Deep ocean riser positioning system and method of running casing
AssigneeOcean Drilling Technology, L.L.C.
InventorsDavid C. Toalson, William A. Hunter, Roger W. Mowell
Life of this patent
Estimating the term…
Abstract
A deep ocean drilling system is disclosed for drilling offshore wells in extremely deep water using smaller and more economical drilling vessels. The system utilizes a reduced diameter drilling riser that reduces the size and cost of conventional floating drilling unit. The reduced diameter drilling riser is detached from the blowout preventer stack and repositioned and attached to a mud return assembly. Large diameter casing is lowered into the wellbore outside of the reduced diameter riser. Thereafter, the reduced diameter drilling riser is released from the mud return assembly and repositioned over and reconnected to the blowout preventer stack.
Claims59
A deep ocean drilling system for drilling an offshore well from a floating drilling vessel comprising:
- a) a reduced diameter marine riser extending from the floating drilling vessel to a lower marine riser package connector;
- b) a retrievable, high pressure blowout preventer stack having one or more annular preventers, one or more ram preventers, and a lower marine riser package mandrel, wherein the lower marine riser package connector may be releasably connected to the lower marine riser package mandrel;
- c) a fluid diverter line extending from the blowout preventer stack to a fluid return mandrel, wherein the lower marine riser package connector may be releasably connected to the fluid return mandrel;
- and
- d) a retrievable lifting and guide frame assembly comprising an upper lifting frame connected to the lower marine riser package connector and a lower guide frame connected to the blowout preventer stack, wherein the lower marine riser package connector and the upper lifting frame are vertically and laterally moveable about a slot formed in the lower guide frame to maintain the axial alignment of the riser and provide a pathway for controlled movement of the riser between the lower marine riser package mandrel and the fluid return mandrel.
A deep ocean drilling system for drilling an offshore well from a drilling vessel comprising:
- a) a reduced diameter marine riser extending from the drilling vessel to a lower marine riser package connector;
- b) a blowout preventer stack having a lower marine riser package mandrel, wherein the lower marine riser package connector may be releasably connected to the lower marine riser package mandrel;
- c) a secondary support mandrel wherein the lower marine riser package connector may be releasably connected to the secondary support mandrel;
- and
- d) a lifting and guide frame assembly comprising an upper lifting frame connected to the lower marine riser package connector and a lower guide frame connected to the blowout preventer stack, wherein the lifting frame restricts the vertical movement of the lower marine riser package connector and a pathway in the guide frame restricts the lateral movement of the lower marine riser package connector to maintain the axial alignment of the riser and control the movement of the riser between the lower marine riser package mandrel and the secondary support mandrel.
A method of running casing in deep water from a floating drilling vessel having a reduced diameter riser for connecting the vessel to the well comprising the steps of:
- a) providing a lower marine riser package connector on the end of the reduced diameter riser to connect the riser to a lower marine riser mandrel on a high pressure blowout preventer stack;
- b) disconnecting the lower marine riser package connector from the lower marine riser mandrel;
- c) repositioning the riser over a secondary support mandrel on the blowout preventer stack;
- d) connecting the lower marine riser package connector to the secondary support mandrel, wherein a fluid diverter line provides fluid communication between the secondary support mandrel and the blowout preventer stack;
- and
- e) lowering a 13⅜″ casing string outside of the riser through the blowout preventer stack and into the well while the well is in fluid communication with the riser.
A riser system for connecting a subsea blowout preventer stack to an offshore drilling vessel comprising:
- a) a riser pipe extending from the drilling vessel to a lower marine riser package connector;
- b) a blowout preventer stack having a lower marine riser package mandrel wherein the lower marine riser package connector may be releasably connected to the lower marine riser package mandrel;
- c) a secondary support mandrel wherein the lower marine riser package connector may be releasably connected to the secondary support mandrel;
- and
- d) a guide frame assembly comprising a guide frame attached to the blowout preventer stack, a guide pin attached to the lower marine riser package connector, the guide pin retained within a slot form in a guide plate, the guide plate being attached to the guide frame by one or more pivotable arms wherein the slot in the guide plate restricts the vertical movement of the lower marine riser package connector relative to the blowout preventer stack and the arms restrict the lateral movement of the lower marine riser package connector between the lower marine riser package mandrel and the secondary support mandrel to maintain the axial alignment of the riser during movement of the riser between the lower marine riser package mandrel and the secondary support mandrel.
