Abstract: The present invention is a method to determine an azimuthal orientation of a borehole seismometer sensor performed by a computing device using a control server having a database and an arithmetic function, the computing device performing a method to determine the azimuthal orientation of a borehole seismometer sensor using long-period surface waves in microseisms, including step S100 in which a data collection unit 100 collects continuous waveform data recorded by a borehole seismometer and a reference seismometer; step S200 in which a frequency band setting unit 200 sets a frequency band to be analyzed in the collected continuous waveform data; step S300 in which a filtering unit 300 performs bandpass filtering on the frequency band to be analyzed; step S400 in which a waveform dividing unit 400 divides seismic waveform into waveform segments with preset time units; step S500 in which a phase shift unit 500 shifts the phase of the divided vertical component waveforms by 90°; step S600 in which a waveform cal

Abstract: A method for determining and tracking an edge of first breaks is provided. The method includes obtaining seismic data associated with subsurface formations, the seismic data relating to a vibration contacting a plurality of portions of the subsurface formations, processing the seismic data to produce processed seismic data comprising one or more attributes, wherein the processed seismic data defines an edge characterizing a plurality of onset times, iteratively performing, using a level sets algorithm, a plurality of tracking operations on the processed seismic data to identify the edge characterizing a plurality of first breaks' onset times, and determining the edge as first breaks.

Abstract: Methods and apparatuses compute and apply surface-consistent frequency-dependent phase corrections, to traces extracted from seismic survey data, using a multi-scale iterative approach.

Abstract: A system and method are described herein for generating a velocity model of returned seismic signals for under-ocean floor environments. The system and method generate a series of source signals, receive a corresponding set of direct signals, reflected signals, and refracted signals, solve a velocity model equation using a full waveform inversion function with respect to the received set of direct signals, reflected signals and refracted signals to minimize a least square misfit function by relaxing a dependency on low frequency reflections in the full waveform inversion function. The system and method then generate the velocity model based on the solution to the velocity model equation, and display the velocity model.

Abstract: A method for speech restoration by an electronic device is described. The method includes obtaining a noisy speech signal. The method also includes suppressing noise in the noisy speech signal to produce a noise-suppressed speech signal. The noise-suppressed speech signal has a bandwidth that includes at least three subbands. The method further includes iteratively restoring each of the at least three subbands. Each of the at least three subbands is restored based on all previously restored subbands of the at least three subbands.

Abstract: Refracted energy travel time can help to derive anisotropic parameters in a target layer. These anisotropic parameters allow us to both explore for new reservoirs and to understand stress and fracturing in existing reservoirs. This information can be used to i) detect oil reservoirs, ii) spot naturally fractured, hence high production zones, iii) detect dominant natural stress directions, iv) better place horizontal wells to optimize production, v) monitoring man made fractures or induced directional stress changes. The method is demonstrated using synthetic and real data.

Abstract: Computing device and method for determining primary and ghost components from recorded P-waves. The method includes receiving seismic data (R, V) with regard to the P-waves, wherein the seismic data includes vertical and radial components recorded with a buried two-component receiver; calculating with a processor a primary component (P) and a ghost component (G) from the vertical and radial components; and computing an image of a subsurface based on the primary and ghost components (P, G). The P-waves form a plane wave.

Abstract: This disclosure presents a method that utilizes the seismic image of the near-surface formation to estimate an effective velocity field equivalent to the unknown true velocity field of the soil column, such that the statics shifts derived from the effective velocity field are essentially the same as the statics shifts that would have been computed using the unknown true velocity field. The effective velocity field derived statics shifts can be used to correct distortions caused by the near-surface formation and restore the sesimic image of the subsurface formation.

Abstract: A method of seismic surveying A method of seismic surveying comprises the step of acquiring imaging seismic data relating to an underlying geological structure at a survey location and simultaneously, or substantially simultaneously, acquiring statics seismic data relating to the near-surface (5) at the survey location. The method may use an imaging source (12) to acquire the imaging seismic data and a separate statics source (13,13?) to acquire the statics seismic data. Alternatively only an imaging source (12) may be used, and the statics seismic data may be obtained from surface waves, airwaves or ground-roll waves that are generated by the imaging source and that have hitherto been regarded only as unwanted noise.

