass filter comprise at least some amount of bandpass overlap. The integrator output is used to generate a scale factor, which is applied to the filtered phase shift signal. The scaled phase shift signal is combined in a computer with a signal generated by a depth encoder.

Abstract: As a means for determining the preferred azimuthal alignment of a horizontal borehole, the reflection travel time vectors between an acoustic source and a plurality of equidistant seismic receivers are measured along a plurality of directional wavefield trajectories. The travel time vectors are resolved to measure the angular orientation of the strike of vertical stress patterns. The alignment of the horizontal borehole is directed perpendicularly to strike.

Abstract: A multivariate stochastic simulation application that involves the mapping of a primary variable from a combination for sparse primary data and more densely sampled secondary data. The method is applicable when the relationship between the simulated primary variable and one or more secondary variables is non-linear. The method employs a Bayesian updating rule to build a local posterior distribution for the primary variable at each simulated location. The posterior distribution is the product of a Gaussian kernel function obtained by simple kriging of the primary variable and a secondary probability function obtained directly from a scatter diagram between primary and secondary variables.

Abstract: The invention is a firing circuit for an exploding bridgewire explosive detonator which is activated only by application of an alternating current of a preselected frequency. The firing circuit comprises a bandpass filter, a voltage multiplier, and a discharge circuit.The invention can be configured to selectively detonate a plurality of exploding bridgewire detonators by assembling a plurality of firing circuits for each exploding bridgewire, each firing circuit having a bandpass filter with a different preselected frequency.

Abstract: The invention is a system for determining the epithermal neutron decay rate of an earth formation penetrated by a wellbore.