Abstract: A multiecho NMR pulse sequence is modified such that the bandwidth of the encoded NMR echo signal is reduced for the second NMR echo signal. This reduction is achieved by reducing the magnitude of the read-out magnetic field gradient, increasing the duration of the acquisition by a proportional amount and decreasing the sample rate by a proportional amount for the second NMR echo signal.

Abstract: Formation Strength and other measurement while drilling parameters are combined to produce a formation volumetric analysis which may including the traditional volumetric components of clay volume, sand volume, total porosity, and water filled porosity. In shaley formations, the volumetric analysis may also include an excess or overpressure porosity. Formation Strength may be derived from measurements of torque and weight on bit and be corrected for such effects as bit dullness, mud weight and hydrostatic pressure balance.

Abstract: The Gibb's artifact in magnetic resonance images is reduced by asymmetrically sampling acquired F.I.D. signals to obtain data, time domain filtering the obtained data with a filter that reduces overshoot, degrades resolution but increases SNR. Then obtaining symmetrical data by complex conjugating the time domain filtered data which improves the resolution, compresses the overshoot, but decreases SNR. Processing the symmetrical data to obtain images with insignificant Gibb's artifacts.

Abstract: A measuring device for use in a producing well is set forth. It includes a sonde having upper and lower centralizers to define an annular flow space therearound. In the preferred embodiment, a motor driven sensor preferably a piezoelectric combination transmitter and receiver is, included to transmit and then receive ultrasonic pulses. They are transmitted downwardly from the housing into fluid flowing in the well. Reflective interfaces are defined by material differences. Gas bubbles droplets and particles in the fluid flow and phases between oil and water, etc. form reflective interfaces to create a scattering effect to transmitted ultrasonic pulses so that a return pulse is formed. The pulses encodes fluid flow velocity as a result of the Doppler shift.

Abstract: A magnetic resonance imaging system is adapted to achieve the imaging of magnetic resonance signals detected from an object by applying a high frequency magnetic field and gradient field to the object in a homogeneous static field in accordance with a predetermined pattern and includes a data pick-up section and image processing section. The data pick-up section is of such a type that, with the use of a predetermined pulse sequence so time-adjusted that a phase difference between two predetermined substances somewhat differing in their magnetic resonance frequency due to a chemical shift is .pi./2 or -.pi./2 on a predetermined time, picks up all magnetic resonance data necessary for reconstruction of an image of a slice excited by the high frequency field into a magnetic resonance within a period of time in which that predetermined nuclear magnetization of the slice is relaxed due to the relaxation of a transverse magnetization.

Abstract: Oil and gas horizons in a wellbore are located by establishing from thermal logs thermal gradients for successive intervals free of drilling-induced thermal disturbances, identifying the mineral abundances surrounding the wellbore at each of said intervals, establishing ideal thermal conductivities for said mineral abundances based on assumptions that sand-rich formations have high thermal conductivities and are water-bearing and that shale-rich formations have low conductivities, determining an ideal heat flow at each interval by multiplying the thermal gradient at such interval by the ideal thermal conductivity of the mineral abundances at the interval, determining the average ideal heat flow for all of the intervals, and identifying the zones of the wellbore exhibiting anomalous ideal heat flows that are higher than the average heat flow.

Abstract: A device and method for transferring data between a bottom of a well and a surface, wherein a transfer of data is provided either by a mud wave generator or by a cable simultaneously or successively.

Abstract: Apparatus and method are disclosed for testing and sampling fluid in an oblong borehole of fracture zones in the area maximum permeability for more efficient recovery and testing in a given sampling period. The tester includes a pair of oppositely extending arms urged against the sides of the borehole causing the tester to rotate until a sampling probe oriented 90.degree. from the arms aligns with the short axis of the borehole. A probe is also disclosed having an elongate slot oriented perpendicular to the borehole for covering a greater horizontal sampling area.

Abstract: A cable head connector is provided for coupling a plurality of nested tubes, each one of which conducts a different fluid, to a downhole geophysical tool such as a seismic sound source. The device includes separate clamps for individually gripping the respective nested tubes. Conduits are furnished for fluidly bypassing the respective clamping devices. The fluid bypass conduits are fluidly coupled to a distribution module for delivering the different fluids individually to the downhole geophysical tool. Additional facilities are provided for sending electrical control signals to the tool.

Abstract: A method of high-speed magnetic resonance imaging in which the object to be imaged is placed in a high static magnetic field. Nuclear spins are excited in an image area by applying a pulse of radio frequency magnetic field. Optionally, a first gradient field, termed a slice selection gradient, may be applied in conjunction with the RF excitation pulse such that spins are excited only in a selected plane of the object. Following an encoding pulse sequence and rephasing of the nuclear spins by the application of a 180.degree. radio frequency pulse, mutually orthogonal phase-encoding and readout gradients are alternatively applied in the image plane to effect a traversal through spatial frequency domain (k-space). In a preferred embodiment of the invention, the readout gradient is applied as a continuous sinusoidal wave, resulting in a slight overlap between the phase-encoding and readout gradients. If phase errors vary slowly in time, only a partial k-space trajectory is required.

Abstract: In order to narrow the dynamic range of an NMR signal and to provide MRI of low cost and high image quality without inducing the distortions of an image other than distortion of phase which can be corrected or the degradations of the measurement accuracies of various parameters, a coil for generating an inhomogeneous magnetic field which varies slowly within region to-be-imaged is added to a coil for generating a static magnetic field of high homogeneity, and current to flow through the former coil is changed so as to control the inhomogeneous magnetic field.

