Abstract: An axially extended downhole seismic source is disclosed. In one embodiment, the seismic source includes multiple pressure storage chambers, each having an inlet valve and an outlet valve. The inlet valve is coupled between the pressure storage chamber and the interior of the drill string, and the outlet valve is similarly coupled between the pressure storage chamber and the annular space around the drill string. A compressible fluid may be provided in the pressure storage chambers, and pistons may be positioned to contact the compressible fluid. For each pressure storage chamber, an inlet piston contacts the compressible fluid and fluid inside the drill string, while an outlet piston contacts the compressible fluid and fluid in the annular space around the drill string. When the outlet valve is closed, the inlet valve can be opened to allow pressure inside the drill string to compress the compressible fluid inside the pressure storage chamber.

Abstract: The present invention discloses a process and apparatus for treating a wellbore, comprising subjecting a substantially same portion of the wellbore to vibratory waves produced by a plurality of vibratory wave generators. The vibratory waves may have about the same frequency or a plurality of frequencies, and the frequencies may partially overlap, not overlap, or be modulated across a range. Additionally, the frequencies may be modulated in an oval, hoop, and flexural modes. The vibratory waves may be produced by firing the vibratory wave generators simultaneously or in sequence. Preferably, the vibratory waves are acoustically streamed in a viscous boundary layer near obstacles, outside a viscous boundary layer near obstacles, or in a free non-uniform sound field. In a preferred embodiment, a vibrating pipe and a piston pulser are used as vibratory wave generators. In another preferred embodiment, a vibrating pipe, piston pulser, and a valve are used as vibratory wave generators.

Abstract: A method and apparatus for measuring properties of fluid flowing through a bore, using a signal transmitted substantially perpendicularly to the direction of flow. A preferred embodiment uses a pair of acoustic transducers mounted in the annular body of the fluid conduit. The tool is constructed so as to be able to operate for a period of years in a downhole environment without maintenance or replacement. An transducer is also described that is adapted to fit within the dimensions of an annular body without suffering a reduction in the length of the transducer backing.

Abstract: A vertical seismic profiling system includes seismic receivers for placement on a drillstring and surface seismic sources. One-way checkshot data may thus be measured without tripping the drillstring. A downhole acoustic tool measures the local interval transit time of the formation, and improves the detection of targets ahead of the drill bit. The local interval transit time may be applied to the time of travel from reflections in front of the bit to establish distance to the bit. The down-going wavetrain may be deconvolved with the total up-going wavetrain to extract the nearest reflector and the relative acoustic impedance at the reflector. A synthetic seismogram may also be created based on reflection depth data and corrected with checkshot data.

Abstract: Disclosed is a sonic well tool for performing acoustic investigations of subsurface geological formations penetrated by a borehole. The well tool generally includes a longitudinally extending body for positioning in said borehole. The tool also includes a transmitter supported by the body for transmitting acoustic energy, and a receiver supported by the body for receiving acoustic energy. Finally, the tool includes an acoustic attenuation section positioned on the body between the transmitter and the receiver. This section includes one or more cavities defined by the body, inertial mass members positioned inside the cavities in a suitable manner to form a gap between the wall of the cavity and the inertial mass members, and an acoustical attenuation fluid in the gap. The method for attenuating sonic waves generally includes transmitting a sonic wave from the transmitter to the tool, passing the sonic wave through the acoustic attenuation section, and receiving attenuated wave at the receivers.

Abstract: The present invention is directed to a device which simply and efficiently compensates for changes in the volume of a fluid trapped in a fluid-filled cavity between two relatively immovable housings and an elastomeric seal ring. The present invention is particularly useful in an acoustic transducer pad assembly designed for installation on logging tools used in deep boreholes in the oil and gas industry where high temperatures and pressures are experienced at downhole locations. In a presently preferred embodiment, the device comprises a transducer unit housing fixedly secured to a metal wear pad housing with an elastomeric seal disposed therebetween to define a fluid-filled cavity between adjacent portions of the housings and the seal. The seal is disposed in a groove of sufficient size to permit the required lateral expansion and contraction by deformation or extrusion of the seal in order to compensate for the expected changes in the volume of the fluid-filled cavity.

Abstract: The present invention is directed to an apparatus useful in downhole logging tools used in the oil and gas industry. The present invention is particularly directed to an acoustic logging tool including improved, articulated transducer pad assemblies for providing improved transducer contact with the wall of a borehole or the inside wall of casing cemented in the borehole. The apparatus of the present invention provides a plurality of articulated transducer pad assemblies disposed about the circumference of an acoustic logging tool in a plurality of separately movable and adjustable groups. These assemblies each include a plurality of articulated joints permitting limited independent movement of each assembly. The assemblies are spring biased at each end into a deployed configuration to maintain good contact with the wall of the borehole or casing. A drive motor overcomes the biasing springs to retract the assemblies to provide a compact tool for tripping to the location of interest within the borehole.

Abstract: Apparatus is provided for assisting a subsurface well logging instrument, perforating tool or wireline service tool in tubing or casing re-entry in deviated boreholes. The apparatus includes a body member, composed of two conjugated halves, rotatably mounted on the well logging cable immediately above the well logging instrument. A pair of wheels are rotatably mounted to the uphole facing portion of the apparatus. These wheel members provide a lifting action upon tubing or casing contact to thereby lift the logging cable off the casing and prevent the logging instrument from engaging in jammed contact with the exposed end of the tubing or casing.

Abstract: A system for orienting a well casing perforating gun for utilization in wells having multiple tubing strings wherein it is desired to perforate the well casing in a zone other than the deepest production zone of the well and includes a hoist and associated apparatus for moving the perforating apparatus through the well and actuating the perforating gun. The perforating apparatus includes an elongated housing supportable on a cable, rollers on the exterior of the housing to support it on the interior of the well casing and/or tubing, the casing perforating gun, an orienting apparatus operable to orient the perforating gun relative to a string of tubing within the casing, a swivel within the housing to permit rotating motion of the lower portion of the housing relative to an upper portion of the housing, and an eccentric weight below the swivel to assist in positioning and aligning the casing perforating gun to the desired position.