A rotating control device includes a bowl housing with an inner aperture to receive a seal and bearing assembly. A plurality of hydraulically-actuated fail-last-position latching assemblies are disposed about an outer surface of the bowl housing to controllably extend a plurality of piston-driven dogs radially into a groove of the seal and bearing assembly. The seal and bearing assembly includes a housing, a mandrel disposed within an inner aperture of the housing, a first interference-fit sealing element attached to a bottom distal end of the mandrel, a plurality of tapered-thrust bearings indirectly mounted to the housing, a preload spacer disposed between top and bottom tapered-thrust bearings, a plurality of jam nuts to adjust a preload of the tapered-thrust bearings and a lower seal carrier attached to the seal and bearing housing comprising a plurality of dynamic sealing elements that contact the mandrel.

A stochastic control method includes determining a property of a solid present in a drilling fluid circulating within a mud circulation system and identifying a mud circulation model that dictates operation of the mud circulation system. The mud circulation model is based on one or more models of one or more uncertainties encountered during a wellbore drilling operation. The method further includes determining an accuracy of the mud circulation model based on a difference between the determined property of the solid present in the drilling fluid and a solid property of the drilling fluid as provided by the mud circulation model, and programming a controller of the mud circulation system based on the mud circulation model to modify operation of the mud circulation system.

A subsea drilling method for controlling the bottom hole annular pressure and downward injection rate during mud cap drilling operations from a mobile offshore drilling unit with a low pressure marine riser and subsea blowout preventer. The method called controlled mud cap drilling uses the hydrostatic head of a heavy annular mud (fluid) managed or observed in order to balance the highest pore pressure in the well and to control the injection rate, by using a subsea mud lift pump and a control system to regulate the process.

A natural gas hydrate solid-state fluidization mining method and system under an underbalanced positive circulation condition, used for performing solid-state fluidization mining on a non-rock-forming weak-cementation natural gas hydrate layer in the ocean. Equipment includes a ground equipment system and an underwater equipment system. The construction procedure has an earlier-stage construction process, underbalanced hydrate solid-state fluidization mining construction process and silt backfilling process. Natural gas hydrates in the seafloor are mined through an underbalanced positive circulation method, and problems such as shaft safety, production control and environmental risks faced by conventional natural gas hydrate mining methods such as depressurization, heat injection, agent injection and replacement are effectively solved. By using the natural gas hydrate solid-state fluidization mining method weak-cementation non-rock-forming natural gas hydrates in the seafloor can be mined in environment-friendly, efficient, safe and economical modes, more energy resources are provided, and energy shortage dilemmas are solved.

A hydrate solid-state fluidization mining method and system under an underbalanced reverse circulation condition are used for solid-state fluidization mining on a non-rock-forming weak-cementation natural gas hydrate layer in the ocean. Equipment includes a ground equipment system and an underwater equipment system. The construction procedure includes an earlier-stage construction process, pilot hole drilling construction process, reverse circulation jet fragmentation process, underbalanced reverse circulation fragment recovery process and silt backfilling process. Natural gas hydrates in the seafloor are mined through an underbalanced reverse circulation method. Problems such as shaft safety, production control and environmental risks faced by conventional natural gas hydrate mining methods such as depressurization, heat injection, agent injection and replacement are effectively solved. By using the method, the weak-cementation non-rock-forming natural gas hydrates in the seafloor can be mined in environment-friendly, efficient, safe and economical modes, more energy resources can be provided, and energy shortage dilemmas are solved.

A re-fracturing method using a perforating gun system in a multistring wellbore casing with an inner well casing installed in an outer well casing. The charges in the perforating system include a case, a liner positioned within the case, and an explosive filled within the liner. The liner shaped with a subtended angle about an apex of the liner such that a jet formed with the explosive creates an entrance hole in the inner well casing and the outer well casing; the liner having an exterior surface, the exterior surface substantially conical proximate the apex; the subtended angle of the liner ranges from 100 to 120. The method includes covering the existing openings with the inner casing, perforating with the perforating system and creating constant diameter entrance holes in the outer casing and fracturing through the inner casing and outer casing.

A stochastic control method includes measuring a fluid property of a drilling fluid circulating within a mud circulation system and identifying a mud circulation model that dictates operation of the mud circulation system. The mud circulation model is based on one or more models of one or more uncertainties encountered during a wellbore drilling operation. The method further includes determining an accuracy of the mud circulation model based on a residue between the measured fluid property of the drilling fluid and a fluid property of the drilling fluid as provided by the mud circulation model, and programming a controller of the mud circulation system based on the mud circulation model to modify operation of the mud circulation system.

The invention provides a mud circulation system for reducing swab pressure while tripping out, including drilling tool components, a normal drilling circulation channel and a tripping circulation channel, the drilling tool components include a drill string, a drill bit, and a top drive, the normal drilling circulation channel includes a first rotary valve, a solid phase control device, a mud tank, a mud pump, and a forth rotary valve connected in sequence, the tripping circulation channel includes a second rotary valve, a tripping mud pump, a tripping mud tank and a third rotary valve connected in sequence; the method to operate the mud circulation system for reducing the swab pressure is as follows: shutting down the mud pump, closing the first rotary valve, and opening the second rotary valve and the third rotary valve before tripping out; determining the pumping flow rate according to relevant parameters.

A system includes a mud pump for pumping a drilling mud from a drilling mud source, through a drill string, out a drill bit and into an annular, and a plurality of chokes disposed down stream from the mud pump, including a first choke disposed between the mud pump and the drill string, and a second choke disposed between the mud pump and a mud tank. The system further includes a fluid discharge conduit in fluid communication with the annular space for transferring the drilling mud to handling equipment in fluid communication with the mud tank. The first choke receives the drilling mud from the mud pump at a first flow rate, the first choke reduces drilling mud flow rate to a second flow rate less than the first flow rate, and the second choke reduces drilling mud flow rate to a third flow rate.

A coiled tubing drilling robot, a robot system and a process parameter control method thereof. The coiled tubing drilling robot is mainly characterized in that a drilling pressure and a drilling speed of a drill string are adjusted by an electric proportional relief valve and an electric proportional flow valve disposed inside the drilling robot; a support mechanism of the drilling robot adopts a single oblique block to prop against a spring piece to clamp a well wall; the coiled tubing drilling robot system consists of a coiled tubing intelligent drilling rig, a wellhead device, a coiled tubing, a drilling robot, a drill string vibration measurement device, a MWD, a power drill and a drill bit.