Abstract: A method for generating a thinned array having an optimal directional response wherein an initial population of possible element occupancy patterns is generated and a relative fitness value for each of the element occupancy patterns in the initial population is determined. Successive populations are generated by manipulating the element occupancy patterns using reproduction, crossover, mutation, elitism, and equality operators. The array response of each occupancy pattern in the successive population is evaluated to determine a fitness value for each. The process of generating and evaluating successive populations is repeated for a specified number of generations, until the maximum population fitness does not significantly increase between generations, or until the population diversity decreases.

Abstract: A method and system are provided for use in marine seismic data surveys to increase fold and offset without increasing streamer length or drag on the streamer boat. Generally the method comprises the use of a second source boat positioned in the steamer path and firing the second source at a time before the recording of information from the first source is finished. By positioning the second source about one streamer length in front of the closest hydrophone, the fold is increased by two for the same length streamer.

Abstract: A method for minimizing non-uniform insonification of subsurface formations in the presence of steep dips when advancing a swath of elongated parallel seismic streamer cables along a line of survey. A first acoustic source is stationed at the leading end of the swath and a second source is stationed at the trailing end of the swath. The sources are activated in alternate cycles at preselected timed intervals to provide down-dip and up-dip seismic data sets. The data sets are processed and merged to eliminate objectionable shadow zones.

Abstract: A system for acquiring and processing seismic data comprises source-means for generating sound waves and receiver-means for recording as data those waves as reflected from sub-surface interfaces, and means for processing the recorded data operable to generate sets of actual data each individually associated with specific sub-surface reflection points, order the data-sets in accordance with receiver and source-means separation, process each data-set to generate additional data intermediate the recorded data, and re-order each data-set and additional data in accordance with receiver and source-means separation for further processing. Each data-set is applied to a filter to generate said additional data intermediate of the recorded actual data. The filter is selected from the group comprising linear, quadratic or spline interpolation filters, frequency space (f-x) filters, tau-p filters, smart filters artificially intelligent filters, neural network filters and (preferably) sinc filters.

Abstract: This invention provides a method for performing three dimensional seismic surveys. In one configuration, receiver lines containing equally spaced receiver stations run in one direction while the source station lines run orthogonal to the receiver station lines. The receiver stations and/or the source stations are offset to obtain a desired spatial sampling (number of bins) or multiplicity of the common mid points. In an alternate configuration, the receiver line spacing is offset by a fraction of the source station spacing and/or the source line spacing is offset by a fraction of the receiver station spacing to obtain the desired spatial sampling. These configurations provide higher spatial sampling (smaller bins) compared to the conventional geometries. The smaller bins may be combined to obtain folds (multiplicity) which is sufficient to provide desired seismic imaging while preserving the benefits provided by the higher spatial sampling by the method of the present invention.

Abstract: A method for producing seismic images from seismic data obtained from two different datums. Traveltimes between the two datums are determined from either measurements or an assumed velocity field. An extrapolation of the data to simulated source and receiver locations is carried out using any form of the wave equation which does not require velocity field information. After extrapolation, the data at the simulated source and receiver locations is processed using standard seismic imaging techniques. The method can be applied to simulate borehole, crosshole, or multi-borehole seismic data.

Abstract: A method for improving the signal to noise ratio from a pair of detectors such as geophones which each detect a noisy signal comprising a signal of interest (S) and a noise signal (N), wherein the signal of interest (S) has a different moveout across the pair of detectors from that of the noise signal (N), and the noise signal (N) from a given source is detected at the first detector at a time .DELTA.t before the corresponding noise signal is detected at the second detector, the method comprising delaying the noisy signal (S+N) detected at the first detector by an amount .tau. being greater than the moveout of the signal of interest but not more than .DELTA.t and subtracting the delayed signal from that detected at the second detector by means of an adaptive filter so as to minimize the power in the resultant signal. The signal detected at the first detection and optionally the resultant signal can also be delayed by an amount .tau..sub.

