Abstract: A method for measuring noise parameters includes generating a noise signal at a noise source. The noise signal includes a first input signal at a first frequency and a second input signal at a second frequency. The first input signal and the second input signal are modulated onto a carrier to generate a modulated signal. The modulated signal is attenuated to a desired power level and applied to a device under test to obtain a noise measurement.

Abstract: This invention is an ultra-low frequency electromagnetic telemetry receiver which fuses multiple input receive sources to synthesize a decodable message packet from a noise corrupted telemetry message string. Each block of telemetry data to be sent to the surface receiver from a borehole tool is digitally encoded into a data packet prior to transmission. The data packet is modulated onto the ULF EM carrier wave and transmitted from the borehole to the surface and then are simultaneously detected by multiple receive sensors disbursed within the rig environment. The receive sensors include, but are not limited to, electric field and magnetic field sensors. The spacing of the surface receive elements is such that noise generators are unequally coupled to each receive element due to proximity and/or noise generator type (i.e. electric or magnetic field generators).

Abstract: According to a preferred aspect of the instant invention, there is provided herein a system and method for improving the computational efficiency of the DMO transformation that has many uses in the seismic processing arts. More particularly, the instant inventor has conceived and invented a faster method of calculating a log-stretch DMO transformation that utilizes multiple independent time windows, each with its own starting and ending time. A particularly preferred usage of the improved DMO method is as an element of a multiple attenuation program such as SRME.

Abstract: A method for identifying, imaging and monitoring dry or fluid-saturated underground reservoirs using seismic waves reflected from target porous or fractured layers is set forth. Seismic imaging the porous or fractured layer occurs by low pass filtering of the windowed reflections from the target porous or fractured layers leaving frequencies below low-most corner (or full width at half maximum) of a recorded frequency spectra. Additionally, the ratio of image amplitudes is shown to be approximately proportional to reservoir permeability, viscosity of fluid, and the fluid saturation of the porous or fractured layers.

Abstract: A method of correlating seismic events associated with different types of seismic transmission modes and includes calculating a shift estimate between a first set of seismic events or attributes associated with the seismic events attributable to one type of transmission mode and a second set of seismic events or attributes associated with the seismic events attributable to a different type of transmission mode using a smoothed version of at least one of the sets of seismic events or attributes associated with the seismic events, and updating the shift estimate using a less severely smoothed or unsmoothed version of the at least one set of seismic events or attributes associated with the seismic events. A related computer system and computer program products associated with the method are also described.

Abstract: Selective recording of SH waves using an array of vector-summed sensors filters out all non-SH waves.

Abstract: A method for imaging multi-directional fractures in a homogeneous basement utilizing time slices or depth slices to select velocity fields that yield the optimal lithological image of said fracture patterns, especially in 3-D seismic cubes. More specifically, the method involves definition of small data subvolumes within a larger 3-D data volume. The data subvolumes are selected to image a specific target. The subvolumes are imaged multiple times, using prestack time migration with different velocity models. Each of the migrated subvolumes is timesliced at selected time intervals. All timeslices corresponding to a given time are then gathered together from the different migrated subvolumes. Each of the constant time timeslice datasets are run through velocity analysis. In one preferred embodiment, the seismic data itself is used to determine velocity. In another preferred embodiment, velocity is determined through semblance techniques.

Abstract: A method is disclosed for attenuating noise in seismic data. The method includes calculating a trace envelope for at least part of at least one seismic trace, generating a filtered envelope from the trace envelope, and transforming the filtered envelope to a filtered trace. In one embodiment, a length of a filter operator used for generating the filtered envelope is inversely related to a maximum frequency to be preserved in the filtered trace.

Abstract: A seismic wavefield is extrapolated using variable extrapolation step size and then phase-shifted linear interpolation is applied to the extrapolated wavefield.

Abstract: Seismic traces of 3D surveys are interpolated using polynomials in 4D space from a less densely sampled real data set of source points S(x,y) and receiver points R(x,y). Input seismic traces should be pre-processed by normal move out (NMO) and static corrections. Input traces contributing to each single interpolated trace are chosen from a selected number of traces closest to each interpolated trace in 4D space. The methodology in accordance with the invention is designed to minimize computational load. The amplitude of an interpolated trace is modeled with a two-term Amplitude vs. Offset (AVO) formulation.

