Abstract: Systems are disclosed for securing near vertically deployed seismic detector systems in a cased well borehole from oscillatory motion during a seismic survey. In one embodiment a generally cylindrical body member of an unsymmetrical shape having one flat side is used opposite a selectably extensible backup locking arm. In a second embodiment a generally symmetrical cylindrical body member having sets of four essentially coplanar contacting feet disposed at 90 degree circumferential spacing an opposite ends is provided. The sets of locking feet on opposite ends of the tool body member are phased 45 degrees apart circumferentially with respect to each other. Locking edges and feet may be magnetically assisted if desired.

Abstract: Method and apparatus for conducting seismic surveys from a single wellbore utilizing an array of seismic detectors and an seismic source suspended downhole from the detectors on a coiled tubing. Actuation of the airgun both generates a seismic signal penetrating the adjacent lateral geological formations and a plurality of air bubbles pass up the borehole to attenuate tube wave propagation in the borehole fluid.

Abstract: A method for selectively affecting the permeability of reservoirs to enhance fluid flow therein includes placing a plurality of acoustical wave generator means in a patterned array with respect to the reservoir and energizing them to create acoustic nodes at targeted areas of the reservoir. The acoustic wave generator means can be located solely on the surface, only below surface or in combination above and below surface. The acoustic wave generator means can be selectively simultaneously or sequentially energized to create nodes at targeted areas of the reservoir.

Abstract: The steel casing of a well is deliberately magnetized with a known orientation by the passage therethrough of a tool having a demagnetizing section and a magnetizing section along with a gyrocompass section and a magnetic compass section. The casing is first demagnetized and then remagnetized with a polarization which can be determined. The two compasses establish the orientation of the remagnetized casing.

Abstract: An electromagnetic source or sources in a sonde in a well bore is caused to emit electromagnetic forces into the well casing. The electromagnetic forces cause displacement of the casing, inducing acoustic waves. The acoustic waves may be either P-waves or S-waves, depending on the type of electromagnetic source used. The response of earth formations to the acoustic waves, once detected, is used to detect fractures in the formations.

Abstract: A method and apparatus for inter-well seismic logging include a seismic source capable of being lowered into a first or surce well and a plurality of receiving and/or detecting means capable of being lowered to at least one second or receiving well. Signals generated from the seismic source pass through the earth and are received by the respective receivers. The recorded data is subsequently computer processed to form a profile which represents the geological configuration between the wells. The seismic source having at least one bender arm assembly including two sets of piezoelectric ceramic crystals and, preferably, a reaction mass connected intermediate the ends thereafter generate the seismic signals.

Abstract: The seismic amplifier includes an amplifying circuit which amplifies an analog signal to provide an amplified analog signal. The amplified analog signal is converted to digital signals. A controlled network connected to the amplifier circuit controls the gain of the amplifier circuit in a manner so that the gain for a current seismic operation, except for an initial seismic operation, is determined during the next previous vibration seismic operation.

Abstract: An acoustic energy source or gun for use in an aqueous environment such as in a borehole, a well, or in open water. The apparatus, when lowered into a water occupied borehole or the like, functions to create a series of acoustic impulses without forming bubbles, as a result of the water rapidly infilling an implosion cylinder or chamber. A piston rod assembly is reciprocally mounted in each acoustic chamber and is actuated by a power source to trigger the desired sound creating series of impulses.

Abstract: Apparatus for multiplexing ancillary devices in a streamer cable towed by a boat in ocean seismic operation, in which the cable includes a plurality of ancillary devices located throughout the cable. The apparatus includes a source providing step pulses located on the boat. Also located on the boat is a circuit providing control signals and a network providing control voltages. A plurality of series connected control pulse circuits are located in the streamer cable with the first control pulse circuit of the series being connected to the step pulse source. The control pulse circuits are responsive to the step pulses for providing a plurality of control pulses in a predetermined sequence. An energizing voltage source located on the boat provides a square wave energizing voltage. A plurality of switching networks are located throughout the cable with each switching network being connected to a corresponding ancillary device.

Abstract: A system for playing back a wide dynamic amplitude range analog signal that is digitized in floating point word form. The word being represented in digital signal form by the general algebraic form Q=.+-.AB.sup.-N where Q represents the amplitude of the analog signal, A represents the mantissa, B indicates the radix of the number system used, N represents the number of fixed gain amplifier steps, and is the exponent of B, each word is represented by a first plurality of binary bits representing N. The playback system includes a first converter receiving a reference voltage which converts the bits representing A to an interim analog signal. A second converter converts the bits representing N to a plurality of control signals. A resistor network is connected to ground and has N number of inputs and an output.

Abstract: A digital seismic telemetry system for recording seismic data from a plurality of seismic signal detectors positioned at selected detector stations. The system includes a plurality of remote units, each of which is positioned at a distinct detector station to receive seismic data from the detector at that station. The remote units each include a storage device for storing seismic data from the detector in digital form, and a remote transmitting unit for transmitting the stored seismic data from the storage device to a master recording unit for recording. A master control unit operably connected with each of the remote units controls the acquisition and the transmission of seismic data from the remote units to the master recording unit and limits the amount of data transmitted at any given time to optimize the bandwidth requirements for the data transmission.

Abstract: A data transmission system, for a well logging system having a logging tool logging a borehole traversing an earth formation and surface equipment adjacent to the borehole for making a well log, includes a sync word generator located in the logging tool, which periodically provides a predetermined digital signal corresponding to at least one sync word. A phase encoder located in the logging tool receives the data in serial digital form and the sync word. The phase encoder provides a phase encoded signal, corresponding to the data and to the sync word, at a predetermined frequency. A cable drive receives the phase encoded signal and provides it to a cable for transmissin up-hole. The surface equipment includes a phase decoder connected to the cable for decoding the phase coded signal to provide at a serial digital signal. An output circuit at the surface provides parallel digital signals in accordance with the serial digital signal corresponding to the sync words and the data.

Abstract: A received analog input signal is applied to a programmable amplifier. The amplifier is controlled by digital signals and by preselected gain of its individual stages to provide an analog signal corresponding to the received input signal. The digital signals are provided by digital signal means in accordance with the analog signal from the programmable amplifier and as such correspond to the logarithm of the received input signal.

Abstract: An amplifying channel provides amplified signals corresponding to a received wide dynamic range analog input signal such as provided by a geophone group. A plurality of level comparators which number one less than the number of amplified signals compare the amplified signals with reference signals corresponding to a predetermined range of a desired output signal. The comparators provide outputs corresponding to the comparison to logic circuitry which develop sampling signals. The amplified signals from the amplified channel are also provided to a plurality of switches which are controlled by sampling pulses provided by the logic circuitry to sample an amplified signal within the range defined by the reference signals and provide it as the analog output signal. The analog output signal is converted to digital signals which are provided with other digital signals corresponding to the gain relationship between the analog output signal and the received analog input signal.