Normal Moveout Patents (Class 367/52)
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Patent number: 7154812Abstract: The invention concerns a method for retrieving local near-surface material information including the steps of:—providing a group of receivers comprising at least one buried receiver and at least one surface receiver positioned either at or very near the Earth surface;—recording a seismic wavefield;—estimating a propagator from said recorded seismic wavefield;—inverting said propagator; and—retrieving said near-surface material information.Type: GrantFiled: January 14, 2004Date of Patent: December 26, 2006Assignee: Westerngeco L.L.C.Inventors: Robbert van Vossen, Andrew Curtis, Jeannot Trampert
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Patent number: 7065004Abstract: A method is disclosed for processing seismic data. The method includes prestack depth migrating the seismic data to generate common image gathers using an initial velocity-depth model. Horizons in the migrated seismic data are selected. Residual migration velocity analysis in the depth-offset domain is performed with respect to each selected horizon, and the velocity-depth model is updated based on the residual migration velocity analysis.Type: GrantFiled: April 22, 2004Date of Patent: June 20, 2006Assignee: PGS Americas, Inc.Inventors: Junru Jiao, Ruben D. Martinez
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Patent number: 6996028Abstract: A number of seismic stacks are precomputed (20) for known velocity fields. The velocity fields are chosen to span the range of velocities of interest. The stacks are then arranged (21) in the 3D memory of a graphics computer (10–14) using time and position as first dimensions and the index of the velocity field as the last dimension. In such 3D space, any velocity field to be used for stacking appears as a surface (S) within a volume. Projecting the seismic stacks onto that surface provides the seismic line stacked for the velocity field of interest.Type: GrantFiled: November 9, 2001Date of Patent: February 7, 2006Assignee: WesternGeco, L.L.C.Inventors: Henrik Bernth, Francois Daube
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Patent number: 6985405Abstract: A method is disclosed for determining interval anisotropic parameters. The method includes determining normal moveout (NMO) velocities and effective anelliptical parameters from seismic data traces. The NMO velocities are processed to obtain interval NMO velocities. The NMO velocities, effective anelliptical parameters and interval NMO velocities are inverted to obtain the interval anisotropic parameters. In one embodiment, the inversion includes damped least squares. In one embodiment, the inversion is preconditioned.Type: GrantFiled: October 23, 2003Date of Patent: January 10, 2006Assignee: PGS Americas, Inc.Inventors: Jiaxiang Ren, Ruben D. Martinez
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Patent number: 6967898Abstract: A method of applying an effective velocity model to vertical seismic profile (VSP) seismic data comprises correcting for offset using a non-hyperbolic effective velocity model so as to take account of the earth's layering and anisotropy. One preferred non-hyperbolic model for the relationship between offset and travel time is: formula (I) where t is the travel time of seismic energy from the source to the receiver, x is the offset between the source and the receiver, and z is the depth of the receiver.Type: GrantFiled: July 9, 2001Date of Patent: November 22, 2005Assignee: Schlumberger Technology CorporationInventor: Scott Leaney
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Patent number: 6898148Abstract: The present invention provides methods to be used in seismic data processing to address problems encountered during data acquisition. The present invention provides a multi-step process to reduce aliasing of seismic data along time slices.Type: GrantFiled: March 26, 2003Date of Patent: May 24, 2005Assignee: WesternGeco, L.L.C.Inventor: Scott William MacKay
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Publication number: 20040190375Abstract: The present invention provides methods to be used in seismic data processing to address problems encountered during data acquisition. The present invention provides a multi-step process to reduce aliasing of seismic data along time slices.Type: ApplicationFiled: March 26, 2003Publication date: September 30, 2004Inventor: Scott William MacKay
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Patent number: 6798714Abstract: A method of performing normal moveout (NMO) correction and stacking of a common-midpoint (CMP) gather of seismic traces in a manner that avoids NMO stretch is disclosed. A CMP gather without NMO correction is modeled as the sum of a series of short overlapping time intervals whose center times follow the NMO curve as it changes with offset. The sample values contained in these intervals are solved simultaneously by performing a statistical fit to the CMP gather based on this model. A CMP stacked trace is formed by summing these intervals at their zero-offset positions at each time sample.Type: GrantFiled: April 30, 2003Date of Patent: September 28, 2004Assignee: Kelman Technologies Inc.Inventor: Stewart Trickett
