Drilling system and method for controlling equivalent circulating density during drilling of wellbores
First Claim
1. A system for subsea wellbore operations, comprising:
- (a) a supply conduit for providing drilling fluid into a wellbore;
(b) a return conduit including a riser conveying the drilling fluid from the wellbore to a predetermined location, the supply conduit and return conduit forming a fluid circuit; and
(c) an active pressure differential device (“
APD device”
) controlling pressure in the drilling fluid in the return conduit, the APD device adapted to selectively receive the drilling fluid from a first selected location on the riser and convey the drilling fluid to a second selected location, wherein the APD device is located at one of (i) in the riser, and (ii) in an annulus of the wellbore.
4 Assignments
0 Petitions
Accused Products
Abstract
A drilling system for drilling subsea wellbores includes a tubing-conveyed drill bit that passes through a subsea wellhead. Surface supplied drilling fluid flows through the tubing, discharges at the drill bit, returns to the wellhead through a wellbore annulus, and flows to the surface via a riser extending from the wellhead. A flow restriction device positioned in the riser restricts the flow of the returning fluid while an active fluid device controllably discharges fluid from a location below to just above the flow restriction device in the riser, thereby controlling bottomhole pressure and equivalent circulating density (“ECD”). Alternatively, the fluid is discharged into a separate return line thereby providing dual gradient drilling while controlling bottomhole pressure and ECD. A controller controls the energy and thus the speed of the pump in response to downhole measurement(s) to maintain the ECD at a predetermined value or within a predetermined range.
198 Citations
26 Claims
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1. A system for subsea wellbore operations, comprising:
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(a) a supply conduit for providing drilling fluid into a wellbore; (b) a return conduit including a riser conveying the drilling fluid from the wellbore to a predetermined location, the supply conduit and return conduit forming a fluid circuit; and (c) an active pressure differential device (“
APD device”
) controlling pressure in the drilling fluid in the return conduit, the APD device adapted to selectively receive the drilling fluid from a first selected location on the riser and convey the drilling fluid to a second selected location, wherein the APD device is located at one of (i) in the riser, and (ii) in an annulus of the wellbore. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A wellbore system for performing subsea downhole wellbore operations comprising:
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(a) a tubing receiving fluid from a source adjacent an upper end of the tubing; (b) a subsea wellhead assembly above a wellbore receiving the tubing, said wellhead assembly adapted to receive said fluid after it has passed down through said tubing and back up through an annulus between the tubing and the wellbore; (c) a riser extending up from the wellhead assembly to the sea level for conveying returning fluid from the wellhead to the sea level, with the tubing, annulus, wellhead and the riser forming a subsea fluid circulation system; (d) a flow restriction device adapted to restrict flow of the fluid returning to the sea level; and (e) a an active fluid flow device for diverting returning fluid around the flow restriction device to control equivalent circulating density of fluid circulating in the fluid circulation system, wherein the active fluid flow device returns the returning fluid to the surface via the riser. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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Specification