Apparatus and method relating to managed pressure drilling (mpd) whilst using a subsea rcd system

Abstract

A subsea rotating control device (RCD) system ( 1; 2 ) adapted to permit a tubular work string to pass there through such that there is an annulus created between the inner throughbore of subsea rotating control device (RCD) system ( 1; 2 ) and the outer surface of the tubular work string. The subsea rotating control device (RCD) system ( 1; 2 ) comprises a system housing ( 10 ) comprising a throughbore, an upper end and a lower end ( 10 L) adapted for connection with a BOP ( 18 ) of a wellhead. The subsea RCD system ( 1; 2 ) further comprises at least two RCD seals ( 302, 2302; 304, 2304 ) arranged for selective mounting within the system housing ( 10 ) and which are selectively actuable between an unsealed configuration and a sealed configuration.

1 . A subsea rotating control device (RCD) system adapted to permit a tubular work string to pass there through such that there is an annulus created between the inner throughbore of subsea rotating control device (RCD) system and the outer surface of the tubular work string, the subsea rotating control device (RCD) system comprising:
 a system housing comprising a throughbore;   an upper end; and   a lower end adapted for connection with a BOP of a wellhead;   
       and the subsea RCD system further comprising:—
 at least two RCD seals arranged for selective mounting within the system housing and which are selectively actuable between an unsealed configuration in which the at least two RCD seals are radially outwardly retracted and a sealed configuration in which the at least two RCD seals are radially inwardly extended; and 
 at least one annular seal arranged for selective mounting within the system housing below the at least two RCD seals, wherein the said at least one annular seal is selectively actuable between an unsealed configuration in which the said at least one annular seal is radially outwardly retracted and a sealed configuration in which the said at least one annular seal is radially inwardly extended. 
 
     
     
         2 . The subsea rotating control device (RCD) system according to  claim 1 , wherein the at least two RCD seals are inflatable such that they can be inflated into the sealed configuration and deflated into the unsealed configuration. 
     
     
         3 . The subsea rotating control device (RCD) system according to  claim 1 , wherein the at least one annular seal is inflatable such that it can be inflated into the sealed configuration and deflated into the unsealed configuration. 
     
     
         4 . The subsea rotating control device (RCD) system according to  claim 1 , wherein the system housing comprises a throughbore and a wellbore fluid and/or drilling mud returns port formed through a sidewall in fluid communication with the throughbore of the system housing. 
     
     
         5 . The subsea rotating control device (RCD) system according to  claim 4 , wherein the port permits wellbore fluid and/or drilling mud located in the throughbore of the subsea rotating control device (RCD) system below the lowermost of the at least two RCD seals and/or the at least one annular seal to exit the throughbore and return to the surface. 
     
     
         6 . The subsea rotating control device (RCD) system according to  claim 1 , wherein the at least two RCD seals are capable of being locked within the throughbore by at least one locking device. 
     
     
         7 . The subsea rotating control device (RCD) system according  claim 6 , wherein the at least one annular seal is capable of being locked within the throughbore by at least one locking device. 
     
     
         8 . The subsea rotating control device (RCD) system according to  claim 7 , wherein, each of the at least two RCD seals and the at least one annular seal comprise their own respective locking device. 
     
     
         9 . The subsea rotating control device (RCD) system according to  claim 8 , wherein each of the at least two RCD seals and the at least one annular seal can be separately and selectively locked and unlocked as required by actuation of their own respective locking device in such a manner to permit one of them to be locked within the throughbore and the other of them to be run into and/or retrieved from the throughbore of the system housing. 
     
     
         10 . The subsea rotating control device (RCD) system according to  claim 9 , wherein each of the said at least two RCD seals are provided within an RCD housing, and the said at least one annular seal is provided within a separate housing from that of the at least two RCD seals. 
     
     
         11 . The subsea rotating control device (RCD) system according to  claim 10 , wherein the at least two RCD seals are rotateably mounted within said RCD housing by at least one bearing mechanism. 
     
     
         12 . The subsea rotating control device (RCD) system according to  claim 1 , wherein each of the said at least two RCD seals and the at least one annular seal comprises a retrieval means to permit running in and/or retrieval of the respective each of the said at least two RCD seals and the said at least one annular seal. 
     
     
         13 . The subsea rotating control device (RCD) system according to  claim 10 , wherein each said seal housing comprises a locking means into which a respective locking device can engage in order to lock said seal housing of said respective seal within the throughbore of the system housing where each said locking device is mounted on the system housing. 
     
     
         14 . The subsea rotating control device (RCD) system according to  claim 13 , wherein each said locking device can be actuated between a radially inwardly projecting configuration and a retracted configuration such that they do not project into said locking means of the respective seal housing. 
     
     
         15 . The subsea rotating control device (RCD) system according to  claim 13 , wherein each said locking device is remotely actuatable between the radially inwardly projecting or locked configuration and the retracted or unlocked configuration, allowing for remote activation of each of the locking devices by an operator from the surface. 
     