A method of running casing from an offshore vessel to a subsea wellhead comprising the steps of:
- a) providing a lower marine riser package connector on the end of the reduced diameter riser to connect the riser to a lower marine riser mandrel on a blowout preventer stack, the blowout preventer stack being attached to the top of a subsea wellhead housing;
- b) disconnecting the lower marine riser package connector from the lower marine riser mandrel;
- c) repositioning the riser over a secondary support mandrel on the blowout preventer stack;
- d) connecting the lower marine riser package connector to the secondary support mandrel;
- e) providing choke and kill lines, hydraulic power and control lines extending from the drilling vessel to the blowout preventer stack, wherein such lines remain functional when the lower marine riser package connector is disconnected from the lower marine riser mandrel and reconnected to the secondary support mandrel;
- f) lowering a first casing string outside of the riser through the blowout preventer stack and into the well;
- g) landing a casing hanger for the first casing string in the subsea wellhead housing, the casing hanger having an internal landing means in the bore of the hanger;
- h) releasing the lower marine riser package connector from the secondary support mandrel and reconnecting the lower marine riser package connector to the lower marine riser package mandrel on the blowout preventer;
- i) lowering a second casing string through the riser and into the well;
- and
- j) landing the casing hanger for the second casing string on the internal landing means of the first hanger.
A method of drilling an offshore well from a drilling vessel having a reduced diameter riser for connecting the vessel to the well comprising the steps of:
- a) providing a lower marine riser package connector on the end of the reduced diameter riser to connect the riser to a lower marine riser mandrel on a blowout preventer stack;
- b) providing a guide frame assembly attached to the blowout preventer stack wherein the lower marine riser package connector extends through a slot in the guide frame assembly;
- c) disconnecting the lower marine riser package connector from the lower marine riser mandrel and repositioning the riser over a secondary support mandrel on the blowout preventer stack, wherein the vertical and lateral movement of the lower marine riser package connector is restricted by the slot in the guide frame assembly to maintain the axial alignment of the riser during movement of the riser between the lower marine riser package mandrel and the secondary support mandrel;
- and
- d) connecting the lower marine riser package connector to the secondary support mandrel.
A deep ocean drilling system for drilling an offshore well from a drilling vessel comprising:
- a) a reduced diameter marine riser extending from the drilling vessel to a lower marine riser package connector;
- b) a blowout preventer stack having a lower marine riser package mandrel, wherein the lower marine riser package connector may be releasably connected to the lower marine riser package mandrel;
- c) a secondary support mandrel wherein the lower marine riser package connector may be releasably connected to the secondary support mandrel;
- and
- d) a guide frame connected to the blowout preventer stack, wherein a pathway in the guide frame restricts the lateral movement of the lower marine riser package connector to maintain the axial alignment of the riser and control the movement of the riser between the lower marine riser package mandrel and the secondary support mandrel.
A retrievable lifting and guide frame assembly for drilling an offshore well from a floating drilling vessel comprising an upper lifting frame connected to a lower marine riser package connector and a lower guide frame connected to a subsea blowout preventer stack, wherein the lower marine riser package connector and the upper lifting frame are vertically and laterally moveable about a slot formed in the lower guide frame to maintain the axial alignment of the lower marine riser package connector and a marine riser connected to the lower marine riser package connector and extending from the floating drilling vessel and to provide a pathway for controlled movement of the riser and lower marine riser package connector between a lower marine riser package mandrel on a blowout preventer stack and a secondary support mandrel laterally removed from the lower marine riser package mandrel.
Dependencies are inferred from the claim text.