Abstract: A velocity independent method of predicting surface-related multiples in any gather of seismic data traces. In one embodiment, the method comprises the steps of regularizing said gather of seismic data traces; performing a double Fourier transformation to transform said seismic data traces from the x-t domain to the k.sub.x -.omega. domain; decomposing said transformed seismic data traces into uncoupled amplitude and phase spectra; and obtaining an estimate of said surface-related multiples by scaling said amplitude spectrum by one-half the value of the reflection coefficient for the first reflection below the earth's surface and by doubling said phase spectrum. The estimated multiples may then be used for automated velocity determination or for multiple attenuation in the original data.

Abstract: A method for determining a representation of an anisotropic earth formation is described, wherein the inversion step for generating the representation from recorded seismic data is performed using several values of a pre-defined anisotropy parameter addition to components of the moveout velocity. The anisotropy parameter is preferably introduced into the moveout equation or dispersion relation, which in turn is used in the inversion process.

Abstract: New methods of generating optimal inversion pulses and adiabatic pulses in magnetic resonance imaging are disclosed. Trajectories, maximum sweep rates, and velocity profiles are used in defining an optimal pulse, over support regions. Adiabatic pulses are optimized by using the trajectory as a constraint of optimization, but selecting trajectories with velocity profiles, without using the adiabatic condition as a constraint for optimizing the velocity profile. A method or inverting MR spins substantially, independently of the pulse duration, by selecting a transition width between 1.4 and 1.9 and dividing that width by the pulse duration is disclosed; and A new method of inverting adiabatic, MR, amplitude modulated spins, with a trajectory defined by sin .alpha./cos .alpha., where .alpha.<0.9 and at least 50% of the trajectory is outside, in a z-x rotating frame of reference that rotates at the instantaneous frequency of the RF pulse is also taught.

Abstract: A method for determining migration before summation including recording seismic reflection traces, for constituting a collection of traces to be migrated before summation and without weight correction. The traces being classified according to a given criterion and using a velocity model. The method including determining, for each point of interest M in a domain (X, Z), at least one line of slope determined on the basis of a line of slope map, in determining the specular rays associated with one point M and for the line of slope, and in computing the time and amplitude characteristics of each of the specular rays for deducing therefrom the reflection factor in each point M.

Abstract: A method of imaging of an object. A plurality of image datasets, for example a real part and an imaginary part of a magnetic resonance image, are acquired, and are transformed separately to a transform space and filtered. The filtered datasets are inverse transformed and recombined nonlinearly to produce the final image. The preferred transformation is a wavelet transformation. Noisy transform coefficients are suppressed by thresholding.

Abstract: A device for examining by nuclear magnetic resonance a volume having small depth, including means for creating a static homogeneous magnetic field B.sub.0 in which a volume to be examine is positioned, a system for creating magnetic field gradients in three directions of space, and a radio frequency transmission/reception system. The means for creating the static magnetic field B.sub.0, the field gradient system, and the radio frequency transmission/reception system are situated on a same side of an open surface, while the volume to be examined is situated on the other side of the surface. The device can be applied to magnetic resonance imaging.

Abstract: The general object of the present invention is to provide a method for determining and displaying the relative changes of elastic moduli and that of density of geologic formations and for utilizing these relative changes and plottings for gas/oil exploration, especially for direct gas and light oil detection. The said relative changes of elastic moduli are the relative change of Lame constant .DELTA..lambda./(.lambda.+2.mu.), the relative change of shear modulus .DELTA..mu./(.lambda.+2.mu.) and/or .DELTA..mu./[.kappa.+(4/3).mu.], the relative change of bulk modulus .DELTA..kappa./[.kappa.+(4/3).mu.]; and the relative change of density is .DELTA..rho./.rho..

Abstract: An inversion pulse is applied to the subject in a static magnetic field. An excitation pulse is applied after a delay time depending on the time constant of the longitudinal relaxation of the spins of proton contained in fat molecule from this inversion pulse. As a result, the spins of proton contained in the fat molecule can be suppressed at high precision. On the basis of the MR signal collected after this suppression, the resonance frequency data of the spins of proton contained in water molecule which is not suppressed or the data corresponding to this resonance frequency, or the magnetic field distribution data of the static magnetic field or the data corresponding to this magnetic field distribution can be determined at high precision.

