Westerngeco L.l.p.

Schlumberger Technology Corporation

Shell Oil Comapny

Ying Ji

Julian Edward Kragh

Ali Ozbek

Philip A F Christie

Ali Özbek

Guido Jozef Maria Baeten

Zijian Tang

Simultaneous sources are separated with a deblending method wherein the fullband data deblended on a source-by-source basis. The fullband data is first decomposed into multiple subbands, and then a non-equispaced subband Radon transform is used to transform the decomposed data into the Radon domain. The deblending process is solved subband by subband by minimising a nonlinear objective function. The solution of the nonlinear objective function is found using a multi-step procedure.

Method and system for separating blended seismic data

Methods and apparatuses for processing seismic data to generate images or determine properties of an interior section of the Earth. The seismic data is processed to filter coherent noise such as ground roll noise from seismic survey data. The noise is attenuated using 3D and/or 2D fan filters, which may have combined low-pass and band-pass filters derived from signal decomposition. The filters are designed with selected operator length, velocity bands of signals and noises and frequency range for a primary trace and adjacent traces within the operator length. The data is decomposed with the filters into signals and noises, and the noises are then filtered from the decomposed data. The process may be repeated for various frequencies and traces within the seismic data. The methods may be used for surveys that have either regular or irregular seismic receiver or seismic source positions.

Coherent noise attenuation

Generating an image of an interior of the Earth from a seismic survey using multiple sources. The multiple sources may be fired simultaneously and the data received by seismic sensors in the seismic survey may be decomposed so that seismic data generated by each of the multiple sources may be determined. Decomposing of the received data may be performed using frequency diverse basis functions and converting the data separation problem into an optimization problem, which can be a one-norm or zero-norm optimization problem in frequency-space domain. The decomposed data may be used to generate the image of the Earth's interior.

Separation of simultaneous source data

Adaptive filtering method to remove ground roll from seismic data. In an M channel adaptive filter, weights Ware set using an adaptive algorithm based on seeking the minimum in the partial differential of cost function J. The cost function includes an expansion of the primary trace d into d=d+&#x394;d (where: dis ground roll contribution and &#x394;d=d+d, where dis the reflected signal component and dis a random noise component) and a corresponding expansion of the reference x into x=x+&#x394;x (where xis ground roll contribution and &#x394;x=x+x; where xis a reflected signal component and xis a random noise component). The delta components are included in the denominator of cost function J to provide an optimal solution of the filter coefficients biased by the reflection signal and random noise is removed.

Noise filtering of seismit data

Designing a multi-dimensional Finite Impulse Response FIR digital filter to attenuate the coherent noise while preserving reflection signals on seismic data, particular in land seismics, includes computing filter coefficients to minimize an l-norm function of differences between a response of a filter with the computed coefficients and a predetermined response which attenuates signals outside a predetermined range of slowness relative to signals within the predetermined range of slowness. Additional constraints may be imposed on the coefficients to improve the attenuation of signals outside the predetermined range of slowness of the desired reflection signals, and/or to improve uniformity within the desired range.

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Cambridge, United Kingdom

Ying Ji