Abstract: A system for underground surveying includes a plurality of substantially rigid frames and a plurality of acoustoelectric sensors for generating electrical signals encoding echo responses of underground surfaces. Each of the frames carries at least one of the sensors, the sensors being disposable in effective physical contact with underground structures upon an insertion of the frames through a ground surface. An acoustic energy generator is disposed on at least one of the frames, while position determination componentry is operatively connected to the sensors for determining locations of the sensors relative to one another. An electronic signal processor is operatively connected to the sensors for analyzing the electrical signals in accordance with the determined locations of the sensors to determine surfaces of an object hidden underground and for generating a video signal encoding an image of the object. A video monitor is operatively connected to the processor for displaying the image of the object.

Abstract: A geophysical attribute migration method for a medium is disclosed. The method comprises forming at least one collection of seismic traces associated with an area of the medium and classified according to a predetermined criterion, and a stack section is produced on the basis of said seismic trace collection using a stacking speed field related to said area.

Abstract: A Petragrid method and apparatus generates grid cell property information that is adapted for use by a computer simulation apparatus which simulates properties of an earth formation located near one or more wellbores. An interpretation workstation includes at least two software programs stored therein: a first program called "Petragrid" and a second simulation program which is responsive to output data produced from the first "Petragrid" program for generating a set of simulation results. The set of simulation results are displayed on a workstation display monitor of the workstation. The first Petragrid software program will: receive well log and seismic data which indicates the location of each layer of a formation near a wellbore, and then grid each layer of the formation, the grid being comprised of a plurality of cells. The first Petragrid software will then generate more accurate data associated with each cell, such as the transmissibility of well fluid through each cell.

Abstract: The invention at hand is a method for mapping two or three dimensional P-wave stacked seismic reflective data, used to identify geophysical characteristics indicative of hydrocarbon, mineral, groundwater supplies and geological faults into a color space. This invention, by accentuating the subtle variations of the seismic waveforms, extends the effective resolution of data interpretation beyond the range allowed by current methodology.This invention accomplishes this by extracting a suite of measurements form a sequence of fixed time domain operator windows, and then using three measurements to form a multivariate attribute to transform the raw stacked seismic data. The measurements used in the multivariate attribute are selected from a standardized suite, and are amplitude based, autocorrelation function based and waveform shape based, with each combination selected to emphasize certain data characteristics.

Abstract: A method and system for producing an indicator for amplitude-versus-offset (AVO) analysis of seismic survey data is disclosed. According to the disclosed method and system, a raw AVO indicator is generated for each of multiple depth points, from the AVO intercept and gradient coefficient values. The indicator is generally a positive amplitude number for those locations having petrophysical importance, while the background neighboring points will have a zero or negative value for the raw indicator. Statistics are derived for a group of depth points that surround the depth point under analysis, in time and in space, from which a probability function may be evaluated, assuming a distribution of values in the background trend of AVO intercept and gradient values, and based upon which the raw AVO indicator will be modified. In one embodiment, the probability function is evaluated to determine the loci of points that are within the background to a certain statistical confidence.

Abstract: Apparatus and method are disclosed for use with a horizon picking method for 3D seismic data. Variables such as picking method, whether simple or iterative, score required of an iterative method and .DELTA.T between target wavelets and seed wavelet are input into the computer. During the picking process, parameters as to the number of successful picks and the number of failed picks because of the method of picking and because of failed picks due to the score not being achieved in the iterative method and because of failed picks due to the difference in time between the target wavelet and the seed wavelet being greater than the .DELTA.T variable are recorded. The number of score failures to pick a target wavelet from a seed wavelet is recorded where the score achieved is less than the input score. A characteristic of such number of score failures, such as the percentage of score failures to the total number of picking tries, is displayed on a CRT screen.

Abstract: A process for generating a surface slice for use in understanding or comprehending the internal structure of a multi-dimensional data volume and specifically a three-dimensional seismic data volume. The surface slice is a local N-1 dimensional representation of the internal structure of N dimensional data, where N represents the original dimension of the data volume. Information from the Nth-dimension is preserved in the N-1 dimensional surface slices. An arbitrary surface intersecting surfaces through the data volume is selected. A variant, an identifiable attribute of data which forms the surfaces of finite extent throughout the data volume, is also selected and isolated to identify the surface. Variants can include, but are not limited to, peaks, troughs, local peaks, local troughs, plus-to-minus zero crossings, and minus-to-plus zero crossings.

