Abstract: Processes and systems described herein are directed to performing marine surveys with marine vibrators that emit orthogonal coded pseudo-random sweeps. In one aspect, coded pseudo-random signals are generated based on coded pseudo-random sequences. The coded pseudo-random sequences are used to activate the marine vibrators in a body of water above a subterranean formation. The activated marine vibrators generate orthogonal coded pseudo-random sweeps. A wavefield emitted from the subterranean formation in response to the orthogonal coded pseudo-random sweeps is detected at receivers located in a body of water. Seismic signals generated by the receivers may be cross-correlated with a signature of one of the orthogonal coded pseudo-random sweeps to obtain seismic data with incoherent residual noise.

Abstract: The disclosed technology relates to log file processing techniques for root cause analysis of a network fabric. A system may be configured to identify a feature of interest in a log file and calculating an abnormal level for the feature of interest. The system is further configured to detect that a performance event has occurred during a time period, determine whether the feature of interest is at the abnormal level during the time period, and identify a correlation between the feature of interest and the performance event based on the determining.

Abstract: A network correlation engine (CE-1) to be coupled to a telecommunication network (NT) comprising at least one network section (Sm) to supply at least one event notification (Am) upon detection of an event relating to the section. The correlation engine comprises at least one event analysis block (Bn) comprising at least a root cause analysis module (RCn) to receive on input the event notification and to supply on output a root cause analysis result (RRn) and a service analysis module (SAn) to receive on input the root cause analysis result from the root cause analysis module of the block is and to supply on output a service impact analysis result (SRn).

Abstract: Seismic surveying techniques are described in which seismic receivers in a seismic array are used as seismic sources. These receiver-sources may be used to determine the near-surface structures of the Earth, geometric properties of the survey array, receiver locations and operations of the survey array. The receiver-sources may be driven by drive sequences to produce amplified receiver-source signals, plane waves, surface waves converging towards a point inside the seismic array, surface waves sweeping through the seismic array and/or the like. The receiver-sources may comprise geophones, hydrophones, accelerometers and/or the like. A driver may be used to drive the receiver-sources and the driver may be controlled by a processor. By encoding drive sequences, seismic data generated by the receiver-sources may be separated from seismic data generated by another seismic source in the seismic array.

Abstract: A method for encoding signals using frequency sweeps in a downhole environment, in some embodiments, comprises: obtaining a digital signal; encoding the digital signal using one or more frequency sweeps to produce an encoded signal; transmitting the encoded signal from a transmitter to a receiver, at least one of the transmitter or receiver disposed downhole; receiving the encoded signal at the receiver; and decoding the encoded signal at the receiver to produce a decoded digital signal.

Abstract: Methods and apparatuses for acquiring marine seismic data to generate images or determine properties of an interior section of the Earth using simultaneous marine vibrator sweeps and methods for processing the acquired seismic data. Phase of sweeps produced by the marine vibrator(s) are controlled to provide for removal of crosstalk. The phases between marine vibrator sweeps may be random or controlled to have a predetermined/desired phase difference. The predetermined phases may be determined to minimize the crosstalk between sweeps based on known seismic velocity of the survey area.

Abstract: A technique includes generating one or more sweep sequences for one or more seismic vibrators for a seismic survey and evaluating a cost for the sequence(s). The technique includes perturbing the sequence(s) and continuing the evaluation and perturbing until the cost is within a limit or a maximum number of perturbations is reached.

Abstract: In an embodiment a semiconductor device correlates a received signal with a known pattern. A correlation output is used as a basis for forming a confidence reference level. The confidence reference level and the correlation output are compared to identify a peak in the received signal indicating that a present signal state of the received signal contains the known pattern.

Abstract: Noise may be filtered or attenuated from seismic data by building a four-dimensional volume using the acquired seismic data and then applying a random noise attenuation filter to the four-dimensional volume. The dimensions of the four-dimensional volume may include a trace number dimension, a time dimension, a shot number dimension, and a cable number dimension. The random noise attenuation filter may filter portions of the acquired seismic data if the seismic data is not correlated with respect to other seismic data in the four dimensional volume.

