Z Terra Inc.

Aramco Services Company

Ioan Sturzu

Alexander M Popovici

Iulian F Musat

Nicolay Tanushev

Tijmen J Moser

Constantinos Tsingas

Sergey Fomel

In some embodiments, a velocity model for a seismic exploration subsurface volume is updated by beam tomography. A set of beams is generated from an input seismic data set, and a beam group is assembled for each beam. Each beam group includes the original beam and a set of related beams (if any). If no related beams are found for a given original beam, the original beam is discarded. The beams in a group are then aligned vertically (in depth or time), and a tomography matrix is assembled from the alignment adjustment values for the beams. The tomography matrix is used to perform a tomographic update of the velocity model, and the updated velocity model is used to generate an image of the subsurface volume. The described systems/methods allow efficiently generating accurate images of subsurface volumes, including in areas having complex geologic structures, allowing reduced image inaccuracies/artifacts.

Beam tomography systems and methods

In some embodiments, a seismic processing method comprises assembling a specularity gather by determining a specularity value at each of a plurality of subsurface locations, and summing trace amplitudes into a plurality of bins, each bin characterized by a range of specularity values. The specularity value at a subsurface location is computed according to an angle between a normal to a local reflector and a direction of a total (source+receiver) traveltime gradient. For example, the specularity may be proportional to (e.g. equal to) a magnitude of the cosine of the angle. A diffraction image may be generated by summing specularity gather data over specularity, with specular event amplitudes attenuated relative to diffractive event amplitudes.

Diffraction imaging systems and methods using specularity gathers

In some embodiments, a time migration diffraction imaging method includes computing a pseudo-depth characterizing a subsurface seismic event by scaling a vertical traveltime using a scaling velocity. A specularity value for a subsurface seismic event is determined according to the pseudo-depth, and a contribution weight for a corresponding seismic trace amplitude is determined according to the specularity value. The specularity value may be determined according to an angle between a traveltime gradient and a normal to a local reflector surface. A diffraction image is generated according to a weighted sum of seismic trace amplitudes. The weighted sum attenuates the contribution of specular events relative to diffraction events.

Time migration diffraction imaging systems and methods

In some embodiments, input seismic data is decomposed into Gaussian beams using plane wave destructor (PWD) filters. The beams are used in a fast beam migration method to generate a seismic image of a subsurface volume of interest. PWD filters are applied to groups of neighboring traces to generate a field of dips/curvatures that fit the input trace data. Beam wavelets are then formed according to the dip/curvature field. Multiple dips (PWD slopes) may be determined at each location in time/space in order to handle intersecting reflection events. Exemplary methods allow an improvement in processing speed by more than an order of magnitude as compared to standard industry techniques such as Kirchhoff migration.

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Houston, TX, United States of America

Ioan Sturzu