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Patent number: 6757216Abstract: A method for assessing the suitability of seismic data for quantitative amplitude analysis, where the concern is excessive residual normal moveout (RNMO). The invention uses a near offset stack and a far offset stack, the time difference between the two, a mute pattern, a reflection shape assumption for the RNMO, and a waveform and frequency for the far stack traces to generate a formula that estimates far stack amplitude error caused by RNMO. The formula can be used to compensate the far stack amplitude where the error is not so great as to require reprocessing of the data. The method can also be applied to interpreted amplitude maps.Type: GrantFiled: May 15, 2003Date of Patent: June 29, 2004Assignee: ExxonMobil Upstream Research CompanyInventors: Peter Varnai, Stefan Hussenoeder, Brian P. West, John E. Eastwood, Spyridon K. Lazaratos
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Patent number: 6757217Abstract: Near-offset and far-offset seismic data volumes are time-aligned by first selecting a plurality of time shifts. The near-offset and far-offset seismic data volumes are cross-correlated at the plurality of time shifts. An initial time-shift volume and a maximum correlation volume are created from the maximal cross-correlations at the plurality of time shifts. Areas of high time shift from the initial time-shift volume and areas of low cross-correlation from the maximum correlation volume are determined. The determined areas of high time shift and low cross-correlation are filtered from the initial time-shift volume, generating a filtered time-shift volume. The filtered time-shift volume is applied to the far-offset seismic volume to generate a time-aligned far-offset volume.Type: GrantFiled: August 29, 2002Date of Patent: June 29, 2004Assignee: ExxonMobil Upstream Research CompanyInventors: John E. Eastwood, Brian P. West, Michael D. Gross, Dwight C. Dawson, David H. Johnston
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Patent number: 6091669Abstract: 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..Type: GrantFiled: September 29, 1998Date of Patent: July 18, 2000Assignee: China National Offshore Oil Corp.Inventor: Xinping Chen
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Patent number: 6058074Abstract: A computer system and method of operating the same to apply overburden corrections to seismic signals prior to amplitude-versus-offset (AVO) analysis is disclosed. The system and method retrieve common midpoint gathers of the seismic signals, and generate analytical, or complex, AVO intercept and AVO slope traces therefrom, effectively stacking the traces in each gather. Over a sliding time window of the stacks, the computer system generates p-measure standard deviation and correlation statistics, preferably using a p-measure value less than one. The AVO intercept and AVO slope traces are then modified, at each depth point of interest corresponding to a time window placement, according to the relationship between the p-measure statistics and the desired statistics for the background distribution.Type: GrantFiled: July 31, 1998Date of Patent: May 2, 2000Assignee: Atlantic Richfield CompanyInventors: Herbert W. Swan, Bruce J. Verwest
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Patent number: 6026057Abstract: A method and computer system for correcting seismic signals in a seismic survey, sensed in horizontal and vertical directions at receiver locations, is disclosed. According to the disclosed method and system, the horizontal and vertical seismic signal traces are processed in prestack gathers, after normal move-out correction. For each reflection event indicated in the prestack gathers, a performance function is evaluated over a range of zero-offset directivity and directivity slope values, using the horizontal and vertical pressure wave components sensed at the receivers. The zero-offset directivity and directivity slope values that return the maximum performance function are stored in connection with the gather and the reflection event, as indicative of the zero-offset dip and offset-dependent directivity of the reflective surface corresponding to the reflected event.Type: GrantFiled: June 4, 1998Date of Patent: February 15, 2000Assignee: Atlantic Richfield CompanyInventors: Bok S. Byun, E. Stuart Nelan, Chi Young
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Patent number: 5999488Abstract: An improved method for eliminating reflections from artificial model boundaries encountered in finite-difference acoustic wave propagation computations is based on applying two different boundary conditions at the artificial boundary. In this method one boundary condition generates reflections having the same polarity as the incident acoustic wave, and the other boundary condition generates reflections with opposite polarity. To apply the improved method simply compute both boundary conditions on a small narrow region adjacent the artificial boundary on a separate set of grids and average the two solutions.Type: GrantFiled: April 27, 1998Date of Patent: December 7, 1999Assignee: Phillips Petroleum CompanyInventor: Brackin A. Smith