Abstract: The present invention provides a seismic surveying method in which vibrators in a first vibrator group are actuated at time T0 and vibrators in a second vibrator group are actuated at time T1, where T0<T1<T0+S1+L and S1 is the sweep time of the first group and L is the listening time. This method enables the time required to complete a seismic survey to be reduced. In other embodiments, vibrators in the first vibrator group may be actuated at time T2, where T1<T2<T1+S2+L and S2 is the sweep time of the first group, and vibrators in the second vibrator group at time T3 where T2<T3<T2+S1+L and T3?T2?T1?T0. Such embodiments providing that by appropriately combining the shot records noise may be eliminated.

Abstract: An appropriate rock physics model is chosen from well-log data and/or experience. The rock physics model is then used to generate a plurality of attribute values, including compression and shear velocities, at different porosities and gas hydrate saturations. Gas hydrates are classified into different ranges of porosity and hydrate saturation based on the population of multiple attributes, and probability density functions for each individual gas hydrate class are created. Probability density distribution functions for individual attributes and a joint conditional probability density functions are created using a Bayesian function. The conditional probability of the occurrences of gas hydrate classes given a set of values of the chosen attributes derived from seismic inversion and or well measurements is inverted. Finally, a maximum a-posteriori (MAP) rule is employed to obtain the optimal porosity and hydrate saturation estimation.

Abstract: The present invention provides a seismic surveying method in which vibrators in a first vibrator group are actuated at time T0 and vibrators in a second vibrator group are actuated at time T1, where T0<T1<T0+S1+L and S1 is the sweep time of the first group and L is the listening time. This method enables the time required to complete a seismic survey to be reduced. In other embodiments, vibrators in the first vibrator group may be actuated at time T2, where T1<T2<T1+S2+L and S2 is the sweep time of the first group, and vibrators in the second vibrator group at time T3 where T2<T3<T2+S1+L and T3?T2?T1?T0. Such embodiments providing that by appropriately combining the shot records noise may be eliminated.

Abstract: A method of seismic surveying comprising the steps of actuating the or each vibrator in a first vibrator group at time T0, and subsequently actuating the or each vibrator in a second vibrator group at time T1 that satisfies T0<T1<T0+S1+L where S1 is the sweep time of the first vibrator group and L is the listening time. At least one of the first vibrator group and the second vibrator group comprises at least two vibrators. The first group and the second group of vibrators may be the same group, or they may be different groups. This method enables the time required to complete a seismic survey to be reduced compared to the prior art “simultaneous shooting” and “slip-sweep shooting” techniques.

Abstract: Methods and systems are provided for acquiring seismic data. Data are collected representing acoustic signals received from the Earth at distinct geographic locations. Data representing an ambient signal at the distinct geographic locations are also collected. For each of the geographic locations, a known time dependence of the ambient signal is correlated with a time dependence of the collected acoustic-signal data to define time-correlated acoustic signal data. The collected acoustic-signal data for the distinct geographic locations are synchronized from the time-correlated acoustic-signal data.

Abstract: A method and system are disclosed for efficiently correlating events within a data processing system and then transmitting messages to various network entities in response to an occurrence of a particular network event. According to the present invention, a network mediation service receives raw message streams from one or more external data sources and passes the streams in real-time to the event notification service. The event notification service then passes the message to the message parsing service for processing. After the message has been parsed by the message parsing service, it is passed back to the event notification service which passes the message along an event channel to the network management service. The message is also passed to the event correlation service for event correlation. A knowledge-based database of message classes that define how to interpret the message text are used by the event correlation service to match correlation rule conditions to the observed events.

Abstract: Seismic prospecting method and device using simultaneous emission of seismic signals obtained by coding a signal by pseudo-random sequences, and notably a periodic signal phase modulated by such sequences. Signals such as, for example, periodic signals phase modulated according to a pseudo-random code (binary for example), produced by a control unit, are for example emitted in the ground by means of vibrators, the seismic signals reflected by the subsoil discontinuities in response to the periodic signals emitted are picked up by receivers coupled with the formation and recorded in an acquisition and recording system. The periodic signals are emitted simultaneously by the vibrators.

