Techniques are described for controlling drilling operations based on real time measurement and analysis of fluid properties in a drilling environment. Sensor data can be collected that provides measurement(s) of fluid properties (for example, density and rheology) of the drilling fluid (in other words, downhole mud) around the drill. The measurements can be provided to a hydraulic model that calculates downhole pressure loss in the annulus. Based on this calculation, a calculation of equivalent circulating density (ECD) can be performed. In some implementations, the calculations are performed in real time with respect to the collection of the sensor data. The real time pressure loss and ECD calculations can be used to control bottom hole circulating pressures. The results of the calculations may be used to automatically control drilling operations.

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 method, comprising acquiring annular pressure data from a wellbore where the annular pressure data is acquired over a time interval and at least a portion of the annular pressure data is acquired during a pumps-off period. At least first and second values are identified from the annular pressure data and the variation between the first and second values are compared to a first threshold. Drilling equipment is operated based on the comparison with the first threshold.

A dual gradient drilling system includes a subsea blowout preventer disposed above a wellhead, the subsea blowout preventer having a central lumen configured to provide access to a wellbore, a lower section of a marine riser fluidly connected to the subsea blowout preventer, a closed-hydraulic positive displacement subsea pump system fluidly connected to the lower section of the marine riser and disposed at a predetermined depth, an annular sealing system disposed above the closed-hydraulic positive displacement subsea pump system, and an independent mud return line fluidly connecting one or more pump heads of the closed-hydraulic positive displacement subsea pump system to a choke manifold disposed on a floating platform of a rig.

A pump with a position indicator is disclosed. The pump includes a pump housing, wherein the pump housing includes a flexible bladder disposed therein; a first fluid zone, wherein the first fluid zone is operable to allow flow of a first fluid into and out of the first fluid zone; and a second fluid zone, wherein the second fluid zone is operable to allow flow of a second fluid into and out of the second fluid zone. The pump further includes a flexible position indicator disposed in the first fluid zone and in communication with the flexible bladder, wherein the flexible position indicator is operable to detect a linear position of the flexible bladder, and wherein the flexible bladder fluidly isolates the first fluid zone from the second fluid zone.

A dual gradient drilling system includes a subsea blowout preventer disposed above a wellhead, the subsea blowout preventer having a central lumen configured to provide access to a wellbore, a lower section of a marine riser fluidly connected to the subsea blowout preventer, a closed-hydraulic positive displacement subsea pump system fluidly connected to the lower section of the marine riser and disposed at a predetermined depth, an annular sealing system disposed above the closed-hydraulic positive displacement subsea pump system, and an independent mud return line fluidly connecting one or more pump heads of the closed-hydraulic positive displacement subsea pump system to a choke manifold disposed on a floating platform of a rig.

A dual gradient drilling system includes a subsea blowout preventer disposed above a wellhead, the subsea blowout preventer having a central lumen configured to provide access to a wellbore, a lower section of a marine riser fluidly connected to the subsea blowout preventer, a closed-hydraulic positive displacement subsea pump system fluidly connected to the lower section of the marine riser and disposed at a predetermined depth, an annular sealing system disposed above the closed-hydraulic positive displacement subsea pump system, and an independent mud return line fluidly connecting one or more pump heads of the closed-hydraulic positive displacement subsea pump system to a choke manifold disposed on a floating platform of a rig.

A multi-fluid drilling system 10 drilling is disclosed for drilling a hole or well 11. The system 10 is coupled to a dual wall drill string 12. The drill string 12 is configured to enable separate flow of a first fluid 14 and a second fluid 16. The system 10 has a hammer 22 and a downhole motor 24. Both the hammer 22 and the motor 24 are supported by and are coupled to the drill string 12. The motor 24 is uphole of the hammer 22. The hammer 22 is arranged so that when supported by the drill string 12 the first fluid 14 when flowing through the drill string 12 is able to flow to and power the hammer 22. As the motor 24 is disposed between the hammer 22 and the drill string 12 the first fluid 14 is also able to flow through the motor 24. To this end the motor 24 has a channel 25 to enable the first fluid to flow from the drill sting 12 to the hammer 22. The channel 25 acts as a part of a flow path or conduit for the first fluid 14.

A method for modifying a return fluid in a wellbore comprising disposing at least one valve along a drill pipe section of a drill string in the wellbore. At least one parameter of interest is determined at at least one location along the wellbore. At least one valve is controllably actuated to discharge at least a portion of at least one fluid from inside the drill string to an annulus in the wellbore to modify a local property of the return fluid in the annulus based at least in part on the measured parameter of interest.

Systems and processes for subsea marine managed pressure operations. One system includes a modified riser joint configured to fluidly connect inline with one or more riser joints. The modified riser joint and the one or more riser joints are connected to form a riser connecting a floating vessel with a wellhead. The system further includes a subsea pressure management sub-system configured to be operatively and fluidly connected to the modified riser joint at a subsea location.