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Patent number: 5999487Abstract: A seismic reflection data acquisition and processing method and device for prospecting in tectonically complex environments are disclosed. In particular, the seismic reflection data acquisition and processing method is useful for providing a summation rate tensor field and a 3D image unit, e.g. in 3D earth seismics or complex tectonics.Type: GrantFiled: March 18, 1998Date of Patent: December 7, 1999Assignee: Elf Exploration ProductionInventors: Christian Deplante, Eric de Bazelaire, Alain Riou
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Patent number: 5991237Abstract: A method for the determination of migration velocities in seismic processing in which a blasting point S is associated with receivers (R.sub.1 to R.sub.n) which are separated by offsets such that in a given speed range, a first set of traces derived from the blasting point and registered on the receivers, and a second set of traces in constant and colinear offset to the first set are migrated. Two migrated images of the part of the site corresponding to the two sets of traces are obtained. The two images are correlated by means of a spatial two-dimensional correlation, the result thereof determining the deviation between the migration used and the investigated velocity. The result is particularly useful in the seismic prospection of a site.Type: GrantFiled: March 17, 1998Date of Patent: November 23, 1999Assignee: Elf Exploration ProductionInventor: Eric de Bazelaire
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Patent number: 5982706Abstract: A method and computer system for deriving and applying normal moveout corrections to seismic survey traces is disclosed. In each common midpoint (CMP) gather, a stacking velocity function of travel time is first determined for near-offset traces. For each reflective event, a time window about a depth point is selected. Time anisotropy and velocity anisotropy values are then determined for the depth point, for example by way of a semblance analysis applied to envelopes of the traces over the full offset range. Normal moveout corrections are then determined by a weighted sum expression of travel time (zero-offset time plus moveout correction) The weighted sum adds a first travel time expression corresponding to a Dix equation expression with a second travel time expression corresponding to a skewed hyperbolic expression that includes the time and velocity anisotropy values, with the weighting dependent upon the offset of the particular trace.Type: GrantFiled: March 4, 1997Date of Patent: November 9, 1999Assignee: Atlantic Richfield CompanyInventor: Bok S. Byun
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Patent number: 5978314Abstract: A method for determining a substantially optimal NMO velocity function for use in stacking a CMP gather of seismic data traces. The method begins with an initial estimate of the NMO velocity function for the CMP gather. This initial estimate is typically determined through conventional seismic velocity analysis. The method then picks a first velocity-traveltime pair falling on the initial estimate of the NMO velocity function and conducts a two-dimensional interpolative search of trial velocity-traveltime pairs in the neighborhood of the pick to find a substantially optimal velocity-traveltime pair. This substantially optimal velocity-traveltime pair is the trial velocity-traveltime pair having the highest stack response and is substituted for the pick in the NMO velocity function. The method then proceeds to find substantially optimal velocity-traveltime pairs to replace each of the other picks on the initial estimate of the NMO velocity function.Type: GrantFiled: March 21, 1997Date of Patent: November 2, 1999Assignee: Exxon Production Research CompanyInventor: Long Don Pham
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Patent number: 5970023Abstract: Marine seismic data sets are generally under-sampled spatially because of the relatively long listening times required in deep water. It is customary to use very long spreads in the field thereby enhancing aliasing and interference from coherent noise. A seismic-signal data processing method is proposed that applies a combination of a forward parabolic Radon transform and a linear Radon transform to the data, followed by a further transform to a three-dimensional frequency domain. In this domain, a deterministic operator is applied to the data to sharpen the Radon-domain response thereof. The data are then scavenged of noise in the Radon domain and inversely transformed back into the time-space domain.Type: GrantFiled: February 19, 1999Date of Patent: October 19, 1999Assignee: Baker Hughes IncorporatedInventors: Ronald E. Chambers, Necati Gulunay
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Patent number: 5933789Abstract: A method and computer system for deriving and applying normal moveout phase and time shift corrections to seismic survey traces is disclosed. Normal moveout time-shift corrections are first applied to traces in a common midpoint (CMP) or common depth point (CDP) gather, based upon stacking velocity analysis applied to envelopes of the traces. One offset in the survey, preferably the maximum offset, is selected as the reference point; the NMO time shift at this reference offset is then selected as a reference NMO time-shift. The traces in the gather are each phase-shifted based upon iterated reference phase dispersion values at the reference offset, times the ratio of the normal moveout time-shifts for the trace in the gather to that of the reference offset (raised to a power). Semblance analysis is performed to identify, for each point in normal incidence time and thus for each reflective event, the optimum reference phase dispersion value.Type: GrantFiled: November 12, 1996Date of Patent: August 3, 1999Assignee: Atlantic Richfield CompanyInventors: Bok S. Byun, David D. Thompson, E. Stuart Nelan