Abstract: A technique includes receiving seismic data acquired in a survey of a region, the region being associated with locations; processing the seismic data to estimate at least one frequency dependent surface wave property over the region; based at least in part on the estimated frequency dependent surface wave property(ies), determining a frequency dependent data processing geometry for each location; and processing the seismic data based at least in part on the determined data processing geometries to derive a spatially continuous representation of a surface wave property across the region.

Abstract: A method for processing geophysical data. The method includes applying a first interferometry on an estimate of a direct ground roll between a receiver location and one or more boundary source locations and an estimate of a direct ground roll between one or more boundary receiver locations and each boundary source location to generate an interferometric estimate of a direct ground roll between the receiver location and each boundary receiver location. The method then includes applying a second interferometry on geophysical data between the source location and each boundary receiver location and the interferometric estimate of the direct ground roll between the receiver location and each boundary receiver location to generate an interferometric estimate of a direct and scattered ground roll between the source location and the receiver location.

Abstract: A method and system of for determining near surface velocity structure and statics corrections includes acquiring multicomponent seismic data associated with a sensor location, computing spectrograms for all orthogonal components of the multicomponent seismic data using a processing unit, calculating a median H/V spectrum, calculating an initial Rayleigh ellipticity solution associated with the sensor location and inverting the values associated with the median H/V spectrum with a forward-modelled Rayleigh ellipticity solution to determine a velocity depth distribution associated with the sensor location.

Abstract: A method is used to convert seismic data between bounding upper and lower surfaces in the time domain to the depth domain. An upper depth surface corresponding to the upper time surface is determined, either from well data or by time-depth conversion of the upper time surface. An interval velocity value is determined for each seismic sample between the bounding time surfaces from velocity data generated from well logs. The seismic times between the bounding time surfaces are then converted to the depth domain by adding the thickness of each seismic sample to the upper depth surface, wherein the thickness of each seismic sample is a function of the seismic sample rate and interval velocity value for each seismic sample. The seismic attribute values from the converted seismic data can be interpolated to a linear depth sampling.

Abstract: A seismic surveying arrangement comprises a vertical source array (26) having at least two sources (27,28) of seismic energy. The source array (26) is disposed such that a first source (28) is located within a weathered layer (35) of the earth's interior and such that a second source (27) is located within the weathered layer at a greater depth than the first source or within a high velocity layer (8) underlying the weathered layer (35). The surveying arrangement also includes a first horizontal receiver array (29) located in the weathered layer, and means for processing seismic data acquired by the first receiver array. The processing means are able to process the acquired seismic data so as to attenuate seismic events involving reflection of seismic energy at at least one boundary face of the high velocity layer. The seismic surveying arrangement may also comprise a second receiver array (30) disposed at a lower depth than the first receiver array (29).

Abstract: A method for improving the seismic resolution in the field of petroleum exploration and development, using the steps of: (1) ensuring the depth and the velocity of the low-velocity layer and the high-velocity layer and the characteristic of the frequency spectrum of the seismic wave at the near-surface using the borehole seismic survey; (2) separating the ghost wave from the seismic record in the high-velocity layer using the processing method of the vertical seismic profiling, and improving the SNR of the seismic record of the direct wave at the high-velocity layer using the uphole stacking of the vertical seismic profiling; (3) evaluating the de-convolution operator of the near-surface by the convolution math-physics equation; (4) evaluating the seismic record with high resolution by the de-convolution math-physics equation; (5) providing the band-pass filtering and geologic interpretation to the seismic record with high resolution.

Abstract: A method of and apparatus for processing seismic data. A method of processing seismic data comprising the steps acquiring seismic data in at least two shots that have different source-receiver azimuths from one another, and selecting events arising from interface seismic waves in each shot. The interface wave events are processed to provide information about azimuthal dependence of the velocity of seismic energy in the near-surface of the earth's interior. The invention may be used to process events arising from Scholte waves in marine seismic data, or to processing events arising from Love waves or Rayleigh waves in land seismic data. The method may be applied to seismic data acquired specifically to provide information about the near-surface or to seismic data acquired to provide information about the underlying geological structure.