Abstract: A Method of measuring local similarities between seismic trace cubes (3D survey) obtained from a volume of an underground zone, corresponding to prestack data or to repeated seismic surveys (4D survey). For each point of the volume considered, the method comprises a) extracting, from each seismic trace cube, a volume neighborhood centered on a point, referred to as current point, and consisting of a set of seismic traces in limited number; b) applying an analysis technique referred to as (GPCA) allowing defining synthetic variables; and c) determining a coherence value from the synthetic extracted variables measuring the local similarity between the seismic trace cubes extracted from the volume neighborhood of the current point. The coherence value thus calculated is assigned to the current point. The coherence values of all of the current points form a coherence cube. An application is finer monitoring of the evolution with time of a reservoir under development.

Abstract: A method is provided to distinguish two blended but different waves in a structure, such as compressional and shear waves, by measuring their corresponding wavenumbers and wave speeds. Other characteristics of the two waves may also be measured such as the propagation coefficients of both waves. All measurements can be calculated at every frequency for which a transfer function measurement is made. The measurements do not depend on the resonance frequencies of the structure and do not require curve fitting to the transfer functions.

Abstract: A method of detecting and locating noise sources each emitting respective signals Sj with j=1 to M, detection being provided by a sound wave or vibration sensors each delivering a respective time-varying electrical signal si with i in the range 1 to N, wherein the method steps include: (a) taking the time-varying electrical signals delivered by the sensors, each signal si(t) delivered by a sensor being the sum of the signals Sj emitted by the noise sources; (b) amplifying and filtering the time-varying electrical signals as taken; (c) digitizing the electrical signals; (d) calculating a functional; and (e) minimizing the functional relative to the vectors nj for j=1 to M so as to determine the directions of vector nj of the noise sources.

Abstract: The present invention provides a method and apparatus for analyzing seismic data. The method includes determining a portion of the seismic data recorded substantially before the arrival of a seismic signal and adding a test signal to the portion of the seismic data recorded substantially before the arrival of the seismic signal.

Abstract: Various systems and methods of the present invention provide amorphous computing systems and methods for use thereof. In some cases, the amorphous computing systems include one or more amorphous hardware elements that are programmed under control of a computer processor such as, for example, an AMD™ or INTEL™ based personal computer. Portions of an algorithm can then be computed by the individual amorphous hardware elements that can be, as one example, an FPGA or some subset of hardware gates available on an FPGA. Methods can include a variety of computations including Wave Equations and Kirchhoff algorithms. Thus, in particular cases, the amorphous computing systems and methods for using such are applied to seismic imaging problems, as well as other problems.

Abstract: A method for processing data sets is disclosed. In one embodiment, the method comprises; (a) defining at least two primary region constraints in the data sets by creating a corresponding constraint data set, (b) combining at least two primary region constraints using gated-logic expressions to create derived regions, (c) creating mapping functions from the gated-logic expressions of the derived regions, and (d) displaying desired derived regions through manipulation of the mapping functions. This method is preferably computer implemented and permits processing of multiple constraints in large data sets (such as, three-dimensional seismic or discontinuity data).

Abstract: The invention concerns a method for the determination of local similarity values for geological units in the subsurface from a seismic 3-D dataset, which consists of a multitude of traces, each of which being formed by a sequence of data points that carry amplitude values, and especially a method for the determination of local dip-dependent similarity values, in each weighted environment of an analysis point, determining the maximum similarity value, which is assigned, together with the corresponding dip angle and dip azimuth, to the respective analysis point.

Abstract: A method of seismic data processing is described in which a particular wavelet is selected from a plurality of wavelets as being most characteristic of a received seismic signal. A subtracted signal can be determined by subtracting a weighted signal of the particular wavelet from the received signal. From the subtracted signal, an additional particular wavelet can be chosen. The process of subtracting a signal and determining an additional particular one of the plurality of wavelets can be repeated until a criterion is met. The method can be repeated at several depths. The resultant spectral analysis can be used to determine, for example, an absorption coefficient.

