Mobil Oil Corporation

Robert A Meek

Andrew F Linville, Jr

Thomas E Shirley

Stanley J Laster

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

Method for removing coherent noise from a series of seismic traces. Each seismic trace included in the series is Fast Fourier Transformed into the frequency domain. For each frequency of the resultant f-x representation, a series of N complex numbers, one corresponding to each trace, is selected. The selected series of complex numbers corresponding to each frequency are processed to produce autoregressive model coefficients from which a polynomial rooting provides complex roots related to wavenumbers and decay constants. Amplitudes and phases for complex non-stationary spatial sinusoids associated with the estimated wavenumbers are then determined. For all frequencies f, the collection of determined wavenumbers, decay constants, amplitudes and phases constitute an f-k representation of the seismic traces. The produced f-k representation is examined to identify components corresponding to seismic data and the f-k components which correspond to seismic data are summed to reconstruct frequency components of an f-x representation of the acquired seismic traces with coherent noise removed.

Method for removing coherent noise from seismic data

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

A seismic record is enhanced through trace restoration and extrapolation. A set of traces surrounding a missing trace or adjacent an edge of the seismic record are transformed into the frequency domain using a fast Fourier transform. Each frequency of the resultant x-f representation a series of complex numbers, one corresponding to each trace, is selected. Autoregressive model coefficients are estimated for this complex series using a recursive least squares method. A complex number is estimated for trace restoration and extrapolation from the series of complex numbers and autoregressive coefficients. After all frequency components are thus processed restored or extrapolated traces are obtained by an inverse Fourier transform.

Method for restoring and extrapolating seismic traces

Method for restoring seismic data to missing or severely noise contaminated traces included in a seismic section. The seismic section is transformed into a data localizing space and muted to retain only the localized data components of the seismic section. The muted transform space is inverse-transformed into the x-t domain to produce first estimates of the seismic data to be restored. The first estimates of the restored data are substituted for the corresponding traces in the original seismic section. Fully restored traces corresponding to the missing or severly noise contaminated traces are determined from the single estimate of the restored traces.

Method of restoring seismic data

Method of restoring null traces in seismic records. The seismic record is transformed from the x-t domain to the f-k domain by a series of fast Fourier transforms. The f-k transform of the seismic record is filtered to retain only coherent events and the filtered f-k transform is inverse-transformed back to the x-t domain. A first determination of the restored trace corresponding to the null trace is selected and substituted for the null trace. The first determination of the restored trace is used to determine a fully restored trace.

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Sanger, TX, United States of America

Robert A Meek