Chevron U.s.a. Inc.

Yonghe J Sun

Yue Wang

Leonard Lin Zhang

Craig Alan Barker

Guojian Shan

Tong Xu

Weihong Fei

Chunling Wu

Michael Gordon Greene

Jianlei Liu

Craig S Huber

Loralee Faye Dickson

Jingru Chen

Mark Chengliang Fan

Zhemin Tan

Jeffrey William Nealon

Brian J Church

James Michael Davenport

A method is described for seismic amplitude analysis that uses a set of artificial and individually separable reflectors consistent with dip fields in the subsurface volume of interest to define an AVA basis functions; the AVA basis functions are used in true-3D AVA modeling and true-3D AVA inversion. The inversion result and well logs representative of the subsurface volume of interest are used to train a model to create a rock property prediction model. The method may apply the rock property prediction model to a second seismic image to generate a rock property volume. The method is executed by a computer system.

System and method for seismic amplitude analysis

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)=&#x2202;t*(s, r; t)/&#x2202;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(x, h); and calculating a conditioned ratio of the weighted CIP gathers G(x, h) over the CIP gathers G(x, h) to get CIP gathers of 1/Q(x, h) is disclosed.

System and method for generating a seismic attenuation model

A method is described for seismic imaging of the subsurface using dip-guided optimized stacking. The method computes weighting functions for a plurality of single-shot migrated images, unstacked seismic images, or partially stacked seismic images based on a slant stack performed using an input dip dataset; applying the plurality of weighting functions to the plurality of single-shot migrated images, unstacked seismic images, or partially stacked seismic images, or a plurality of dip-filtered images to create a plurality of weighted images; and summing the plurality of weighted images into a stacked seismic image. The method may be executed by a computer system.

System and method for dip-guided seismic image stacking

A method is described for seismic imaging of complex subsurface volumes using prismatic seismic energy. The method receives a seismic dataset and an earth model. The earth model is perturbed such that prismatic reflections will generate perturbed seismic amplitudes in a target area and seismic imaging is performed using the perturbed model. A second seismic image is generated using a second earth model; the second earth model may be the original earth model or a second perturbed model wherein the perturbation generates different seismic amplitudes in the target area. The two seismic images are differenced to generate a prismatic seismic image that can be used to identify geologic features that are poorly illuminated in conventional imaging. The method may be executed by a computer system.

System and method for prismatic seismic imaging

A method for seismic imaging of a subsurface volume of interest may include an imaging technique such as reverse time migration which uses a conditioned velocity model that replaces at least one sharp velocity transition with a gradual velocity transition including a velocity overshoot layer. The method may be performed by a computer system.

Enhanced seismic imaging systems and methods employing modified velocity model contrasts

A method is described for processing residual moveout in seismic image data gathers representing critical reflections. The method includes receiving seismic image data arranged as a function of an angle or offset parameter including a high-velocity-contrast event with post-critical. The method also includes applying a wavelet de-stretch filter to the seismic data to correct wavelet stretching. The method also includes applying a fan-filter to remove coherent noise in the one or more post-critical traces; picking residual moveout of the high-velocity-contrast event; adjacent-trace differencing to detect the impact of phase change at critical reflections in residual moveouts, and applying a median-filter to the residual moveout to reduce the impact of phase change of the high-velocity-contrast event in the one or more post-critical traces. The median-filtered and reconstructed residual moveout is used for improving a velocity model used for generating the seismic image gathers.

System and method for velocity analysis in the presence of critical reflections

A method is described for of creating a high-resolution velocity model of a geological medium that includes generating a long-wavelength anisotropic velocity model using tomographic inversion of seismic data gathers and combining the long-wavelength velocity model with an attenuation model. The method further includes performing prestack depth migration on the seismic data gathers using the long-wavelength velocity and attenuation model to produce seismic image gathers, applying a dip-consistent filter to the seismic image gathers, and transforming the filtered seismic image gathers to the time domain. The method further includes generating a full-band impedance model by performing impedance inversion of the time-domain filtered seismic image gathers using the long-wavelength velocity and attenuation model. The full-band impedance or velocity model is calibrated in the frequency domain in a manner independent of the spatial coordinates. The full-band impedance or velocity model is used for detecting fluid pressure anomalies in the geological medium.

Creating a high resolution velocity model using seismic tomography and impedance inversion

A method is described for residual moveout analysis using dynamic warping. The residual moveout curves or surfaces may be used to flatten common image gathers or derive velocity models. The method may be executed by a computer system.

System and method for computing residual moveout from seismic images

A method for determining values of anisotropic model parameters of a Tilted Transversely Isotropic (TTI) Earth model, the method including obtaining an initial TTI earth model that substantially flattens common-imaging-point gathers and substantially ties seismic data to well data; inputting checkshot data and/or VSP data to determine updated values of Vpnear the well locations; determining an incremental improvement &#x394;&#x3b4;; extrapolating the relative change &#x394;&#x3b4; from near-well locations to the entire three dimensional TTI earth model; determining updated values of Vp=Vp(1&#x2212;&#x394;&#x3b4;); inputting near-to-mid-offset/angle and mid-to-far-offset/angle residual moveout information; and providing updated values of &#x3b4; and &#x3b7;.

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Cypress, TX, United States of America

Yonghe J Sun