Abstract: An electromagnetically driven vibratile piston underwater transducer element generates acoustic intensity levels in excess of 25 peak Watts per square inch of radiating surface in the low audible frequency region within the approximate range 500 to 2500 Hz. The design achieves an efficiency greater than 50% and a very low Q of less than 2. The electromagnetic design employs two separate independent air gaps and a unique mechanical coupling system that combines the electromechanical forces generated in each gap in the proper phase and transmits the combined oscillatory force to drive the vibratile piston.

Abstract: A marine seismic streamer employs a plurality of sections connected together sequentially with fluid blocking connectors. Each section contains a plurality of groupings of hydrophones with the hydrophones within each grouping connected together to provide a single seismic signal output for such groupings. The two terminal groupings of each section have variable hydrophone densities along their lengths so as to discriminate against noise generated in the streamer by the action of the fluid blocking connectors in producing pressure waves in the fluid fill within the streamer.

Abstract: Communication with a measuring-while-drilling equipment sub, when the sub is at the surface, is established by placing a transmitter-receiver within transmitting range of the electrode/antenna array of the sub. The transmitter-receiver must be compatible with the sub equipment and be capable of transmitting to the sub instructions to dump the sub memory and/or add data to the sub memory.

Abstract: This invention is an improved type of shear wave vibrator are carried by a support vehicle and utilizing telescoping tubes for energy engagement within an underlying earth medium. A shear wave vibrator so constructed is particularly desirable for use over marshy or soft surface earth areas. The device consists of a jack assembly supporting a shear wave vibrator relative to a suitable carrier vehicle in vibrationally isolated manner. The vibrator structure consists of a pair of parallel, elongatable telescoping blades for earth penetration and engagement with a passive reaction mass pivotally secured across the top portion of the telescoping blades and an active mass/vibrator system pivotally secured across the lower portion of the telescoping blades adjacent the earth surface.

Abstract: A flexible line array transducer assembly for detecting underwater acoustical signals. The assembly includes an array of spaced-apart piezoelectric elements arranged generally in a line and selected to have low cross-coupling characteristics, low sensitivity to incoherent mechanical perturbations in the directions longitudinal and lateral to the axis of the array, and high sensitivity to coherent mechanical perturbations such as acoustical signals. The elements are polarized in a direction generally transverse to the array and each include opposing surface areas which are generally parallel with the linear axis of the array. Electrodes are disposed on the opposing surface areas of the elements and are coupled to conductors which carry signals produced by the piezoelectric elements when the elements are stressed by acoustical signals. A porous, open-cell material is disposed about the piezoelectric elements as an encasement to maintain the elements in place and mechanically isolate the elements.

Abstract: The invention concerns a method for surveying the focal point (F, F') of a focussed ultrasonic field (8, 14) and an apparatus for carrying out the method. According to the invention an ultrasonic field (4, 12) produced by an ultrasonic transmitter (2) is measured at several sites in a plane in the path of the waves at the site of the imaging device (6). The values determined at these sites are compared with given reference values for which the position of the focus is known. In an advantageous device, one surface of the imaging device (6) is equipped with several piezoelectric transducers.

Abstract: A method for predicting the ground vibration and airborne noise at any position resulting from a blasting operation using the data obtained from one or more single-charge low level blasts. By using convolution in the frequency domain, large charge weight nonlinear vibrations are considered, such that the optimum excitation frequency (detonation delays) is induced for minimizing objectionable ground and air vibrations and noise. The method also allows optimization of the number, position and loading of the blast holes, and the number and position of charges detonated per delay period, to produce maximum removal of material without damage to surrounding structures.

Abstract: A high ambient liquid pressure-resistant electrical connector is shown with an airgun having a solenoid actuated valve mounted on the airgun. A multi-conductor electrical cable is connected by this pressure-resistant connector to a plurality of terminals of the solenoid valve for protecting from ambient liquid the terminals and the adjacent portions of the conductors. This pressure-resistant electrical connector includes a connector housing having an upper end and a lower end, with the lower end of the housing being mounted to the airgun. The connector housing has a fluid sealant chamber for enclosing the electrical terminals and adjacent portions of the conductors connected to the terminals and includes at least one barrier for engaging the cable to protect against ambient liquid seeping past the barrier to the electrical terminals. The connector housing defines a cylindrical space carrying a spring-loaded piston.

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: Thermal fluxmeter with a plurality of thermocouples comprising a continuous thin layer of a first conductor or semiconductor material such as constantan, covered on at least one of its faces by a succession of areas comprised of very thin deposits of a second conductor or semiconductor material such as copper, having a thermoelectric power different from that of the first material; the characteristic of the invention is that at least one channel traverses from side to side through each deposit area and through the underlying thin layer, said channels being offset in the same direction with respect to the center of the traversed area; said channels may be provided with an inner coating of a deposit of the second material; appropriately, the thin layer is deposited on a substrate of insulating material.