Abstract: An edge-wound NMR solenoidal sample coil is made by winding at least two turns of flattened wire around a cylindrical coilform such that the major cross-sectional axis of the flat wire is perpendicular to the axis of the solenoid. The space between turns near the center is greater than the space between turns at the ends but less than the major cross-sectional dimension of the flat wire. The flattened wire is magnetically compensated by forming copper tubing around paramagnetic wires. The resulting solenoid has considerably higher .eta..sub.F Q and B.sub.1 homogeneity than prior-art solenoids of comparable size and transverse transparency. Similar principles may be used to improve the segmented, transparent, loop-gap resonator for breast and other imaging applications by using segmented planar ring resonators, tightly coupled by means of balanced transmission lines at the magic angle, with outermost conductive surfaces oriented more in the radial than axial direction.

Abstract: The present invention provides a system for drilling boreholes having a downhole subassembly which contains an acoustic measurement-while-drilling system. The acoustic system contains an acoustic transmitter and receiver for determining the acoustic velocity through the formations surrounding the borehole ad an acoustic transmitter and a set of receivers for determining the bed boundaries surrounding the borehole formation utilizing the acoustic velocities measured by the system. The downhole subassembly also contains a computing system which performs computations downhole and transmits certain answers uphole during the drilling operations. The bed boundary information is utilized to drill the wellbore along a desired wellbore path. The downhole computing system correlates the acoustic sensor measurements with other measurement-while-drilling measurements and transmits selected correlated information uphole.

Abstract: A method and apparatus for detecting rock movement. The first step involves using at least one electromagnetic induction coil as a sensor. The second step involves monitoring changes in induced electromotive force in the at least one electromagnetic induction coil over a selected time interval. This new approach is based upon changes in magnetic permeability as a result of rock movement in accordance with Faraday's law of electromagnetic induction. When a plurality of these new sensors are used the speed of the rock movement may also be determined.

Abstract: In the sensor: torsion beams 7a, 7b are fixedly connected between the centers of opposite outer sides of central fixed board 1 and the corresponding centers of opposite inner sides of a window 5; electrodes 11a, 11b, 12a, 12b are mounted on a front and a rear surface of weight portions 9a, 9b; and, an outer cover 21, which is constructed of an upper and a lower board 17, 19 provided with electrodes 23a, 23b, 25a, 25b corresponding to the electrodes of the weight portions, is mounted on a side surface of an outer frame 15 in which both the central fixed board 1 and the weight board 3 are received, so that the central fixed board 1 is rotatably supported. It is possible to increase the length of each of the torsion beams 7a, 7b. These electrodes 11a, 11b, 12a, 12b may be produced through a single path in printing process.

Abstract: A device for retrieving ocean bottom seismic cable as the cable is pulled up from the bottom and hauled aboard a vessel. The cable is first led over a front wheel located on an arm which is pivotally mounted for movement about an axis. The cable is then passed under a second wheel before it is brought aboard the vessel, optionally via one or more additional wheels. A damper is provided between a fixed point on the arm, spaced apart from the axis and a fixed point on the vessel, so that the front wheel is raised in response to lower tension in the cable and is lowered in response to an increase in tension in the cable, thereby counteracting any variations in the tension of the cable.

Abstract: A method for determining intrinsic transverse relaxation time of a first mobile phase in a porous medium using nuclear magnetic resonance measurement sequences. The sequences are measured at first and second wait times. At least two different interecho spacing times are used for each wait time. The first and second wait time are selected to provide different magnetization recoveries of the first phase, and are selected to be longer than the longitudinal relaxation time of a second mobile phase. For the measurements made at the first interecho spacing time, components of signals in the measurements corresponding to the first phase are separated from components corresponding to the second mobile phase by determining differences between the signals measured at the first and at the second wait times. The step of separating is performed for each of the interecho spacing times.