Abstract: This invention provides a method for performing three dimensional seismic surveys. In one configuration, receiver lines containing equally spaced receiver stations run in one direction while the source station lines run diagonal to the receiver station lines. The receiver stations and/or the source stations are offset to obtain a desired spatial sampling (number of bins) or multiplicity of the common mid points. In an altemate configuration, the receiver line spacing is offset by a fraction of the source station spacing and/or the source line spacing is offset by a fraction of the receiver station spacing to obtain the desired spatial sampling. These configurations provide higher spatial sampling (smaller bins) compared to the conventional geometries. The smaller bins may be combined to obtain folds (multiplicity) which is sufficient to provide desired seismic imaging while preserving the benefits provided by the higher spatial sampling by the method of the present invention.

Abstract: A method for increasing the signal-to-coherent-noise ratio of seismic signals propagating along multi-azimuthal trajectories by abating Rayleigh wave contamination. A plurality of seismic receivers surround a nest of vibrators separated by a first uniform incremental spacing whereupon the vibrators emit chirp signals. The chirp signals are received by the seismic sensors, the received signals are stacked, auto-correlated, integrated and the integrated signal level is tabulated as a function of vibrator separation. The first vibrator separation is repeatedly uniformly expanded by a selected increment and the steps of emitting, receiving, stacking, auto-correlating and tabulating are repeated after each incremental separation. The separation corresponding to the minimal integrated signal level is selected.

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: An overturned wave is identified in initial seismic data and revised seismic data gathering parameters are calculated (e.g., a range of locations for a seismic source and detectors laterally displaced from the source). The gathered seismic data is used to image the interface by using an imaging algorithm capable of migrating downgoing and upcoming reflections.

Abstract: An improved method of three-dimensional seismic acquisition of sub-surface impedance boundaries in the earth is disclosed. A rectangular grid pattern is formed from a series of substantially equally spaced and parallel source lines, each of which is formed by a plurality of equally spaced seismic energy sources, and a series of substantially equally spaced and parallel receiver lines, each of which is formed by a plurality of equally spaced seismic energy receivers. The rectangular grid is formed such that a ratio of the spacing between receiver lines and the spacing between sources yields a remainder greater than zero and a ratio of the spacing between source lines and the spacing between receivers also yields a remainder greater than zero.

Abstract: A method of performing a marine seismic survey is disclosed Seismic receivers, either hydrophones or geophones, are deployed in a set of parallel lines in the survey area. The acoustic energy is generated from a conventional marine seismic source towed by a vessel traveling in paths which are substantially perpendicular to the lines of receiver stations. The paths may pass over the lines of receiver stations, and may also pass outside of the receiver area. Alternative embodiments are disclosed which include sequencing of multiple sets of receiver station lines with one another, so that shots fired along different segments of the path correspond to the different sets of receiver stations. In addition, multiple sources may be towed and alternatively fired, to improve the survey efficiency.

Abstract: The invention involves providing a plurality of substantially parallel and equally spaced source lines, each of which are formed by a plurality of equally spaced seismic energy sources. A plurality of substantially parallel and equally spaced receiver lines are also provided, each formed by a plurality of equally spaced seismic energy receivers. The source and receiver lines are overlaid in a transverse crossing manner, forming a rectangular grid, so that a source and a receiver are only substantially coincident every second or greater number of crossings. For each seismic disturbance, an array of common mid-point seismic reflections ("CMP's") is produced. Each CMP forms the center of one of multiple sub-bins which together form a standard bin. Stated otherwise, by slightly varying the source, receiver and line intervals so that receiver and source coincidence occurs, but only at every second or greater crossing, the number of CMP's per bin has been multiplied.

Abstract: A broadline seismic survey is carried out by positioning a plurality of areal arrays of seismic detectors along each of a plurality of broadline receiver lines along the surface of the earth. Array centers along an inline direction of each receiver line are staggered by one-half of an array interval from array centers along the inline direction of adjacent receiver lines. Each detector array on a given receiver line is elongated in a cross-line direction to such receiver line to effect an areal array coverage between broadline centers of the adjacent receiver lines being on opposite sides of the given receiver line. The seismic detectors in each array are connected in common to a recording means.