Abstract: 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.

Abstract: P-wave velocity in a near-surface region of a land area is estimated from a combination of seismic data based upon waves in the near-surface region generated in response to a shock in each of a plurality of upholes drilled in the land area and vibrator dynamic data generated in the near-surface region in response to vibrator action on the land area.

Abstract: A method for tomographic modeling of seismic wave travel times from well drilling records generated by drill string vibrations during drilling and identifying in the recorded vibration at least one of direct, reflected, refracted, converted and diving waves so as to measure wave velocity in near surface layers.

Abstract: For determination of the laminar structure and other characteristics of a ground, oscillation sensors for detecting the vertical component or vertical and horizontal components of oscillations are disposed at three or more points within a comparatively small area at ground level to simultaneously measure microseisms at the respective points, if necessary with locations of said points being varied and measurements be performed at the respective locations and the vertical oscillation data or vertical and horizontal oscillation data thus generated are analyzed. This method not only permits an expedient, positive and accurate assessment of the laminar structure and other characteristics of the ground but also permits the measurement of ground structure even when the area available for measurement is small.

Abstract: For determination of the laminar structure and other characteristics of a ground, oscillation sensors for detecting the vertical component or vertical and horizontal components of oscillations are disposed at three or more points within a comparatively small area at ground level to simultaneously measure microseisms at the respective points, if necessary with locations of said points being varied and measurements be performed at the respective locations and the vertical oscillation data or vertical and horizontal oscillation data thus generated are analyzed. This method not only permits an expedient, positive and accurate assessment of the laminar structure and other characteristics of the ground but also permits the measurement of ground structure even when the area available for measurement is small.

Abstract: A computationally efficient semi-recursive Kirchhoff migration algorithm is capable of obtaining accurate images of complex structures in complex geological environments which commonly give rise to multivalued arrivals. The method alternates wave-equation datuming (downward continuation) and Kirchhoff migration. Breaking up the complicated velocity structure into small depth regions allows traveltimes to be calculated in regions where the computation is well behaved and where the computation corresponds to energetic arrivals. Because traveltimes are computed for small depth domains, the effects of multivalued arrivals are implicitly accounted for in the migration and the adverse effects of caustics and headwaves do not develop. The invention can use any simple first-arrival traveltime algorithm, and thus benefits from the computational efficiency, robustness, and simplicity of such algorithms.

Abstract: A computer system and method for correcting seismic data for phase distortion due to the effects of the near-surface layer are disclosed. Phase error corrections are performed on multiple frequency bands, beginning with a primary band and then proceeding with adjacent frequency bands. The primary band phase constant and time lag corrections are derived in a manner in which the phase correction is applied to the correlation function prior to selection of the peak time lag value, improving the accuracy of the time lag decomposition. Corrections for the secondary bands are made in such a way that the phase corrections at a tie frequency within the overlap frequencies between each secondary band and its adjacent bands are forced to be equal. At each step, surface-consistent decomposition of the phase static components and the time lag static components is performed using a weighted least-squares approach.

Abstract: A phase locked loop circuit having a voltage controlled oscillator for generating a clock signal with a frequency determined by a voltage control signal supplied to the voltage controlled oscillator, an AD-conversion circuit for sampling a target signal with a timing determined by the clock signal and for converting sampled values into digital data, a phase locked loop control circuit for generating control data with values representing values of the digital data, and a DA-conversion circuit having an adjustable conversion characteristic for converting the control data into an analog signal and for outputting the analog signal to the voltage controlled oscillator as the voltage control signal.

