Abstract: A gradient field controller (30) generates current pulses with a preselected profile. Eddy current compensation circuits (42) alter the current pulse profile by adding additional components of selectable frequencies with selectable amplitudes or gains. A power amplifier (32) amplifies the modified current pulse and applies them to gradient field coils (34) of a magnetic resonance imager. A probe or coil (50) monitors the induced gradient response which is integrated (52) to provide an electronic representation of the induced gradient profile. A least squares analysis routine (72) determines the time constant and amplitude of a component attributable to a first eddy current which degrades the induced gradient profile. A filter frequency correction factor calculating routine (76) calculates appropriate filter frequency settings and a gain calibration factor calculating routine (78) calculates the gain settings for the compensation circuits (42).

Abstract: A probehead of an MR apparatus according to this invention includes transmitting and receiving coil elements for transmitting an RF field and receiving an MR signal based on an MR phenomenon induced in an object to be examined, respectively, and switching units for controlling decoupling of the transmitting and receiving coil elements. At least the switching unit provided for the transmitting coil element includes a plurality of PIN diodes connected in parallel with each other, and reactance elements connected in series with the plurality of PIN diodes and having reactance components, absolute values of which are sufficiently larger than resistance components of the PIN diodes in an on-state.

Abstract: A method of a device for determining the spectral distribution of a nuclear magnetization in a limited volume, wherein each sequence of r.f. and gradient excitation comprises a sub-sequence which dephases the nuclear magnetization everywhere outside a defined layer. This sub-sequence is followed by three r.f. pulses, the first two of which are layer-selective. These three r.f. pulses excite the nuclear magnetization in an area of intersection between said layer and two layers which extend perpendicularly to one another and to said layer. In order to suppress undesirable FID signals and to enhance the spectrum, phase cycling is performed.

Abstract: A magnetic resonance imaging system comprises a static field generating section for generating a static field applied to an object, a gradient field application section for applying a gradient field in the form of a pulse to the object disposed in the static field, a high frequency wave transmitting/receiving section for applying an excitation pulse of a high frequency field to the object disposed in the static field and for detecting a magnetic resonance signal excited in the object, and a controlling/processing section for driving the gradient field application section and high frequency wave transmitting/receiving section at a predetermined timing and for processing the magnetic resonance signal to obtain magnetic resonance image data. The system further comprises at least one auxiliary coil, and a current supply section for supplying a current for compensating to the auxiliary coil.

Abstract: A magnetic resonance apparatus comprising a magnet for generating a stationary magnetic field, a magnetic field gradient coil for generating gradient magnetic field pulses, and a radio frequency coil disposed within the magnet and the magnetic field gradient coil for transmitting radio frequency pulses and receiving a magnetic resonance signal. A radio frequency shield member is also disposed between the magnetic field gradient coil and the radio frequency coil. The radio frequency shield member includes a plurality of electrically conductive strips each extending in the direction of axis of the magnet and at least partly overlapping with respect to a neighboring conductor strip and a plurality of non-conductors sandwiched between the adjacent two conductive strips. A ring-shaped conductor having a capacitor inserted therein is disposed at each of the axial ends of the radio frequency coil along arcuated end portion of the radio frequency coil.

Abstract: Methods and apparatus are provided to extract oil and brine fluids from a representative porous sample. The petrophysical properties of these extracted oil and brine fluids may be determined by conventional or other testing methods. The oil fluids and brine fluids are separated from each other by separate distillation and condensation, and by removing the solvent from the oil fluids. The amounts of oil and brine fluids from the sample may then be separately determined. The apparatus uses a desiccant container at the top of a soxhlet tower beneath the cold finger (which condenses the solvent gases that have been evaporated) in a pressure soxhlet extractor to capture any brine or water and thus, separate the brine or water from the oil and/or solvent which remain in the soxhlet extraction chamber at the bottom of the soxhlet tower.

Abstract: A resonance exciting coil (C) excites magnetic resonance in nuclei disposed in an image region in which a main magnetic field and transverse gradients have been produced. A flexible receiving coil (D) includes a flexible plastic sheet (40) on which one or more loops (20) are adhered to receive signals from the resonating nuclei. Velcro straps (46) strap the flexible sheet and the attached coil into close conformity with the surface of the portion of the patient to be imaged. An impedance matching or coil resonant frequency adjusting network (50) is mounted on the flexible sheet for selectively adjusting at least one of an impedance match and the peak sensitivity resonant frequency of the receiving coil. A preamplifier (52) amplifies the received signals prior to transmission on a cable (24). A selectively variable voltage source (70) applies a selectively adjustable DC bias voltage to the cable for selectively adjusting at least one of the impedance match and the LC resonant frequency of the receiving coil.

Abstract: A magnetic resonance system is arranged to invert the polarity of a slicing gradient magnetic field pulse each time the selective excitation is repeated, and additively combine two types of imaging data corresponding to the opposite polarities of the slicing gradient field pulse to form a magnetic resonance image.

Abstract: An apparatus for transferring a whole core sample having a first end and an opposing second end from the interior of an inner barrel comprising:a split receiving tube having an interior surface sized and adapted to receive the whole core sample from the inner barrel;a liner made of heat shrink material extending over a substantial portion of the interior surface of the split receiving tube;first and second discs sized and adapted to be placed on the first and second ends, respectively, of the whole core sample; anda force assembly for forcing the whole core sample from the inner barrel into the liner in the split receiving tube.