Abstract: The invention comprises a seismic recording apparatus and method. A multichannel recorder is connected to a cable formed from a plurality of signal conductors. Each of the signal conductors is connected to a different channel of the recorder via a multiplexer. The cable has a plurality of takeouts located at spaced distances along its length. Each of the takeouts is connected to a different signal conductor of the cable. A switch means is operably connected to one of the takeouts for selectively interconnecting the takeout and any one or more of several seismic detector connections upon receipt of a remotely generated signal. The invention also includes a number of detector conduits, each of which has one end operably connected to a different one of the seismic detector connections of the switch means. Each detector conduit has at least one geophone located along its length and operably connected thereto. A control means is provided for transmitting a signal to the switch means.

Abstract: The invention comprises a seismic recording apparatus and method. A multichannel recorder is connected to a cable formed from a plurality of signal conductors. Each of the signal conductors is connected to a different channel of the recorder via a multiplexer. The cable has a plurality of takeouts located at spaced distances along its length. Each of the takeouts is connected to a different signal conductor of the cable. A switch means is operably connected to one of the takeouts for selectively interconnecting the takeout and any one or more of several seismic detector connections upon receipt of a remotely generated signal. The invention also includes a number of detector conduits, each of which has one end operably connected to a different one of the seismic detector connections of the switch means. Each detector conduit has at least one geophone located along its length and operably connected thereto. A control means is provided for transmitting a signal to the switch means.

Abstract: Method and system for creating a vertical seismic profile (VSP) whereby the spacing interval between units, either seismic sources or receivers, in a borehole increase exponentially as their distance from the surface increases, and the spacing interval between units, either seismic sources or receivers, along the surface of the earth decreases exponentially as their distance from the surface intercept of the wellbore increases. In a preferred embodiment of this invention, the common depth point (CDP) fold of the data gathered is substantially flattened across the reflectors surveyed.

Abstract: A novel method of geophysical exploration is provided whereby shot points and receiver locations are positioned such that seismic data resulting therefrom can advantageously be processed employing 3-D processing techniques to obtain a better image of the earth's subsurface structure. In one embodiment, shot points, or alternatively, receiver locations are arranged along generally sawtooth or zig zag lines so that common midpoint bins of seismic signals include a generally uniform distribution of source-receiver pair azimuths. In another embodiment, both the shot points and receiver locations are arrayed along generally alternating, sawtooth or zig zag lines.

Abstract: A method and system for geophysical exploration including obtaining, processing, displaying and interpreting seismic data. Seismic energy is imparted into the earth's subterranean formation along at least two linear independent lines of action in a seismic survey. At least two linearly independent components of the seismic wave energy imparted along each line of action are detected within the seismic survey. A concord of seismic signals is produced from the seismic wave energy detected for selected combinations of receiver and source locations. An orientation module operates on the concord of the seismic signals so as to generate synthetic concords of seismic signals so as to focus on a particular component of the seismic wave energy in order to infer the geologic characteristics of the earth's subterranean formations.

Abstract: A method for conducting a three-dimensional subsurface seismic survey utilizing a plurality of seismic receivers arranged in an orthogonally uniform pattern is disclosed. A predetermined pattern of shotpoints is arranged such that every point in the surface area of interest is sampled over a desired range of offsets and a full range of azimuths. The utilization of shotpoints outside the pattern of receivers allows examination of a subsurface area which is greater than the area of the pattern itself. The output of each receiver in the pattern is simultaneously recorded for seismic energy applied to the surface of the earth. Where the area of interest is quite large, a multitude of patterns of seismic receivers may be utilized to ensure coverage of the entire area. In a marine application of the present invention a plurality of seismic receivers are arranged in an orthogonally uniform pattern under a body of water or by utilizing multiple parallel marine streamers towed by one or more tow boats.

Abstract: A process for tomographic development of seismic section data having known source and receiver positions. The process employs forward modeling to estimate travel times of the rays through the earth medium. The medium is assigned a cellular constitution and ray tracking proceeds through individual cell analysis within a two dimensional neighborhood to join a series of individual cell velocity values, e.g. the velocity values at the cell corners. Ray tracing proceeds utilizing derived expressions for position, orientation, and travel time of the ray in the cell as a function of cell dimensions, initial ray position, ray orientation, and the neighborhood velocity values. A travel time equation is then derived and used to construct a model parameter estimation and finalized estimated data output.

Abstract: A source array useful in vertical seismic profiling is disclosed wherein a first set of source elements having horizontal extent is spaced to have at least a first direction and a second direction, and a second set of source elements having vertical extent are spaced below the first set of source elements. The source elements in the source array are sequentially activated to focus the seismic energy along selected radial paths through the earth's subsurface.

