A method for estimating downhole pressure in wells during a treatment procedure. A pressure head in a treatment well may be determined without requiring downhole sensors. The method for measuring downhole pressure may be used in long horizontal wells. By improving the accuracy of such pressure head estimates and providing the data substantially in real time, the data can also be used to control the treatment being applied to the well. The pressure head may be determined by detecting pump harmonics at a detector, typically positioned outside of the well and/or not in direct contact with the fluid in the well. The detector may be a microseismic array.

A method for estimating downhole pressure in wells during a treatment procedure. A pressure head in a treatment well may be determined without requiring downhole sensors. The method for measuring downhole pressure may be used in long horizontal wells. By improving the accuracy of such pressure head estimates and providing the data substantially in real time, the data can also be used to control the treatment being applied to the well. The pressure head may be determined by detecting pump harmonics at a detector, typically positioned outside of the well and/or not in direct contact with the fluid in the well. The detector may be a microseismic array.

Embodiments relate to relate to marine vibrators that incorporate one or more piston plates that act on the surrounding water to produce acoustic energy. An example marine vibrator may comprise: a containment housing; a piston plate; a fixture coupled to the containment housing; a mechanical spring element coupled to the piston plate and the fixture; a driver disposed in the marine vibrator, wherein the driver is coupled to the piston plate and the fixture; and a container coupled to the piston plate, wherein the container is configured to hold a variable mass load; wherein the marine vibrator has a resonance frequency selectable based at least in part on the variable mass load.

Embodiments relate to relate to marine vibrators that incorporate one or more piston plates that act on the surrounding water to produce acoustic energy. An example marine vibrator may comprise: a containment housing; a piston plate; a fixture coupled to the containment housing; a mechanical spring element coupled to the piston plate and the fixture; a driver disposed in the marine vibrator, wherein the driver is coupled to the piston plate and the fixture; and a container coupled to the piston plate, wherein the container is configured to hold a variable mass load; wherein the marine vibrator has a resonance frequency selectable based at least in part on the variable mass load.

A reaction mass seismic survey source that is located in an underground casing. The seismic source includes a non-planar base plate; a reaction mass located on the non-planar base plate; and a flextensional element housed in a recess of the reaction mass and configured to vibrate the non-planar base plate when actuated, to generate seismic waves underground.

A system for near-surface subsurface imaging for detecting and characterizing subsurface heterogeneities comprises a non-contact acoustic source that senses a plurality of acoustic waves that travel through a surface; an instrument that outputs probing electromagnetic signals through the surface that interact and are affected by scattered signals of the acoustic waves and further senses vibrational modes of a subsurface below the surface; an imaging device that dynamically generates a time sequence of images of properties of the acoustic waves and maps elastic wave fields of the acoustic waves; and a processor that analyzes dynamic multi-wave data of the images to quantify spatial variations in the mechanical and viscoelastic properties of the subsurface.

A system for near-surface geophysical subsurface imaging for detecting and characterizing subsurface heterogeneities comprises an instrument that outputs probing electromagnetic signals through a ground surface that interact and are affected by scattered signals of acoustic waves that travel through the ground surface and further senses vibrational modes of a subsurface below the ground surface; an imaging device that dynamically generates a time sequence of images of properties of the acoustic waves and maps elastic wave fields of the acoustic waves; and a processor that analyzes dynamic multi-wave data of the images to quantify spatial variations in the mechanical and viscoelastic properties of the subsurface.

Embodiments related to marine acoustic vibrator for marine geophysical surveys. An embodiment may include an apparatus, wherein the apparatus may comprise: a coil element comprising a coil; a coil clamp constraining motion of the coil element in at least one direction; and a spring disposed in a load path of the coil clamp. Additional apparatus and methods are disclosed herein.

Embodiments related to marine acoustic vibrator for marine geophysical surveys. An embodiment may include an apparatus, wherein the apparatus may comprise: a coil element comprising a coil; a coil clamp constraining motion of the coil element in at least one direction; and a spring disposed in a load path of the coil clamp. Additional apparatus and methods are disclosed herein.

Apparatus and techniques are disclosed relating to a two-axis sensing element. In various embodiments, a two-axis sensing element includes a mounting plate that includes a first pair of mounting slots oriented in a first direction and a second pair of mounting slots oriented in a second, different direction. Further, in various embodiments, the two-axis sensing element may include a first pair of bender elements and a second pair of bender elements. The first pair of bender elements may be mounted through the first pair of mounting slots such that the first pair of bender elements is oriented in the first direction and the second pair of bender elements may be mounted through the second pair of mounting slots such that the second pair of bender elements is oriented in the second, different direction. In various embodiments, the mounting plate may transect each of the bender elements into two cantilever portions.