Abstract: The preferred embodiment of this invention includes a logging sonde, an elongated pair of oppositely polarized piezoelectric plates connected to each other by their flat surfaces, and an electrical pulse applying means for applying electrical pulses across the pair of plates so as to bend and vibrate the plates in a direction perpendicular to the length of the plates. Vibration of the plates in a fluid contained in a well creates in the fluid a positive compressional wave in one direction and simultaneously a negative compressional wave in the opposite direction. The two compressional waves will interfere to produce a dipole shear wave in the earth surrounding the well. The dipole shear wave arrival is detected at two locations in the fluid spaced longitudinally along the well from each other and from the plate.

Abstract: The shear wave source of this invention includes a housing and means for applying forces to the shot hole wall. The force applying means applies a number of forces to the shot hole wall along lines normal to a plane close to the shot hole. No pressure waves, but only shear waves are generated at distant points on the plane. At least one of the forces is applied in opposite direction to the other forces to reduce the net recoil of the housing.A first, second and third force are applied at three source points in the observation plane along three lines normal to the plane to generate respectively a first, second and third shear wave in the plane. The first and third forces are equal in magnitude and the second force has twice the magnitude of the first force. The first and third forces are applied along lines in the same direction, but the second force is applied along a line opposite in direction to the lines of the first and third forces.

Abstract: Two adjacent riser pipes having substantially a common axis are connected by the riser connector of this invention in the manner described below.A connector box, adapted to be attached to the end of one of the pipes, has an abutment surface and adjacent to it a channel transverse to the common axis of the pipes. A locking dog fits slidably in the channel, and has a tapered surface facing the abutment surface of the box and at an angle less than 45.degree. to the direction of the channel. A connector pin, adapted to be attached to the end of the other pipe, has a flange. When the flange is in contact with the abutment surface of the box and when the locking dog is pushed towards the flange by a force applying means, the flange of the pin is held between the tapered surface of the dog and the abutment surface of the box, and the connections between the box, pin, and dog are preloaded by forces greater in magnitude than the force applied by the force applying means.

Abstract: To increase the energy of seismic waves transmitted by a vibrator, one or more compliant members are connected between the driver and the base plate of the vibrator. The compliance of the compliant member is such that it is substantially rigid at the natural frequency of the vibrator, and that the natural frequency of the driven load of the vibrator is in the siesmic spectrum but is higher than the natural frequency of the vibrator.

Abstract: This invention provides for methods and systems for measuring the dielectric constant of an earth formation. In a preferred embodiment, an alternating current is passed through a portion of the formation and a reference resistor in series with the portion. The capacitance and the dielectric constant of the portion may be determined from the phase difference between the voltage across the reference resistor and the voltage across the portion. This phase difference may be obtained by generating a voltage which is in phase with the voltage across the reference resistor, but which has the magnitude of the voltage across the portion. To obtain the phase difference by an alternate digital method, the voltage across the referenced resistor and the voltage across the portion are each transformed into a square wave signal. The two square wave signals are then compared to obtain the sign and the magnitude of the phase difference between the two square waves.

Abstract: Disclosed herein are improvements in a recoil reducing system of a gas gun which create pulses in a liquid medium by introducing therein gas under high pressure. The release of high pressure gas from the barrel of such a gas gun causes recoil of the barrel. To reduce recoil, a reaction plate is attached to the barrel by metal rods so that the high pressure gas will impinge upon the reaction plate before escaping into the medium, and the force exerted on the reaction plate by the impinging gas will at least partially balance the force of recoil. In a preferred embodiment of this invention, a layer of shock absorbent material is interposed between the reaction plate and the impinging gas to absorb some of the energy of the gas. Flexing of the metal rods is thereby reduced and the life of the rods is extended. Alternatively, the flexing of the rods is reduced by connecting each rod to the reaction plate through a chain link type of connection comprising two rings, each ring passing through the other ring.

Abstract: This invention provides for transmission of composite swept sine wave seismic signals wherein auto-correlation side lobes of such signals are reduced. The frequency spectrum of a desired swept sine wave seismic signal is divided into a number of consecutive segments, and the segments are arranged to form a sequence of segments by the order of frequency content. Component swept sine wave seismic signals each covering a segment in the sequence are generated simultaneously from the same location to produce the desired seismic signal. The component swept sine wave seismic signals are generated in a manner so that they alternate as upsweeps and downsweeps for consecutive segments in the sequence of segments. The seismic signal comprising the sum of the component swept sine wave seismic signals will have an auto-correlation function with reduced side lobes.

Abstract: A method and apparatus for seismic prospecting which utilizes two transducer plates that are spaced apart, with two sets of bellows placed in between and sealingly attached thereto, to transmit electrically controlled hydraulic pressure signals onto the two plates. When pressure is applied within one set of bellows, the two plates are pushed apart. When pressure is applied within the second set of bellows, the two plates are pulled together. To accomplish this pulling action of the second set of bellows, two closure plates placed between the two transducer plates are used, one attached to one transducer plate and one attached to the other transducer plate. The first closure plate is attached to the first transducer plate in such a manner that it lies between the second transducer plate and the second closure plate. By applying pressure to the second set of bellows that push apart these two closure plates, the two transducer plates are pulled towards each other.