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Patent number: 5719822Abstract: A method of processing seismic signal data that uses a special Radon transform for dip moveout (DMO) including the steps of applying conventional pre-DMO steps to the traces, applying a special Radon DMO transform to the traces to obtain a post-DMO section in Radon domain, applying a conventional inverse Radon transform to obtain a post-DMO section in space-time domain with a time and space DMO shift on the traces, and applying conventional post-DMO steps to the resultant traces.Type: GrantFiled: October 4, 1996Date of Patent: February 17, 1998Assignee: Vector Seismic Data Processing, Inc.Inventor: Cheng-shu Wang
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Patent number: 5712805Abstract: A method for reconstructing the acoustic field on the surface of a vibrating object based on measurements of the radiated acoustic pressure includes solving the Helmholtz equation directly using the expansion of a set of independent functions that are generated by the Gram-Schmidt orthonormalization with respect to the particular solutions to the Helmholtz equation. The coefficients associated with these independent functions are determined by requiring the assumed form of solution to satisfy the pressure boundary condition at the measurement points. The errors involved in these coefficients are minimized by the least squares method. Once these coefficients are specified, the acoustic pressure at any point, including the source surface, is completely determined.Type: GrantFiled: February 16, 1996Date of Patent: January 27, 1998Assignee: Wayne State UniversityInventors: Zhaoxi Wang, Sean F. Wu
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Patent number: 5684754Abstract: A computer-implemented method and system of correcting seismic survey data for the effects of NMO stretch is disclosed. The method operates upon a CDP gather of seismic survey data after normal move-out correction (NMO) has been applied. A semblance analysis is used to derive a stretch coefficient .kappa. profile over the gather, as a function of time and offset. The values of the stretch coefficient profile .kappa. are used in producing a time-varying filter that is applied, preferably by way of a time-domain multiplication, to incremental windows in time for each trace, with the products added to one another to generate a corrected trace. After all of the traces in the gather are corrected, an event-weighted filter is applied to the traces by way of a correlation operation, to remove high-frequency artifacts in the corrected traces. The corrected and filtered traces are then ready for stacking and conventional processing.Type: GrantFiled: December 13, 1995Date of Patent: November 4, 1997Assignee: Atlantic Richfield CompanyInventors: Bok S. Byun, E. Stuart Nelan
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Patent number: 5663928Abstract: A method of analysing and processing seismic reflection data for the determination of a high resolution spatial hyperbolicity correction velocity field.The method is characterised in that:for the set of normal moveout-corrected gathers, the maximum values of the positive and negative residues of the NMO correction are determined: a time range analysis is determined located on either side of a time t.sub.0 and of which the width is equal to not more than twice the absolute value of the maximum residual moveout,a family of 2n+1 residual correction hyperbolas or parabolas are constructed, each having its apex centered on said time t.sub.0 and, at the value of the maximum offset, presenting a value of time that is equal to one of the 2n+1 equidistant time values predetermined on the analysis range, and including the value t.sub.0 and the extreme values of said analysis range,2n+1 sets of static corrections are determined for each of the offsets, defined by the time differences presented relative to said time t.Type: GrantFiled: June 18, 1996Date of Patent: September 2, 1997Assignee: Elf Aquitaine ProductionInventors: Eric De Bazelaire, Jean-Pierre Dunand
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Patent number: 5596546Abstract: A method of preserving frequency components in digitally sampled signals exceeding a maximum frequency related to a predetermined digital sample interval. The signals correspond to a plurality of sensors positioned at spaced apart locations, and the signals from each of the plurality of sensors are digitally sampled at the predetermined digital sample interval. The method includes the steps of determining time adjustment values corresponding to each sensor which provide amplitude correspondence between each of the signals generated by each of the sensors in response to different propagation times of energy from an energy source to each of the sensors; adjusting a time of acquisition of each digital sample from each of the sensors by applying the corresponding time adjustment value to generate time-adjusted samples; and combining all the time adjusted samples into a combined output signal having a sampling time interval smaller than the predetermined digital sample interval.Type: GrantFiled: December 21, 1994Date of Patent: January 21, 1997Assignee: Western Atlas International, Inc.Inventor: R. Daniel Wisecup