Abstract: An approximate method for imaging seismic data that originates from steeply dipping or overturned strata. The method provides a viable alternate approach to the generalized f-k migration that does not rely explicitly on some form of perturbation series expansion and thus avoids the steep-dip instability that is present in previously-known methods. This method is particularly useful in the presence of a moderate lateral velocity gradient, something that prior-art methods have trouble accommodating. An advantageous feature of the disclosed method is that the migration/imaging operators are composed of simple numerical coefficients.

Abstract: An efficient method for evaluating static corrections based upon molecular dynamics simulation. This approach combines the global minimization mechanism of simulated annealing and the deterministic approach of molecular dynamics simulation and finds the surface-consistent source and receiver static corrections by minimizing the objective function. The objective function is a measure of the reflection coherency of the whole data set.

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: A multi-dimensional assemblage of time/velocity functions are sampled for velocity as a function of incremental time. The samples are stored in a matrix arranged in columns along the time axis and rows across the velocity axis. The count of the number of samples resident in the respective cells of each row is indexed. A desired statistical operator is applied to the count indices in the rows to provide a family of filtered histograms in time-sequential order. The filtered histograms may be edited by delimiting acceptable velocities to lie between preselected percentiles.

Abstract: Acoustic energy is used to detect and identify objects buried in soil by imaging acoustic energy reflected from the soil and buried objects. Acoustic energy is injected into soil at an oblique angle relative to the surface of the soil, reflected and received. Signals representative of the reflected energy are processed to generate image signals used to generate images representative of the reflected energy. Objects buried within the soil are identified by viewing the images. In one embodiment, obliquely oriented acoustic energy signals are carried from a source to a soil sample by a first duct and reflections of that energy are carried to a receiver within an adjacent second duct. The ducts acoustically isolate the source from the receiver. A beveled end of the first duct and the second duct are supported above the soil sample for noncontact operations. In another embodiment, an acoustic energy source is obliquely supported upon and forced into engagement with soil in a reservoir.

Abstract: Data representing a two-dimensional image of the resistivity of a sector of a borehole wall is processed to produce selected flow-line data delineating the boundaries of beds of subsurface earth formations along sectors of the borehole. The latter bed-delineating image data for several circumferentially-spaced sectors is further processed to derive and present data defining the orientations of dip planes, by matching the bed-delineating flow-lines for the several sectors. This is done by focusing the latter flow-lines on a root flow-line, correlating those flow-lines to the root flow-line, and linking the flow-lines to the root flow-line according to a path of minimum cumulative cost.

Abstract: Time-coherency traces generated during velocity analysis are displayed in panels where each panel contains traces representing a single selected trial stacking velocity function and a plurality of common midpoint locations along a seismic line of exploration. Points selected from the panels, optimally by comparison with stacked sections, are used to generate a time velocity funtion for stacking, NMO correction, interval velocity determination, or other uses.

Abstract: Regional velocity spectra coherency peaks are associated with peak events on a stacked seismic section of CMP gathers and used for editing siesmic data. In addition, travel time and spatial location along a seismic line data are displayed for stratigraphic and structural interpretation.

Abstract: The present invention provides methods for processing and displaying seismic data to emphasize potential hydrocarbon bearing strata. The methods treat measured attributes from the seismic data as components of a vector, estimate a background vector which represents uninteresting geologic behavior, and then form at least one new attribute which quantifies departures from this uninteresting behavior. The new attributes(s) and other attributes are then appropriately displayed.

Abstract: Regional coherency maxima are displayed in various domains and interactively edited to produce stacking velocity functions, horizon velocity functions, and sets of edited velocity spectra regional coherency peaks for use in geophysical exploration for oil and gas.

Abstract: The present invention relates generally to seismic exploration and more particularly to a method for inversion of seismic data to yield estimates of formation lithology. Seismic data representing a measure of reflectivity of subsurface formations to seismic energy imparted therein can be inverted to obtain measures of formation elastic properties. By cross-plotting selected formation elastic properties on a color-binned lithology diagram, a lithology section can be produced having increased lithological resolution.

Abstract: A blast recorder and method for monitoring and processing vibrations from blasts, and for displaying the results in a nearly real time basis and in a manner which is easily interpreted by a relatively unskilled field worker and corresponds to a form which closely correspond to the real damage causing aspect of the blast than heretofore.

