Abstract: A method for processing seismic data in the x-t domain to derive a slant stack in the p-tau domain wherein partial slant stacks are computed over a plurality of small groups of traces which are iteratively merged using linear interpolation into successively larger groups of traces to exhibit the p-tau data characteristics.

Abstract: Disclosed is an array of seismic energy receiver elements spaced specifically for attenuation of horizontally traveling seismic waves. In one embodiment, the rows of seismic energy receiver elements are spaced apart a crossline distance d and have a total crossline extent D, and d is less than the velocity divided by the maximum frequency of the noise to be attenuated and D is greater than the velocity divided by the minimum frequency of the noise to be attenuated. In another embodiment, two or more arrays of seismic energy receiver elements are interleaved. Also disclosed herein is a method for processiong seismic energy signals to attenuate predetermined wavelengths of seismic waves.

Abstract: A method and apparatus for filtering seismic data are provided. More particularly, the method and apparatus of the present invention attenuate surface wave generated noise in seismic-trace signals. Seismic data comprising multicomponent seismic-trace signals acquired with single station, multicomponent geophone arrays are comb filtered to produce a plurality of comb filtered signals for each component of the multicomponent seismic-trace signal. The comb filtered signals are sorted into orthogonal sets and a measure of rectilinearity for each orthogonal set is obtained. Surface wave generated noise can then be attenuated in each orthogonal set with its respective measure of rectilinearity.

Abstract: Seismic data are passed through a preselected number of migration stages. During each stage, data are migrated a plurality of times, where the migration-velocity function is a minor fraction of the velocity required to fully migrate the data in a single stage. The cascaded migration migrates data having steeply-dipping events with greater accuracy and with less noise or artifacts than does a single-stage migration.

Abstract: A method for recursively, continuously estimating the noise and signal components of a seismic trace. More particularly, a method for suppressing the noise component in seismic data so as to enhance the resolution of seismic events contained therein. The signal component of each seismic trace is determined recursively from the preceding estimate of the signal component in each preceding seismic trace.

Abstract: In a seismic exploration system, an adaptive seismometer group recorder having enhanced operating capabilities for acquiring, processing, and storing seismic signals is provided. The adaptive seismometer group recorder includes a solid state memory, a microprocessor and input means for electronically downloading operating programs into the solid state memory whereby menus of recorder operating parameter are provided by the operating programs to the microprocessor to electronically reconfigure the SGR for various geological settings. The microprocessor is responsive to coded signals for selecting sets of recorder operating parameters from the menu of recorder operating parameters provided by the operating programs. The electronically downloaded menus of recorder operating parameters digitally reconfigure the operating characteristics of the seismometer group recorder without necessitating the implementation of hard wired circuitry changes.

Abstract: A method for avoiding aliasing in .tau.-p transformation or "slant stacking" of seismic data is disclosed which features identification of frequency components of the data likely to be aliased during correlative summation steps and removal thereof from the data prior to summing.

Abstract: Field seismograms are gathered into sets having reflections from asymmetrical common reflection points where there is a conversion between longitudinal waves and shear waves. The gathered seismograms are stacked to produce a seismic section which emphasizes the reflections from particular types of formations. In particular, reflections from formations having a significant difference in longitudinal to shear wave velocity, such as oil and gas saturated formations, are emphasized in the stacked section.

Abstract: The stacking velocity required for common midpoint stacking in three-dimensional seismic exploration is determined by determining the stacking velocity in three directions for a common midpoint. The magnitude of the thus determined stacking velocities in any three directions defines an ellipse centered at the common midpoint. The equation of the thus defined ellipse determines the stacking velocity in any direction about the common midpoint.

Abstract: This disclosure relates to improved methods and apparatus for vertically stacking seismic-trace data collected by a digital field recorder during seismic prospecting utilizing plural initiations of a low energy surface seismic source. Seismic-trace data generated by consecutive seismic source initiations and acquired at a common detector location is weighted and summed together, and the sum is normalized prior to being recorded. Accordingly, the signal-to-noise ratio of the seismic-trace data is improved. The methods and apparatus by which the weighting values are calculated and applied provides computational simplifications which reduce the program storage requirements and increase the computation speed of the microcomputer circuit preferably used to perform the calculations and leads to savings in hardware power, size, and complexity.