Abstract: A thin dielectric sheet (36) has a first or loop coil (30) defined on one surface thereof and a second or Helmholtz coil (32) defined on an obverse surface thereof. The dielectric sheet and associated coils may be laid flat (FIG. 3) or bent to match a selected curved surface of the subject (FIGS. 6-8). The first and second coils are arranged symmetrically about an axis or plane of symmetry (34). The first coil has an associated magnetic field along a y-axis and the second coil has an associated magnetic field along the x-axis. Circuits (40 and (42) tune the first and second magnetic resonance coils to a preselected magnetic resonance frequency. Magnetic resonance signals of the selected frequency received by one of the coils are phase shifted 90.degree. by a phase shifting circuit (50) and combined with the unphase shifted signals from the other coil by a combining circuit (52). The combined signals are amplified (54) and conveyed to electronic image processing circuitry (E) of a magnetic resonance scanner.

Abstract: A method of flowing a high viscosity substance, such as a delayed cross-linked fracturing gel, through a conduit or well fracture at a low apparent viscosity comprises selecting a cross-linkable fluid having nonhomogeneous flow properties and flowing the fluid through the conduit or well fracture at fluid conditions which produce nonhomogeneous flow of the fluid at low apparent viscosity, and preferably at a minimal apparent viscosity. Also included is a method of determining the fluid conditions at which the fluid flows nonhomogeneously at a low or minimal apparent viscosity. The method may further comprise crosslinking the fluid while inputting shear energy to the fluid and determining the ranges of shear energy input to the fluid which produce nonhomogeneous flow of the fluid at a low apparent viscosity. The fluid may then be flowed at flow rates which create fluid shear energies within the ranges which produce nonhomogeneous flow at a low or minimal apparent viscosity in a conduit or well fracture.

Abstract: A method for simultaneously obtaining a three-dimensional nuclear magnetic resonance (NMR) angiographic image of moving spins associated with fluid flow in a region of a living organism sample, and a three-dimensional NMR image of stationary tissue in the same sample region, by immersing the sample in a main static magnetic field; nutating, in an excitation subsequence of each of a plurality of NMR sequences, the nuclear spins and the generating a flow-encoding magnetic field gradient selected to cause a resulting NMR response echo signal from the spin of a moving nucleus to be different from the NMR response echo signal from the spin of a substantially stationary nucleus.

Abstract: An apparatus for nuclear magnetic resonance imaging capable of obtaining images at arbitrary cross sectional planes with an ultra high speed imaging method using a gradient field amplifier of resonant amplification type. The apparatus includes both a linear type amplifier having three channels and a resonant type amplifier having at least two channels. A nuclear magnetic resonance imaging is carried out with both of the linear and resonant type amplifiers supplying currents to the gradient coils.

Abstract: The invention demonstrates remote tuning of an NMR probe over a length of transmission line while retaining very high efficiency relative to the equivalent locally turned coil. Fixed capacitances for partial tuning are employed at the load such that a desired range of efficiency is achievable for a selected range of capacitance values at both load and source for the intervening transmission line.

Abstract: A conjoint probe apparatus having an adjustable extendable probe end for embedding in the porous media for in situ sensing of changes in the dielectric constant of the carbonaceous constituents undergoing microwave pyrolysis, and a mechanism for indicating the sensed changes, for adjusting the radiation in dependence upon such changes, the degree of extension of the probe end being adjustable in dependence upon the sensed frequency of the attendant radiation.

Abstract: Measuring apparatus for use with a motor driven rotary saw blade is disclosed so that dynamic measurements can be obtained while cutting lengthwise a core sample from a well borehole. The core sample is held, and the motor driven rotary driven saw blade is used to cut along the length of the core sample. Selected transducers are installed, and all the transducers connect to a CPU which also has connections with a clock, memory and recorder. Data is recorded either as a function of time or as a function of the location of the cutting tool along the core sample. Transducers include a current monitor for current operating the motor, a microphone measuring sound levels generated by the saw blade cutting through the core sample, a tension measuring device which provides the force which causes the motor to traverse along the length of the core sample, and also X, Y, Z coordinate vibration sensors such as accelerometers.

Abstract: Drilling muds and particulate matter are removed from the surface of core produced from a wellbore while maintaining naturally occurring fluids in the core substantially as existing at the time of removal from the wellbore.

Abstract: In order to have the number of times of signal measurements in a phase encode direction or a readout direction and raise the speed of imaging, the following steps are performed by way of example:(i) For a measurement region E required by a conventional method, any desired partial region E.sup.+ is set (here, the combination between the region E.sup.+ and a region obtained by moving the region E.sup.+ in point symmetry with respect to the origin of a measurement space includes the region E).(ii) A signal h.sup.+ is measured on the region E.sup.+.(iii) An image is reconstructed from the signals h.sup.+ on a region neighboring the origin, thereby to obtain a phase image .theta..(iv) A reconstructed image is obtained by a predetermined computation employing .theta..

Abstract: Apparatus is provided for measuring resistivities along the length of a core sample of a porous rock under confining pressure and varying fluid saturations. A confining pressure sleeve surrounds the core sample. Resistivities are measured along the length of the core sample by a plurality of electrodes extending through such sleeve as fluid saturations vary.

Abstract: A magnetic field generating system for use in a magnetic resonance imaging system to apply a static magnetic field and additionally a gradient field and a high frequency field to a body under examination in order to excite a magnetic resonance and to collect magnetic resonance data about the magnetic resonance. The field generating system comprises a superconducting including magnet a superconducting coil for generating the static magnetic field, a gradient coil for generating the gradient field and a high frequency coil for generating the high frequency field. At least part of the superconducting magnet is made of a metal member, and at least part of the metal member is interposed between the superconducting coil the gradient coil provided with non-conductive sections for impeding an eddy current.