A stimulation tool for dislodging material from a perforation formed through a tubular disposed in a wellbore includes a main body formed at least in part from a material that is buoyant in a wellbore fluid, a ballast, a magnet, and a pressure pulse generator. The tool is configured to descend downhole by force of gravity when the ballast is attached and couple, by the magnet, to an interior surface of the tubular upon arrival at a downhole location proximate the perforation. When the tool is coupled by the magnet to the interior of the tubular, the tool transmits pressure pulses from the pressure pulse generator into the perforation, thereby dislodging material from the perforation. The tool de-couples from the interior surface and releases the ballast, thereby permitting the tool to ascend uphole, driven at least partially by a buoyant force exerted by the wellbore fluids.

An example downhole motor may include a first housing and a second housing with first and second portions characterized by non-parallel longitudinal axes. The second housing may be rotatably coupled to the first housing, and the first portion of the second housing may be arranged in a fixed, non-parallel longitudinal orientation with the first housing. A drive shaft may be at least partially within the first housing, and the motor may further comprise a selectively engageable torque coupling between the drive shaft and the second housing, positioned within the first housing.

An antenna for use in a downhole tubular. The antenna comprises a generally cylindrical housing and a coiled conductor located within a portion of the housing and separated therefrom by insulating material. The portion of housing has a greater internal diameter than an external diameter of the coiled conductor.

A method of drilling a wellbore includes drilling the wellbore through a formation by injecting drilling fluid through a drill string and rotating a drill bit. The drill string includes a shifting tool, a receiver in communication with the shifting tool, and the drill bit. The method further includes retrieving the drill string from the wellbore through a casing string until the shifting tool reaches an actuator. The casing string includes an isolation valve in an open position and the actuator. The method further includes sending a wireless instruction signal to the receiver. The shifting tool engages the actuator in response to the receiver receiving the instruction signal. The method further includes operating the actuator using the engaged shifting tool, thereby closing the isolation valve and isolating the formation from an upper portion of the wellbore.

A device for wellbore operations is configured to self-determine its downhole location in a wellbore in real-time and to self-activate upon arrival at a preselected target location. In embodiments, the device is configured to self-determine its direction of travel and self-deactivates if the device determines that it is not travelling in the downhole direction. In embodiments, the device has a flowback valve that blocks fluid flow therethrough when the device is inactivated but permits fluid flow through the device to exit at the device's trailing end when the device is activated. In embodiments, at least a portion of the device is dissolvable in the presence of wellbore fluids. In embodiments, at least a portion of the device is coated with a protective coating to shield the device from treatment fluids. A downhole tool having a pass-through constriction configured to be overcome by the device is also disclosed.

An assembly and a method for cooling a downhole logging tool. The assembly includes a coiled tubing assembly having a downhole logging tool and a coiled tubing pipe. The coiled tubing pipe is coupled to the downhole logging tool. The coiled tubing pipe includes a cooling fluid tube. The cooling fluid tube conducts a cooling fluid to the downhole logging tool.

In described examples, there are methods and systems for communicating data signals in wells. The methods and systems may facilitate communication of data signals, for example, from an open-hole section of a well, or in a well having a discontinuous metallic well structure.

Embodiments of the invention provide an untethered apparatus for measuring properties along a subterranean well. According to at least one embodiment, the untethered apparatus includes a housing, and one or more sensors configured to measure data along the subterranean well. The data includes one or more physical, chemical, geological or structural properties in the subterranean well. The untethered apparatus further includes a processor configured to control the one or more sensors measuring the data and to store the measured data, and a transmitter configured to transmit the measured data to a receiver arranged external to the subterranean well. Further, the untethered apparatus includes a controller configured to control the buoyancy or the drag of the untethered apparatus to control a position of the untethered apparatus in the subterranean well. The processor includes instructions defining measurement parameters for the one or more sensors of the untethered apparatus within the subterranean well.

A method of drilling a wellbore includes drilling the wellbore through a formation by injecting drilling fluid through a drill string and rotating a drill bit. The drill string includes a shifting tool, a receiver in communication with the shifting tool, and the drill bit. The method further includes retrieving the drill string from the wellbore through a casing string until the shifting tool reaches an actuator. The casing string includes an isolation valve in an open position and the actuator. The method further includes sending a wireless instruction signal to the receiver. The shifting tool engages the actuator in response to the receiver receiving the instruction signal. The method further includes operating the actuator using the engaged shifting tool, thereby closing the isolation valve and isolating the formation from an upper portion of the wellbore.

A telemetry apparatus for use in a well can include multiple segments, the segments comprising at least one buoyancy control device, at least one telemetry device, and at least one articulation device that controls a relative orientation between adjacent ones of the segments. A method of communicating in a subterranean well can include installing at least one telemetry apparatus in the well, the telemetry apparatus comprising a telemetry device and a buoyancy control device, and the telemetry device communicating with another telemetry device at a remote location. A well system can include at least one telemetry apparatus disposed in a wellbore, the telemetry apparatus comprising multiple segments, the segments including at least one buoyancy control device and at least one telemetry device.