Abstract: A 3-D seismic prospecting method is provided which employs an areal array of sources and receivers by which seismic traces are generated. The areal array is segregated into a plurality of shells and angularly separted sections from which a preselected number n.sub.1 of source-receiver pairs are selected for a particular common midpoint. By means of the shells and sections, the source-receiver pairs so selected have associated therewith a wide range of offsets and azimuth angles for the preselected fold n.sub.1. The seismic traces corresponding to the selected source-receiver pairs are summed to give a stacked trace corresponding to the common midpoint.

Abstract: A method for conducting a three-dimensional subsurface seismic survey utilizing a plurality of seismic receivers arranged in an orthogonally uniform pattern is disclosed. A predetermined pattern of shotpoints is arranged such that every point in the surface area of interest is sampled over a desired range of offsets and a full range of azimuths. The utilization of shotpoints outside the pattern of receivers allows examination of a subsurface area which is greater than the area of the pattern itself. The output of each receiver in the pattern is simultaneously recorded for seismic energy applied to the surface of the earth. Where the area of interest is quite large, a multitude of patterns of seismic receivers may be utilized to ensure coverage of the entire area.

Abstract: In a method of acquiring seismic data in a prospecting area, an array of excitation vibration receivers is placed on or over the terrestrial surface. A plurality of excitation vibration sources is disposed in the vicinity of the array, each source emitting excitation vibrations with a frequency spectrum in a specific frequency band. These bands are adjacent and together cover the frequency band of usable seismic data signals. When the excitation vibrations are emitted by the plurality of sources, the excitation vibration echoes reflected from strata beneath the terrestrial surface are registered by the receivers. The above steps are repeated for a plurality of successive trace increment displacements to produce an emission figure and to cover the prospecting area. The method and the device implementing it can be used for acquisition of terrestrial or marine seismic data.

Abstract: A detailed seismic survey is achieved when there is general knowledge of a formation with generally steep dip by first locating the central location point and then mapping radial shot lines and receiver lines therefrom. The shot lines need to extend across the dip and beyond. The receiver lines need to extend a normal distance as with conventional 3-D seismic surveys. Shots from the central location progressing outwardly will reflect first with equal incident and reflector paths, then with a short incident to long reflector path, and finally to where long incident and short reflector paths are achieved. The data collected radially to describe the formation is near one-tenth of that required for conventional 3-D surveys where the shot lines and the receiver lines are mapped in parallel survey lines.

Abstract: A 3-D radial seismic survey method is described suitable for accurately defining by migration processing an area having a dome-like subsurface structure. Radial survey lines are plotted with polar symmetry with respect to a center position at the center of the dome, such lines traversing the steep dip in all directions at approximate right angles. Hence, the developed data is efficiently acquired data useful for defining the structure. Bisecting survey lines may be provided as the original lines diverge to satisfy sampling requirements for migration. Data is acquired and sorted into bins that are annulus sectors and which are maintained sufficiently uniform in size to be within a maximum-to-minimum ratio of 2-to-1. Seismic source and receiver lines may be coincident or angularly offset.

Abstract: Three-component three-dimensional seismic data is acquired by locating a plurality of receivers off the seisimic shot line of a seismic source. The angle between the seismic shot line and a line extending between the seismic source and each receiver is used to normalize the signals generated by the two shear wave detectors in each receiver by mathematically rotating the orientation of the receiver and the orientation of the seismic source to produce horizontal shear wave signals and vertical shear wave signals generally equivalent to those that would have been produced if each receiver and seismic source were aligned along a seismic shot line.

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 seismic prospecting method comprising the use of at least two vehicles for moving an acoustic wave emission assembly and a reception assembly such as a seismic streamer. The method consists in performing successive cycles of emission of acoustic waves, of reception and of recording of the acoustic waves coming from reflecting interfaces of the subsoil and combining the recording so as to provide multiple coverage. The vehicles follow paths such that the angle formed by the respective advancing directions remains greater than or equal to 90.degree. in absolute value.

