Abstract: A method of seismic exploration is disclosed wherein a signal recording obtained from subsurface geophone receivers placed below the weathered layer is used to characterize the waveform of the downgoing signal generated in the earth by a surface seismic source. The reflections of the source signal measured at the earth's surface at a point remote from this source are then deconvolved with an operator derived from the subsurface waveform in order to eliminate or compensate for the filtering effect of the weathered layer. Successive measurements of the downgoing source signal are taken at the earth's surface as the source is advanced along a seismic line. One of such surface signals can be combined with the subsurface signal recording in order to derive a transfer function indicative of such filtering effect for the intervening weathered layer.

Abstract: A downhole tool carries an inflatable packer by means of which radial pressure may be applied to the surrounding formation. Transducers within the packer measure the radial direction and extent of formation displacements responsive to such pressure. In this way one can determine the directions of maximum and minimum horizontal in-situ formation stress.

Abstract: Some of the laterally spaced air gun sub-arrays which are combined to form the sequentially fired source arrays of a marine prospecting system are shared between neighboring arrays. This double usage of said sub-arrays allows a larger number of full size arrays to be fired sequentially without requiring the deployment of additional sub-arrays which may exceed the capabilities of the towing vessel. In this way multiple profiles can be collected more efficiently in performing three-dimensional seismic surveys.

Abstract: An impact type surface seismic source powered by compressed air includes an elongated piston which moves within the bore of a cylindrical firing tube suitably mounted above an earth contacting target. The firing tube consists of two or more tubular sections slidably joined in telescopic relation. When the piston is allowed to fall from a cocked position, compressed air enters the bore above the piston through side ports and drives the piston downwardly. At the same time, the inner sliding section or sections of the firing tube are exposed to the same air pressure within the bore and are also driven downwardly. In this way, the bore of the firing tube lengthens automatically to provide a longer stroke for the piston and thus a greater attained kinetic energy of impact for a given operating pressure as the piston reaches the target. The apparatus is designed for mounting on a transport vehicle so that the firing tube itself may be raised in operation and lowered for reduced vehicle profile during transport.

Abstract: A baseplate assembly for an impulsive, vehicle-transported seismic wave generator for use on rocky, irregular earth surfaces is comprised of a small diameter, earth-contacting, freely movable target member which is laterally confined in the center of a surrounding wide area frame adapted to support vehicle weight directly against the earth. Such a target member may safely be subjected to high dynamic loading per unit area responsive to the impact of a descending mass.

Abstract: Apparatus for generating seismic waves including an upstanding hollow cylindrical housing within which an impact piston latched in a cocked position is adapted to be propelled downwardly by high pressure expanding gas in the confined chamber above it within the housing so as to strike a target plate resting on the ground adjacent the lower end of the housing. After each blow against the target, the piston is retracted upwardly by means of hydraulic cylinders which recompress the gas in the chamber to its original pressure. Since there is no need for recharging the pressure chamber after each shot, economical rapid cycle operation is facilitated.

Abstract: A rigid, earth-contacting target for use with an acoustic signal generator is designed to be impacted by a mass propelled downwardly by compressed air or other energy source. The target includes an upper impact-receiving member slidably interfitted with a lower ground-contacting member. An elastomeric disc is confined between the upper and lower members so as to experience three-dimensional compression in response to such impact. The bulk modulus of the elastomer determines the degree to which the rate of acceleration of the lower member is reduced as compared to that of the upper member, and thus in turn, controls the frequency content of the resultant acoustic pulse.

Abstract: A man-portable, easily disassembled seismic source is described which utilizes a self-propelled projectile. The projectile, carrying a container of compressed gas, is supported over a rigid earth-contacting target at one end of a lightweight linear guide or track. When the support is removed, the container is automatically vented to atmosphere in an upward direction. In this way, the projectile is jet-propelled to the target, which in turn produces an acoustic pulse in the earth.

Abstract: The weight of a transport vehicle and the actuator of an impact type seismic source carried thereby is partially transferred by means of hydraulic lift cylinders to a freely movable earth contacting baseplate positioned beneath the actuator. In operation a mass is propelled by the actuator along a prescribed slant path to strike the baseplate. Shear strain is induced in elastomeric pads sandwiched between the hydraulic lift cylinders and the baseplate if the baseplate shifts sideways under such a slanting blow. The pads then exert a force to restore the vehicle and the actuator to a correct perpendicular alignment over the baseplate. Upper and lower position locator means fixed respectively to the hydraulic lift cylinders and to the baseplate interface with the elastomeric pads and fit slidably within each other so as to transmit vertical force from vehicle to baseplate.

Abstract: A vibratory seismic surface source includes a single vibrating mass, the energy of which is coupled to the earth through a ground contacting base plate. Means are provided for varying the inclination and azimuth of the vector path traversed by the reciprocating mass, such that any desired combination of compressional and shear waves, both SH and SV type, may be generated and recorded simultaneously at a point on the earth's surface remote from the source.

