The present invention relates to acoustic wavefields produced using sources appropriately delayed in time and focused at known positions and times in a heterogeneous medium. Seismoelectric conversion occurs if the acoustic focus point coincides with a discontinuity in electrical and hydrological medium properties, thus generating a current density. The current generates a potential difference, which can be observed at a distance by an array of monitoring electrodes. Since the acoustic wavefield is precisely located at a position and time, this electrical source behaves like a controlled virtual electrode whose properties depend on the strength of the acoustic wavefield and on the medium properties. This procedure can be used to increase the robustness and resolutions of electrical resistivity tomography and to identify hydrological parameters at various points in the medium by scanning the medium by changing the position of the acoustic focus.

The present invention relates to acoustic wavefields produced using sources appropriately delayed in time and focused at known positions and times in a heterogeneous medium. Seismoelectric conversion occurs if the acoustic focus point coincides with a discontinuity in electrical and hydrological medium properties, thus generating a current density. The current generates a potential difference, which can be observed at a distance by an array of monitoring electrodes. Since the acoustic wavefield is precisely located at a position and time, this electrical source behaves like a controlled virtual electrode whose properties depend on the strength of the acoustic wavefield and on the medium properties. This procedure can be used to increase the robustness and resolutions of electrical resistivity tomography and to identify hydrological parameters at various points in the medium by scanning the medium by changing the position of the acoustic focus.

Disclosed are devices and methods for marine geophysical surveying. An example device may comprise a shell, a base plate, wherein the base plate is coupled to the shell, a driver disposed within the shell, an inner spring element disposed within the shell, wherein the inner spring element is coupled to the driver, wherein outer ends of the inner spring element are coupled to outer ends of the inner spring element at spring element junctions, an outer spring element disposed within the shell, wherein outer ends of the outer spring element are coupled to the spring element junctions, and a back mass disposed on the outer spring element.

Methods for seismic exploration of a subsurface formation increase productivity by simultaneously actuating closely located vibratory sources. Individual vibrations generated by different sources actuated simultaneously are encoded to enable separation of seismic data corresponding to each of the individual vibrations.

An acoustic logging tool includes a support structure and a set of acoustic transducers coupled to the support structure. The set of acoustic transducers includes a first acoustic transducer and a second acoustic transducer facing the same direction. Each of the first and second acoustic transducers includes a substrate having a first end, a second end, a first side, and a second side. Each acoustic transduce further includes a first piezoelectric element coupled to the first side of the substrate and a second piezoelectric element coupled to the second side of the substrate. The first and second ends of the substrate extend beyond the first and second piezoelectric elements and are fixed to the support structure.

A sensor system for use in a wellbore is provided that can include a piezoelectric transducer for transmitting an acoustic wave into a fluid medium positioned in the wellbore by repeatedly bending between two positions in response to an actuation signal. The piezoelectric transducer can include at least four piezoelectric layers stacked on top of one another. Each of the four piezoelectric layers can be coupled to an adjacent layer via a bonding material. Each of the four piezoelectric layers can include a piezoelectric material, a top electrode coupled to a top surface of the piezoelectric material, and a bottom electrode coupled to a bottom surface of the piezoelectric material. The sensor system can also include a hydrophone for detecting a reflection or a refraction of the acoustic wave off an object in the wellbore and transmitting an associated signal to a processing device.

Apparatus and techniques are described, such as for obtaining information indicative of an acoustic characteristic of a formation, including using a transducer assembly, comprising a base plate, a first piezoelectric slab and a second piezoelectric slab. The base plate includes a first region extending axially in a first direction beyond the first and second piezoelectric slabs along a specified axis of the base plate and a second region extending axially in a second direction, opposite the first direction, beyond the first and second piezoelectric slabs. In various examples, a length of the first region along the specified axis is different than a length of the second region to provide an asymmetric configuration. In various examples, an anchoring element is mechanically coupled to the base plate at a location corresponding to a node location of a specified acoustic vibration mode.

Systems and methods of near surface imaging and hazard detection with increased receiver spacing are provided. The system includes: a first string of one or more acoustic sources, a second string of one or more acoustic sources opposite the first string, a first one or more hydrophones mounted within a predetermined distance of the first string, and a second one or more hydrophones mounted within the predetermined distance of the second string. The first one or more hydrophones records an acoustic shot generated from the first string. The second one or more hydrophones records the acoustic shot and acoustic reflections corresponding to the acoustic shot. The system generates an image from the recorded acoustic shot and the acoustic reflections.

An adaptable seismic source system that includes a first seismic source having at least one moving plate and a second seismic source also having at least one moving plate. Each of the moving plates of the first and second seismic sources creating a pressure wave. Each seismic source is comprised of a fixed center plate having opposed sides and a pair of movable plates that are arranged at respective opposed sides of the center plate; a coupling member that is disposed between the first and second seismic sources for enabling a sliding action between the first and second seismic sources and a controller coupled with the first and second seismic sources for exciting the seismic sources to provide a combined output with a lower frequency spectrum.

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.