Abstract: A method and system for acquiring spectral information from an energy sensitive nuclear detector is disclosed. The method includes detecting nuclear radiation at a detection device and generating an electronic input pulse indicative of energy deposited in the detection device. The method further includes integrating the electronic input pulse at an integrating device to produce an integrated output signal and digitally sampling the integrated output signal of the integrating device at intervals to produce a stream of digital samples. The method further includes resetting the integrator synchronously with a sampling clock when a limit condition is reached.

Abstract: A method and system for acquiring spectral information from an energy sensitive nuclear detector is disclosed. The method includes detecting nuclear radiation at a detection device and generating an electronic input pulse indicative of energy deposited in the detection device. The method further includes integrating the electronic input pulse at an integrating device to produce an integrated output signal and digitally sampling the integrated output signal of the integrating device at intervals to produce a stream of digital samples. The method further includes resetting the integrator synchronously with a sampling clock when a limit condition is reached.

Abstract: A method and system for acquiring spectral information from an energy sensitive nuclear detector is disclosed. The method includes detecting nuclear radiation at a detection device and generating an electronic input pulse indicative of energy deposited in the detection device. The method further includes integrating the electronic input pulse at an integrating device to produce an integrated output signal and digitally sampling the integrated output signal of the integrating device at intervals to produce a stream of digital samples. The method further includes resetting the integrator synchronously with a sampling clock when a limit condition is reached.

Abstract: A method and system for acquiring spectral information from an energy sensitive nuclear detector is disclosed. The method includes detecting nuclear radiation at a detection device and generating an electronic input pulse indicative of energy deposited in the detection device. The method further includes integrating the electronic input pulse at an integrating device to produce an integrated output signal and digitally sampling the integrated output signal of the integrating device at intervals to produce a stream of digital samples. The method further includes resetting the integrator synchronously with a sampling clock when a limit condition is reached.

Abstract: A downhole controller is used to tune the resonance frequency of an antenna after each NMR measurement sequence. At the end of the sequence, the downhole controller causes a pulse sequencer to generate a calibration pulse. The downhole controller then observes a voltage decay across the antenna after the calibration pulse. The downhole controller performs a Fast Fourier Transform (FFT) of the voltage decay to derive the resonant frequency of the antenna. The downhole controller determines a difference between the determined resonance frequency and the Larmor frequency and makes corresponding corrections by activating switches of the resonance tuning circuit. After each NMR measurement sequence, the downhole controller repeats the calibration to keep the antenna tuned to a frequency near the Larmor frequency.

Abstract: An NMR tool includes RF antennae and a cylindrical permanent magnet to establish a static magnetic B0 field for performing the NMR measurement sequence. The magnetic field of the magnet is polarized across the diameter of the magnet. A ferrite material is located adjacent to the permanent magnet. The antennae are located near opposite ends of the ferrite material and are formed from corresponding coils that are wound around the ferrite material such that the magnetic moments of the antennae are parallel to the longitudinal axis of the magnet.

Abstract: An NMR logging tool includes at least one antenna and a pulse sequencer. The pulse sequencer is coupled to said at least one antenna and is adapted to receive state descriptors that are indicative of states of an NMR measurement sequence. The pulse sequencer uses the antenna(e) to perform the NMR measurement sequence downhole in a subterranean formation in response to the state descriptors.

Abstract: A downhole controller is used to tune the resonance frequency of an antenna after each NMR measurement sequence. At the end of the sequence, the downhole controller causes a pulse sequencer to generate a calibration pulse. The downhole controller then observes a voltage decay across the antenna after the calibration pulse. The downhole controller performs a Fast Fourier Transform (FFT) of the voltage decay to derive the resonant frequency of the antenna. The downhole controller determines a difference between the determined resonance frequency and the Larmor frequency and makes corresponding corrections by activating switches of the resonance tuning circuit. After each NMR measurement sequence, the downhole controller repeats the calibration to keep the antenna tuned to a frequency near the Larmor frequency.

Abstract: An NMR tool includes RF antennae and a cylindrical permanent magnet to establish a static magnetic B0 field for performing the NMR measurement sequence. The magnetic field of the magnet is polarized across the diameter of the magnet. A ferrite material is located adjacent to the permanent magnet. The antennae are located near opposite ends of the ferrite material and are formed from corresponding coils that are wound around the ferrite material such that the magnetic moments of the antennae are parallel to the longitudinal axis of the magnet.

Abstract: The present invention is based on a digital pulse sampling and detection technique which samples a nuclear pulse train at a constant frequency asynchronously with the actual pulses, which occur at random times. The shape of pulses representative of the interaction of nuclear particles or gamma-rays with a nuclear detector is analyzed to determine the pulse length. Nuclear particles or gamma-rays are detected. A signal is formed containing pulses representative of the particles or gamma-rays. The pulses are sampled at a constant frequency to form a digital image of the pulse train. The pulse length is determined by counting the number of pulses with a first number of consecutive samples above a threshold and by counting the number of pulses with a second number of consecutive samples above the threshold. A ratio of the first and second number of consecutive samples is obtained. The ratio is used to adjust the pulse length.

Abstract: A communications system for providing communication between a downhole well logging apparatus and external equipment in which a portion of the external equipment is placed in an aperature in a side wall of the well logging and electromagnetic signals are exchanged.