Subsea mechanism to circulate fluid between a riser and tubing string
First Claim
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1. A subsea assembly, comprising:
- a riser extending through a body of water and connected to a blow-out preventer (“
BOP”
) positioned at a sea floor;
a tubing string extending within the riser such that a riser annulus is defined between the tubing string and the riser;
a subsea test tree (“
SSTT”
) positioned along the tubing string;
a work string extending below the sea floor to a formation depth and defining a tubing volume therein;
a riser fluid disposed in the riser annulus, the riser fluid in the riser annulus having a fluid volume at least equal to the tubing volume; and
a circulation mechanism positioned along the tubing string above the SSTT to allow selective communication of the riser fluid between the tubing string and the riser annulus through a port defined through the tubing string.
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Accused Products
Abstract
A circulation mechanism in a subsea assembly is selectively actuated to allow fluid communication between the riser annulus and tubing string to immediately kill the well using heavy-weight fluid in the riser annulus; perform well control operations by adjusting the weight or other properties of fluid in the tubing string or riser annulus; and/or to circulate the riser of a deep-water well undergoing well testing or intervention.
22 Citations
22 Claims
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1. A subsea assembly, comprising:
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a riser extending through a body of water and connected to a blow-out preventer (“
BOP”
) positioned at a sea floor;a tubing string extending within the riser such that a riser annulus is defined between the tubing string and the riser; a subsea test tree (“
SSTT”
) positioned along the tubing string;a work string extending below the sea floor to a formation depth and defining a tubing volume therein; a riser fluid disposed in the riser annulus, the riser fluid in the riser annulus having a fluid volume at least equal to the tubing volume; and a circulation mechanism positioned along the tubing string above the SSTT to allow selective communication of the riser fluid between the tubing string and the riser annulus through a port defined through the tubing string. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of using a subsea assembly, the method comprising:
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deploying a tubing string into a riser to define a riser annulus between the tubing string and the riser, the riser being connected to a blow-out preventer (“
BOP”
) positioned at a sea floor above a well;filling the riser annulus with a sufficient volume of a riser fluid to fill a tubing volume of a work string extending to a formation depth into the well below the sea floor; actuating a circulation mechanism to allow communication of the riser fluid between the riser annulus and the tubing string, the circulation mechanism being positioned as part of the tubing string above a subsea test tree (“
SSTT”
); andfilling the tubing volume with the riser fluid by flowing the riser fluid from the riser annulus into the work string through the tubing string. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of using a subsea assembly, the method comprising:
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deploying a tubing string into a riser, thereby forming a riser annulus between the riser and the tubing string, the riser annulus having a volume of riser fluid therein, the riser being connected to a blow-out preventer (“
BOP”
) positioned at a sea floor above a well; andselectively communicating the volume of riser fluid from the riser annulus and into the tubing string to thereby fill a tubing volume of a work string extending to a formation depth into the well below the sea floor. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification