Abstract: A system is provided for measuring both the temperature and pressure of fluid in a borehole utilizing a single small diameter tube extending from the surface to the desired downhole test location in a borehole. Downhole fluid pressure is transmitted through the small diameter tube, while a sheathed thermocouple line extending along the flow path of the tube is used for transmitting downhold fluid temperature information to the surface. A continuous surface read-out of both pressure and temperature is thus possible, and the temperature read-out may be used to both monitor downhole fluid temperature and increase the accuracy of the fluid pressure measurement system.

Abstract: This invention relates to methods and apparatus for analyzing a multi-phase fluid flowing along a hydrocarbon well in order to determine, at each depth, the average static proportion of one of the phases by means of a local measurement. At each depth the local static proportion of the phase under investigation is determined at a point in the flow, which point is situated on a circle having a radius r in the transverse -section corresponding to the depth, where the radius r is substantially equal to 0.7 R, and R is equal to radius of the well. The local static proportion at this point is related to the average static proportion by a determined relationship.

Abstract: A method is provided for troubleshooting gas-lift wells, to identify whether gas-lift valves on the production tubing are open or closed, without the use of wireline tools. The method may also be used to detect leaks in the production tubing or in the well casing. A quantity of a tracer gas is injected into the lift-gas at the wellhead, and its return in fluid produced from the well is monitored as a function of time. The tracer's return pattern may be correlated with the depth of entry points and volumes of lift-gas, entering along the length of the production tubing.

Abstract: An Rf coil system for the detection of MR resonance signals is constructed from a first system of coils for making an overall picture and a second coil system which covers substantially the same area, consists of several coils and for local imaging having a higher resolving power. In particular the latter coils preferably include magnetic resonance sensitive material which become visible on an image formed from detected MR resonance signals for indicating the position of each coil.

Abstract: A method is provided for generating an improved torque-drag model for at least the collar portion of the drill string in a directional oil or gas well. The techniques of the present invention determine the stiffness of incremental portions of the drill string, and uses this information, the borehole clearance, and the borehole trajectory to determine the contact locations between the drill string and the sidewalls of the well. The contact force at these determined locations can be calculated, taking into consideration all significant kinemataic, esternal, and internal forces acting on that incremental portion of the drill string. More acurate torque-drag analysis provided by the improved model of the present invention assists in well planning, prediction, and control, assists in avoiding drilling problems, and reduces total costs for the well.

Abstract: The method includes a critical time shift of a refocusing pulse between two (90.degree.) excitation pulses which produce multiple quantum coherence signals and which are followed by a (90.degree.) read pulse (using a critical timing a refocusing pulse serving the same purpose can also be applied between the second excitation pulse and the read pulse). With respect to the center of the time path between the excitation pulses or between the excitation pulse and the read pulse the time shift is chosen to be such that give resonances do not occur positively or negatively in the spectrum whereas other resonances do occur therein (i.e. at substantially maximum strength). The MRI method can be combined with the use of spatially selective gradients in order to obtain localized spectra or images.

Abstract: An improved NMR probe and method are described which substantially improve the resolution of NMR measurements made on powdered or amorphous or otherwise oreintationally disordered samples. The apparatus mechanically varies the orientation of the sample such that the time average of two or more sets of spherical harmonic functions is zero.

Abstract: The present invention relates to antennas for nuclear magnetic resonance imaging devices. The antenna (10) of the invention essentially is formed of two support plates (11, 12) made of electrically insulating material. Spacers (13) hold the two plates at a fixed distance apart in two parallel planes, and releasably fixing at least one of the two plates (11) to the spacer means (13). At least first and second turns (17, 18) of electrically conductive material are fixed on respective first faces (15, 16) of the two plates in order to form two current loops substantially centered on a common axis (100) perpendicular to the faces with capacitive coupling together of the ends of each current loop. The invention is applicable to scanners, in particular for scanning the human brain.

Abstract: An improved NMR apparatus and method are described which substantially improve the resolution of NMR measurements made on powdered or amorphous or otherwise orientationally disordered samples. The apparatus spins the sample about an axis. The angle of the axis is mechanically varied such that the time average of two or more Legendre polynomials are zero.

Abstract: During oil and gas well drilling operations, at the wellsite surface the percentage by volume of hydrocarbon gas present in the return drilling fluid is monitored in order to determine the percentage of gas saturation in the formation. Rate of penetration of the drill bit is monitored as well. A pore saturation function is derived wherein anomalously low values thereof relative to expected values for productive zones indicate flushing ahead of the drill bit of hydrocarbons out of the pore volume of cuttings in the return fluid. A mud filtrate flow rate is then determined from the drilling rate, gas saturation, and formation porosity. Pressure differential in the vicinity of the drill bit is also determined, comprised of the difference between the drilling fluid column pressure and pore pressure. Formation permeability is then directly determined in real time during the drilling operation from a functional relationship between the filtrate flow rate, pressure differential, and viscosity of the drilling fluid.

Abstract: An NMR method for acquiring the volume localized, in vivo proton spectra of spin-spin coupled metabolites employs a series of stimulated echo pulse sequences (90-TE/2-90-t.sub.1 -90-TE/2). The value of period t.sub.1 is different for each of the pulse sequences in the series, and the NMR signals produced by the series of pulse sequences are acquired and digitized to form a two-dimensional data array. A two-dimensional Fourier transformation is performed on this data array to produce an array of data that is employed to generate a contour plot.

