Patent classifications
G01V2210/584
METHOD AND APPARATUS FOR EXTRACTING DOWNGOING WAVELET AND ATTENUATION PARAMETERS BY USING VERTICAL SEISMIC DATA
A method for extracting a downgoing wavelet and attenuation parameters from VSP data, comprising: performing upgoing and downgoing P-waves separation processing on VSP data to obtain downgoing P-wave data; performing a FFT on seismic data with a preset time window length starting from the P-wave first arrival time and cut from the downgoing P-wave data to obtain FFT transformed downgoing P-wave data and a multi-trace downgoing P-wave log spectrum; subtracting a downgoing wavelet log spectrum from the multi-trace downgoing P-wave log spectrum to obtain a wavelet-corrected multi-trace downgoing P-wave log spectrum; performing, based on parameters of the wavelet-corrected multi-trace downgoing P-wave log spectrum, a correction and an inverse FFT on the FFT transformed downgoing P-wave data to obtain a downgoing wavelet; and obtaining attenuation parameters based on P-wave first arrival time and the parameters of the wavelet-corrected multi-trace downgoing P-wave log spectrum. The method can extract a downgoing wavelet and attenuation parameters with high accuracy. Also provided are an apparatus for extracting a downgoing wavelet and attenuation parameters from VSP data, a computer device, and a computer-readable storage medium.
Determining a seismic quality factor for subsurface formations from a seismic source to a first VSP downhole receiver
A method or system is configured for determining a seismic attenuation quality factor Q for intervals of subsurface formations by performing actions including receiving vertical seismic profile traces. The actions include filtering the vertical seismic profile traces with an inverse impulse response of a downhole receiver. The actions include transforming the vertical seismic profile data from the particle motion measured by the downhole receiver to the far-field particle motions represented by the source wavelet. The actions include determining a ratio of the spectral amplitudes of the direct arrival event of the transformed vertical seismic profile data and the source Klauder wavelet. A quality factor Q is generated representing an attenuation of the seismic signal between the source at ground level surface and the downhole receiver.
Look-ahead VSP workflow that uses a time and depth variant Q to reduce uncertainties in depth estimation ahead of a drilling bit
Disclosed are methods, systems, and computer-readable medium to perform operations including: receiving seismic data acquired by at least one receiver of a geologic survey system configured to perform a geologic survey of a subterranean formation, wherein the seismic data is associated with reflected acoustic signals generated by at least one source of the geologic survey system; calculating a ground force signal by stacking the acoustic signals generated by the least one source; calculating, using the ground force signal, a time and depth variant quality factor (Q) of the subterranean formation; and compensating, based on the time and depth variant Q, attenuation in the seismic data.
DETERMINING A SEISMIC QUALITY FACTOR FOR SUBSURFACE FORMATIONS FROM A SEISMIC SOURCE TO A FIRST VSP DOWNHOLE RECEIVER
A method or system is configured for determining a seismic attenuation quality factor Q for intervals of subsurface formations by performing actions including receiving vertical seismic profile traces. The actions include filtering the vertical seismic profile traces with an inverse impulse response of a downhole receiver. The actions include transforming the vertical seismic profile data from the particle motion measured by the downhole receiver to the far-field particle motions represented by the source wavelet. The actions include determining a ratio of the spectral amplitudes of the direct arrival event of the transformed vertical seismic profile data and the source Klauder wavelet. A quality factor Q is generated representing an attenuation of the seismic signal between the source at ground level surface and the downhole receiver.
SEISMIC IMAGING BY VISCO-ACOUSTIC REVERSE TIME MIGRATION
A method for generating a seismic image representing a subsurface includes receiving seismic data for the subsurface formation, including receiver wavelet data and source wavelet data. Source wavefield data are generated based on a forward modeling of the source wavelet data. Receiver wavefield data are generated that compensate for distortions in the seismic data by: applying a dispersion-only model to the receiver wavelet data to generate a first reconstructed back-propagated receiver wavefield portion, applying a dissipation-only model to the receiver wavelet data to generate a second reconstructed back-propagated receiver wavefield portion, and combining the first back-propagated receiver wavefield portion and the second back-propagated receiver wavefield portion into the receiver wavefield data. The method includes applying an imaging condition to the receiver wavefield data and the source wavefield data and generating, based on applying the imaging condition, visco-acoustic reverse time migration (VARTM) result data.