Abstract: Disclosed is a method of datuming seismic trace data from a first horizon to a lower second subsurface horizon, both located above a target horizon. A seismic source and receiver are positioned along the first horizon and each assigned a coordinate representing a position along the first horizon. The seismic trace data includes both header information and seismic data. The header information includes the coordinates assigned to the source and receiver. The seismic data is a record of reflection amplitude versus travel time of a seismic signal traveling from the source, downward through and intersecting the second horizon at a downward intersection point, reflecting upward from the target horizon, upward through and intersecting the second horizon at an upward intersection point, and upward to the receiver. The method generally includes determining for both the downward upward intersection points, coordinates along the second horizon corresponding to positions along the second horizon.

Abstract: In the presence of an anisotropic near-surface earth layer, orthogonally oriented microspreads are provided from which shear-wave velocity vectors V.sub.si.theta. and V.sub.s.theta. may be determined. The respective velocities are calculated from measurements of the direct path first arrivals and of the velocity of the boundary waves propagating along the upper boundary of the near surface layer. The ratio of the near-surface shear-wave velocity vectors is used to scale the static time corrections attributable to seismic data received by shear wave sensors whose axes of responsivity coincide with the orientation of the microspreads.

Abstract: A method of geophysical prospecting wherein nonhyperbolic distortion is reduced from marine seismic data, or land seismic data over a low seismic velocity layer, is disclosed. The method comprises replacing the seismic velocity of the water or low seismic velocity layer with sediment seismic velocity and using analytic ray tracing to determine a mapping function to correct recorded seismic data for removal of the distortion, which occurs because of the high seismic velocity contrast at the water or low seismic velocity layer.

Abstract: Disclosed is a method for processing geophysical data that have been gathered over irregular topography. According to the method, a datum is established that lies above the highest topographic peak. The data are time-shifted from the surface to the datum using a replacement velocity that is an extrapolation of the underlying formation velocity. The wavefields beneath the surface are forwardly modeled using a modeling velocity substantially equal to zero. Between the surface and the datum, the wavefields are upwardly modeled using the replacement velocity.

Abstract: Disclosed is a technique for processing seismic data to enable the data to be migrated without stacking. Seismic data provided in common midpoint gathers are converted to a domain defined in terms of the travel time and the first power of velocity of reflected waves, and migration is performed in this domain. The migrated seismic data is converted back to the offset domain, wherein velocity analyses may be performed prior to stacking of the data.

Abstract: A method for static correction includes a three step process which eliminates the problems of assuming hyperbolic moveout curves and forming base traces from common midpoint gathers while addressing long spatial wavelength variations. First, after calculating and applying an approximate high-frequency static correction to the individual shot and receivers (using traditional automatic methods), depth migration iterations are employed to coarsely tune the near-surface velocity layer. Second, after applying this correction, the remaining statics are incorporated into the model by tomography, which accounts for the velocity and thickness of the weathering layer and buried anomalies. Third, any residual misalignments are addressed using a multi-windowed statics adjustment within the common image point (CIP) gathers.

Abstract: Weathering corrections are determined from first arrival times of refraction stacked traces of common end point gathers. The refraction stacked traces are generated by selecting traces having receiver source offsets greater than the crossover distance and stacking such traces over at least an interval comprising first arrival times. Optionally, a predictor function is used to select first arrivals and the first arrivals are selected from a refraction stacked trace section.

Abstract: When a record mark portion arranged on the upstream side of a data area is reproduced, the peak value of a reproduction signal of the record mark portion is compared with a reference level. An overwrite preventing circuit is arranged so as to output an inhibiting signal for inhibiting data writing when the comparison output exceeds a predetermined level. With this preventing circuit, a data portion need not be checked in a read mode prior to a write mode.

Abstract: A method of removing multiple reflection events from seismic records is described. A shallow primary reflection event is used as a model for a deeper primary, and is distorted responsive to the predicted static correction to yield a model for the multiple. The method is applied to common depth point (CDP) records, in which the common-midpoint contribution of the multiple to each CDP record can be assumed to be equal. Preferably, a total least squares correlation step is used to design a convolutional filter applied to the data records to remove the multiples therefrom.