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Patent number: 5555530Abstract: A method for improving the signal to noise ratio from a pair of detectors such as geophones which each detect a noisy signal comprising a signal of interest (S) and a noise signal (N), wherein the signal of interest (S) has a different moveout across the pair of detectors from that of the noise signal (N), and the noise signal (N) from a given source is detected at the first detector at a time .DELTA.t before the corresponding noise signal is detected at the second detector, the method comprising delaying the noisy signal (S+N) detected at the first detector by an amount .tau. being greater than the moveout of the signal of interest but not more than .DELTA.t and subtracting the delayed signal from that detected at the second detector by means of an adaptive filter so as to minimize the power in the resultant signal. The signal detected at the first detection and optionally the resultant signal can also be delayed by an amount .tau..sub.Type: GrantFiled: December 6, 1993Date of Patent: September 10, 1996Assignee: Schlumberger Technology CorporationInventor: Richard J. Meehan
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Patent number: 5544126Abstract: A method of seismic shot-record migration includes the steps of generating seismic or acoustic waves into an earth formation from one or more sources with the sources being spaced some finite distance from each other. Next, one or more spaced receivers receive a seismic signal after the signal reflects or diffracts off of a subterranean feature. Next, a source location and a receiver location is arbitrarily selected. Finally, input data is mapped or migrated according to one of two equations, or both equations, to produce output data. The output data is then suitable for further processing by other seismic analysis techniques.Type: GrantFiled: November 4, 1993Date of Patent: August 6, 1996Inventor: John R. Berryhill
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Patent number: 5521881Abstract: Disclosed is a method of processing seismic data containing multiples, which method generally includes as a step, determining the two-way travel time to a suspected multiple generating event. This method includes the application of a normal moveout operation to the recorded seismic trace utilizing the primary event velocities. Once the normal moveout has been applied to the data, all of the events in the trace are shifted downward in time by an amount of time equal to the two-way travel time to the suspected multiple generating event as previously determined. Once the normal moveout operation and the two-way travel time shift have been applied to the trace, a reverse normal moveout operation is applied to the trace utilizing an extended velocity function, which is a function of the original primary and the velocity within the suspected multiple generating layer. The resulting trace is now a trace containing only multiples.Type: GrantFiled: September 2, 1994Date of Patent: May 28, 1996Assignee: Exxon Production Research CompanyInventors: Yiu-Wa A. Lau, Long D. Pham
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Patent number: 5515335Abstract: A method for generating improved displays of seismic data by processing seismic amplitude versus offset data to correct for overburden effects. Analytic traces are calculated for the zero offset reflectivity, A, trace and the amplitude versus offset slope, B, trace of the AVO data. Statistics for the A and B traces within a selected window in time and common depth point space about a selected sample point are calculated. The statistics include root mean square amplitudes of the A and B traces and the correlation coefficient. Desired statistics are selected and used with the measured statistics to correct the A and B traces.Type: GrantFiled: August 16, 1993Date of Patent: May 7, 1996Assignee: Atlantic Richfield CompanyInventor: Herbert W. Swan
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Patent number: 5440525Abstract: A method for displaying seismic data to provide direct indications of the presence of hydrocarbons. Seismic data is processed using conventional amplitude versus offset techniques to obtain zero offset reflectivity, or A, traces and the amplitude versus offset slope, or B, traces. AB cross plots of each trace are then generated. Each sample point on the cross plot is then assigned a value corresponding to its deviation from the regression line of the cross plotted AB points. The assigned values are then plotted in their corresponding time sample positions to generate a trace or display providing a direct indication of hydrocarbons.Type: GrantFiled: October 25, 1993Date of Patent: August 8, 1995Assignee: Atlantic Richfield CompanyInventors: Samir K. Dey-Sarkar, Douglas J. Foster, Steven W. Smith, Herbert W. Swan