Abstract: Method and apparatus for increased accuracy of an image of object density pixel values obtained by forming linear combinations thereof. A measured variable M is related to an integration of the actual object density .rho. over space q by a transform function F, i.e., M(t)=.intg.F(t, q).rho.(q)dq, and an estimated object density .rho.* is obtained by an approximate inversion of the transform function, i.e., .rho.*(q)=.SIGMA.E(t,q)M(t), where the sum is over the samples taken. (In the case of magnetic resonance imaging, M is the magnetization induced in a coil transverse to the main magnetization coil, the transform function F(t,q) includes sinusoidal components, and the inversion function G includes an inverse Fourier transform.) Therefore, the estimated object density .rho.* is related to the actual object density .rho. by.rho.*(q)=.intg..SIGMA.E(t,q)F(t,q').rho.(q')dq',and .SIGMA.E(t,q)F(t,q') is termed the kernel A(q,q').

Abstract: The present invention provides a nuclear magnetic resonance ("NMR") tool for determining geological properties of formations surrounding a borehole when said tool is traversed in the borehole. One embodiment of the NMR tool includes at least one permanent magnet that is disposed substantially parallel to a longitudinal axis of the tool to generate a static magnetic field at a known distance in the formation. Radio frequency magnetic field in the zone of interest is generated by passing current at a radio frequency through a linear electrical conduction path along the longitudinal axis of the tool. The frequency may be swept during operation of the tool. The return path for the RF current is through the formation. A receiver detects signals from the formation responsive to the induced radio frequency magnetic field, which are processed to provide information about a formation parameter such as the formation porosity, hydrocarbon saturation and permeability of the zone of interest.

Abstract: A method for making seismic while drilling (SWD) measurements by determining and analyzing the reference signal downhole near the drill bit and sending a limited quantity of information to the surface by measurement-while-drilling (MWD) telemetry. In one embodiment, a library of anticipated drill bit wavelets is stored in memory downhole and in memory at the surface. The best matching wavelet is identified by the processor downhole and then a code identifying the wavelet and a scaling factor is sent to the surface. At the surface, the best matching wavelet is retrieved based on the code received and then a reconstructed signal is created using the retrieved wavelet and the scaling factor. In another embodiment, key characteristics of the signal such as central frequency, frequency band, etc., are calculated downhole and transmitted to the surface. These key characteristics are then used to reconstruct the reference signal which is then used for correlation of surface detected signals.

Abstract: A Petragrid method and apparatus generates grid cell property information that is adapted for use by a computer simulation apparatus. An interpretation workstation includes at least two software programs stored therein: a first program called "Petragrid" and a second simulation program for generating a set of simulation results for display. The first Petragrid software program will: receive well log and seismic data which indicates each layer of a formation, grid each layer of the formation where the grid is comprised of a plurality of cells, and generate more accurate data associated with each grid cell, such as the transmissibility. The more accurate data for each cell will be transmitted to the second simulation program which will respond by generating a set of more accurate simulation results for each cell of the grid, and overlaying the more accurate simulation result for each cell onto each of the corresponding cells of the grid being displayed on the workstation display by the Petragrid software.

Abstract: NMR data for imaging perfusion of blood is acquired from a series of slice locations using a cardiac gated NMR pulse sequence. Data for the slice locations are acquired by a corresponding series of data acquisition segments performed during the R--R interval of each cardiac cycle. Selective rf saturation pulses are interleaved with the data acquisition segments to uniformly condition spin magnetization in each slice location.

Abstract: A method of designing a shielded gradient coil assemblies (22) with a flared primary coil (60) for magnetic resonance imaging systems is provided. The method includes generating a first continuous current distribution for a primary coil (60) using an inverse approach. The first continuous current distribution is confined within predetermined finite geometric boundaries of a surface defined by three dimensions and generates a magnetic gradient field across an imaging region (14). The magnetic gradient field is constrained to predetermined values at specified spatial locations within the imaging region (14). The current distribution and magnetic field are converted into a stored energy and magnetic field domain where a finite element analysis is performed to generate a second continuous current distribution for a shielding coil (62). The second continuous current distribution is confined within predetermined finite geometric boundaries of a surface surrounding the primary coil (60).