Abstract: A method and apparatus for immediate, substantially real-time representation of the traces of seismic measurements in which the exponents and sign of the signal sample from the stream of data transmitted to a data recording unit (2) are uncoupled and are displayed as gradations of color on a monitor (6) of a personal computer. in this manner a quick overview of the measurement can be obtained, and the correctness of the installation and the operability of the receivers can be determined.

Abstract: A novel method of geophysical exploration is described for obtaining estimates the formation lithology from measures of formation anisotropy. First and second measures of formation anisotropy can be transformed into estimates of formation lithology by crossplotting them onto a lithology diagram. In one embodiment of the present invention, the lithology diagram comprises two separate axes representing measures of formation azimuthal anisotropy and transverse isotropy for a selected formation property which defines regions of separate lithologies. The lithology diagram can provide a novel means for discriminating formation lithology from the measures of formation anisotropy.

Abstract: An improved method and apparatus for processing seismic data records is disclosed. Data is normal moveout corrected by an operator providing estimates of velocity of seismic energy in rock layers in the earth. According to the invention, the system provides an immediate display of the seismic data processed in response to operator commands relating to estimated velocity, whereby the operator is permitted to perform normal moveout correction by inputting new velocity commands, essentially in real time.

Abstract: Disclosed is separation of the compressional and shear components of the wavefield measured in 3-component vertical seismic profiling. The separation involves working in the zx plane defined by the borehole axis (z) and the surface seismic source space therefrom along the x-axis, and in successive and overlapping windows each defined by (i) a depth interval centered at the depth level currently being processed and including several depth levels above and below and (ii) a time interval sufficiently long to allow the relevant seismic wavefield to be measured by the geophones. The total wavefield measurements in a window are rotated to give the wavefield along the borehole axis (z) and that perpendicular to it in the zx plane of interest.

Abstract: A computer-implemented technique for dip filtering of seismic data whereby seismic data of a selected attribute in space and time coordinates is displayed in accordance with a 3-D illumination model such that the apparent angle of illumination of the data relative to an apparent viewing position is optimally adjusted to achieve best differentiation and display presentation of seismic dipping events, fault indications, excessive multiple indications, and the like. The method requires a perceptual view of a seismic section as a 3-D surface from which a vector of images can be derived. Thereafter, vector of images surface components are derived and, in accordance with a pre-determined illumination model, i.e. composed as a function of azimuth and elevation relative to a display, the vector of images of the seismic data are transformed to produce enhancing a specific eye view/illumination alignment.

Abstract: A vehicle for seismic surveying fitted with a shock source device, and an electronic control and display device. The control and display device has a display panel which provides a display of required shock positions, and a movable display which moves along the display of impact positions in dependance upon vehicle travel to facilitate positioning of the vehicle at the required shock positions.

Abstract: A computer system displays, in two dimensions, a representation of a three-dimensional volume. The three-dimensional volume representation is a tessellation of cells, represented as three-dimensional units. The three-dimensional volume is represented by a plurality of digital numbers. A designator designates which of the digital numbers are to be represented in the two-dimensional display. Each digital number is represented by one cell. Also, each digital number represents a color. Each corresponding cell is colored in accordance with the digital number. A designator designates which of the digital numbers is to be represented by a cell in the three-dimensional representation. A cursor, controlled by a mouse, may be used to indicate which of the three-dimensional volume representation is to be excavated by indicating at the appropriate cells and then electronically ordering the excavation.

Abstract: A transcriber system for receiving previously recorded data in a first medium and outputting the data in a second medium, and which includes at least one input device for receiving the data in the first medium, an output device for outputting the data in the second medium, a control and processing device which controls the input and output devices for a selected mode of transcription and in one embodiment, for selected processing of the data in the field. In one embodiment, the transcriber system receives seismic data from tape cartridges and/or solid state memory devices and outputs the seismic data onto a magnetic tape for later processing and analysis or transmission to a remote facility via a satellite link. The transcription system can include a printer/plotter for analysis of different seismic data recording and processing arrangements in the field.

Abstract: Disclosed is separation of the compressional and shear components of the wavefield measured in 3-component vertical seismic profiling. The separation involves working in the zx plane defined by the borehole axis (z) and the surface seismic source, and in successive and overlapping windows each defined by (i) a depth interval centered at the depth level currently being processed and including several depth levels above and below and (ii) a time interval sufficiently long to include the receipt of the relevant seismic energy by the geophones.