Abstract: A product-sum operation portion for performing a product-sum operation (wavelet transformation) with respect to an input time-series signal by using as a base of integral a complex function in which the imaginary number portion is &pgr;/2 shifted in phase from the real number portion, a phase calculation portion for calculating a phase &thgr; from the ratio between the real number portion and the imaginary number portion of a result of the product-sum operation, a peak time detection portion for detecting a time point at which the calculated phase &thgr; changes from 2&pgr; to zero, as a peak time, are provided. Since the wavelet transformation is performed by using a basic wavelet function that is localized in terms of time and frequency, a peak time can be promptly detected. Furthermore, since a differential operation is not employed but the product-sum operation is performed, false detection caused by noises or the like can be prevented.

Abstract: This invention relates to mapping the hydrocarbon reservoir characteristics by mapping the reservoir formations that display dynamic elastic nonlinearity responses to the seismic signals. The main reason of this nonlinear behavior in the reservoir rocks is their bulk rock property: the porosity, fractures, differential pressure and pore saturation. To map these bulk rock properties, the interaction of the two seismic waves as they propagate through elastically nonlinear rocks is recorded. Two compressional seismic signals are transmitted from the surface. Seismic reflection data using surface or borehole detectors are recorded. One of the transmitted signals is a conventional swept frequency and the other is a mono-frequency signal. During the propagation of these two signals through the elastically nonlinear reservoir rocks, there is an interaction between the two signals. The sum and difference frequencies of the two primary seismic signals that were transmitted from the surface are created.

Abstract: The present invention provides a method for forming wellbores. In one method, one or more wellbores are drilled along preplanned paths based in part upon seismic surveys performed from the surface. An acoustic transmitter conveyed in such wellbores transmits acoustic signals at a one or more frequencies within a range of frequencies at a plurality of spaced locations. A plurality of substantially serially spaced receivers in the wellbores and/or at surface receive signals reflected by the subsurface formations. The sensors may be permanently installed in the boreholes and could be fiber optic devices. The receiver signals are processed by conventional geophysical processing methods to obtain information about the subsurface formations. This information is utilized to update any prior seismographs to obtain higher resolution seismographs. The improved seismographs are then used to determine the profiles of the production wellbores to be drilled.

Abstract: A non-destructive method of measuring physical characteristics of a medium, such as uncemented sediment, sandstone, or limestone. A pseudo-random code is generated and is used to generate a pseudo-random acoustic signal. This signal is transmitted into the medium to be measured through the use of a transducer, such as a piezoelectric element, and is received by a plurality of hydrophones. The received signal is then processed to obtain an image of its velocity and attenuation. A universal geoacoustic model of the medium for a given set of measured data is determined, and the model is solved to obtain a pair of permeability-porosity results for the medium. The one of this pair of permeability-porosity results which is correctly indicative of the physical characteristics of the medium is then determined.

Abstract: A non-destructive method of measuring physical characteristics of a medium, such as uncemented sediment, sandstone, or limestone. A pseudo-random code is generated and is used to generate a pseudo-random acoustic signal. This signal is transmitted into the medium to be measured through the use of a transducer, such as a piezoelectric element, and is received by a plurality of hydrophones. The received signal is then processed to obtain an image of its velocity and attenuation. A universal geoacoustic model of the medium for a given set of measured data is determined, and the model is solved to obtain a pair of permeability-porosity results for the medium. The one of this pair of permeability-porosity results which is correctly indicative of the physical characteristics of the medium is then determined.

Abstract: 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.

Abstract: An apparatus and method are provided for detecting buries objects, geological formations or sediment properties by transmitting an acoustic signal and receiving a scattered signal. An acoustic source and an array of receivers are used to correlate the scattered signal with the transmitted signal.

Abstract: A non-destructive method of measuring physical characteristics of sediments to obtain a cross-sectional distribution of porosity and permeability values and variations, and of shear modulus and shear strength. A pair of boreholes have borehole entries spaced apart from each other at a predetermined distance, and a plurality of hydrophones are spaced at predetermined known positions. A pseudo-random binary sequence code generator as a source of seismic energy is placed into another borehole and activated to transmit pseudo-random wave energy from the source to the hydrophones. Seismic wave characteristics are measured in a multiplicity of paths extending from the source to the hydrophones, using cross-bore tomography.