Abstract: Seismic traces are stacked in a plurality of orthogonal measures to form multiple stacked traces at a positive offset. The stacking process determines the apparent velocities as functions of the travel time at the positive offset. The interval acoustic velocity of the first layer is then determined from knowledge of surface topography, source-receiver offset, two-way travel times and the first reflector apparent velocities. The first layer velocity information enables the incident and emergent angles of the raypaths at the surface to be calculated, as well as enabling the dip angles and spatial coordinates of the reflection points on the first reflecting boundary to be determined.Seismic data corresponding to the second reflecting boundary are then spatially mapped to the first reflecting boundary by ray tracing and by a new method for calculating the apparent velocities at the first boundary. The process is repeated for each succeedingly deeper boundary.

Abstract: A method is disclosed for obtaining shear wave data from common depth point gathered compressional wave traces using variations in the amplitude of the gathered compressional waves with source-receiver offset. The shear wave data can be used to generate pseudo-shear wave seismic sections.

Abstract: A method of reducing Rayleigh waves (ground roll) in land seismic exploration employs a unique combination of amplitude output from and spacing of the vibrator sources making up a land seismic exploration system. The velocity of the Rayleigh wave for the prospect to be explored is determined. At least one receiver is used and is spaced from the vibrator sources a distance sufficient to establish the receiver as being in the far-field. The output of each of the vibrator sources is locked in phase and frequency and known separations between the vibrator sources are maintained. The frequency is varied and the individual output amplitude of each vibrator source is varied at each frequency so that the resultant Rayleigh waves traverse the known separations resulting in out-of-phase Rayleigh waves between the sources.

Abstract: An acoustic well logging method employing a tool having at least two acoustic transmitters and at least two acoustic receivers. In a preferred embodiment, one receiver is positioned midway between the two transmitters, and the other receiver is spaced from the first receiver along the longitudinal axis of the tool between the transmitters. Two signals, each representing an acoustic wave that has propagated from a transmitter through a portion of the formation surrounding the borehole to a receiver, are recorded when the tool is in each of two positions relative to the longitudinal axis of the well. In each of the tool positions, one recorded signal is associated with the midpoint receiver and the other with another receiver. From the four recorded signals, a new signal is generated. This derived signal has Fourier amplitude spectrum indicative of the formation parameters, but is independent of components associated with the transmitters and receivers.

Abstract: Three-dimensional seismic prospecting is conducted using a less than complete multifold array of seismic sources and receivers which are positioned so that the resulting system of linear static connection equations according to common depth point are continuously coupled.

Abstract: An area of a seam is defined and a series of shot locations and detectors are arranged along one side of the area to determine reflected signals. Transmitted signals are also received from a line of shot locations on the other side of the area. The signals received are processed according to an adaptive lag-summing technique to give a map showing the geological faults in the seam.

Abstract: The invention relates to a method of determining the location in the earth of sub-surface boundaries and/or the acoustic properties of sub-surface features substantially in the absence of the far field source wavelet and noise and with errors due to reflections of sound waves from the water being substantially compensated for. The invention uses point sound sources or arrays thereof at a first depth and then scales the energy, pressure and spacing of a similar source at a second depth to provide data which is used to obtain a seismic record.

Abstract: In a method and device for the study of surface layers and subjacent layers of interest, the device comprises receivers and at least two transmission sources spaced at a distance such that a set of traces produced by one of the transmission sources does not interfere with a set of traces produced by the other transmission source when the two sets of traces are on the same time-section.

Abstract: The present invention indicates that in exploration of permafrost regions of the world for oil and gas accumulations, flexure noise can be attenuated by careful placement of the vibratory source vis-a-vis the receiver array during collection of the Vibroseis.RTM.-type data. If the explorationist adopts a survey strategy in which the vibratory source is separated from the receiver array by a pressure ridge or its equivalent over the ice formation of the region under survey, then - surprisingly - the seismic reflection signals can be easily collected and displayed. Result: continuity of events from onshore reflectors can be easily followed offshore through the transition zone into deeper sea ice regions. He is aided in formulating his exploration strategy by the use of aerial and/or radar photographs or LANDSAT unmanned satellite data for mapping the pressure ridges of the area under survey.