Abstract: A method of processing data of seismic traces for geophysical interpretation of the earth's subsurface includes the steps of determining a modified Hilbert transform of an input trace of data values to detect rapid and slow changes in the input trace with reduced sensitivity to noise and providing results of modified Hilbert transform to enable identification of any detected rapid or slow changes. The modified Hilbert transform is advantageously a windowed Fourier transform, wherein the input trace is represented as x(t), where t indicates time, a window function is represented by win(?), a first function is defined as g(?)=x(t??)·win(?), X(t,?) is the Fourier transform of g(?), hi(t) represents a sum over imaginary portions of X(t,?), hr(t) represents a sum over real portions of X(t,?), and the modified Hilbert transform is h(t)=hr(t)+i·hi(t). In its most general form, for any integer n greater than 1, hr(t)=??Real {X(t,?)}n and hi(t)=??Imag{X(t,?)}n.

Abstract: A seismic data acquisition unit includes a data acquisition and digital circuit which receives an analog seismic signal and digitizes the signal. The digitized seismic data uses data telemetry and a repeater device to receive the compressed data and transmit the compressed data to a seismic central control unit. The data decompressor takes the data from the data compressor and decompresses the data. The decompressed data is then compared with the original digitized data to determine the amount of noise resulting from the compression process. The compression noise is compared to the ambient noise, and if the compression noise exceeds a predefined criterion, then the compression ratio in the data compressor is adjusted for a lower degree of compression. The process is repeated until the amount of compression noise, relative to ambient noise, is satisfactory.

Abstract: A method of processing sonic wireline or logging while drilling data acquired in a borehole that includes filtering the sonic data to attenuate tool-borne and borehole-borne arrivals; migrating the filtered sonic data; and beamforming the filtered and migrated sonic data to determine a position of a reflector with respect to the borehole. The sonic data may be processed down-hole, transmitted to the surface, and used for geosteering purposes while drilling. The filter may comprise an adaptive noise-attenuating filter capable of attenuating noise arising from different borehole modes from desired signal and allowing for changes in the source signature.

Abstract: A hardware interface usable to communicate with electrically erasable read-only memory devices and, optionally, other external controls or devices, includes self-monitoring power supply circuitry, an EEPROM driver and noise and signal degradation prevention circuitry, and optional input/output circuitry which provides for programmatically cycling power to the memory device. The self-monitoring power supply circuitry is capable of determining whether a power supply has reached the hardware interface. The EEPROM driver and noise and signal degradation prevention circuitry reduces signal noise and/or signal degradation and driver circuitry for programming, monitoring, and downloading information to and from the EEPROM devices. The digital input/output circuitry is capable of controlling the power supply to the hardware interface, downloading or monitoring information to the hardware interface, or controlling/responding to external devices or controls.

Abstract: A method for enhancing signal-to-noise (S/N) ratio of seismic data is presented. An ensemble of input traces is decomposed into a plurality of frequency bands of traces. Trace and signal power and then a maximum allowable signal-to-noise ratio are estimated for each frequency band. Weights are calculated which are functions of the inverse noise power or rms. The amplitudes in each of the traces are reformed using a fitting function which utilizes the estimated weights to create true relative amplitude signal enhanced traces. The weighting function has data adaptive parameters which can be changed to accommodate noise characteristics such coherency, incoherency, Gaussian and non-Gaussian distributions, etc. The method may be applied across many different coordinate systems. The method may be applied iteratively to seismic data to shape the noise distribution of the seismic data.

Abstract: A method for identifying, imaging and monitoring dry or fluid-saturated underground reservoirs using seismic waves reflected from target porous or fractured layers is set forth. Seismic imaging the porous or fractured layer occurs by low pass filtering of the windowed reflections from the target porous or fractured layers leaving frequencies below low-most corner (or full width at half maximum) of a recorded frequency spectra. Additionally, the ratio of image amplitudes is shown to be approximately proportional to reservoir permeability, viscosity of fluid, and the fluid saturation of the porous or fractured layers.

