Western Atlas International, Inc.

Baker Hughes Corporation

Westerngeco L.l.p.

Western Altas International Inc.

James E Gaiser

Frederick James Barr

Josef Paffenholz

Frederick J Barr

Erika Angerer

Steve A Horne

A method and apparatus for use in seismic prospecting are disclosed. The method comprises partitioning a plurality of converted split shear-wave data resulting from a common event and recorded at a plurality of azimuths and a plurality of offsets as a function of the azimuths and offsets; separating fast and slow split shear-wave wavefields in the partitioned data; deriving at least one attribute of at least one of the separated fast and slow shear-wave wavefields; and analyzing the derived attribute. The apparatus comprises, in one aspect, a program storage medium encoded with instruction that perform the method when executed by a computing device or a computer programmed to perform the device.

Layer stripping converted reflected waveforms for dipping fractures

Method is provided for determining the orientation or horizontal geophones used in marine seismic surveying. First-arrival signals are processed by rotating a coordinate system mathematically until the signal from the transverse receiver has minimum energy. The amount of rotation is used to calculate, from the known azimuth from the source, any misalignment of the horizontal geophone as the receiver is placed on the ocean bottom.

Method for determining horizontal geophone orientation in ocean bottom cables

The objective of this invention is to provide a method for estimating, in the frequency domain, deconvolution operators for removing spurious resonant coupling responses from the cross-line and the vertical seismic signal components in OBC surveys. The purpose is to balance the spectral response of the respective signal component in amplitude and phase in a manner consistent with the field geometry.

Horizontal and vertical receiver-consistent deconvolution for an ocean

Ocean bottom seismic cables are subject to rolling motions due to seismic wave fields and current action which cause poor receiver ground-coupling and signal distortion, particularly along the cross-line and vertical axes. Two multi-axial receivers are mounted on opposite sides of the cable in a single cluster. When the cable rolls, the axial response of one receiver of the cluster cancels the axial response of the other receiver of that cluster.

Method for manufacturing a seismic cable

An unconstrained transformation filter operator that is efficient in terms of computer resources and that improves circularly symmetric migrated impulse response for steep dips. The filter operator combines selected desirable attributes of the more efficient McClellan transformation filter with selected desirable attributes of the more accurate Laplacian transformation filter. The novel filter operator is not constrained along the k.sub.x and k.sub.y spatial axes by the requirement that it equal cos (k). The transformation filter is averaged over all azimuths to improve its accuracy of response.

Unconstrained 2-D transformation filter

A receiver consistent deconvolution operator models the damped oscillatory wavetrain that is related to geophone coupling to the water bottom. The operator is a best-fitting function that endeavors to describe the difference in coupling response between a well-coupled in-line geophone relative to an imperfectly-coupled cross-line geophone. The operator is applied to the cross-line signals to compensate the signals for the distortion due to imperfect cross-line ground coupling.

Method for improving the coupling response of a water-bottom seismic

A method for using a compressional-wave source to produce converted shear waves which are subjected to Alford 4-component rotation to align the observation coordinates with the natural coordinates of the principal anisotropic axes of a birefringent formation. The static time shift between the fast and the slow shear wavefields due to shear-wave splitting is determined so that they can be synchronized thereby to isotropize the birefringent formation. From those data, fracture-plane orientation can be determined. Based on those data, the direction of a deviated bore hole is aligned perpendicular to the fracture plane strike. For a deep-seated target formation, shallower layers are isotropized prior to rotation and synchronization of the converted shear wavefields originating from that deeper formation.

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Littleton, CO, United States of America

James E Gaiser