System and method for generating a seismic attenuation model
A method is described for seismic imaging improved by an estimation of attenuation including receiving a pre-migration seismic dataset D(s, r; t) representative of a subsurface volume of interest wherein s indicates source location, r indicates receiver location, and t is the recorded travel time; calculating a pre-migration attenuated travel time t*(s, r; t); computing a time derivative of the pre-migration attenuated travel time wherein 1/Q(s, r; t)=∂t*(s, r; t)/∂t; performing a first migration on D(s,r;t) to generate common image point (CIP) gathers G(x, h) wherein x is subsurface image point and h is angle or offset; performing a second migration on D(s, r; t)*1/Q(s, r; t) to generate weighted common image point (CIP) gathers G.sub.1/Q(x, h); and calculating a conditioned ratio of the weighted CIP gathers G.sub.1/Q(x, h) over the CIP gathers G(x, h) to get CIP gathers of 1/Q(x, h) is disclosed.
Seismic imaging by visco-acoustic reverse time migration
A method for generating a seismic image representing a subsurface includes receiving seismic data for the subsurface formation, including receiver wavelet data and source wavelet data. Source wavefield data are generated based on a forward modeling of the source wavelet data. Receiver wavefield data are generated that compensate for distortions in the seismic data by: applying a dispersion-only model to the receiver wavelet data to generate a first reconstructed back-propagated receiver wavefield portion, applying a dissipation-only model to the receiver wavelet data to generate a second reconstructed back-propagated receiver wavefield portion, and combining the first back-propagated receiver wavefield portion and the second back-propagated receiver wavefield portion into the receiver wavefield data. The method includes applying an imaging condition to the receiver wavefield data and the source wavefield data and generating, based on applying the imaging condition, visco-acoustic reverse time migration (VARTM) result data.
SYSTEM AND METHOD FOR GENERATING A SEISMIC ATTENUATION MODEL
A method is described for seismic imaging improved by an estimation of attenuation including receiving a pre-migration seismic dataset D(s, r; t) representative of a subsurface volume of interest wherein s indicates source location, r indicates receiver location, and t is the recorded travel time; calculating a pre-migration attenuated travel time t*(s, r; t); computing a time derivative of the pre-migration attenuated travel time wherein 1/Q(s, r; t)=∂t*(s, r; t)/∂t; performing a first migration on D(s,r;t) to generate common image point (CIP) gathers G(x, h) wherein x is subsurface image point and h is angle or offset; performing a second migration on D(s, r; t)*1/Q(s, r; t) to generate weighted common image point (CIP) gathers G.sub.1/Q(x, h); and calculating a conditioned ratio of the weighted CIP gathers G.sub.1/Q(x, h) over the CIP gathers G(x, h) to get CIP gathers of 1/Q(x, h) is disclosed.
SYSTEM AND METHOD FOR COMPENSATING FOR ATTENUATION OF SEISMIC ENERGY
A method is described for seismic data processing including receiving a seismic dataset D(s, r; t) representative of a subsurface volume of interest; calculating a pre-migration attenuated travel time t*(s, r; t); performing a first migration on D(s, r; t) to generate common image point (CIP) gathers G(x, h); performing a second migration on D(s, r; t)*t*(s, r; t) to generate weighted common image point (CIP) gathers G.sub.t*(x, h); and calculating a conditioned ratio of the weighted CIP gathers G.sub.t*(x, h) over the CIP gathers G(x, h) to get CIP gathers of attenuated traveltime t*(x, h). The CIP gathers of attenuated traveltime t*(x, h) may be used to perform seismic tomography to generate an attenuation (Q) model.
Developing a three-dimensional quality factor model of a subterranean formation based on vertical seismic profiles
Systems and methods develop a three-dimensional model of a subterranean formation based on vertical seismic profiles at a plurality of well locations. This approach can include receiving seismic data for the subterranean formation including the vertical seismic profiles; for each vertical seismic profile, injecting a ground force into the vertical seismic profile to provide a reference trace at depth zero to estimate energy loss in each receiver providing data in the vertical seismic profile and estimating time and depth variant quality factors for the well location associated with the vertical seismic profile based on the seismic profile; estimating quality factors for points within a three-dimensional volume representing the subterranean formation by interpolating between the time and depth variant quality factors for the location associated with each vertical seismic profile; and combining estimated quality factors to generate a three-dimensional quality factor model of the three-dimensional volume representing the subterranean formation.