Abstract: 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.

Abstract: A seismic survey area is divided into a number of “bins” 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: The amplitude spectrum is generated within a selected time window of a seismic time scale recording. The rate of change, Q, of the natural logarithm of the signal amplitude is measured with respect to frequency. A Q-derived static time shift is computed and applied to the selected seismic time scale trace to correct the raw seismic times for dispersion-induced time distortion. Amplitude-correction and phase-correction filters are applied to the static-corrected trace to provide a new time scale trace corrected for velocity dispersion which is processed to provide a physical model of the subsurface of the earth.

Abstract: A method for measuring the principal axis of fracture-induced formation anisotropy. Amplitude vectors are measured from CMP gathers oriented along in-line and cross-line wavefield trajectories. The amplitude vectors are resolved with the known orientations of the seismic lines of survey to estimate the azimuth of the anisotropic axis.

Abstract: A method for spectral noise abatement from seismic data. The data are decomposed into organizational components from which a noise component can be resolved by well-known iterative methods. A statistic is calculated by comparing the measured spectral content of the data with a model spectrum. The seismic data are scaled in proportion to the ratio between the model spectrum and the measured spectrum, following which the processed signal traces are displayed as representative of a cross section of the earth.

Abstract: The relative amplitudes of seismic reflection data contains very useful information about the subsurface earth formations. Surface and subsurface-consistent amplitude processing identifies and corrects for the variability introduced by instrumentation and surface distortions. Dynamic amplitude decomposition, the subject of this disclosure, identifies and compensates for reflection amplitude fading due to subsurface transmission absorption media.

Abstract: Seismic data from co-located sensors of different genera are formatted into common velocity-receiver gathers and common pressure receiver gathers. A first ratio between the velocity signature amplitudes and the pressure signature amplitudes is measured within a fixed analysis window. A second ratio is measured between the pressure and velocity signatures for a weighting-zone window of limited extent. The first and second ratios are combined to form an equalization operator. The pressure and velocity signatures from within the weighting zone window are combined in the presence of the equalization operator to define a transient-free time-scale datum.

Abstract: A method for displaying seismic attributes in an open three-dimensional format is provided. The conventional two-dimensional variable-amplitude traces that represent the magnitude of a selected seismic attribute as a function of time are converted to three-dimensional format. The three-dimensional converted traces are hung beneath a model of their corresponding data-gathering stations to provide a forest of seismic traces in a wire-frame environment. The open configuration of the seismic traces permits the interpreter to see a perspective view of the structure of the subsurface of the earth from any desired viewing angle.

Abstract: A set of raw common shot gathers are resorted as common receiver gathers. The wavefield envelopes from the common receiver gathers are migrated using one half the near-surface velocity to provide migrated data sets. The migrated data sets are resorted back into common shot gathers and subtracted from the original raw common shot gathers to provide coherent-noise-reduced data sets.

Abstract: A three dimensional residual modeling operator is applied to seismic times that have been preprocessed by application of NMO and velocity independent DMO. The residual operator compensates for vertical velocity variation and anisotropy and its use precludes the need for ray tracing.

Abstract: This is a method for optimizing the coordinates of transducer stations involved in a common mid point gather. Relative reflection-data misalignments between the traces of the gather are attributed to errors in the reported offsets between transducers. Each trace of the gather is iteratively cross-correlated with a pilot trace, using a different offset increment for each iteration. The offset increment that maximizes the correlation coefficient is accepted as the most likely offset residual appropriate to the trace in question. The offset residual is applied to the nominal offset to provide a range measurement vector. The intersection of the range measurement vectors from a plurality of interdependent common mid-point gathers is the best estimate of the transducer location.