Managed pressure and/or temperature drilling system and method

1. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by:

injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string; and

returning gas hydrates cuttings and the drilling fluid (returns) to a surface of the wellbore and/or a drilling rig; and

while drilling the wellbore:

separately injecting a coolant along an annulus of a concentric tubular string conducting the returns to control a temperature of the gas hydrates cuttings, thereby preventing or discouraging disassociation of the gas hydrates cuttings; and

communicating pressure and temperature from sensors disposed along the concentric tubular string to a rig control system.

2. The method of claim 1 , wherein:

the concentric tubular string is a concentric riser,

the annulus is an outer annulus of the concentric riser,

the concentric riser has a bore and extends from the drilling rig to a floor of a sea,

the outer annulus and the bore are isolated from one another,

the drill string is disposed through the riser bore,

the gas hydrates cuttings are returned to the drilling rig via an inner annulus formed between the riser bore and the drill string.

3. The method of claim 2 , wherein a layer of insulation is disposed around an outer surface of the riser.

4. The method of claim 1 , wherein:

at least a portion of an outer surface of the drill string is exposed to a sea,

the returns are diverted into a multiphase pump at a floor of the sea, and

the returns are pumped to the drilling rig via a discharge line.

5. The method of claim 4 , wherein:

the concentric tubular string is a discharge line, and

the annulus is an outer annulus of the discharge line.

6. The method of claim 4 , wherein:

the multiphase pump has a pressure sensor and a temperature sensor in fluid communication with an inlet of the pump and a pressure sensor and a temperature sensor in fluid communication with an outlet of the pump, and

the pump sensors are in communication with the rig control system.

7. The method of claim 1 , wherein a pressure of the returns is controlled to prevent or discourage disassociation of the gas hydrates cuttings.

8. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by:

injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string; and

returning gas hydrates cuttings and the drilling fluid (returns) to a surface of the wellbore and/or a drilling rig; and

while drilling the wellbore, separately injecting a coolant along a tubular string conducting the returns to control a temperature of the gas hydrates cuttings, thereby preventing or discouraging disassociation of the gas hydrates cuttings,

wherein:

the tubular string is a concentric riser having a bore and an outer annulus and extending from the drilling rig to a floor of a sea,

the coolant is injected into the outer annulus,

the outer annulus and the bore are isolated from one another,

the drill string is disposed through the riser bore,

the gas hydrates cuttings are returned to the drilling rig via an inner annulus formed between the riser and the drill string,

pressure sensors and temperature sensors are disposed along the riser, and

the pressure and temperature sensors in communication with a rig control system and the bore of the riser string.

9. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by:

injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string; and

returning gas hydrates cuttings and the drilling fluid (returns) to a surface of the wellbore and/or a drilling rig; and

while drilling the wellbore, separately mixing a coolant with the returns to control a temperature of the gas hydrates cuttings, thereby preventing or discouraging disassociation of the gas hydrates cuttings.

10. The method of claim 9 , wherein:

at least a portion of an outer surface of the drill string is exposed to a sea,

the returns are diverted into a multiphase pump at a floor of the sea, and

the returns are pumped to the drilling rig via a discharge line.

11. The method of claim 10 , wherein:

the returns are diverted at a wellhead, and

the coolant is mixed with the returns at the wellhead.

12. The method of claim 10 , wherein:

the multiphase pump has a pressure sensor and a temperature sensor in fluid communication with an inlet of the pump and a pressure sensor and a temperature sensor in fluid communication with an outlet of the pump, and

the sensors are in communication with a rig control system.

13. The method of claim 9 , wherein:

the returns are transported through a first annulus formed between the drill string and a tie-back casing;

the coolant is injected into a second annulus formed between the tie-back casing and a second casing, and

the coolant mixes with the returns at a bottom of the second casing.

14. The method of claim 13 , wherein the drilling fluid has a first density and the coolant has a second density that is substantially less than the first density.

15. The method of claim 13 , wherein the coolant is a gas.

16. The method of claim 13 , wherein:

a wellhead is attached to the second casing, and

the method further comprises injecting a second fluid in the wellhead, and

the second fluid mixes with the returns.

17. The method of claim 16 , wherein:

the returns are transported to the drilling rig via a riser, and

the method further comprises injecting a third fluid into the riser, and

the third fluid mixes with the returns.

18. The method of claim 9 , wherein a pressure of the returns is controlled to prevent or discourage disassociation of the gas hydrates cuttings.

19. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string;

returning gas hydrates cuttings and the drilling fluid (returns) to a floor of a sea;

separating the gas hydrates cuttings from a rest of the returns at the seafloor;

disassociating the gas hydrates cuttings into a gas and H 2 O; and

transporting the disassociated gas to a drilling rig.

20. The method of claim 19 , wherein the gas hydrates cuttings are disassociated in a subsea separator.

21. The method of claim 20 , further comprising:

diverting the returns into the subsea separator,

wherein the disassociated gas is transported to the drilling rig via a gas return line.

22. The method of claim 21 , further comprising pumping the rest of the returns from the separator into a riser extending from the drilling rig to the seafloor.

