The present invention provides a method and device for determining an excitation point of a seismic source. The method includes: determining, according to a selected medium type, a distribution region corresponding to the selected medium type in a three-dimensional surface model corresponding to a preset surface range, where a preset position of the excitation point of the seismic source is located in the preset surface range, and a first mapping position corresponding to the preset position of the excitation point of the seismic source is located in the three-dimensional surface model; determining a second mapping position in the three-dimensional surface model according to the first mapping position and the determined distribution region; and determining, according to the second mapping position, a target position of the excitation point of the seismic source corresponding to the second mapping position in the preset surface range.

A downhole imaging system comprises an imaging device operably coupled to a drill string and configured to generate an image of a subterranean formation from within a wellbore. The downhole imaging system comprises a processor operably coupled to the imaging device. The imaging device includes a sensor comprising a transmitter and a receiver, and a coding mask located between the sensor and the subterranean formation. Downhole assemblies including such devices and methods of generating an image of a subterranean formation in a wellbore are also disclosed.

A method and systems for performing a borehole operation with a borehole fluid that includes applying an amplitude oscillation deformation force to a sample of the borehole fluid over a period of time, measuring the deformation force from the sample, determining a storage modulus of the borehole fluid over the period of time based on the measured deformation force, determining a gel strength of the borehole fluid by correlation with the storage modulus, comparing the gel strength with a desired gel strength and if the gel strength is outside of an acceptable range of the desired gel strength, adjusting a drilling parameter, a composition of the borehole fluid, or a combination thereof, and using the borehole fluid in the borehole operation. Determining the storage modulus and the gel strength may be done using a processor and the force may be applied using a piezoelectric device.

An acoustic transducer is provided. The acoustic transducer includes a housing, a backing, a piezocomposite element adjacent the backing within the housing, and a diaphragm covering on an outward facing surface of the piezocomposite element.

A transducer, method, and downhole tool for acoustic logging. The acoustic transducer comprises a piezoelectric material comprising a body and grooves formed on the body. The grooves comprise a first groove that intersects with a second groove on the body. The method of acoustic logging a wall comprises transmitting an acoustic pulse at the wall using the acoustic transducer. The method also comprises generating a signal indicative of a reflection of the pulse using the acoustic transducer; and determining an acoustic parameter based on the signal using a processor. The acoustic logging tool is locatable in a wellbore intersecting a subterranean earth formation. The acoustic logging tool comprises the acoustic transducer and a processor configured to determine an acoustic parameter based on a signal generated by the acoustic transducer, the signal being indicative of the acoustic wave.

A marine sensor system includes an enclosure that defines an interior volume. The enclosure is configured to be immersed in water. A sensor having a positive output node and a negative output node is disposed within the interior volume of the enclosure. A first parasitic capacitance between the positive output node and the enclosure is substantially equal to a second parasitic capacitance between the negative output node and the enclosure. A cross feed signal that is propagated through a path in water outside the enclosure is coupled to the output nodes in a balanced manner, which enables a differential amplifier to reject the cross feed noise.

Various embodiments include methods and apparatus structured to investigate a structure of multiple strings of pipe in a wellbore and material around the pipes in the wellbore. An array of acoustic receivers can be used to monitor sound energy from the structure and material within and around the structure. The received sound energy can be segregated and coherent signal processing of the received sound energy can be conducted with respect to location. A bond map of the structure and regions around the multiple strings of pipe can be derived from the coherent signal processing. Additional apparatus, systems, and methods can be implemented in a variety of applications.

Various embodiments include methods and apparatus structured to investigate a structure of multiple strings of pipe in a wellbore and material around the pipes in the wellbore. An array of acoustic receivers can be used to monitor sound energy from the structure and material within and around the structure. The received sound energy can be segregated and coherent signal processing of the received sound energy can be conducted with respect to location. A bond map of the structure and regions around the multiple strings of pipe can be derived from the coherent signal processing. Additional apparatus, systems, and methods can be implemented in a variety of applications.

An underwater acoustic source can include a first piston coupled to a second piston and a plurality of linear magnetic actuators directly connected to each of the first piston and the second piston. Each of the plurality of linear magnetic actuators include a linear shaft positioned within the cylindrical magnetic assembly and mounted to the first end of the rigid ferromagnetic housing and the second end of the rigid ferromagnetic housing, such that the linear shaft is stationary, and linear bearings positioned between the cylindrical magnet assembly and the linear shaft to allow the cylindrical magnet assembly to translate along the linear shaft relative to the cylindrical electrical coil, and wherein each of the plurality of linear magnetic actuators is activated, the first piston and the second piston oscillate towards and away from each other, causing acoustic waves to be generated in water.

Methods of mapping a subterranean formation using imploding particles are described. In some cases, the particles contain a material that generated a gas which passes through a water-insoluble coating to create a void within the particle. In some aspects, the implosive particles have a coating that dissolves in the subterranean formation.