Abstract: Apparatus and method for recording seismic signals on a logging chart as a function of the depth of a logging sonde within a well bore includes apparatus for analyzing the seismic signals. The method utilizes the recording of information relating to the slope of a seismic signal received from the sonde. A recording trace is made using successive horizontal sweeps with no vertical deflection, and presence of a mark on the recording can indicate a positive slope for the seismic signal, and the absence of a mark can indicate a negative slope. An apparatus of the present invention utilizes this method to record well logging information obtained from seismic signals.

Abstract: A variable frequency seismic pulse is produced by releasing a weighted piston within a partially evacuated cylinder. The piston compresses residual air in the cylinder before striking a base plate held firmly in contact with the ground. Controlling the pressure of the gas remaining in the cylinder controls the frequency and amplitude of the seismic pulse applied to the ground. The seismic pulse can be applied at various angles from vertical from a thumper mounted on a vehicle or from a hand-held thumper.

Abstract: An improved portable seismic energy source including a base member having cylindrical sidewalls and an open lower end for resting on the earth's surface, a horizontal baseplate secured to the base member upper end, the baseplate having a central opening therein, a gun mounted on the horizontal baseplate for firing a projectile through the opening therein to impact the earth's surface and generate a seismic signal, a spatter plate mounted to the base member such as by means of a vertical cylinder secured to the lower surface of the baseplate with the lower end of the cylinder being affixed to the spatter plate, the spatter plate having an opening therein in register with the cylinder so that a projectile fired passes through the opening, the spatter plate being positioned above the earth's surface, and a flexible diaphragm secured at its periphery to the lower circumferential surface of the base member and having a central opening therein, the diaphragm being stretched over the top of the spatter plate, the sp

Abstract: A digital scan converter is provided with a memory, each cell of which contains brightness data for presenting a corresponding video signals on a raster scan display at positions corresponding with the respective cells; a logical unit for supplying, in response to the applied video signals and the brightness data stored in memory, new brightness data overwriting that stored in memory; an address conversion circuit for converting the addresses established in polar coordinates into addresses expressed in Cartesian coordinates to store the new brightness data in memory; and with a circuit connected to the memory for reading out the brightness data and for presenting corresponding video signals on the raster scan display.

Abstract: A gas gun assembly for measuring depths of reflectors in a well bore includes a housing having a central chamber and bottom bulkhead through which a first valve bore extends. Coupling structure is provided to connect the housing to the well. A cap closure for the chamber has a second valve bore therethrough of diameter larger than the diameter of the first valve bore and is located in axial alignment with the first valve bore. A valve stem has one end axially movable within the second valve bore while closing the same and the other end movable into and out of the first valve bore. A predetermined pressure condition is established across the bulkhead. The valve stem is then released for rapid equalization of pressure across the bulkhead to produce an acoustic pulse in the well bore.

Abstract: A lightweight rigid housing and baseplate structure for a seismic transducer. The baseplate (12) includes a central hub (26) for receiving a lower piston rod (76). Upper and lower skin plates (32 and 36) extend radially outward from the central hub (26). A plurality of equally angularly spaced reinforcing plates (40) also extend radially outward from the hub (26) and have their upper and lower edges rigidly connected to the upper and lower skin plates. A housing assembly (78) rigidly connects an upper piston rod (74) to the baseplate (12), and includes a frusto-conical section (82). The lightweight rigid housing (78) and baseplate (12) structure provides a seismic transducer having in-phase force distribution over substantially the entire area of the baseplate as it is engaged with the earth.

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: A robust air gun fire time sensor consists of a housing to which is secured a protruding nonmagnetic internal barrel having a bore. The bore is closed at one end by a magnetic end cap defining an air chamber and the bore is in fluid communication with the firing chamber of an air gun. A generator coil surrounds the barrel. A bar magnet is floatingly mounted inside the bore and is urged against a shoulder formed in the end cap. When the air gun is charged with compressed air, some of the air becomes entrapped in the air chamber. When the air gun is fired, the entrapped compressed air in the air chamber pushes the bar magnet away from the shoulder. The collapsing magnetic field creates a transient electric pulse in the generator coil.

Abstract: In a public key cryptographic system (FIG. 1) for communicating securely over an insecure communication channel (3), a sender (1, 2) enciphers a data message (D) using a public enciphering knapsack key (H) to generate an enciphered message (S.sub.H). An authorized receiver (4 6, 7, 20, 21, 22) with knowledge of a private deciphering key (E), a modulus (M) and an integer multiplier (W) generates a private enciphering key (A) which is employed in further enciphering the received enciphered message to form a doubly enciphered message (S.sub.E, S.sub.E). The doubly enciphered message is deciphered using the private deciphering key alone to recover the original data message.