Abstract: The Fracture Trend Identification method is practiced by the Fracture Trend Identification software adapted for analyzing compressional 2-D seismic data in order to identify zones in a rock formation containing open, natural fractures. The Fracture Trend Identification method comprises one or two or more of the following steps: loading seismic data into the workstation software and visually quality controlling it, and then generating variance sections and reviewing them visually to identify faulting, identifying seismic events that corresponds to a formation of interest, extracting seismic attribute data from various zones of the seismic events, identifying frequency anomalies by interpreting the extracted seismic attribute data of the various zones of the seismic events, identifying and removing any potentially false positive frequency anomalies, and confirming any remaining ones of the anomalies not removed during the removing step and ranking the confirmed ones of the remaining anomalies.

Abstract: A method is disclosed for calculating the quality factor Q from a seismic data trace. The method includes calculating a first and a second minimum phase inverse wavelet at a first and a second time interval along the seismic data trace, synthetically dividing the first wavelet by the second wavelet, Fourier transforming the result of the synthetic division, calculating the logarithm of this quotient of Fourier transforms and determining the slope of a best fit line to the logarithm of the quotient.

Abstract: A method for making a time-lapse seismic survey in a marine environment, the method designed to eliminate multiple surface reflections and changes in sea state and conditions. Seismic sources and receivers are positioned at predetermined conditions for a first set of data in which at least two sets of seismic signals are recorded at each receiver, proximate in time, such that there are insignificant changes in the subsurface formation. At a later point in time the seismic source(s) and receiver(s) are positioned at the same place when the first seismic data set was generated. A seismic source emits a sound wave and the seismic receiver receives what will be called a “monitor signal” and the two-way water travel time is again determined. A model is then developed for the first and second seismic data sets in that includes the subsurface signal, changes in the subsurface signal and the effect of multiple reflections.

Abstract: A method is disclosed for marine seismic surveying in which a seismic signal is detected in a body of water with a motion sensor and a pressure sensor positioned at a location proximate the bottom of the body of water. Seismic signals are detected with pressure sensors positioned in one or more streamer cables being towed in the body of water near the location proximate the bottom of the water at which a motion sensor and a pressure sensor are positioned. The signals detected by the motion sensor and pressure sensor positioned proximate the bottom of the body of water are used for calibrating the seismic signals detected with the pressure sensors positioned in the streamer cables.

Abstract: System and method for performing anisotropy corrections of post-imaging seismic data for a subsurface formation. The method may receive seismic data, preferably pre-stack seismic data comprising a plurality of traces, e.g., collected from a plurality of source and receiver locations. The seismic data may be imaged/migrated to produce imaged seismic data, which is organized into an arrangement that preserves aspects of the relative seismic propagation angle in the subsurface. One or more anisotropic parameters and corresponding corrections may be determined by analyzing the organized imaged seismic data. The determined parameters or corrections may be used to correct at least a subset of the imaged seismic data, thereby producing corrected seismic data which is useable in analyzing the formation. The corrected data may then optionally be stacked to produce a collection of corrected stacked traces, and/or analyzed as desired. The pre-stack data and/or the corrected seismic data may optionally be displayed.

Abstract: A frequency domain based method using matrix rank reduction for removing noise from seismic data sets is provided using a variety of 3D eigen filtering techniques. A rank reduced grid of traces or proxy cube that is representative of an original grid of Traces, but that has a better signal to noise ratio results since the surviving data elements represent the bulk of the composite signal related to genuine reflectors—whereas the trivial elements replace a large portion of the composite signal related to random noise. There is no compression of the elements of the representative matrices. The use of a series of proxy cubes in place of the co-ordinate pair related original CUBEs of seismic data results in several advantages including reduced processing time and better accuracy at the boundaries of the subject section.

Abstract: A method is disclosed for processing seismic data from concurrently recorded co-located pressure sensors and geophones. The seismic data are processed by first determining an upgoing wavefield and a downgoing wavefield in the seismic data. Adaptive subtraction is then applied to at least one of the upgoing wavefield and the downgoing wavefield to remove the noise from the signal. In alternative embodiments, the upgoing wavefield can be used as a noise model for the downgoing wavefield or the downgoing wavefield can be used as a noise model for the upgoing wavefield.

Abstract: This invention relates to improved methods to generate shaped sweeps, and for the acquisition of vibroseis data with a shaped pilot sweep.

Abstract: A seismic data set is processed by applying a transform to the seismic data set that corrects for time shifts in the seismic data set resulting from azimuthal variation. Alternatively, a seismic data set is sorted to common offset gathers. Then, the following steps are applied to each common offset gather: A transform is applied to the common offset gather that corrects for time shifts in the common offset gather resulting from azimuthal variation. The transformed common offset gather is inverse transformed.

