Abstract: An untethered downhole tool includes a first body, a second body, a logging sensor, a motor, and a controller. Each of the first and second bodies includes a housing that defines an inner volume and a magnetic anchor configured, in an active state, to attach the body to a wellbore tubular. The motor is attached to one of the first or second bodies and coupled to a spooler. The controller is communicably coupled to the motor and the first and second magnetic anchors. The controller is configured to adjust one of the first or second magnetic anchors from the active state to an inactive state; and activate the motor to operate the spooler to spool the cable from the spooler to increase a length of a portion of the cable between the spooler and the detached first or second body.

Abstract: A downhole tool includes a body configured to move in a wellbore formed from a terranean surface to a subterranean formation in a direction downhole of the terranean surface independent of a downhole conveyance attached to the body; one or more sensors positioned in the body, the one or more sensors configured to measure a value associated with at least one of the wellbore or the terranean surface; and at least one mass positioned in the body and configured to adjust an orientation of the body in response to one or more forces acting on the body as the downhole tool moves in the wellbore in the direction downhole of the terranean surface.

Abstract: An untethered device includes a housing, a magnetic actuator that is coupled to the housing, and a buoyancy device. The buoyancy device includes an attachment plate that is securable to the magnetic actuator, a degradable ballast weight that is coupled to the attachment plate, and a buoyancy-enhancing feature that is positioned adjacent to the attachment plate.

Abstract: An untethered device includes a housing, a magnetic actuator that is coupled to the housing, and a buoyancy device. The buoyancy device includes an attachment plate that is securable to the magnetic actuator, a degradable ballast weight that is coupled to the attachment plate, and a buoyancy-enhancing feature that is positioned adjacent to the attachment plate.

Abstract: An untethered downhole tool includes a first body, a second body, a logging sensor, a motor, and a controller. Each of the first and second bodies includes a housing that defines an inner volume and a magnetic anchor configured, in an active state, to attach the body to a wellbore tubular. The motor is attached to one of the first or second bodies and coupled to a spooler. The controller is communicably coupled to the motor and the first and second magnetic anchors. The controller is configured to adjust one of the first or second magnetic anchors from the active state to an inactive state; and activate the motor to operate the spooler to spool the cable from the spooler to increase a length of a portion of the cable between the spooler and the detached first or second body.

Abstract: A method and a system for collecting data at a fixed point in a wellbore are provided. An exemplary method includes dropping an untethered measurement tool (UMT) in the wellbore, switching a first magnet to drop a ballast from the UMT at a ballast drop condition, switching a second magnet to attach the UMT to a wall of the wellbore at a wall attachment condition. Data is collected in the UMT while the UMT is attached to the wall of the wellbore. The second magnet is switched to release the UMT from the wall of the wellbore at a wall release condition. The UMT is collected from the wellbore and the data is downloaded from the UMT.

Abstract: An untethered downhole tool includes a first body, a second body, a logging sensor, a motor, and a controller. Each of the first and second bodies includes a housing that defines an inner volume and a magnetic anchor configured, in an active state, to attach the body to a wellbore tubular. The motor is attached to one of the first or second bodies and coupled to a spooler. The controller is communicably coupled to the motor and the first and second magnetic anchors. The controller is configured to adjust one of the first or second magnetic anchors from the active state to an inactive state; and activate the motor to operate the spooler to spool the cable from the spooler to increase a length of a portion of the cable between the spooler and the detached first or second body.

Abstract: An apparatus includes a ballast that is configured to couple to an untethered downhole tool. The ballast includes a composite material. The composite material includes a first portion and a second portion. The first portion includes metallic particles. The first portion is configured to, while the ballast is coupled to the untethered downhole tool, provide weight to the untethered downhole tool to lower the untethered downhole tool into a well formed in a subterranean formation. The second portion includes a polymer matrix. The metallic particles of the first portion are distributed throughout the polymer matrix of the second portion. The second portion is configured to dissolve in response to being exposed to downhole fluid within the well at specified downhole conditions, thereby releasing the metallic particles of the first portions from the polymer matrix that has dissolved.

Abstract: Provided here are methods and system to detect an untethered device in a wellhead. The untethered device includes a housing, a transducer, and one or more sensors configured to measure data along the subterranean well. The transducer emits acoustic signals that are received by microphones on the surface of the wellhead. Based on these acoustic signals, the location of the untethered device is determined and appropriate valves may be opened or closed by an operator.