Abstract: A method and apparatus are disclosed for signal-to-noise optimization of seismic-trace signals during seismic prospecting utilizing plural initiations of a low energy surface seismic source. The method and apparatus optimize signal-to-noise ratio by vertically stacking, that is, summing, inverse power weighted seismic-trace signals from each of the plural initiations wherein the exponent used for weighting is selectable for optimizing the signal-to-noise ratio of the composite seismic-trace signal. The range of exponents provided is correlated to the range of ambient noise, including nonstationary noise, commonly encountered during seismic prospecting, especially vibroseis seismic prospecting, for the purpose of optimizing the quality of seismic-trace data.

Abstract: In seismic exploration, seismic reflection signals are obtained along a line of exploration. These seismic reflection signals are time shifted to correct for moveout caused by horizontal dipping and diffraction subsurface events. These connected signals are stacked with a dip independent velocity parameter to provide a zero source-to-receiver seismic record section enhanced in signal-to-noise ratio.

Abstract: A method for migration of velocity spectra is disclosed wherein migration of common depth point gathers is accomplished without prior determination of the velocity/depth field.

Abstract: In seismic exploration a seismic source transmits seismic energy into the earth and seismic detectors record the seismic waves returning to the earth's surface from reflecting subsurface interfaces. The downgoing transmitted seismic energy and the upcoming reflected seismic waves are transformed into the frequency domain, downward continued, and summed to produce a migrated seismic depth section.

Abstract: The present invention relates to a method and apparatus for conditionally updating source-detector array parameters related to a seismic exploration system, especially during generation and collection of seismic data using a vibratory source detector array positioned at known locations along a line of survey at the earth's surface. The updated array and source parameter are generated as bits of digital data in a microcomputer system of a ground position controller housed in a recording truck associated with the exploration system of interest.

Abstract: A method of seismic exploration by which substantially plane or substantially cylindrical seismic energy waves are simulated by combining reflectional signal traces of conventional spherical seismic waves. Seismic sources and receivers are established in sets at positions such that at least one of the sets includes a plurality of positions spaced over an extent of the area being explored having either one or two dimensions which are large relative to a seismic energy wavelength. Seismic energy is imparted into the earth from the sources and signals are generated in response to seismic energy received at the receivers. The generated signals are then combined into a form simulating the reflection response of the earth to seismic energy having a substantially continuous wavefront in either one dimension, simulating a cylindrical seismic energy wave, or two dimensions, simulating a plane seismic wave.

Abstract: A method for deriving seismic information of more generalized nature over a relatively large and previously unexplored expanse of land to determine relevant strike, dip, velocity and related information. The method consists of the placing of a plurality of seismic sources and receivers in respective lines arranged in a cross pattern, each line being generally at right angles each to the other, and thereafter exciting the sources and recording the received energy for further processing to derive the strike, dip and velocity information for selected strata by using travel times of signal return.

Abstract: This specification discloses a system and method for processing deconvolved seismic traces to compensate for phase distortion introduced in deconvolving the traces. The method provides for automatically processing the traces in an automatic data processing machine. A filter is generated from the signal pulse of the seismic energy applied to the earth in obtaining the seismic traces and this filter is applied to the deconvolved seismic traces to phase correct the traces.

Abstract: A seismic cable assembly has approximately 500 equally spaced elemental sensor units to receive seismic signals generated in the earth by a seismic impulse generator or "shot". The sensor units each include 3 hydrophones or geophones spaced about 6 feet apart, for a sensor unit length of about 12 feet, to receive seismic signals up to several hundred hertz. Signals representing seismic waves received at each of these 500 units are transmitted from the cable, to a central control and recording unit, mounted in a vehicle such as a towing ship. Connected to the cable will be one or more array-forming systems for processing seismic data from the sensor to synthesize various direction-sensitive hydrophone arrays located along the seismic cable.

Abstract: A seismic prospecting roll along switch incorporating electronically controlled switches in an improved switch arrangement requiring far fewer switches than previous systems. In a simple form, one switch is provided for each geophone input with one contact of each switch connected to one of the inputs and the other contact of each switch connected in pairs, appropriately selected, to the inputs of amplifier and filter channels. A controller is provided for electronically closing the appropriate switches for each roll along position. In most roll along positions geophone inputs are connected out of order to the signal processing channels and the sequence is corrected by a modified multiplexer which connects the processing channels to a system analog to digital converter.