Abstract: Data are acquired using multi-array logging tool in a borehole having an angle of inclination to a normal to the bedding plane of earth formations. The multi-array measurements are filtered using angle dependent filters to give a filtered curve corresponding to a target one of the multi-array measurements using angle dependent filters. Correlation coefficients are determined for a set of possible dip angles and a relative dip angle is estimated from the correlation coefficients. This dip angle estimate together with bed boundaries obtained from the multi-array measurements are used for inverting multi-component measurements alone or jointly with multi-array measurements to refine the relative dip angle interpretation and give horizontal and vertical formation resistivity.

Abstract: A method is disclosed for separating energy resulting from actuating at least two different seismic energy sources from seismic signals. The sources are actuated to provide a variable time delay between successive actuations of a first one and a second one of the sources. The method includes sorting the seismic signals such that events therein resulting from actuations of the first source are substantially coherent in all spatial directions, coherency filtering the first source coherency sorted signals, sorting the seismic signals such that events therein resulting from actuations of the second source are substantially coherent in all spatial directions, and coherency filtering the second source coherency sorted signals.

Abstract: A method for determining from measured reflection data on a plurality of trace positions, a plurality of subsurface parameters. The method includes the steps of: preprocessing the measured reflection data into a plurality of partial or full stacks; specifying one or more initial subsurface parameters defining an initial subsurface model; specifying a wavelet or wavelet field for each of the partial or full stacks of the measured reflection data; calculating synthetic reflection data based on the specified wavelets and the initial subsurface parameters; optimizing an objective function, including the weighted difference between measured reflection data and synthetic reflection data for a plurality of trace positions simultaneously; and outputting the optimized subsurface parameters. A device for implementing this method is also included.

Abstract: The present invention provides a method and system for processing an input seismic record to suppress noise energy, for example multiple energy, and to enhance signal. A primary signal component is determined from an input seismic record. A residual record is obtained from the input seismic record and the determined primary component record, for example, by determining a difference of the two records. A next primary signal component record is then obtained from the residual record. The primary component record and the next primary component record are combined to form a reconstructed record. A subsequent residual record may then be obtained and further primary signal components extracted.

Abstract: The present invention provides a method of performing the time picking step in a VSP (vertical seismic profile) survey. In a preferred embodiment of the invention the time picking step is carried out on a combined three-component amplitude of the received seismic energy, which contains the amplitude of all the seismic energy received at the receiver. The amplitude of the direct pulse in the combined trace will not decrease to zero as the offset of the source is changed, as can be the case for the single-component amplitude of the direct pulse. In a particularly preferred embodiment of the invention, the combined three-component amplitude is calculated by summing the Hilbert instantaneous amplitudes of the x-, y- and components of the seismic data using the equation (I). The present invention also provides two new time picks. One time pick involves finding the maximum positive gradient of A(t).

Abstract: A method and apparatus for determining isolating and/or removing a signal of interest from acoustic data. The method and apparatus may be used to measure formation slowness in a cased borehole, in which case the signal of interest may be a casing arrival signal. The casing arrival signal may be detected, rebuilt and removed from a set of acoustic data. Semblance processing is applied to the acoustic data with the casing signal removed, yielding a coherent formation slowness log. A filter band may be defined and automatically administered to detect and remove the signal of interest such as the casing signal.

Abstract: A method of separating and localizing sources of traveling waves, by obtaining linearly independent time-differentiated instantaneous observations of the sources, from spatial derivatives of the traveling wave acquired using a distributed sensor or a sensor array. The sources are blindly separated by direct application of (static) independent component analysis on the time-differentiated observations, yielding both the sources and their direction cosines relative to the sensor geometry. The method is suited for arrays of small aperture, with dimensions shorter than the coherence length of the waves. In one preferred embodiment, three sources are separated and localized from differential observations on four coplanar sensors positioned on the corners of a square.