Abstract: A computergraphics system display seismograms in a three-dimensional presentation of the subsurface formations of a section of the earth from which the seismograms were obtained. Digital seismic sections are converted to video signals which are recorded on a video recorder. The seismic sections are successively displayed on a television monitor to produce a visual impression of movement through the subsurface formations represented by the successive seismic sections.

Abstract: A method for developing a novel seismic data attribute enables improvements in seismic data processing and interpretation. Seismic signals or trace data are first rectified and then Hilbert transformed and processed with the arc tangent function to develop a new instantaneous phase parameter referred to as phase of rectified trace (PORT). Output data may be further enhanced with tri-modal, interactive color display.

Abstract: In seismic exploration, the response characteristics of an array of seismic sources is displayed by contours of equal values of amplitude response as a function of azimuth and dip angle in a stereoscopic polar projection. The projection includes a center point on an axis extending away from the center point representing amplitude response at locations on the line of exploration. Points disposed circumferentially about said axis amplitude response at different azimuth angles from the line of exploration and points at different radial distances from the center point represent amplitude response at different dip angles.

Abstract: A cathode ray tube is used for quality control in conjunction with a method and apparatus for monitoring seismic data gathers. As seismic reflection data is acquired, it is displayed on a cathode ray tube and visually monitored to determine whether information channels are to be deleted due to excess noise, improper amplification, etc., prior to recording the acquired data.

Abstract: In accordance with the present invention, progressive changes in amplitude as a function of offset of common gathers can be more easily identified by emphasizing the degree of amplitude variation between traces of each gather along a seismic line, and after generating semblance coefficients, displaying the resulting "weighted" offset traces or representations of such traces as function of either horizontal offset or centerpoint values. A significant --and progressive --change in P-wave reflection coefficient as a function of the angle of incidence (within sections) indicates valuable characteristics, say the fluid hydrocarbon-bearing potential and/or lithology of the reflecting horizon.

Abstract: The present invention indicates that gas-containing strata of an earth formation have low Poisson's ratios and that the acoustic contrast (with the overburden rock) has a surprising effect as a function of the angle of incidence on a seismic wave associated with an array of sources and detectors: viz., a significant--and progressive--change in P-wave reflection coefficient as a function of the angle of incidence (within a gather of data) indicates the lithology of the reflecting horizon and the capping strata.

Abstract: In accordance with the present invention, progressive changes in amplitude as a function of offset of common gathers can be more easily identified by emphasizing the degree of amplitude variation between "near" and "far" amplitude vs. time traces of each gather along a seismic line, and displaying the resulting near and far offset sections side-by-side. A significant--and progressive--change in P-wave reflection coefficient as a function of the angle of incidence (within sections) indicates valuable characteristics, say the fluid hydrocarbon-bearing potential and/or the lithology of the reflecting horizon.

Abstract: The present invention provides for the accurate mapping of shallow crustal earth formations by means for refractive seismic waves to identify structure as well as elastic parameters of the strata undergoing survey to indicate deposits of ore, marker rock, economic minerals and the like. In one aspect of the present invention, a "roll-along" technique is used in the field, such technique being both practical and economical. In accordance with another aspect of the invention, there is a provision for (i) stacking displays that allow for accurate identification of shape of the surveyed strata; and (ii) final depth displays of the refracting bed segments associated with seismic shear and compressional wave velocities as well as Poisson's ratio to indicate presence of ore, marker rocks, economic minerals and the like.

Abstract: A real-time monitor which displays analog representations of digital seismic data having been recorded on magnetic tape such that adjacent seismic traces are partially overlapped, whereby the appearance of an error is enhanced and is disclosed. The monitor display is controlled by a computer which may be of a type similar to computers used in the seismic data storage system for other purposes so that it may serve as a back-up computer. This system is implemented by incorporating into magnetic tape data storage drives read-after-write circuitry so that the data put on the tape can be read off the tape immediately thereafter and used to control the monitor means. In this way, the monitor is in fact operating in real-time and operates on precisely that data which in on the tape; thus any errors displayed on the real-time monitor include any errors made in the actual recordation of the data onto magnetic tape.

Abstract: Amplitude-versus-time information of a seismic time section is automatically migrated so that events on the time section are displaced, both vertically and horizontally, into positions on a seismic depth section that correspond to actual spatial positions of seismic reflectors in the subsurface. The migration is continuous in the sense that it moves the entire waveforms, not merely previously picked events.

