An acoustic generator including a piezoelectric crystal, an impedance matching layer directly bonded to the crystal with Van der Waals forces.

An acoustic generator including a piezoelectric crystal, an impedance matching layer directly bonded to the crystal with Van der Waals forces.

Systems and methods for producing controlled vibrations within a borehole. In one example, the system includes a movement mechanism and a controller. The movement mechanism is configured to enable translational movement of a first surface relative to a second surface to allow the first surface to impact the second surface to produce a plurality of beats. The frequency and amplitude of the beats may be selectively controlled by suppressing or dampening the beats. The controller is configured to selectively control an amplitude or frequency of the beats to encode information therein, where the amplitude of a beat may be selectively controlled by dampening or suppressing the impact of the first surface and the second surface.

Systems and methods for producing controlled vibrations within a borehole. In one example, the system includes a movement mechanism and a controller. The movement mechanism is configured to enable translational movement of a first surface relative to a second surface to allow the first surface to impact the second surface to produce a plurality of beats. The frequency and amplitude of the beats may be selectively controlled by suppressing or dampening the beats. The controller is configured to selectively control an amplitude or frequency of the beats to encode information therein, where the amplitude of a beat may be selectively controlled by dampening or suppressing the impact of the first surface and the second surface.

A method includes injecting an aqueous-based injection fluid into a wellbore at a first temperature, where the aqueous-based injection fluid includes phase-changing nanodroplets having a liquid core and a shell. The method also includes exposing the phase-changing nanodroplets to a second temperature in the wellbore that is greater than or equal to a boiling point of the liquid core to change a liquid in the liquid core to a vapor phase and expand the phase-changing nanodroplets, thus removing debris from the wellbore and surrounding area.

A method includes injecting an aqueous-based injection fluid into a wellbore at a first temperature, where the aqueous-based injection fluid includes phase-changing nanodroplets having a liquid core and a shell. The method also includes exposing the phase-changing nanodroplets to a second temperature in the wellbore that is greater than or equal to a boiling point of the liquid core to change a liquid in the liquid core to a vapor phase and expand the phase-changing nanodroplets, thus removing debris from the wellbore and surrounding area.

At least one of pressure pulses, lateral oscillations, and axial oscillations can be generated by a distal downhole tool and a proximal downhole tool while cement is pumped into a well for cementing the well. Also, the generation of at least one of pressure pulses, lateral oscillations, and axial oscillations by the proximal downhole tool can continue even when the cement is no longer pumped around a tubing and is curing. In order to do so, a backflow path from a point downstream of the second vibration tool toward a wellhead is provided. Then a fluid, usually other than cement, is pumped from the wellhead, through the proximal downhole tool, and back into an annulus toward the wellhead. As such, a production tubing may remain centralized while the cement is curing.

At least one of pressure pulses, lateral oscillations, and axial oscillations can be generated by a distal downhole tool and a proximal downhole tool while cement is pumped into a well for cementing the well. Also, the generation of at least one of pressure pulses, lateral oscillations, and axial oscillations by the proximal downhole tool can continue even when the cement is no longer pumped around a tubing and is curing. In order to do so, a backflow path from a point downstream of the second vibration tool toward a wellhead is provided. Then a fluid, usually other than cement, is pumped from the wellhead, through the proximal downhole tool, and back into an annulus toward the wellhead. As such, a production tubing may remain centralized while the cement is curing.

A pressure pulse system includes a stator, a rotor rotatably positioned in the stator, and a valve assembly configured to induce a pressure pulse in response to rotation of the rotor within the stator, wherein the valve assembly includes a first valve plate coupled to one of the stator and the rotor and including a flow passage, and a second valve plate coupled to the other of the stator or the rotor to which the first valve plate is not coupled and comprising a first flow passage and a second flow passage that is spaced from the first flow passage, wherein the valve assembly provides a first flowpath and a second flowpath between the flow passage of the first valve plate and the second flow passage of the second valve plate.

A casing string is augmented with one or more variable flow resistance devices or “vibrating tools” to facilitate advancement of the casing and distribution of the cement in the annulus once the casing is properly positioned. Vibrating tools in the form of plugs can be pumped down and landed inside the casing string. The method includes vibrating the casing string while advancing the casing down the wellbore or while the cement is pumped into the annulus, or both. After the cementing operation is completed, the devices may be drilled out or retrieved with fishing tools to reopen the casing string for further operations. One or more wipers may be provided on the plugs, but the section housing the flow path may be free of wipers to allow the size and flow capacity of the flow path to be optimized.