Abstract: A method and a system for collecting data at a fixed point in a wellbore are provided. An exemplary method includes dropping an untethered measurement tool (UMT) in the wellbore, switching a first magnet to drop a ballast from the UMT at a ballast drop condition, switching a second magnet to attach the UMT to a wall of the wellbore at a wall attachment condition. Data is collected in the UMT while the UMT is attached to the wall of the wellbore. The second magnet is switched to release the UMT from the wall of the wellbore at a wall release condition. The UMT is collected from the wellbore and the data is downloaded from the UMT.

Abstract: Techniques for operating a tool include moving a tool in a magnetized tubular member that generates a stationary magnetic field. The tool includes a housing that defines an interior volume, a first magnetic field sensor positioned on or within the housing at a first location, and a second magnetic field sensor positioned on or within the housing at a second location apart from the first location by a separation distance. The techniques further include detecting a first magnetic field amplitude distribution sensed by the first magnetic field sensor started at a first time instant; detecting a second magnetic field amplitude distribution sensed by the second magnetic field sensor started at a second time instant; determining a time difference between the first and second time instants based on the identified magnetic field amplitudes; and determining a speed of the tool based on the separation distance and the time difference.

Abstract: A downhole tool includes a body configured to move in a wellbore formed from a terranean surface to a subterranean formation in a direction downhole of the terranean surface independent of a downhole conveyance attached to the body; one or more sensors positioned in the body, the one or more sensors configured to measure a value associated with at least one of the wellbore or the terranean surface; and at least one mass positioned in the body and configured to adjust an orientation of the body in response to one or more forces acting on the body as the downhole tool moves in the wellbore in the direction downhole of the terranean surface.

Abstract: An apparatus for determining properties of an uncharacterized downhole fluid. The apparatus comprises an oscillation driver circuit comprising an amplifier having an output and an input, a feedback loop between the output and input of an amplifier or a logic gate, an electromechanical resonator disposed within the feedback loop such that a the resonator is driven by the oscillation driver circuit, wherein a resonant frequency of the resonator defines an oscillation frequency of the oscillator circuit, and a switch device for causing the oscillator circuit to stop driving the resonator, which thereby enables observation of a decay rate of the oscillation of the electromechanical resonator within the uncharacterized fluid. The electromechanical resonator is enclosed in a conductive layer to protect the resonator against capacitive effects of the downhole fluid.

Abstract: A system and method for targeted delivery of treatment material to a specified depth in a wellbore, including placing a container to the specified depth and allowing the container to fail at the depth due to wellbore pressure to release the treatment material.

Abstract: Provided here are methods and system to detect an untethered device in a wellhead. The untethered device includes a housing, a transducer, and one or more sensors configured to measure data along the subterranean well. The transducer emits acoustic signals that are received by microphones on the surface of the wellhead. Based on these acoustic signals, the location of the untethered device is determined and appropriate valves may be opened or closed by an operator.

Abstract: Provided here are methods and system to detect an untethered device in a wellhead. The untethered device includes a housing, a transducer, and one or more sensors configured to measure data along the subterranean well. The transducer emits acoustic signals that are received by microphones on the surface of the wellhead. Based on these acoustic signals, the location of the untethered device is determined and appropriate valves may be opened or closed by an operator.

Abstract: A system and method for targeted delivery of treatment material to a specified depth in a wellbore, including placing a container to the specified depth and allowing the container to fail at the depth due to wellbore pressure to release the treatment material.

Abstract: Provided here are methods and system to detect an untethered device in a wellhead. The untethered device includes a housing, a transducer, and one or more sensors configured to measure data along the subterranean well. The transducer emits acoustic signals that are received by microphones on the surface of the wellhead. Based on these acoustic signals, the location of the untethered device is determined and appropriate valves may be opened or closed by an operator.

Abstract: An apparatus for determining properties of an uncharacterized downhole fluid. The apparatus comprises an oscillation driver circuit comprising an amplifier having an output and an input, a feedback loop between the output and input of an amplifier or a logic gate, an electromechanical resonator disposed within the feedback loop such that a the resonator is driven by the oscillation driver circuit, wherein a resonant frequency of the resonator defines an oscillation frequency of the oscillator circuit, and a switch device for causing the oscillator circuit to stop driving the resonator, which thereby enables observation of a decay rate of the oscillation of the electromechanical resonator within the uncharacterized fluid. The electromechanical resonator is enclosed in a conductive layer to protect the resonator against capacitive effects of the downhole fluid.

Abstract: Near-field magnetic resonance is used to retrieve information stored in sensors passing through a fluidic channel in a fluidic medium, and can also be used for recharging a power source in the sensors. The sensors have been previously injected into a downhole and/or reservoir environment, and are then retrieved in order to access the information the sensors have obtained by measuring physical and/or chemical properties of the downhole and/or reservoir.