Abstract: A method of monitoring a microseismic event includes detecting the event to produce a first signal dependent on the event. The first signal includes noise at a frequency of, for example 50 Hz. A first sample of the first signal is taken. Then a second sample of the first signal is taken, the second sample occurring n/f seconds after the first sample, where n is an integer (e.g. 1). Subtracting the first and second samples from each other produces a farther signal dependent on the event in which the noise has been at least partly compensated for.

Abstract: A system and method of creating a filter for use with locally dense seismic data is disclosed. The method includes obtaining survey geometry characteristics from a locally dense seismic survey. A filter is designed which uses spatial derivatives of the wavefield of order between (1) and the maximum order of spatial derivatives of the wavefield that can be estimated within a group. The filter can be designed so as to separate up/down going components, p/s components, or both up/down and p/s components. Partial derivatives in space and time of the wavefield can be calculated, using, for example, a taylor series expansion as an approximation. The seismic data is filtered by combining estimated near surface material properties, the seismic data, and the calculated partial derivatives.

Abstract: The present invention provides methods to be used in seismic data processing to address problems encountered during data acquisition from a limited number of receivers. The present invention applies parametric methods to provide superior wavemember resolution.

Abstract: Correcting a signal offset may include observing a finite duration signal yn that comprises a representation of a mixture of a desired signal that may include data of interest, and an undesired signal based on interference of an external interference source. The undesired signal may include an offset component which may be modeled as comprising a step function u defined by unknown step function parameters. The unknown step function parameters may be estimated using, for example, a maximum likelihood method. Thereafter, yn may be corrected based on the estimated step function parameters.

Abstract: A method for attenuating water layer multiples from a gather of seismic data traces. The method includes predicting a plurality of receiver side water layer multiples in the gather of seismic data traces using a convolutional operator derived from a water layer model, adaptively subtracting the receiver side water layer multiples from the gather of seismic data traces, predicting a plurality of source side water layer multiples using the convolutional operator derived from the water layer model, and adaptively subtracting the receiver side water layer multiples and the source side water layer multiples from the gather of seismic data traces to generate a plurality of primaries in the gather of seismic data traces.

Abstract: A method for correcting seismic data for periodic distortion introduced by acquisition parameters by filtering modified unitary transform data. A vertical transform is applied to seismic data to obtain frequency-space seismic data. These data are decomposed into an amplitude component and a phase response component. The phase response component is saved for the inverse process. A horizontal transform is applied to the amplitude component of the F-X data to obtain modified transform data. Because this transformation is performed in the X direction, it is here also referred to as the horizontal forward Fourier transformation. A K filter based on the period of the energy to be suppressed or eliminated is applied to this F-K data. The K filter may be, for example, a notch filter or any suitable filter. The data are then inverted to obtain T-X data with distortion suppressed or eliminate.

Abstract: A method for absolute preserved amplitude processing of data obtained by seismic prospecting known as VSP. The method comprises reception, by seismic receivers (R) arranged in a well and coupled with the surrounding formations, of seismic waves generated by a source (S) and reaching directly the receivers (direct or downgoing waves DW) or after reflections on discontinuities (D) (upgoing waves UW). The method has an application of precise measurement of the amplitudes of reflected and diffracted seismic events on monocomponent or tricomponent VSP data, in addition to conventional seismic wave propagation time and velocity measurements.

Abstract: A method is disclosed for identifying primary events in seismic data. The method includes sorting the data by frequency so that at least some primary events are separated from non-primary events, thus generating a frequency sorted gather. Amplitudes in the frequency sorted gather above a selected base amplitude are attenuated. The events are then coherency filtered and the attenuated amplitudes are replaced with amplitudes corresponding to the coherent events.

Abstract: The present invention relates to a novel method for selective recording of SH waves using an array of sensors that filter out all non-SH waves.

Abstract: A seismic signal is represented as a combination of a geologic signal and a noise signal. The representation of the seismic signal is decomposed into a linear combination of orthonormal components. One or more components are identified in which the geologic signal and the noise signal are uncorrelated. The noise signal is expanded as a product of an unknown noise amplitude modulation signal and a known noise spatial periodicity signal at the identified components. The expansion is solved for an estimate of the noise amplitude modulation signal at the identified components. The noise signal is estimated by multiplying the estimated noise amplitude modulation signal by the noise spatial periodicity signal. The estimated noise signal can be removed from the seismic signal to generate an estimate of the geologic signal.