Abstract: This invention utilizes data collected in the course of reflection seismic prospecting methods to produce a map, such as a vertical profile or a three-dimensional picture, of subterranean earth formations. This is accomplished by aplanatic mapping of received seismic wave trains in the memory unit of a computer taking into account the travel times of waves, the location of the source, the location of the receiver, and the velocity with which the waves travel from the source point to the deflecting point in the earth and from then to the receiver. The data recorded by each source receiver doublet is digitalized and stored aplanatically in the memory unit, taking into account both signs and amplitudes of the signals. The accumulated data represents a map of the earth formations. Sections of this map are plotted to provide desired views of the formations.

Abstract: The present invention indicates that gas-containing strata of an earth formation have low Poisson's ratios and that the acoustic contrast with the overburden rock has a surprising effect as a function of the angle of incidence on a seismic wave associated with an array of sources and detectors: viz., a significant--and progressive--change in P-wave reflection coefficient as a function of the angle of incidence occurs. Thus, differentiating between high-intensity amplitude anomalies of nongas- and gas-containing media is simplified: progressive change in amplitude intensity of resulting traces generated by the field array as a function of offset between each source-detector pair, is associated with the last-mentioned medium only.

Abstract: The present invention indicates that gas-containing strata of an earth formation have low Poisson's ratios and that the acoustic contrast with the overburden rock has a surprising effect as a function of the angle of incidence on a seismic wave associated with an array of sources and detectors: viz., a significant--and progressive--change in P-wave reflection coefficient as a function of the angle of incidence occurs. Thus, differentiating between high-intensity amplitude annomalies of nongas- and gas-containing media is simplified: progressive change in amplitude intensity of resulting traces generated by the field array as a function of offset between each source-detector pair, is associated with the last-mentioned medium only.

Abstract: Sample and hold circuits are utilized to divide data stored in memory into a plurality of channels for display. First-in-first-out buffers are utilized to compensate for the difference between the time required to read data from a memory and the time required for a sample and hold circuit to sample and hold the data.

Abstract: A novel seismogram display and method for making same are provided wherein a portion of the areas under certain ones of the positive and negative wavelet lobes of each seismic trace is shaded. Each shaded area originates at or near a null point. The novel seismogram allows an interpreter to correlate both partially shaded lobes per wavelet, instead of one completely shaded, single lobe per wavelet. The invention therefore greatly simplifies and enhances the correlation and interpretation process.

Abstract: A two dimensional display is prepared representing a cross section of the earth and designed to establish natural data lineations. The vertical axis is marked in terms of a parameter of depth below the earth's surface and along the horizontal axis, are marked seismic receiver stations. For each station, a graph of an intrinsic lithologic property as a function of depth is computed and plotted beneath the corresponding station. Contour crossing points are determined at unit intervals along the plotted graph together with the sign of the corresponding derivative. Contour crossing points, beneath adjacent stations, that match as to numerical value and derivative sign are connected by contour segments. Shading patterns are applied to the zones between contour segments to enhance the natural lineation of the chosen intrinsic lithologic function.

Abstract: A seismic triggered seismograph (10) has a transducer (12) that measures particle vibration along three orthogonal axes and a microphone (14) which measures atmospheric overpressure. The four parameters measured produce signals which are passed through delay circuits (58, 60, 62, 90) and then connected for recording on magnetic tape (21). The seismic signals are examined before being input to the delay circuits (58, 60, 62) and when any of the signals exceeds a predetermined threshold, a tape transport (154) and recording mechanism are activated so that the signals are recorded when they emerge from the delay circuits. Both the delay circuits (58, 60, 62, 90) and the magnetic recording are implemented with analog format. At the end of a predetermined time interval following a seismic event, a calibration signal is applied to the magnetic recording. Following the calibration signal, the transducer (12) is activated by a standard amplitude signal for indicating calibration of the transducer (12).

Abstract: Disclosed is a seismic data gathering system for use in well drilling operations. A seismic pulse generator may be placed in the drill string near the drill bit and advanced in the well for generation of seismic pulses at any depth. An array of seismometers, rotationally symmetric about the well, may be arranged at the surface to detect both pulses refracted above the seismic pulse generator and pulses reflected at interfaces below the generator. According to the method of the invention, the refracted and reflected seismic pulse data may be reduced and analyzed to determine the drilling direction of the drill bit, the lithology through which the drill is passing, the position and approximate shape of nearby oil or gas reservoirs otherwise missed, and to look ahead of the drill bit to determine geologic conditions in advance of the drilling.