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 system for regulating a pump down operation may include a controller, a motor drive, a parameter estimation unit and a controller design unit. In examples, the controller may be configured to identify a difference between a downhole tension set-point to an actual downhole tension. The motor drive may be configured to adjust a line speed set point of the motor drive based at least in part on the difference from the controller to create an actual line speed from the motor drive to follow the downhole tension set-point. The parameter estimation unit may be configured to produce a fluid drag coefficient, a friction coefficient, and a line speed delay constant. The controller design unit may be configured to send one or more control gains to the controller based at least in part on the fluid drag coefficient, the friction coefficient, and the line speed delay constant.

In one example, an apparatus includes a TLT (Time of Flight (TOF)/LiDAR tool) with one or more optical transmitters and optical receivers that are operable to cooperate to obtain data concerning a downhole feature when the apparatus is deployed in a downhole environment. This apparatus further includes a first device operable to determine a position, speed, and/or orientation, of the TLT, when the TLT is deployed in the downhole environment, a second device configured to store locally and/or transmit the data to a location on a surface, a power source connected to the TLT, the first device, and the second device, and a housing within which the TLT, first device, second device, and power source are disposed, and the housing includes a connector configured to interface with a piece of downhole equipment.

A chemical stick launcher includes a stack of vertically mounted low voltage electrically operated valves providing spaces between the valves for chemical sticks. The valves are manipulated by a controller to drop sticks from the compartments between the valves after suitable time delays so the launcher can supply chemicals to a hydrocarbon well over a period of time. The stack is insulated to reduce the operating temperature of the launcher and thereby allow a wider variety of chemical compositions to be used. The low voltage electrically operated valves include a front panel providing a visual indicator of whether the valves are open or closed. The valves are mounted on the stack so the front panels face in the same direction so a standing person can see all the indicators from a single position.

A wellbore positioning system includes a first wellbore casing element bearing a first magnetic pattern that encodes first information associated with the wellbore or a drone. The first wellbore casing element is configured for placement down-hole in the wellbore. The first wellbore casing element extends along a central axis and defines an axially oriented passage. Also, the system includes an untethered drone configured for relative movement in the passage of the first wellbore casing element. The drone is configured to detect the first magnetic pattern and determine a position of the drone within the wellbore based on the first information.

A bottom hole assembly (BHA) includes a whipstock having a latch release mechanism and a milling tool having a plurality of blades and a lock mechanism. The BHA also includes a collar coupled to the whipstock and disposed about a portion of the milling tool, wherein the blades of the milling tool abut the collar. The milling tool is releasably coupled to the whipstock by the interaction of the latch release mechanism and the lock mechanism.

The disclosure relates to a system, downhole device and method for monitoring a wellbore, in particular in a lateral section, during stimulation, with an equipment enabling retrieval in many conditions. The method includes monitoring the wellbore with a distributed fiber optic sensor to determine one or more characteristics of the stimulation operation using detected backscattered optical signals on the distributed fiber optic sensor. The cable is retrieved by exerting a traction force. The disclosure also relates to a downhole device for receiving a cable and retainers to maintain the cable and having a weakpoint configured to break when subjected to a force along the longitudinal axis greater than a predetermined threshold. The system comprises the cable having the distributed fiber optic sensor, the downhole device and a surface monitoring system for determining the characteristic of the stimulation operation using detected backscattered optical signals on the distributed fiber optic sensor.

A floating drift apparatus for verifying the inner diameter of tubulars as the tubulars are made up into a tubular string being run into a wellbore. A float section provides buoyancy to float the apparatus in fluid within the bore of a tubular, and a drift section has a drift element with a diameter substantially equal to the tubular inner diameter being verified, which may be the drift diameter. When running a tubular string, the apparatus is inserted into the bore of the tubular string, floating in the fluid. As joints of tubular are made up and run into the wellbore, the tubulars move downhole around the apparatus. Preferably, the floating drift apparatus can be visually detected. If an undersize ID is encountered, the floating drift apparatus will be pushed downhole and no longer visible; the operator can remove the undersize ID tubular from the string.

A floating drift apparatus for verifying the inner diameter of tubulars as the tubulars are made up into a tubular string being run into a wellbore. A float section provides buoyancy to float the apparatus in fluid within the bore of a tubular, and a drift section has a drift element with a diameter substantially equal to the tubular inner diameter being verified, which may be the drift diameter. When running a tubular string, the apparatus is inserted into the bore of the tubular string, floating in the fluid. As joints of tubular are made up and run into the wellbore, the tubulars move downhole around the apparatus. Preferably, the floating drift apparatus can be visually detected. If an undersize ID is encountered, the floating drift apparatus will be pushed downhole and no longer visible; the operator can remove the undersize ID tubular from the string.

Aspects of the subject technology relate to systems and methods for determining positions of cementing plugs during a cementing process. Systems and methods are provided for determining a length of an optical fiber line deployed into a wellbore for a cementing process, measuring signal intensity data as a function of distance from the optical fiber line, the optical fiber line being attached to a lower cementing plug and an upper cementing plug, the upper cementing plug being attached to the optical fiber line by an attenuation assembly, generating signal intensity profiles based on the signal intensity data as a function of a round trip delay of a light signal in the optical fiber line, and determining positions of the lower cementing plug and the upper cementing plug based on the signal intensity profiles of the optical fiber line.