Western Atlas International, Inc.

Westerngeco L.l.p.

Baker Hughes Corporation

Other

Ronald E Chambers

Alfonso Gonzalez

Necati Gulunay

Craig J Beasley

Josef Paffenholz

Subhashis Mallick

Ricky L Workman

Loran D Ambs

William Henry Dragoset, Jr

Gary Arthur Sitton

Frederick J Barr

David Lee Nyland

Roy Malcolm Lansley

Everett C Mobley

Noel Donald Zinn

Neil Jones

Andrew Ashby

Walter S Lynn

Attributes of a seismic data set that are indicative of the quality of the seismic data are displayed in a quality control (QC) hypercube. The axes of the hypercube may be the source position, the source line, the receiver position and a processing step. In a pre-migration QC cube, two of the three axes of the cube are defined by the locations of seismic data. In a migrated QC cube, two of the three axes are defined by the migrated output bin position of processed seismic data. The third axis of the cube contains information about the quality of the data. The QC attributes may be simple amplitudes, or they may be attributes derived from the amplitudes of the seismic data, such as RMS values and/or spectral values. In a migrated QC cube, the attributes may include seismic velocity, seismic fold and distribution of source-receiver azimuths.

Quality control cube for seismic data

A seismic survey area is divided into a number of &ldquo;bins&rdquo; of a convenient shape and size. The data from the suite of shot and receiver positions are analyzed and all shot-receiver pairs that have a common sort point (CSP) are assigned to the spatial bin in which the CSP is located. The CSP maybe a common mid-point (CMP). The data within each bin are analyzed to give a figure of merit of the adequacy of the sampling for each bin. These figures of merit are displayed in a color display that makes the inadequacies of the sampling apparent, making it possible to modify the planned acquisition geometry prior to the actual deployment of the receiver lines. Alternatively, a figure of merit is determined for the overall survey.

Method of determining merit of offset and azimuth distributions in seismic data acquisition

Lines of existing data are extrapolated to provide additional lines of seismic data by using small inline gates of existing cables. At each frequency slice of a space gate on the existing cables, a 2-D prediction error filter that can predict the data in forward and backward directions is designed. A prediction filter is obtained from the prediction error filter and applied to a cable at an edge of the space gate to predict a first missing cable. By repeating this process using overlapping inline gates, overlapping inline gates of the extrapolated cables may be obtained. By suitable weighting of the inline gates of the extrapolated cables, a complete cable length is extrapolated. The process may be repeated using the first extrapolated cable in the derivation to give additional extrapolated cables. The invention may be used for interpolating cables of dealiased cables between existing cables using a masking and filtering operation in the frequency-wave number domain. In an alternate embodiment, existing lines of seismic data are sorted to give a crossline sort. The crossline sorted data are interpolated in the frequency-wave number domain to provide interpolated data between the lines of existing swaths of 3-D seismic data.

3-D seismic trace extrapolation and interpolation

A method for determining water bottom reflectivities whereby pressure signals and velocity signals are combined to generate combined signals having signal components representing downwardly-travelling energy substantially removed. The pressure and velocity signals correspond to seismic waves generated at source locations n in a water layer and detected by co-located pressure and velocity receivers at receiver locations m in the water layer. The combined signals correspond to each pairing of source location n and receiver location m. The combined signals are transformed from the time domain to the frequency domain, generating transformed signals. A source peg-leg term and a receiver peg-leg term is calculated for each transformed signal, generating filtered signals. An optimization algorithm is applied to the filtered signals, using the corresponding source and receiver peg-leg terms to determine the water bottom reflectivity values R.sub.n and R.sub.m at the source locations n and the receiver locations m, respectively.

Method for deriving surface consistent reflectivity map from dual sensor

A conventional CMP gather is Radon transformed from t-x space to the .tau.-p domain. The Radon-transformed data are windowed or zoned into a plurality of data sets, each having an common independent range of selected characteristics. All except one data set are muted. The zero ordinate of the p-axis is shifted to become centered through the contents of the retained data set which is then inverse-transformed back to t-x space. The process is repeated for each of the remaining windowed data sets. The processed windowed data sets are summed.

Radon moveout

A seismic streamer position control module has been invented having a body with a first end and a second end and a bore therethrough from the first end to the second end for receiving a seismic streamer therethrough, at least one control surface, and at least one recess in which is initially disposed the at least one control surface, the at least one control surface movably connected to the body for movement from and into the at least one recess and for movement, when extended from the body, for attitude adjustment. In one aspect the seismic streamer position control module body has tapered ends.

Seismic streamer position control module

A system for supporting marine seismic equipment such as sensors and positioning equipment deployed behind a marine seismic vessel. The vessel tows a lattice like web instead of individual streamer cables to carry hydrophones, and can deploy a geophone supporting web from the vessel to rest on the sea floor. The web can be formed with individual conductor members for providing structural support and signal transmission capabilities. The lattice construction of the web provides for redundant signal transmission capabilities in the event of individual conductor failure. The web provides this enhanced signal transmission capability while permitting high density sensor placement.