Abstract: An impact-type surface seismic source utilizing a closed air system includes a heavy pistons supported above an earth contacting base plate partially within a hollow upstanding cylindrical housing, having a closed top and an open bottom. The housing side walls are provided with ports which communicate with a source of high pressure air. Preparatory to a firing operation, the piston blocks these ports, but upon a firing signal the piston is released and falls under gravity permitting high pressure air to enter the bore of the housing through the ports, thus driving the piston downwardly to strike the base plate. As the piston is retrieved and nears its original position, blocking the side ports, it mechanically actuates a valve so as to vent any air trapped above the piston within the housing bore. The vent remains open until the piston again falls.

Abstract: Multiple vehicle-transported impact-type surface seismic sources designed to shoot along slant paths to create combined compressional and shear wave pulses in the earth are provided with radio controlled actuators. The azimuth of each shooting path is automatically referenced to magnetic north so that signals of equivalent wave form contents are produced despite vehicle misalignments and without reliance upon individual vehicle operators.

Abstract: A vibratory seismic surface source includes a single vibrating mass, the energy of which is coupled with the earth through a ground contacting base plate. The vibrating mass is connected to the base plate by means of a ball and socket joint which constitutes a universal pivot for the vibratory axis of the mass. Thus, this vibratory axis may be made to assume any vector path with respect to a seismic line. In this manner, any desired combination of compressional and shear waves, both SH and V type, may be generated and recorded simultaneously at a point on the earth's surface remote from the source.

Abstract: A full waveform seismic source is described which is adapted to propel a heavy mass powerfully downward against the surface of an earth-contacting target plate. Means are provided for rotating the barrel of the actuator about two mutually perpendicular horizontal axes so that energy can be delivered to the earth along a plurality of preselected slant paths. In this way, any desired combination of compressional and shear waves, both SH and SV type, may be generated at a point on the earth's surface. The target is contoured so that any slant path followed by the accelerating mass always impacts the target normal to its surface.

Abstract: A vibratory seismic surface source includes a single vibrating mass, supported above and independently of an earth-contacting base plate. Means are provided for varying the inclination and azimuth of the vibrator axis. After the vibrator is oriented in any desired direction, it is then lowered along its vibratory axis so that it bears directly against the hemispherically concave upper surface of the base plate. When the vibrator is actuated in this position of contact, any desired combination of compressional and shear waves, both SH and SV type, may be generated and recorded simultaneously at a point on the earth's surface remote from the source.

Abstract: A vibratory seismic surface source includes a hydraulic vibrator the energy of which is coupled into the earth through a ground contacting base plate. The vibrator is supported above and independently of the base plate so that it may be pivoted about a first rotational axis within a truck-mounted gimbal-type frame which itself is tiltable about a second horizontal rotational axis perpendicular to the first. After the vibratory axis is oriented in the desired direction the vibrator is lowered so as to contact a suitably contoured upper surface of the base plate. Inclination of the vibrator is accomplished by "push-pull" operation of pairs of oppositely-directed hydraulic cylinders.

Abstract: An ultrasonic borehole televiewer is modified to provide a vertical array of receiving transducers arranged above and below a conventional transmit/receive transducer. The variation in amplitude of reflected energy detected across this array for each firing of the televiewer is a measure of the extent to which scattered energy is present in addition to specular reflections. This in turn is an index of the relative smoothness or roughness of the borehole surface on a scale comparable to or smaller than the wavelength of the incident energy.

Abstract: Distortion in vibrator-type seismic records is corrected by measuring and using the actual ground force imparted by the source to develop an inverse filter. The ground force signal and the reflected seismic data are both subjected to the same deconvolution or other standard processing technique, thereby automatically filtering out flaws introduced by any such technique.

Abstract: A plurality of similar open-ended fluid conduits are interconnected between a like number of fluid volume zones within a fluid-filled vessel, such as a clarifier, having a steady upflowing fluid supply, and a small continuously draining collector box adjustably suspended from the top of the vessel and immersed a few inches below the fluid level. The conduits discharge into the collector box through orifices on which a common head is maintained, so as to draw down each fluid zone at the same rate. Thus, the collector box acts as a weir. The conduits are spaced so as to minimize the existence of channeling or lateral currents, which interfere with the most efficient settlement of solid matter. Orifice plates interconnected with the discharge ends of the conduits within the collection box are easily accessible through a hatch in the top of the covered vessel for cleaning, and adjustments.

Abstract: A full waveform seismic source is described which is adapted to propel a heavy mass powerfully downward against the surface of an earth-contacting target plate. Means are provided for rotating the barrel of the actuator about two mutually perpendicular .[.horizontal.]. axes so that energy can be delivered to the earth along a plurality of preselected slant paths. In this way, any desired combination of compressional and shear waves, both SH and SV type, may be generated at a point on the earth's surface. The target is contoured so that any slant path followed by the accelerating mass always impacts the target normal to its surface.