A sea scooter has a main housing, a left arm pivotably attached to the left side of the main housing, a right arm pivotably attached to the right side of the main housing, a left barrel secured to the left arm, and a right barrel secured to the right arm. Each barrel has a fan and a motor for propelling the sea scooter through water. The left and right arms are locked by the first and second locking assemblies into a folded configuration against the left and right sides of the main housing when the sea scooter is not in use, and the left and right arms are pivoted away from the left and right sides of the main housing in a use configuration when the sea scooter is in use in the water. The motor is sand-proof and water-proof.

A system, method, and computer-readable medium for determining the flow rate and fluid density in an electrical submersible pump (ESP) and controlling the ESP based on the flow rate and density. In one implementation, an ESP system includes an ESP, drive circuitry, a current sensor, a voltage sensor, and a processor. The ESP includes an electric motor. The drive circuitry is electrically coupled to the ESP and is configured to provide an electrical signal to power the ESP. The current sensor is configured to measure a current of the electrical signal. The voltage sensor is configured to measure a voltage of the electrical signal. The processor is configured to calculate speed of a shaft of the electric motor based on a frequency induced by rotation of the motor detected in the current. The processor is also configured to calculate a density of fluid in the ESP based on the speed.

A downhole-type system includes a rotatable shaft; a sensor that can sense an axial position of the shaft and generate a first signal corresponding to the axial position of the shaft; a controller coupled to the sensor, in which the controller can receive the first signal generated by the sensor, determine an amount of axial force to apply to the shaft to maintain a target axial position of the shaft, and transmit a second signal corresponding to the determined amount of axial force; and multiple magnetic thrust bearings coupled to the shaft and the controller, in which each magnetic thrust bearing can receive the second signal from the controller and modify a load, corresponding to the second signal, on the shaft to maintain the target axial position of the shaft.

A downhole-type system includes a rotatable shaft; a sensor that can sense an axial position of the shaft and generate a first signal corresponding to the axial position of the shaft; a controller coupled to the sensor, in which the controller can receive the first signal generated by the sensor, determine an amount of axial force to apply to the shaft to maintain a target axial position of the shaft, and transmit a second signal corresponding to the determined amount of axial force; and multiple magnetic thrust bearings coupled to the shaft and the controller, in which each magnetic thrust bearing can receive the second signal from the controller and modify a load, corresponding to the second signal, on the shaft to maintain the target axial position of the shaft.

An electrical submersible well pump assembly has shaft couplings. One of the couplings has a lower hub that rotates in unison with the motor shaft and an upper hub that rotates in unison with the pump shaft. A helical spring clutch engages both hubs when the motor shaft is being driven by the motor. Ceasing driving rotation of the motor shaft causes the spring clutch to disengage from the upper hub, enabling the pump shaft to rotate the upper hub without rotating the lower hub.

An electrical submersible well pump assembly has shaft couplings. One of the couplings has a lower hub that rotates in unison with the motor shaft and an upper hub that rotates in unison with the pump shaft. A helical spring clutch engages both hubs when the motor shaft is being driven by the motor. Ceasing driving rotation of the motor shaft causes the spring clutch to disengage from the upper hub, enabling the pump shaft to rotate the upper hub without rotating the lower hub.

An electric stator surrounds an electric rotor. A magnetic coupling is attached to an end of the electric rotor. The magnetic coupling is configured to transmit rotational force to or from a separate rotational device. A housing surrounds and isolates the electrical rotor, the electric stator, and a portion of the magnetic coupling, from a wellbore fluid. The housing is flooded with an incompressible fluid. A pressure within the housing is substantially the same or lower than a pressure within a wellbore environment.

An electric stator surrounds an electric rotor. A magnetic coupling is attached to an end of the electric rotor. The magnetic coupling is configured to transmit rotational force to or from a separate rotational device. A housing surrounds and isolates the electrical rotor, the electric stator, and a portion of the magnetic coupling, from a wellbore fluid. The housing is flooded with an incompressible fluid. A pressure within the housing is substantially the same or lower than a pressure within a wellbore environment.

In at least one embodiment, the liquid circulation system comprises a rotor located within a tank, a stator having a plurality of coils outside the tank, and an exterior tank wall that is non-magnetic and that is located next to the rotor and between the rotor and the stator,
wherein an axis (R) of rotation of the rotor is in parallel with the exterior tank wall, the coils of the stator are arranged along the axis (R) of rotation of the rotor so that the rotor is configured to be rotated by the stator in a touchless manner through the exterior tank wall by means of a varying electromagnetic field driven by the stator to circulate a liquid within the tank.

A motorized pump including a motor and a pump around the motor. The pump rotor is integrated with the motor rotor, wherein the pump rotor has vanes. The motorized pump may be employed as an electrical submersible pump (ESP) in a wellbore.