Abstract: The present invention is a downhole seismic source capable of generating seismic forces in excess of 1000 newtons. The source produces seismic waves for seismic applications, particularly cross borehole measurements and vertical seismic profiling. Coupled with motion sensing devices, the present invention also performs as a seismic logging tool. The source is comprised of an outer housing, a means for clamping the source securely to the wellbore, and a linear electromagnetic actuator which utilizes permanent magnetic material having remanent magnetic field exceeding about 0.9 T such as rare earth permanent magnetics. The source has a diameter of about 12.5 cm to fit within a typical wellbore and the actuator has a length of about 1 meter.

Abstract: A dual chamber seismic air gun which discharges both chambers simultaneously to counterbalance the reactive forces generated by the discharges. The chambers are symmetrical within the housing of the gun so that the movement of the internal parts during operation also counterbalance each other. The gun is mounted coaxially on the air supply of a seismic array to provide a good profile for towing.

Abstract: The invention is a method of performing a plurality of vibratory seismic surveys simultaneously. A plurality of vibratory sources transmit signals into the earth. Each vibratory source successively transmits the same signal, except that an offset phase of the signal is selectively shifted for successive transmissions. The offset phase of the signal transmitted by each vibratory source is selected to enable the signal from each of the vibratory sources to be recovered by data processing.

Abstract: The potential for failure of a formation is predicated by using standard logging apparatus and techniques to monitor the change in a formation characteristic over an extended time period. Changes in this characteristic are attributed to absorption of fluid by the formation which could lead to a possible breakdown of the structural integrity of the formation.

Abstract: A flexural disk transducer includes two thickness poled piezoelectric disks each of which is bonded on one side to a metal backing plate of substantial thickness and on the other side to a thin metal "skin" or plate. The metal backing plates are, in turn, bonded to a ring-shaped metal spacer member having a rectangular "C" shaped cross section with the axially extending web made sufficiently thin and the radially extending flanges grooved such that the spacer member is sufficiently compliant that it has minimal effect on the resonant frequency of the disks. The disks are coated on each side with a thin layer of conducting material such as silver or copper and have radially extending wires serving as connections to such layers. The entire assembly is contained within a handling ring with the wire connections and the space between the assembly and the handling ring filled with electrical potting material. A thin layer of neoprene rubber covers the exposed faces of the disks for waterproofing.

Abstract: An acoustic transducer, especially adapted for hydrophones, is disclosed. The transducer comprises a piezoelectric ceramic disk with a main or signal electrode, a common electrode and a feedback electrode; negative feedback is provided around an associated amplifier and the transducer. The transducer is useful in either a sonic receiver or a sonic transmitter. Various ceramic disk configurations are disclosed and several electrode configurations are disclosed. The negative feedback minimizes the undesired effects of the high Q characteristic of the piezoelectric ceramic transducer. The transducer exhibits improved frequency response characteristics including increased bandwidth and reduced resonance effects, fixed or linear phase shift over a broad range and improved transient response. Also, the effect of normal manufacturing variations upon sensitivity, frequency and phase response is minimized.

Abstract: An improvement for the drive control system of a vibratory sound source used in seismic exploration comprising apparatus for generating a feedback signal proportional to the instantaneous acceleration of the reaction mass structure of the sound source's hydraulic drive system. Degenerative feedback of the signal so developed is used to reduce distortion of the vibratory seismic signal imparted into the earth.

Abstract: Non-active columnar members are disposed on both sides of an active columnar member consisting of a piezoelectric ceramic material or a magnetically strainable material. Levers are connected to the active and non-active columnar members via first and second hinges. Convex shells are connected to the levers via third hinges. The displacement of the active columnar member is enlarged via the lever action, thereby enabling a miniaturized ultrasonic wave transmitter having high power capability.

Abstract: A method for determining the position of a subterranean plane reflector relative to a known location on the earth surface from unprocessed seismic data received at a number of colinear acoustic receiver locations. A traveltime curve associated with the reflector is identified from the seismic data. From two points on the traveltime curve, a signal indicative of the reflector's dip angle is generated. Using the dip angle signal, signals indicative of the position of each imaged point of the reflector are generated. The inventive method assumes knowledge of the average velocity of seismic waves in the subterranean formation above the reflector, and that such formation region can adequately be considered to have constant velocity equal to such average velocity. The method may be applied to process raw data generated during a vertical seismic profiling operation.

Abstract: An apparatus for introducing vibrations into the ground including a container having electrodes mounted therein with electrical connections leading from a source of electric potential to said electrodes, salt water substantially filling the container, and means for placing the container on the ground in position to transmit vibrations to the ground.