Abstract: Seismic data is cross correlated with a correlation reference which is an amplitude modified version of a nonlinear sweep. The amplitude modification provides both deboost and tapering.

Abstract: A geophysical prospecting method comprises injecting signal energy in the form of at least two pseudo-random pulse sequences of the complementary sequence type into an underground formation. Next, the signal energy is detected after it has been attenuated by passing through the underground formations in the form of response signals. The response signals are correlated with reference signals comprising at least two pseudo-random binary sequences to yield correlations. The correlations are summed so that the resultant signal which corresponds to the subsurface response signal does not have secondary lobes. The method is applicable to seismic prospecting and more particularly to cross-well seismic surveying. It is also applicable to acoustic prospecting for logging measurements. In a preferred embodiment, the pseudo-random sequences comprise a pair of Golay sequences.

Abstract: An improved method for filtering noise bands from seismic data is described. The data is analyzed to determine the frequency component of the undesired noise, and a precise autocorrelation function is generated and used to design a filter to remove the undesired frequency component from the data. The filter can be band pass, band reject, notch, low pass, or high pass, and multiple bands of noise can be removed from the seismic data in a single filtering operation.

Abstract: Methods and apparatus for processing vibrative seismic data. Baseplate phaselock vibrative energy, reaction mass phaselock vibrative energy and ground force phaselock vibrative energy are transmitted into the earth using a land vibrator and the reflections of the transmitted waves recorded. The source signature of the land vibrator is computed for each type of vibrative energy and the source signature is correlated with the corresponding recorded data to produce an image of the subsurface. Regardless of the type of phaselock vibrative energy generated into the subsurface, the images of the subsurface produced by the correlation of the source signature and the recorded data are substantially the same. The correlated data may be then analyzed to yield useful information related to the characteristics of the subsurface.

Abstract: Method and apparatus for removing sinusoidal noise from seismic traces comprised of a seismic data component and a sinusoidal noise component. Seismic traces acquired by conventional seismic exploration of a subsurface formation are utilized to produce a frequency domain amplitude spectrum of the traces. The amplitude spectrum is analyzed to determine a line frequency equivalent to the sinusoidal noise frequency to be removed. A filter order N (number of filter weights) is selected and the exact autocorrelation function of the selected sinusoidal frequency is determined for lags 0, 1, . . . , N-1. An autocorrelation matrix is produced utilizing the determined autocorrelation values and predictive deconvolution techniques are applied to the autocorrelation matrix to produce a convolutional filter which will remove sinusoidal noise at the determined frequency while leaving other frequencies minimally attenuated.

Abstract: An offshore reflection seismic prospection method is provided including a vibratory signal coded in accordance with a pseudo-random code.Correlation of the signals received by the seismic sensors by means of the cycle of the coded signal transmitted allows seismic plots to be obtained similar to what a pulsed source would provide firing at time intervals equal to the duration of the cycle of the coded signal. Correlation with time shifted cycles reduces the distance between plots recorded on the same sensor. The transmissions coming from two or more vibrators, transmitting the same coded signal with shifted cycles, may be separated by correlation with one of the cycles used.

Abstract: A method of producing random sweeps for seismic vibrator sources is described which produces correlograms with reduced side lobe contamination. Digital random phase digital codes activate non-impulsive sources. Detected signals are processed using periodic sweep correlations. The method is especially useful in urban areas where permitting requirements limit the drive level and frequency range of a vibratory seismic source.

Abstract: A transmission which requires only a single source to transmit is generated in accordance with a code which is binary (a pulse train having two levels which produces a specific harmonic line spectrum). The pulses are generated by pulse time modulation of the position and duration of pulses in a sweep which extends to the upper end of the spectrum.

Abstract: Sweeps of seismic signals consisting of pulse trains having a predetermined number of pulses in which the periods or durations of the pulses are randomized and in which the wave shape and relative time displacements of the pulses in different trains provides substantially constant spectral level over a frequency range containing several octaves.

Abstract: The disclosed invention is a method of seismic exploration using non-impulsive vibratory sources activated by filtered stationary, Gaussian codes. The method adds a distortion-free quality to the full-waveform seismic records.