Abstract: The present invention indicates that in exploration of permafrost regions of the world for oil and gas accumulations, flexure noise can be attenuated by careful placement of the vibratory source vis-a-vis the receiver array during collection of the Vibroseis.RTM.-type data. It has been surprisingly found that if the explorationist adopts a survey strategy in which the vibratory source is separated from the receiver array by a pressure ridge or its equivalent over the ice formation of the region under survey, then the seismic reflection signals can be easily collected and displayed. Result: continuity of events from onshore reflectors can be easily followed offshore through the transition zone into deeper sea ice regions.

Abstract: A seismic data recording system includes a central station and a plurality of remote seismic data recording units that are deployed within a desired region relative to the central station. The differential locations of the remote recording units relative to the central station are determined by receiving and recording electromagnetic positioning signals at the central station. A portion of the electromagnetic positioning signals is concurrently received and recorded at the respective remote recording units. The portion of the positioning signals recorded at each remote recording unit is combined with the recorded positioning signals from the central station to determine the required differential locations.

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: A novel method for determining and displaying the shear-velocity reflectivities of geologic formations is disclosed wherein a compression-wave common-depth-point seismic-data-gathering technique is utilized to produce both normal incidence compressional-velocity reflectivity sections and shear-velocity reflectivity sections for reflection points in given geologic formations. The subject method includes the gathering of common-depth-point information for a plurality of incidence angles, (theta) and estimating the linear coefficients (R.sub.pp,0 and R.sub.pp,1) of a linear function fitted to the amplitudes vs. sin.sup.2 (theta) measured for each point of reflection. The common-depth-point gather is conducted at angles of offset of less than 20-30 degrees such that assumptions concerning various elastic parameters: density, compressional wave velocity and shear-wave-velocity can be made which allow the application of linear fitting techniques to the gathered data.

Abstract: In a seismic recording and processing system in which a line of sources and a separate line of receivers are provided and each of the source operations from each of the source points is recorded on all receiver points. A method is described for determining the differential static correction between each adjacent pair of source points in terms of the differences in travel times from each pair of source points, to all pairs of receiver points. This is provided even though the lines of source points and receiver points may be parallel to or at angles to each other, and the spacings of source points and receiver points in their separate lines may be the same or different.

Abstract: A method for deriving seismic information from over a relatively large expanse of land to determine relevant strike, dip, velocity and related information. The method consists of the utilization of a plurality of strike, dip, velocity (SDV) cross patterned source-receiver arrays disposed at spaced known locations over a selected terrain, thereafter to derive localized and offset seismic data relative to selected pairs or groups of the SDV cross patterns with further signal processing to smooth and integrate strike, dip and velocity information over a specific substratum. The method utilizes information as derived from each SDV cross pattern, as well as offset seismic signal information derived from source/receiver combinations spanning two selected SDV cross patterns.

Abstract: In seismic exploration a method for improving seismogram displays is disclosed wherein seismograms having an offset which produces poor signal power are muted and seismograms having offsets with high signal power are stacked. The signal power in a CDP set is determined as a function of different values of assumed acoustic velocity of the earth. This signal detection is repeated for successive values of travel time and offset. The maximum signal power is plotted for values of velocity as a function of travel time and for different ranges of offset to form contours of the maximum signal power as a function of time and offset.

Abstract: The field locations of seismic shot points are chosen to produce partial multifold data, the static correction equations of which are at least partially coupled. The seismic cross sections resulting therefrom are substantially improved.

Abstract: A method for improvement of the signal-to-noise ratio of seismic data records comprising determination of the angle of incidence of acoustic waves transmitted into the earth with respect to subterranean reflecting layers which yields minimum attenuation of the acoustic wave during passage through intermediate layers is disclosed. The offset or distance between source and receiver is then selected so that the waves used to generate representations of the structure of the earth are incident on the reflector at substantially the optimal angle, thus yielding maximum signal strength, and maximizing the signal-to-noise ratio. Minimum offsets, to eliminate multiple surface/evaporite layer reflections from seismic records may be indicated as well.

Abstract: An improved method of generating synthetic seismograms for use in determining the accuracy of hypothesized subterranean structures is disclosed. The method features defining hypothesized detector locations corresponding to real detector locations rather than interpolating from arbitrary detector locations generated by specifying of initial ray path angles as input data. The accuracy of the results is improved by elimination of interpolation.