Abstract: A method of seismic exploration uses recordings from both surface receivers and buried sensors to determine the full elastic effect of the near surface layer on an applied seismic wave. The surface receivers are arranged relative to the seismic source location so that rotational effects may be detected. Buried sensors are located so that vertical effects may be detected. This full elastic effect may be used in subsequent seismic data acquisition to reconcile the effect of the near surface so that the response of the underlying rock formations may be known.

Abstract: A method for properly migrating seismic data which has been elevation-static corrected. The method is comprised of assigning a zero (or very small) migration velocity for data located below a datum, yet above the original recording surface elevation. A best estimated earth velocity is input into the migration algorithm to represent the earth below the original recording surface. For seismic data collected in water-covered environments where the water bottom is irregular, the method contemplates that the data lying above the water bottom are migrated using the migration velocity of water. The data lying at or below the water bottom are migrated with a migration velocity of zero. In a second step, are elevation-static corrected and migration is performed where the velocity is zero between the datum and the original surface. Data below the surface is migrated using the estimated earth velocity.

Abstract: An earth impedance determination and compensation system for use with a seismic vibrator utilizes output signals from accelerometers on the baseplate and reaction mass portions of the vibrator to create a signal indicative of the near-surface weathered earth layer impedance below the baseplate. The impedance signal is utilized to generate parameter signals which are indicative of the compressional and shear wave patterns generated by the baseplate and may be used to more rapidly and accurately design seismic source arrays to optimize the wave pattern emanating therefrom. One of the parameter signals is directly indicative of the travel time thickness of the weathered surface layer and may be used to accurately determine the static correction factor attributable solely to weathered layer topography.

Abstract: A method useful in seismic data processing for correcting data for the effects of the low velocity layer. At least three sets of traces having common offsets are displayed as a function of centerpoint. From this, the first refraction arrival for each trace may be hand picked, this first refraction arrival representing a compressional wave refracted along the lower boundary of the low velocity layer. An equation is set up for each source-receiver pair in which the transit time of the first refraction arrival is a function of three independent factors: the source to receiver distance; a low velocity layer component for the source; and a low velocity layer component for the receiver. These equations are solved in a simultaneous, least squares fashion to yield surface consistent solutions to the low velocity layer component at each source and receiver location.

Abstract: A method of determining source and receiver statics in a marine exploration area overlying a near surface low velocity layer employing a marine vessel for towing a seismic energy source and a marine detector cable, and an on-bottom seismic energy source and seismic detector located at an offset from the marine seismic line of exploration. The towed seismic energy source generates a seismic reflection signal for detection by the towed marine detector cable and a seismic refraction signal to be detected by the on-bottom seismic detector. The on-bottom seismic energy source generates a seismic refraction signal for detection by the towed marine detector cable.

Abstract: A method of determining source and receiver statics in a marine seismic exploration area overlying a near surface low velocity layer employing a seismic marine energy source, an on-bottom seismic detector cable for measuring seismic reflection signals, and an on-bottom remote seismic monitor for measuring seismic refraction signals.

Abstract: Disclosed is a method of processing geological seismic reflection data to compensate for lateral variations in the attenuation effect which the weathered layer has on the reflected seismic energy waves as they approach an array of detectors at the surface. Absolute amplitudes of the waves are summed for each trace throughout a test window at the depth to be explored. The amplitudes are normalized by taking the ratio of each sum to the sum of the absolute amplitudes obtained throughout a standard window, in the corresponding trace. In a particular embodiment disclosed, the test window scans each trace in increments, and the absolute amplitude sum obtained at each position is normalized to the standard window in that trace. The ratios thus obtained, when plotted, reveal the positions of large-amplitude reflecting strata without weathered-layer distortion.

Abstract: A method for correcting seismic data for the effects of the low-velocity-layer. According to the method, estimates of the seismic velocity in the low-velocity-layer and the depth of the low-velocity-layer are used to extrapolate the seismic data to simulated source and receiver positions located at the base of the low-velocity-layer. The data are then extrapolated to an arbitrary reference datum using a selected replacement velocity. The principles of wave equation datuming are used for these extrapolations.