Abstract: The specification describes methods of and apparatus for converting seismic data to migrated seismic depth sections. The apparatus includes a curve follower for following lines of continuity on seismic time sections which represent reflections from particular subsurface interfaces. The curve follower generates signals representing occurrence times and horizontal distances at successive increments along the lines of continuity. These signals are applied to a digital computer which performs a migration operation and generates signals representing the attitude, actual depth and horizontal displacement of successive points on the interfaces. An automatic plotter plots reflection segments at the correct attitude, actual depth and horizontal displacement to produce the migrated seismic depth section.

Abstract: Seismic exploration on land and on ocean beds is performed by emitting vibrational acoustic signals of long time-duration within a desired frequency spectrum at one or a number of points, the signals corresponding to the waves received from the reflectors being then processed. The method further consists in forming the complex spectrum of the received signal corresponding to the emitted signal in respect of each frequency band, in forming the complex spectrum of a reference of the emitted signal in respect of each frequency band and in dividing the complex spectrum of the received signal by the complex spectrum of the reference of the emitted signal, at least an external portion of each complex spectrum being eliminated in the case of each complex spectrum.

Abstract: The electronic roll-along switch consists of several input multiplexers, each having a number of inputs that are connected to seismic detectors, and an output line. A plurality of multiple-input sample-and-hold modules are provided. Corresponding inputs of the respective sample-and-hold modules are paralleled. The output lines of the input multiplexers are connected in consecutive order to the paralleled input of the sample-and-hold modules. The output of each sample-and-hold module is connected to an output amplifier which is couplable to a multichannel seismic recording system. A master controller provides circuitry for connecting any set of several seismic detectors to a like number of channels in the seismic recording system.

Abstract: A seismic prospecting roll along switching system using a relatively small number of switches to provide roll along prospecting while also providing variable gapping with minimum loss of active channels. In a simple form two sets of switches are provided with each set having one switch provided for each geophone input and with switch outputs connected in pairs, appropriately selected, to the inputs of signal processing channels. The two sets of switches are connected to the processing channels in a skewed or staggered manner with the amount of skew corresponding to a selectable gap. A controller is provided for electronically closing the appropriate switches from each set in accordance with the desired gap. Additional switch sets may be employed to provide additional selectable gaps while maintaining complete utilization of processing channels.

Abstract: In seismic exploration, linear, multiple fold, common depth point sets of seismograms with three dimensional reflection geometry are used to determine the dip and strike of the subsurface reflecting interfaces and the average velocity of the path of the seismic energy to the reflecting interface. The reflections in each set appear with time differences on a hyperbola with trace spacings determined by the source receiver coordinate distance along the lines of exploration. The offset of the apex of this hyperbola is determined from a normal move-out velocity search of the type performed on two dimensional CDP sets. This search identifies the correct stacking velocity and hyperbola offset which are used to determine dip, strike and average velocity.

Abstract: An illustrative embodiment of the present invention includes methods for Seismic Data Processing which may be used to enhance the signal/noise ratio of seismic signals taken by use of the Common Depth Point or Hundred Percent Coverage survey techniques. The methods preserve time alignment and amplitude of the signals while effectively removing the noise therefrom. Small portions of the record centered at a selected time on a selected trace are processed to extract the coherent signal component from the reference trace as determined by comparison with other spacewise adjacent traces. Output records comprising the enhanced signal data and the noise data are produced.

Abstract: A method of enhancing a "gather" formed of a plurality of unmoved out common depth point (CDP) data traces. The gather is formed of a plurality of seismic traces arranged in a display in which time varies along the horizontal axis and distance between source and detector (range) varies along the vertical axis. The gather is incrementally processed by cross correlating trace segments within a defined area or search window. To this end, the center trace within the window is selected as a reference trace which is multiplied by a taper function and cross correlated with the other traces in the window to provide a coherent trace and a separate noise trace, both of which are produced in the output. The window is shifted on the gather and the procedure is repeated until every trace has been processed. In the cross correlation technique, the trace segments in the window are examined along a derived hyperbolic curve.