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Patent number: 5297108Abstract: A method for detecting errors in estimated seismic velocities used in a normal moveout correction of a gather of traces selected from conventional, common midpoint seismic data. Zero offset reflectivity and amplitude versus offset slope traces are derived from the NMO corrected gather. Analytic traces are calculated for the zero offset reflectivity and amplitude versus offset slope traces. The analytic zero offset reflectivity trace is multiplied by the complex conjugate of the analytic slope trace and the imaginary part of the product indicates estimated velocity errors. The velocity error indicator is used to correct the velocity estimates so that the normal moveout process may be reperformed without the errors caused by incorrect velocity estimates. Alternatively, the velocity error indicator itself is plotted on a seismic section as an indicator of characteristics of subsurface earth formations.Type: GrantFiled: June 14, 1993Date of Patent: March 22, 1994Assignee: Atlantic Richfield CompanyInventor: Herbert W. Swan
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Patent number: 5285422Abstract: A three dimensional residual modeling operator is applied to seismic times that have been preprocessed by application of NMO and velocity independent DMO. The residual operator compensates for vertical velocity variation and anisotropy and its use precludes the need for ray tracing.Type: GrantFiled: March 8, 1993Date of Patent: February 8, 1994Assignee: Western Atlas International, Inc.Inventors: Alfonso Gonzalez, Everett C. Mobley, Ronald E. Chambers
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Patent number: 5237538Abstract: A space time gate is selected surrounding a coherent noise to be removed from an array of seismic traces. Signal-plus-noise within the selected gate is extracted from the array of seismic traces. Coherent noise within the gated signal-plus-noise is estimated and subtracted from such gated signal-plus-noise to provide a signal estimate. This signal estimate is restored into the array of seismic traces.Type: GrantFiled: February 20, 1992Date of Patent: August 17, 1993Assignee: Mobil Oil CorporationInventors: Andrew F. Linville, Jr., Robert A. Meek
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Patent number: 5197039Abstract: The present invention provides methods for processing seismic data which include performing normal moveout velocity analysis in such a manner as to include the effects of the offset dependence of reflection amplitude and simultaneously determining from the seismic data the moveout velocity and the variation of reflection amplitude with offset.Type: GrantFiled: March 29, 1988Date of Patent: March 23, 1993Assignee: Shell Oil CompanyInventors: Chris T. Corcoran, Aaron J. Seriff
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Patent number: 5136553Abstract: A method of geophysical exploration is provided for reducing distortion or smearing of reflection event amplitudes in seismic data resulting from residual normal moveout. In particular, the seismic data are sorted into ordered gathers of seismic signals and corresponding reflection events are aligned along hyperbolic loci of traveltimes. The hyperbolically aligned reflection events are then corrected for residual normal moveout by aligning corresponding reflection events along nonhyperbolic loci of traveltimes.Type: GrantFiled: December 19, 1990Date of Patent: August 4, 1992Assignee: Amoco CorporationInventors: Michael C. Kelly, Richard O. Lindsay
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Patent number: 5128899Abstract: A method for removing residual moveout includes sorting the results of common offset depth migration into common image point gathers. A subset of image point gathers are selected for analysis. Each common image point gather is separated vertically into windows, each of which centers on a strong event. For each window, all the offset traces are summed to produce a brute stack trace to be used as an anchor. All offsets are cross-correlated to the anchor to determine how much each trace window should be shifted to sum most constructively with the anchor. A set of dynamic shifts is produced, which when applied, will remove the residual moveouts and produce a truly flat image for stacking. These shifts vary with depth and offset and can be interpolated between the selected image point gathers.Type: GrantFiled: July 16, 1991Date of Patent: July 7, 1992Assignee: Conoco Inc.Inventors: Mark Boyd, Shein S. Wang, James M. Tippett, Douglas W. Hanson
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Patent number: 5029145Abstract: A novel method of geophysical exploration is provided whereby shot points and receiver locations are positioned such that seismic data resulting therefrom can advantageously be processed employing 3-D processing techniques to obtain a better image of the earth's subsurface structure. In one embodiment, shot points, or alternatively, receiver locations are arranged along generally sawtooth or zig zag lines so that common midpoint bins of seismic signals include a generally uniform distribution of source-receiver pair azimuths. In another embodiment, both the shot points and receiver locations are arrayed along generally alternating, sawtooth or zig zag lines.Type: GrantFiled: May 29, 1990Date of Patent: July 2, 1991Assignee: Amoco CorporationInventors: David Marsden, David E. Overton