Abstract: A magnetic resonance apparatus acquires a magnetic resonance signal matrix as follows. While a gradient field is applied to an object to be examined, a plurality of selective inversion pulses having different frequencies as high-frequency fields are sequentially applied to the object. Thereafter, a non-selective excitation pulse as a high-frequency field is applied to the object without application of a gradient field. In addition, a magnetic resonance signal generated upon application of the non-selective excitation pulse is acquired. Such a series of sequences are repeated a plurality of times, while the frequencies of the selective inversion pulses are sequentially selected to cause a magnetization vector of a nuclear spin of an area corresponding to either of "-1" and "1" an Hadamard matrix to be inverted by each selective inversion pulse.

Abstract: A method of heteronuclear decoupling in magnetic resonance spectroscopy and a device for determining a spectrum where spectra of a first type of nucleus which is spin-coupled to a second type of nucleus are decoupled inter alia in order to obtain a higher resolution. In inter alia phosphorous spectroscopy, during signal acquisition of resonance signals of the first type of nucleus, decoupling pulses are applied to the second type of nucleus, which decoupling pulses have been modulated in amplitude as well as in frequency or phase. The decoupling pulses need hardly be optimized. Very good decoupling is achieved, notably when use is made of surface coils for the transmitter and receiver coils exhibiting a substantial field inhomogeneity. When surface coils are used, suitable decoupling is achieved across a comparatively large volume.

Abstract: Apparatus is presented for measuring weight, torque and side force (bending) on a drill bit for oil and gas well drilling. This apparatus includes radial holes which do not pass completely through the wall of the drill collar sub, but instead, pass only partially through the wall of the drill collar sub. Strain gages are located in the partial radial openings. These strain gages measure each of the three parameters of weight, torque and bending. Each partially formed hole is sealed by a plug and retained in place by a retaining ring. For torque and bending measurements, the strain gages are arranged with symmetry of position between diametrically opposed holes. The strain gages are positioned in an array which departs from symmetry of position to minimize errors in the weight measurement caused by pressure changes in the drilling fluid.

Abstract: A field gradient generator in an NMR imaging apparatus comprises three sets of field gradient generating coils for respectively generating field gradients in three orthogonal directions in a space to be observed. Each set of coils includes a plurality of unit coils through which individual currents respectively flow. There are prepared a plurality of unit drivers which are for exclusive uses of the respective unit coils or are connected arbitrarily to each unit coil. Thereby, the lowering of an allowable operating voltage is implemented by use of a parallel operation of the unit drivers.

Abstract: In a nuclear magnetic resonance signal detecting system in which a body subject to measurement placed in a static magnetic field is irradiated with a magnetic field of high frequency by means of a high-frequency magnetic field radiating coil and in which a nuclear magnetic resonance signal of the body is detected by means of a nuclear magnetic resonance signal detecting coil, a high-frequency coil system for the nuclear magnetic resonance measurement comprises a plurality of coil groups juxtaposed to one another in a given direction and each implemented in such a structure as to be divisible in the direction orthogonal to the given direction, for detecting a magnetic field in the axial direction coinciding with an axis extending through the coil groups and/or generating a magnetic field in the axial direction.

Abstract: A scan controller for an NMR imaging device, wherein the scan controller stores control signal waveforms in a waveform memory; stores control signal amplitudes in an amplitude memory; stores data related to the control signal duration in a time memory; reads the waveform memory by using an address counter which operates based on data read out from the time memory and outputs the waveform memory read out value after conversion to analog. The amplitude of the control signal is multiplied by the waveform of the control signal and converted from digital data to analog so that the resulting amplitude is related to the amplitude of the signal stored in the amplitude memory. In this manner high amplitude resolution is attained and requirement for large scale memory capacity is reduced.

Abstract: A system corrects for phase angles degradation due, for example to eddy currents, and uses the corrected phase angles to determine flow. The system acquires flow compensated low resolution images and uncompensated low and normal resolution images of a flowing fluid. The images include phase angle data. The phase angle data of the low resolution images are subtracted from the corresponding phase angle data of the normal resolution images to obtain phase angle corrected compensated and uncompensated images. The phase angle corrected compensated images are subtracted from the phase angle corrected uncompensated images to obtain flow images with minimized phase angle distortion. Reliable and accurate flow velocity for each pixel is thereby obtained using the minimized phase angle distortion flow images.

Abstract: A method of measuring acoustic vibrations affecting the fluid in a well at a plurality of points which are angularly distributed around the axis of the well and which are in the proximity of the wall of the well by means of an apparatus including an elongate body which is rotatable about its longitudinal axis and having at least one acoustic vibration detector disposed at the end of an arm which is hinged to the body. The arm is moved away from the body so as to place its end at a determined distance from the wall of the well, and the arm is then caused to rotate continuously about the axis while simultaneously recording the signals produced by the detector. The method is suitable for use in a relief well to locate a well which is blowing out.

Abstract: An r.f. transmitter coil is coupled to individually or group-wise independently drivable antenna wire elements, each independently drivable element being driven by its own power amplifier via a sliding contact. An r.f. supply source is coupled to the inputs of the power amplifiers via an input network which provides a phase distribution among the r.f. signals supplied to the amplifiers for the coil to transmit with a circularly polarized r.f. field.