23. The method of claim 21 , wherein the disassociated gas is transported to the drilling rig by using a vacuum pump.

24. The method of claim 19 , wherein the gas hydrates cuttings are disassociated in a riser extending from the drilling rig to the seafloor.

25. The method of claim 24 , further comprising pumping the rest of the returns from the riser to the drilling rig via a return line.

26. The method of claim 24 , wherein:

a blow out preventer (BOP) is disposed along the riser, and

the BOP is selectively actuatable to engage an outer surface of the drill string and divert the gas to an outlet line extending to the drilling rig.

27. The method of claim 19 , further comprising:

encouraging the disassociation by mixing a hydrates inhibitor or heated fluid with the gas hydrates cuttings.

28. The method of claim 19 , further comprising:

encouraging the disassociation by controlling pressure of the gas hydrates cuttings.

29. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string;

returning gas hydrates cuttings and the drilling fluid (returns) to a surface of the wellbore and/or a drilling rig; and

injecting a coolant along a tubular string conducting the returns to control a temperature of the gas hydrates cuttings, thereby preventing or controlling disassociation of the gas hydrates cuttings,

wherein:

at least a portion of an outer surface of the drill string is exposed to a sea,

the returns are diverted into a multiphase pump at a floor of the sea,

the returns are pumped to the drilling rig via a discharge line,

the discharge line is concentric, and

the coolant is injected along an outer annulus of the discharge line.

30. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string;

returning gas hydrates cuttings and the drilling fluid (returns) to a surface of the wellbore and/or a drilling rig; and

mixing a coolant with the returns to control a temperature of the gas hydrates cuttings, thereby preventing or controlling disassociation of the gas hydrates cuttings,

wherein:

at least a portion of an outer surface of the drill string is exposed to a sea,

the returns are diverted into a multiphase pump at a floor of the sea,

the returns are pumped to the drilling rig via a discharge line,

the returns are diverted at a wellhead, and

the coolant is mixed with the returns at the wellhead.

31. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string;

returning gas hydrates cuttings and the drilling fluid (returns) to a surface of the wellbore and/or a drilling rig; and

mixing a coolant with the returns to control a temperature of the gas hydrates cuttings, thereby preventing or controlling disassociation of the gas hydrates cuttings,

wherein:

at least a portion of an outer surface of the drill string is exposed to a sea,

the returns are diverted into a multiphase pump at a floor of the sea,

the returns are pumped to the drilling rig via a discharge line

the multiphase pump has a pressure sensor and a temperature sensor in fluid communication with an inlet of the pump and a pressure sensor and a temperature sensor in fluid communication with an outlet of the pump, and

the sensors are in communication with a rig control system.

32. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string;

returning gas hydrates cuttings and the drilling fluid (returns) to a surface of the wellbore and/or a drilling rig; and

mixing a coolant with the returns to control a temperature of the gas hydrates cuttings, thereby preventing or controlling disassociation of the gas hydrates cuttings,

wherein:

the returns are transported through a first annulus formed between the drill string and a tie-back casing;

the coolant is injected into a second annulus formed between the tie-back casing and a second casing, and

the coolant mixes with the returns at a bottom of the second casing.

33. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string;

returning gas hydrates cuttings and the drilling fluid (returns) to a floor of a sea;

separating the gas hydrates cuttings from a rest of the returns at the seafloor; and

disassociating the gas hydrates cuttings into a gas and H 2 O in a riser extending from a drilling rig to the seafloor,

wherein:

a blow out preventer (BOP) is disposed along the riser, and

the BOP selectively actuatable to engage an outer surface of the drill string and divert the gas to an outlet line extending to the drilling rig.

34. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string;

returning gas hydrates cuttings and the drilling fluid (returns) to a floor of a sea;

separating the gas hydrates cuttings from a rest of the returns at the seafloor;

disassociating the gas hydrates cuttings into a gas and H 2 O; and

encouraging the disassociation by mixing a hydrates inhibitor or heated fluid with the gas hydrates cuttings.

35. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string;

returning gas hydrates cuttings and the drilling fluid (returns) to a floor of a sea;

separating the gas hydrates cuttings from a rest of the returns at the seafloor;

disassociating the gas hydrates cuttings into a gas and H 2 O; and

encouraging the disassociation by controlling pressure of the gas hydrates cuttings.

36. A method for drilling a wellbore into a gas hydrates formation, comprising:

drilling the wellbore into the gas hydrates formation by:

injecting drilling fluid through a drill string disposed in the wellbore and rotating a drill bit disposed on an end of the drill string; and

returning gas hydrates cuttings and the drilling fluid (returns) to a surface of the wellbore and/or a drilling rig; and

while drilling the wellbore, separately injecting a coolant along a tubular string conducting the returns to control a temperature of the gas hydrates cuttings, thereby preventing or discouraging disassociation of the gas hydrates cuttings,

wherein:

at least a portion of an outer surface of the drill string is exposed to a sea,

the returns are diverted into a multiphase pump at a floor of the sea, and

the returns are pumped to the drilling rig via a discharge line.