Abstract: The disclosed invention is a method of seismic exploration using non-impulsive vibratory sources activated by stationary, Gaussian codes in urban areas. The method adds a distortion-free quality to the full-waveform seismic records.

Abstract: The disclosed invention is a method of seismic exploration using non-impulsive vibratory sources activated by stationary, Gaussian codes in a wellbore environment. The method adds a distortion-free quality to the full-waveform seismic records.

Abstract: The invention provides an apparatus for seismic prospecting which is to effect a correlation in real time between a pilot signal and a picked-up seismic signal. With N being the number of samples corresponding to the desired thoroughness of investigation, the apparatus comprises the following: a buffer of N samples of the pilot signal; at least one buffer for a sample of the picked-up signal; at least one calculation circuit, in which the correlation operations are carried out; at least one result memory, which is to contain the N points of the correlation function; and a circuit for addressing the memories.

Abstract: Sweeps of seismic signals consisting of pulse trains having a predetermined number of pulses in which the periods or durations of the pulses are randomized and in which the wave shape and relative time displacements of the pulses in different trains provides substantially constant spectral level over a frequency range containing several octaves even though the durations of the pulses correspond to a frequency range not exceeding an octave during the sweep are transmitted through the medium being explored such as an earth formation to receptors such as geophones or hydrophones. Groups of signals contained in less than the entire length of the sweep which are transmitted and which are received can be cross correlated to vary the effective duration of the sweep. The cross correlation output of successively occurring sweeps may be stacked to reduce the side lobe amplitude of the cross correlation outputs from each sweep, from which outputs seismograms may be constructed.

Abstract: A method is disclosed for determining if sign-clipped variations of full-waveform traces can be used in subsequent cross-correlation processing without undue hardship. In accordance with one aspect, the present invention examines skewness of the amplitude spectrum of the full waveform. If the former significantly differs from conventional Gaussian distribution over the frequency range of interest, i.e., the amplitude spectrum is non-Gaussian, sign-clipped versions thereof can be used in subsequent cross-correlation processing without undue loss in processing accuracy. In another aspect, the present invention is used to edit a series of traces, one at a time, gathered by a large multichannel collection system. In this aspect, the different spectral noise estimates, including cross-correlation estimates generated from sign-clipped versions of the full-waveform traces, are advantageously used.

Abstract: The disclosed invention is a method of seismic exploration using non-impulsive vibratory sources activated by stationary, Gaussian codes. The method has the channel-capacity economy of sign-bit recording and the distortion-free quality of full-waveform seismic records, even through zero memory, non-linear representations ("ZNL's") are employed either during the collection or the processing steps that produce such final records. As a result, stratigraphic facies can be both economically and surprisingly indicated.

Abstract: A method determines the extent of subsurface reactions in which random acoustic signals are radiated from a whole area covered by the reaction or from a boundary region, hereafter termed reaction front, between largely undisturbed rocks and those already covered by the reaction. The signals are recorded by at least two receivers positioned at different locations outside the reaction area. The recorded signals are cross-correlated as a function of a time shift between the recorded signals so that at least one surface confining the reaction area is determined from the cross-correlation.

Abstract: The disclosed invention is a method of seismic exploration using vibratory sources activated by stationary, Gaussian codes. The method has the channel-capacity economy of sign-bit recording, at both the sources and receivers, without the sacrifice of any desired seismic information in the final processed records. Even the relative amplitudes between traces may be recovered in the method.

Abstract: Quasi periodic pulse trains are generated and swept in repetition frequency over an octave. Spectral harmonics of the pulse trains which prevent the trains from having a constant or "flat" power spectrum over a frequency range much greater than an octave are reduced or eliminated by adjusting the shape of the pulses in the trains. By means of selecting the timing of the pulses, other harmonics are reduced or preferentially augmented. The spectral energy of the signals which are generated during a transmission interval is of the type which possesses an autocorrelation function with a narrow main lobe and low side lobe levels which is especially suitable for echo location purposes such as in geophysical exploration in which seismograms are constructed by cross correlation of the signals which are transmitted with those which are received from the geological reflection surfaces.