Abstract: A system and methods for the inspection of a well borehole and the formation around said borehole. The system includes a coiled tubing unit for injecting flexible coiled tubing into a wellbore through a wellhead, a pump and valves for control of injection of fluids such as water, nitrogen, light-hydrocarbons, natural gas, and carbon dioxide through the coiled tubing into the wellbore, and a sensor for visually inspecting and/or acoustically examining the wellbore and a region around the sensor within a slug of fluid injected into the wellbore from the coiled tubing. The method includes the steps of injecting coiled tubing having an inspection sensor into a wellbore to a selected location, injecting an optically transparent or acoustically homogenous fluid into the wellbore through the coiled tubing to form a slug of such fluid around the sensor, and transmitting signals from the sensor representative of well conditions to the surface.

Abstract: NMR-PET scanner apparatus is provided wherein a PET detector is disposed within a magnetic imaging structure of an NMR device. The output of the PET detector is conveyed through light pipes to photodetectors which are shielded and disposed without the magnetic imaging structure of the NMR device to avoid interaction between the photodetectors and the magnetic field generated by the magnetic imaging structure of the NMR device.

Abstract: The apparatus of the present invention relates to a down hole tool capable of extraction of valid samples and making pressure measurements useful in calculating formation permeability. The tool incorporates the features of a straddle packer to allow formation fluid specimens to be taken at large flow rates without depressing the pressure below the formation fluid bubble point. When used in combination with a pressure probe the tool is used to obtain meaningful permeability readings in a larger radius area than previously permitted with known designs. Additionally, the apparatus of the present invention allows flow control during the creation of the pressure pulse which enhances extraction of valid samples and the permeability determination.

Abstract: A load cell is mounted on a polished rod between a rod clamp and a hanger bar. The polished rod is connected to a string of sucker rods that drive a reciprocating pump for lifting fluid from a borehole. The load cell includes a tubular body which is fitted with strain gauges for measuring compressional forces applied to the cell. The ends of the tubular body are shaped with annular spherical surfaces which mate with corresponding surfaces on washers at each end. Each of the washers tightly surrounds the polished rod and as a result of the loading on the polished rod, the washers and rod are forced into coaxial alignment with the load cell. Optionally, the polished rod can receive a centralizing sleeve which forces it to be centered within the tubular body of the load cell or the washers at either end thereof.

Abstract: A method and an apparatus for nuclear magnetic resonance imaging, using a shim coil which adjusts a static magnetic field to improve the homogeneity of the static magnetic field, capable of determining an appropriate amount of current to flow through the shim coil in accordance with a nuclear magnetic resonance signal due to water, in order to achieve an accurate adjustment of the homogeneity of the static magnetic field. The determination of the amount of current may be made by selecting current parameters for which a half-width of the nuclear magnetic resonance signal spectrum due to water is the smallest. The determination of the amount of current may be made by selecting current parameters for which a peak value of the nuclear magnetic resonance signal spectrum due to water is the largest.

Abstract: A plug release indicator is provided which includes an elastomeric probe, with a wire embedded therein, which extends into the interior area of a plug housing or well casing. The wire has a lip at one end and an anchor at the other end, such that when a cementing plug contacts and deflects the probe, the lip moves thereby closing a micro-switch. The micro-switch closes an electrical indicating circuit including a power supply, indicator light, buzzer, or the like. In a second embodiment, a wire contacts the cementing plug and rotates a shaft containing a magnet therein. The magnet then activates a magnetic switch thereby closing the electrical indicating circuit. Another embodiment includes an electrically conductive surface embedded within an electrically insulating rotatable shaft. Upon rotation of the shaft, the conducting surface completes an electrical circiut through adjacent electrical contacts and the electrical indicating circuit is closed.

Abstract: A method is provided for determining the state of wear of a multicone drill bit. Vibrations generated by the working drill bit are detected and converted into a time oscillatory signal from which a frequency spectrum is derived. The periodicity of the frequency spectrum is extracted. The rate of rotation of at least one cone is determined from the periodicity and the state of wear of the drill bit is derived from the rate of cone rotation. The oscillatory signal represents the variation in amplitude of the vertical or torsional force applied to the drill bit. To extract periodicity, a set of harmonics in the frequency spectrum is given prominence by computing the cepstrum of the frequency spectrum or by obtaining an harmonic-enhanced spectrum. The fundamental frequency in the set of harmonics is determined and the rate of cone rotation is derived from the fundamental frequency.

Abstract: A radio-active tracer, carried by a pressurized gas, is injected through an axially displaceable tube into a flow stream of steam within a well tubing string to perform a steam injection survey of underground formations intersected by a well bore into which the tubing string extends. The injection tube is guided for displacement from a retracted position at an acute angle to the flow stream direction to an injection position within the tubing string through a riser port, swab valve and steam inlet connection located below a storage zone within a lubricator pipe from which a logging tool is inserted into the tubing string.

Abstract: A method for determining the wear of cutting portion of a tool during drilling of a formation wherein a measurement is taken of the weight W applied to the tool and the torque T required to rotate said tool, the weight on the tool W and the torque T being linked by an equation of the type T=uW+vW.sup..alpha. in which u and v are parameters and .alpha. is a coefficient depending in part on the formation.