An overshot assembly can include a distal body portion. The distal body portion can have a central axis, a length along the central axis, and an outer surface. An outer surface of the distal body portion can define, along at least a portion of the length, at least one drill string engagement portion having a first radial distance from the central axis of the distal body portion. The drill string engagement portion(s) can be configured to bias against and slide along an inner surface of a drill string. At least one recessed portion can be inwardly spaced from said first radial distance from the central axis. The recessed portion(s) can each be configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion. A plane that is perpendicular to the central axis of the distal body portion can extend through each drill string engagement portion of the at least one drill string engagement portion and each portion of the at least one recessed portion.

An overshot assembly can include a distal body portion. The distal body portion can have a central axis, a length along the central axis, and an outer surface. An outer surface of the distal body portion can define, along at least a portion of the length, at least one drill string engagement portion having a first radial distance from the central axis of the distal body portion. The drill string engagement portion(s) can be configured to bias against and slide along an inner surface of a drill string. At least one recessed portion can be inwardly spaced from said first radial distance from the central axis. The recessed portion(s) can each be configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion. A plane that is perpendicular to the central axis of the distal body portion can extend through each drill string engagement portion of the at least one drill string engagement portion and each portion of the at least one recessed portion.

A launching system for an autonomous unit (RAU) carrying a logging tool for oil and gas well logging robotic, said system comprising a main body provided with first and second control valves and a draining valve, sensors and a end cap electrically connected to a control room for transmission of the data collected by the logging tool carried by the RAU, said End Cap collecting data and charging the electrical battery of the robotic autonomous unit (RAU) carrying said logging tool to be launched by said main body and performing a schedule of logging tasks in the well; and a connection for a wellhead. The method for installation and uninstallation of the autonomous unit in the said system as well as a rescue system for the said robotic autonomous unit in case of hindered motion of the RAU for any reason are also described.

A launching system for an autonomous unit (RAU) carrying a logging tool for oil and gas well logging robotic, said system comprising a main body provided with first and second control valves and a draining valve, sensors and a end cap electrically connected to a control room for transmission of the data collected by the logging tool carried by the RAU, said End Cap collecting data and charging the electrical battery of the robotic autonomous unit (RAU) carrying said logging tool to be launched by said main body and performing a schedule of logging tasks in the well; and a connection for a wellhead. The method for installation and uninstallation of the autonomous unit in the said system as well as a rescue system for the said robotic autonomous unit in case of hindered motion of the RAU for any reason are also described.

There is provided a wireline coring recovery system of a seafloor drilling rig, including: a winch, a rope, a submersible tension sensor, a cover, a main shaft and a catcher. One end of the rope is wound on the winch, and the other end of the rope is connected to an upper end of the catcher after the rope passes over a first pulley provided below the submersible tension sensor and then through a tapered hole on the cover. The catcher is provided in a center hole of the main shaft. The present application further provides a method of using the wireline coring recovery system. By the cooperation of the compression rod skewed teeth, the first rotating core skewed teeth, the second rotating core skewed teeth and the compression spring, the inner core barrel is readily recovered or released.

A fishing tool with a collapsible distal end.

Disclosed herein are aspects of an expandable metal fishing tool for use in a wellbore. The expandable metal fishing tool, in one aspect, includes a mandrel. The expandable metal fishing tool, according to this aspect, further includes one or more expandable members positioned at least partially along an interior surface or an exterior surface of the mandrel, wherein the one or more expandable members comprise a metal configured to expand in response to hydrolysis, and further wherein a combined volume of the one or more expandable members is sufficient to expand radially to engage a downhole tubular within a wellbore in response to the hydrolysis.

A reverse-circulation drilling assembly having an overshot subassembly and a head subassembly. In the event retrieval of the drilling assembly by reverse-circulation fails, the drilling assembly can be retrieved using a secondary overshot.

A stabilizer apparatus for applying an electrical signal to a drill string antenna, comprising: an elongate member; and a fin extending radially from the elongate member, the fin having an angled leading face and an electrode face that opposes the elongate member, the electrode face including an electrode to apply electrical signals to a conductive member of the drill string antenna.

There is provided a wireline coring recovery system of a seafloor drilling rig, including: a winch, a rope, a submersible tension sensor, a cover, a main shaft and a catcher. One end of the rope is wound on the winch, and the other end of the rope is connected to an upper end of the catcher after the rope passes over a first pulley provided below the submersible tension sensor and then through a tapered hole on the cover. The catcher is provided in a center hole of the main shaft. The present application further provides a method of using the wireline coring recovery system. By the cooperation of the compression rod skewed teeth, the first rotating core skewed teeth, the second rotating core skewed teeth and the compression spring, the inner core barrel is readily recovered or released.