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Patent number: 4995007Abstract: The present invention provides improved methods for processing seismic data which include the effects of offset dependence of reflection amplitudes. The methods of the present invention provide a way to estimate and remove the effect of stretch and small moveout velocity errors on the measurement of offset dependence for the case of small offsets (less than about 30 degrees angle of reflection). Further, the methods of the present invention provide an improved estimate of the correct movement velocity.Type: GrantFiled: December 21, 1989Date of Patent: February 19, 1991Assignee: Shell Oil CompanyInventors: Chris T. Corcoran, Jacques P. Leveille, Eduardo S. Velasco
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Patent number: 4980866Abstract: In applying residual movement correction to common offset depth migrated data, common offset depth migration is applied using the best available velocity/depth model. Post migrated parts, which are depth migrated common midpoint gathers, are saved. The post migrated parts are treated as if they were in time not depth. Normal movement based on a constant velocity is removed. Velocity functions time-velocity pairs, are derived for the post migrated parts with normal movement removed using a standard velocity analysis program. Normal moveout based on these velocity functions is applied. The events on the post migrated parts ae not imaged to the same depth. The corrected post migrated parts are then stacked and displayed.Type: GrantFiled: November 30, 1989Date of Patent: December 25, 1990Assignee: Conoco Inc.Inventors: Shein S. Wang, Thomas D. Cavanaugh, Douglas W. Hanson
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Patent number: 4922362Abstract: A method for the determination and deconvolution of the signature of an unknown, non-impulsive source signal. The method supposes that that an array of receivers is positioned at the earth's surface to detect and record the seismic signals resulting from the interaction of the source with the earth's subsurface. The traces of data recorded are time-shifted by an amount determined by a coherency analysis of the data. The signal is estimated from the time-shifted data with a weighting factor applied at each trace. A deconvolution filter is determined from the estimate and is weighted at each frequency according to the strength of the source at that frequency. The filter is then applied to the time-shifted data.Type: GrantFiled: June 1, 1989Date of Patent: May 1, 1990Assignee: Schlumberger Technology CorporationInventors: Douglas Miller, Jakob Haldorsen
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Patent number: 4907205Abstract: A method is described for enhancing seismic data and, more particularly, for attenuating multiple reflection events in seismic data. Seismic data are sorted into common endpoint gathers, and selected multiple reflection events are corrected for time delays associated with the reflection of the seismic energy from common reflecting interfaces and aligned. The aligned multiple reflection events are attenuated and the resulting enhanced seismic data can then be inverse time-delay corrected for subsequent processing, including repetitions of the aligning and attenuation steps to suppress additional multiple reflection events in the seismic data.Type: GrantFiled: April 29, 1988Date of Patent: March 6, 1990Assignee: Amoco CorporationInventor: Dennis A. Yanchak
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Patent number: 4881209Abstract: Method for processing converted mode seismic data. Compressional and converted compressional to shear wave data is acquired by generating compressional energy into a subsurface formation and recording the amplitude of reflections as a function of time at spaced locations along a line of exploration. A series of compressional to shear wave velocity (Vp/Vs) ratios are selected based on an analysis of the acquired seismic data and the shear wave velocity for each Vp/Vs ratio is determined according to the following relationship: ##EQU1## where k=Vp/Vs. Data corresponding to each Vp/Vs ratio is stacked together, the series of stacks are correlated to the originally acquired seismic data to determine the actual Vp/Vs ratio for the formation and the shear wave velocity is derived. The originally collected data is then corrected for normal moveout and stacked.Type: GrantFiled: October 12, 1988Date of Patent: November 14, 1989Assignee: Mobil Oil CorporationInventors: Marvin G. Bloomquist, Barry N. Warner
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Patent number: 4878204Abstract: A method for carrying out dip moveout correction on seismic data which provides true-amplitude seismic images is provided. A calibration process is used to design a set of filters that correct the seismic amplitudes during dip moveout correction so as to provide true-amplitude imaging. These filtrs can be designed and applied in any known implementation of dip-moveout, in three or two dimensions.Type: GrantFiled: October 28, 1988Date of Patent: October 31, 1989Assignee: Geophysical Service, Inc.Inventors: James L. Black, Cameron B. Wason