Abstract: A seismic exploration method is disclosed for filtering the signals produced by a detector placed at different depths in a well in response to an emission of acoustic waves from a source on the surface: the signals comprising downgoing wave components and upgoing wave components.The filtering consists in sampling from among the N signals to be processed a group of n signals s.sub.l . . . s.sub.n detected at respective levels x.sub.l . . . x.sub.n, in determining the propagation time t.sub.k of the acoustic waves from the level x.sub.l to each level x.sub.k, in advancing the signals s.sub.k by the time t.sub.k in relation to s.sub.l and in adding s.sub.l and the signals s.sub.k thus shifted to obtain a sum z.sub.l, in calculating a sum y.sub.l of s.sub.l and of the signals s.sub.k delayed by the time t.sub.k in relation to s.sub.l, in generating a signal u.sub.l *, defined as an optimum estimation of the upgoing wave component, from the sums y.sub.l and z.sub.

Abstract: A monopulse radar comprising a pilot signal generator (20) for injecting phase and amplitude-defined pilot signals into the separate receiving channels (6-12, 3, 16-19) to obtain correction signals through the variation in the mutual phase and amplitude relationship between the separate receiving channels for correcting angle error signals derived from target return signals. The pilot signal generator (20) and the transmitter (1) are tunable and a control circuit is incorporated for adapting the pilot signal generator (20) relative to the frequency of the target return signals.

Abstract: A borehole logging device for obtaining shear wave velocities in formations adjacent the borehole, a device which utilizes a closely controlled, relatively low frequency torsional shear wave. The system includes an elongated housing for suspension within the borehole, said housing including a shear wave source for generating shear waves directly within the borehole wall, and including two spaced, variable reluctance torsional detectors which are also placed in direct contact with the borehole wall. The torsional detectors are, of course, at known spacing from the source such that cross-correlative procsssing of the detector output signals will enable a very accurate phase difference indicative of the shear wave velocity in the formation.

Abstract: 1.

Abstract: The frequency of operation of a tuned flyback type transformer is controlled by a voltage controlled oscillator whose output frequency varies with EHT in such a way that EHT tends to stay constant despite beam current or input voltage variations.

Abstract: A mobile generator for producing waves for seismic exploration. A hammer, mounted on an elongated boom, is dropped to strike an anvil embedded in the ground to create a ground wave. The boom is pivotal between positions selected according to the nature of the wave to be created. A pair of hydraulic piston actuators move the boom between its selected positions. A tensioning device is connected to the cable which drops the hammer in such a manner as to prevent the hammer from rebounding after an impact.

Abstract: Disclosed is a system for acoustic noise logging in a production well which includes up-hole components and down-hole components including at least two sonic detectors, the up-hole and down-hole components being linked together by a four-wire interconnecting means. In addition, the down-hole components include at least three additional parameter detectors. These additional parameter detectors may include a temperature detector, a conductivity detector and a location detector. The first of these detectors produces a frequency proportional to, for example, temperature. The second detector frequency modulates the temperature signal, for example, in response to location. The third detector amplitude modulates the signal depending on whether or not a conductivity threshold has been exceeded.The foregoing permits simultaneous monitoring of a plurality of down-hole parameters simultaneously without the necessity for multiplexing and yet employs only a four wire interconnecting means.

Abstract: An improved acoustic transport member for use in a keyboard having key operated strikers individually actuatable for inducing acoustic energy in the form of sound waves which propagate through the member from selected inducing positions therealong. A first portion of the member is fabricated in the form of a series of tabs to provide discrete impact positions for generating sound waves in response to impact actuation of related strikers. A second portion integrally connected with the first portion links all of the tabs and functions as a sound corridor for receiving and transporting all sound waves generated as a result of the selected striker impacting its related tab. An aperture is provided through the tabs. A peripheral rim of the aperture provides sound reflecting boundaries that define sound passages on the tabs for directing the sound waves in different directions in communicating the sound waves from the tabs into the corridor.

Abstract: An antenna beam switching system comprising three antennas whose apertures re disposed in a common plane and which, by means of selective shunting of one or more phase shifters associated with each of the antennas, allows for three dimensional beam switching in at least four directions in space.

Abstract: An acoustic transport member for use in a keyboard having key operated strikers individually actuatable for inducing acoustic energy in the form of sound waves which propagate through the member from selected inducing positions therealong. A first portion of the member is fabricated to provide discrete impact positions for generating sound waves in response to impact actuation of related strikers. A second portion integrally connected with the first portion links all impact positions for receiving and transporting all sound waves generated by the first portion. A step joins the first with the second portions to allow communication of the sound waves from the first portion into the second portion yet thereafter provides unidirectional acoustic separation therebetween which effectively minimizes wave dispersion by substantially isolating the propagating sound waves in the second portion from coming into contact with successive impact positions of the first portion.