Marine seismic web

Marine seismic data sets are generally under-sampled spatially because of the relatively long listening times required in deep water. It is customary to use very long spreads in the field thereby enhancing aliasing and interference from coherent noise. A seismic-signal data processing method is proposed that applies a combination of a forward parabolic Radon transform and a linear Radon transform to the data, followed by a further transform to a three-dimensional frequency domain. In this domain, a deterministic operator is applied to the data to sharpen the Radon-domain response thereof. The data are then scavenged of noise in the Radon domain and inversely transformed back into the time-space domain.

Reducing aliasing artifacts in seismic data processing using sharpened

A method for acquiring and processing seismic survey data from two or more seismic sources activated simultaneously or nearly simultaneously or for a single source moved to and fired at different locations. In one aspect such a method includes acquiring seismic survey trace data generated by the source or sources, attaching source geometry to the traces, soring the traces according to a common feature thereof, (e.g. to CMP order), interpolating data points for discontinuities on the traces, selecting two halves or two portions slightly more than half of the traces, filtering the trace data for each of the two portions to filter out data related to a second one of the two seismic sources, reducing the filtered trace data to two halves of the data and deleting interpolated data, and then merging the two halves to produce refined useful seismic data related to a first one of the seismic sources. In one aspect the method includes re-processing the data and filtering out the trace data for the second seismic source to produce refined useful seismic data related to the second seismic source. In one aspect the sources are fired temporally close together and, in one particular aspect, they are fired substantially simultaneously.

Methods for acquiring and processing seismic data

A method for controlling the position and shape of marine seismic streamer cables, whereby a plurality of real time signals from a marine seismic data acquisition system and a plurality of threshold parameters from an input device are received. The real time signals are compared to the threshold parameters to determine if the streamer cables should be repositioned. The streamer cables are repositioned when the real time signals exceed the threshold parameters.

Adaptive control of marine seismic streamers

Wide-angle reflections that have been overcorrected using a simple two-term hyperbolic moveout correction are adjusted by application of a bi-quadratic term. The biquadratic term is derived by scanning the overcorrected reflections for residual velocity. The residual velocity is used to calculate an adjustment as a linear function of the first power of the travel time to each receiver versus the fourth power of the corresponding receiver offset.

Extended offset data processing

A high-order polynomial regression curve is fitted to a global set of first arrival times as a function of the nominal ranges between a plurality of acoustic sources having known geodetic coordinates and a plurality of acoustic detectors whose coordinates are imperfectly known. The order of the polynomial is chosen to be that order that minimizes the variance of the parameters about the regression curve. The polynomial is used as a quasi-velocity function for iteratively optimizing the best estimate of the ranges between each detector and every source station. The best estimate of the detector position is derived by multi-lateration using the computed ranges.

Method for verifying the location of an array of sensors

A computer-aided method for providing a de-aliased output data set d.sub.L (t,x.sub.L,y.sub.L) from a spatially aliased, three-dimensional, input data set of known seismic signals, a(t,x,y), where L is an interpolator. The known data set is zero-padded by L. The zero-padded data set is zero-masked. The zero-padded data set is divided by a zero-padded, zero-masked data set to provide an interpolation operator H.sub.L. L-1 zero traces are interleaved between the known traces of data set a(t,x,y) to provide a zero-inserted data set c.sub.L ((t,x.sub.L,y.sub.L) whose transform is C.sub.L (m,k.sub.xL,k.sub.yL). The product of (H.sub.L) with (C.sub.L) is (D.sub.L) which is inverse-transformed to provide the desired de-aliased data set d.sub.L (t,x.sub.L,y.sub.L).

Unaliased spatial trace interpolation in the f-k domain

Sparsely spatially-sampled seismic time-scale trace gathers may be aliased for certain spatial and temporal frequencies. Aliasing may be avoided by application of a spatial interpolation scheme that uses the phase difference between the f-k phase spectra of the odd and the even traces to generate an interpolation operator in the f-k domain. The operator is multiplied point-by-point with the f-k transform of the original recorded trace gather. The resulting complex product is inverse transformed to the t-x domain whereupon the interpolated traces are interleaved between the original recorded traces to unwrap the aliased events.

A method of reducing effects of noise in seismic signals generated by a plurality of seismic sensors at spaced apart locations from a seismic source is disclosed. Each of the signals is represented by a signal trace in a record section. The method includes the steps of isolating noise in the signal traces, time aligning corresponding portions of the noise in the traces thereby generating time-aligned noise traces, stacking the time-aligned noise trace to generate a stacked noise trace, replicating the stacked noise trace at each corresponding trace position in the record section, restoring the replicated traces to the original trace time positions by reversing the step of time-aligning to generate noise signature traces, comparing the noise signature traces to corresponding signal traces to generate filters which substantially minimize a measure of the difference between the noise signature traces and the signal traces. The noise signature traces are then filtered and the resulting filtered noise signature traces are subtracted from the signal traces. In a preferred embodiment the steps of comparing, generating filters, filtering and subtracting comprise linear adaptive filtering. In a particular embodiment the step of isolating the noise comprises bandpass filtering the signal traces.

Growing community of inventors

Houston, TX, United States of America

Ronald E Chambers