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Patent number: 4876673Abstract: An improved method and apparatus for processing seismic data records is disclosed. Data is normal moveout corrected by an operator providing estimates of velocity of seismic energy in rock layers in the earth. According to the invention, the system provides an immediate display of the seismic data processed in response to operator commands relating to estimated velocity, whereby the operator is permitted to perform normal moveout correction by inputting new velocity commands, essentially in real time.Type: GrantFiled: January 19, 1988Date of Patent: October 24, 1989Assignee: Mobil Oil CorporationInventor: Douglas W. McCowan
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Patent number: 4858202Abstract: An improved method is disclosed for obtaining shear wave data from common depth point gathered compressional wave traces using variations in the amplitude of the gathered compressional waves with source receiver offset. The gathered compressional waves are corrected for normal moveout and the normal moveout corrected waves are further corrected for residual normal moveout by correcting stacking velocities of the normal moveout corrected traces.Type: GrantFiled: September 21, 1987Date of Patent: August 15, 1989Assignee: Mobil Oil CorporationInventors: Thomas J. Fitch, Neal R. Goins, Ray S. Spratt
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Patent number: 4849887Abstract: Traveltime and reflector position for horizons of interest are used to generate a lateral coherency display representative of a subterranean horizon. According to a particular aspect, the display can include assigning maximum coherency values of each subsurface reflector, a single display value selected to contrast with display values assigned to lesser values of coherency for each subsurface reflector. According to other aspects, the invention is employed in connection with normal moveout correction and statics correction of seismic data.Type: GrantFiled: August 28, 1987Date of Patent: July 18, 1989Assignee: Amoco CorporationInventor: Joseph J. Skylas
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Patent number: 4817060Abstract: A process for directly detecting the presence of hydrocarbons in a rock formation includes generating a plurality of seismic rays at spaced intervals from one another above or within the surface of the rock formation being surveyed to form a normal move-out corrected common mid-point gather; determining an approximate angle of incidence for each seismic ray; applying predetermined weighting factors to time samples of each of the reflected rays before stacking the time samples to form a trace; extracting the reflectivity of compressional longitudinal waves (p-waves) and shear waves (s-waves) of each sample; determining the p-wave reflectivity as a function of the s-wave reflectivity; and subtracting the p-wave reflectivity so determined from the extracted p-wave reflectivity thereby to define a fluid factor which gives a direct indication of the presence of hydrocarbons in the rock formation being surveyed.Type: GrantFiled: May 26, 1987Date of Patent: March 28, 1989Assignee: Soekor (Proprietary) LimitedInventor: George C. Smith
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Patent number: 4813027Abstract: A method and apparatus for stacking a plurality of seismic midpoint gathers to provide an enhanced pictorial representation of seismic events is disclosed. The approximate propagation velocity corresponding to a selected event in a common midpoint gather, is determined by summing the common midpoint gather using first and second weights to provide respective first and second weighted sums over offset based on an estimated velocity corresponding to the event, and developing from the sums a velocity error value indicative of the approximate error between the estimated velocity and the actual velocity. The common midpoint gather is then re-stacked in accordance with the determined propagation velocity to provide an enhanced pictorial representation of the seismic event. The first and second weighted sums are taken over a time window centered upon an estimated zero offset travel time for the event.Type: GrantFiled: July 17, 1987Date of Patent: March 14, 1989Assignee: Arabian American Oil CompanyInventor: Hans Tieman
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Patent number: 4802146Abstract: A moveout correction process and stacking velocity estimation process to permit stacking of vertical seismic profile (VSP) data is disclosed wherein the primary reflection time is determined by using the two-way travel time, the root mean square velocity of acoustic pulses in the formation and the first arrival time of direct path acoustic pulses.Type: GrantFiled: May 23, 1985Date of Patent: January 31, 1989Assignee: Mobil Oil CorporationInventor: George P. Moeckel
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Patent number: 4797861Abstract: A computationally-economical method for converting a set of aerially-distributed seismic traces into a new, clearly-resolved, three-dimensional display of a volume of the earth without use of dip-dependent or azimuth-dependent migration velocities.Type: GrantFiled: March 30, 1988Date of Patent: January 10, 1989Assignee: Western Atlas International, Inc.Inventor: Craig J. Beasley