Mobil Oil Corporation

Mobil Oil Co

Andrew F Linville, Jr

Robert A Meek

Thomas E Shirley

Mohamed T Hadidi

Andrejs Jurkevics

Paul G Griffith

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.

Method for removing coherent noise from an array of seismic traces

In seismic exploration, seismic reflections from subsurface formations are recorded in the form of a time-distance array of seismic traces. This array is transformed into a frequency-distance domain. Frequencies at which coherent noise resides within the frequency-distance domain are determined. Wavenumbers corresponding to such frequenices are removed by filtering. The wavenumber-filtered, frequency-distance domain of seismic traces are then transformed back into a time-distance array of seismic traces.

Method for removing coherent noise from seismic data through f-x

In seismic exploration, seismic reflection from subsurface formations are recorded in the form of a time-distance of seismic traces. This array is transformed into a time-wavenumber domain. Wavenumbers at which coherent noise resides within the time-wavenumber domain are determined. Frequencies corresponding to such wavenumbers are removed by filtering. The frequency-filtered, time-wavenumber domain of seismic traces are then transformed back into a time-distance array of seismic traces.

Method for removing coherent noise from seismic data through T-K

An improved method for cancelling a stationary sinusoid corrupting a data trace is described. The frequency of the corrupting sinusoid is determined precisely and a Wiener-Levinson least squares filter is designed, using a reference sinusoid at precisely the determined frequency and correlated with the corrupted data trace. The filter is applied to the reference trace yielding a noise estimate which can then be subtracted from the data trace.

Process for cancelling stationary sinusoidal noise in seismic data

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.

Method of digital filtering

Method to process seismic data to yield useful information regarding the subsurface area explored. Generated seismic energy travels into a subsurface formation where it is distorted and attenuated. The distorted and attenuated seismic pulse is detected by a geophone or other seismic receiver and recorded. The received seismic traces are first compensated for the attenuation effects of the earth filter and the compensated seismic traces are then used to produce a close approximation of a zero-phase, band-limited output wavelet of the reflectivity of the geophysical formation under exploration.

Method of processing geophysical data to compensate for earth filter

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. The sinusoidal noise is then removed from the seismic data by convolving the acquired seismic traces with the filter.

Method and apparatus for removing sinusoidal noise from seismic data

Method to process seismic data to yield useful information regarding the subsurface area explored. Seismic data which is acquired from the seismic exploration is autocorrelated and the amplitude spectrums estimated, stacked and averaged to reduce the effects of nonwhite reflectivity upon the data. The amplitude spectrum is cepstral windowed a first time to reduce the effects of reflectivity leakage on the amplitude spectrum, amortized at both low and high frequencies so that the amplitude spectrum will approximate the analog wavelet and cepstral windowed a second time to eliminate any remaining rapidly varying components of the amplitude spectrum. The resultant amplitude spectrum is then used to estimate the phase spectrum for the wavelet and a two-sided least squares filter is then designed to shape the estimated seismic wavelet into a zero-phase, low sidelobe output wavelet.

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Dallas, TX, United States of America

Andrew F Linville, Jr