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.

Abstract: Arrays of seismic wave sources and seismic wave sensors are towed over an area to be refraction surveyed in such a way that source and sensor geodetic positioning is duplicated during successive source firings. A plurality of traces having these same source/reflection point/sensor geometry are gathered from those produced by each series of successive source firings at the same location and stacked to generate a new trace having improved signal to noise ratio. Positioning is accomplished by uniformly spacing each of the sensors and sources in their respective arrays, the sources being spaced at integer multiples of the spacing of the sensors, and towing both arrays behind the same boat. If irregular or rapidly changing seismic statics are not present, all traces from common reflection points may also be gathered, corrected for normal moveout and stacked to generate a composite trace having enhanced primary reflection returns as well as improved signal to noise ratio.

Abstract: An improved method for three-dimensional seismic exploration of the subterranean structure of the earth is disclosed wherein arrays of sources of acoustic energy and of detectors of reflected energy are used. The configurations of both arrays are conjointly experimented with to improve the signal-to-noise ratio of the resultant data; the signals output by the detectors are summed, and are correlated with those output with respect to all acoustic energy emitted within a given array of sources.

Abstract: Faults in a mineral seam are located by an in-seam seismic technique which involves locating shots and detectors in the seam and firing the shots sequentially. The detectors pick up the reflections of the shots from faults and a common reflection point is determined by analyzing the seismic traces from the detectors.

Abstract: A method determines the extent of subsurface reactions in which random acoustic signals are radiated from a whole area covered by the reaction or from a boundary region, hereafter termed reaction front, between largely undisturbed rocks and those already covered by the reaction. The signals are recorded by at least two receivers positioned at different locations outside the reaction area. The recorded signals are cross-correlated as a function of a time shift between the recorded signals so that at least one surface confining the reaction area is determined from the cross-correlation.

Abstract: The present invention relates to a method and apparatus for selectively generating a next-in-time positional code for disconnectably connecting recording circuitry to different but contiguous sets of detectors, i.e. an "active" array, from among a plurality of detectors positioned along the line of survey. For this purpose a microcomputer system that includes a system bus connected (via a port) to the rollalong switch, is employed.

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 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 method of seismic exploration and in particular a method of generating and gathering field seismic data. Paths or seismic lines are traversed across the earth or water layers overlying the earth and over subsurface earth formations thereunder, and seismic energy is generated and transmitted into the earth and a portion thereof is reflected from the subsurface formations back toward the surface of the earth where the reflected seismic energy is detected and recorded. In conducting the seismic survey, a long linear array of seismic sources is simultaneously activated to produce a seismic pulse that is focused essentially vertically into the earth, and seismic energy is reflected from subsurface formations thereof and is detected by a long array of seismic detectors and is recorded.

Abstract: A method and apparatus for determining the acoustic properties of the earth utilizes one or more identical, non-interacting, first spaced arrays of point sound sources and one or more identical, non-interacting, second spaced arrays of point sound sources with corresponding arrays of the first and second sources containing the same number of point sound sources in the same spatial relationship, with the spacing between the point sources of the second array or arrays being a factor .alpha. greater than the spacing between corresponding point sources of the first array or arrays. The energy of the radiation emitted by each point source of the first array(s) is greater than that emitted by the corresponding point sources in the second array(s) by a factor of .alpha..sup.3.

Abstract: A method of seismic exploration comprises transmitting waves from transmission sources into the medium to be explored and picking up signals in a receiver and recording these as traces, the signals being produced by reflection in the medium, the sequential transmission of the sources taking place at intervals less than the reflection time of the longest transmitted waves, the repeated transmission of any one source taking place at intervals at least equal to the said reflection time and therein being an intercorrelation function of a series of transmission instants of all the sources and a series of transmission instants of any one of the sources to give a relationship between the maximum peak amplitude and the secondary residue amplitude greater than a predetermined value and grouping the recorded traces corresponding to the same reflection point, adjusting the traces in relation to the associated source providing the information relating to the reflection point and adding together the adjusted traces relati

Abstract: A method for removing an undesired surface wave from a reflected wave in a method for seismic exploration is accomplished by placing first and second detector arrays at a location on the surface of the earth in the direction of movement of the surface wave. The array has a length less than the length of the shortest wave length of the interfering wave to be eliminated. Signals from both arrays are recorded and processed by first adding the received signals to form a first output, subtracting added signals to form a second output, shifting one of the output signals by 90.degree., adjusting its amplitude and subtracting the phase shifted and adjust signal from the remaining signal thereby removing the surface wave.

Abstract: Seismic sources and detectors are each positioned in a series of shotholes along a course to be explored. The sources in the shotholes are activated in a sequence along the course and caused to emit seismic waves. The detectors remaining along the course sense or detect the seismic waves which are then recorded. Since the detector at each shothole has performed its function, that of sensing signals from earlier shots in the sequence, its disposal by destruction when the source in the shothole with it is activated does not impair further surveying efforts.

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: 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.