     
         16 . The subsea rotating control device (RCD) system according to  claim 1 , wherein at least one of the two RCD seals and the said annular seal device can be:—
 i) run into the throughbore of the system housing, typically through an upper end of the system housing; and 
 ii) locked to the system housing within the throughbore of the system housing. 
 
     
     
         17 . The subsea rotating control device (RCD) system according to  claim 1 , wherein at least one of the said two RCD seals and the said annular seal are capable of being unlocked from and retrieved from the throughbore of the system housing, by pulling it upwards through the throughbore of the system housing and further pulling it upwards through the upper end of the system housing into the surrounding subsea environment on a workstring. 
     
     
         18 . The subsea rotating control device (RCD) system according to  claim 17 , wherein the at least two RCD seals can be retrieved and run into the throughbore either on its own by a running/retrieval tool or can be retrieved and run into the throughbore with the at least one annular seal. 
     
     
         19 . The subsea rotating control device (RCD) system according to  claim 1 , wherein the at least two RCD seals comprise an outer RCD housing and said at least two RCD seals are mounted within and are rotatable with respect to the outer RCD housing. 
     
     
         20 . The subsea rotating control device (RCD) system according to  claim 19 , wherein the two RCD seals further comprise one or more bearings to couple them to the RCD housing such that the two RCD seals are rotatable on the bearing with respect to the stationary outer RCD housing such that the said each respective RCD seal seals against and is rotatable with the work string which passes through the throughbore of the system housing. 
     
     
         21 . The subsea rotating control device (RCD) system according to  claim 20 , wherein each of the upper and lower RCD seals is formed from a resilient material and which is inflatable such that when in an inflated state has an inner diameter which is a friction fit such that it comprises an inner diameter that matches the outer diameter of the work string such that each of the upper and lower RCD seals are forced against the outer surface of the work string and seals against the outer surface of the drill string such that it does not permit drilling fluid or other well fluids located in the annulus to pass through the throughbore of the two RCD seals in the upwards direction from downhole to up-hole when in the inflated state. 
     
     
         22 . The subsea rotating control device (RCD) system according to  claim 20 , wherein the said two RCD seals comprise an in use de-energised or deflated inner diameter which is greater than the outer diameter of the drill string which passes there through such that when the said two RCD seals in use are de-energised, they allow the free movement of the drill string there through and therefore do not impede the movement there through and therefore do not seal against the outer diameter of the drill string. 
     
     
         23 . The subsea rotating control device (RCD) system according to  claim 22 , wherein each of the said two RCD seals can be selectively energised or de-energised by the respective introduction or removal of fluid from a respective cavity or chamber in fluid communication with a surface of the said two RCD seals and more preferably said respective cavity or chamber is in fluid communication with an outer surface of each of the said two RCD seals such that when fluid is pumped into said respective cavity or chamber, the said two RCD seals are forced inwards into contact with the tubular work string passing through the system housing to thereby form a seal in the annulus between the outer surface of the tubular work string and the inner throughbore of the system housing. 
     
     
         24 . The subsea rotating control device (RCD) system according to  claim 1 , wherein the said annular seal comprises an in use de-energised or deflated inner diameter which is greater than the outer diameter of the work string which passes there through such that when the said annular seal in use is de-energised it allows the free movement of the work string there through and therefore does not impede the movement there through and therefore does not seal against the outer diameter of the work string and the said annular seal further comprises an in use energised or inflated inner diameter which matches the outer diameter of the work string which passes there through such that when the said annular seal in use is energised it seals against the outer diameter of the work string and therefore does not permit drilling fluid located in the annulus to pass through the throughbore of the annular seal in the upwards direction from downhole to up-hole when in the inflated state. 
     
     
         25 . The subsea rotating control device (RCD) system according to  claim 24 , wherein the annular seal can be selectively energised or de-energised by the respective introduction or removal of fluid from a cavity or chamber in fluid communication with a surface of the said annular seal and more preferably said cavity or chamber is in fluid communication with an outer surface of the said annular seal such that when fluid is pumped into said cavity or chamber, the said annular seal is forced inwards into contact with tubular work string passing through the system housing to thereby form a seal in the annulus between the outer surface of the tubular work string and the inner throughbore of the system housing. 
     
     
         26 . The subsea rotating control device (RCD) system according to  claim 23 , wherein the subsea RCD system further comprises a hydraulic fluid control system capable of controlling the pressure of fluid within the respective chamber and in particular within the two RCD seal chambers. 
     
     
         27 . The subsea rotating control device (RCD) system according to  claim 26 , wherein the hydraulic fluid control system is capable of controlling the pressure of fluid within the two RCD seal chambers such that said pressure is maintained at a positive delta pressure compared with the pressure of the wellbore fluids and/or drilling mud within the throughbore of the system housing. 
     
     
         28 . The subsea rotating control device (RCD) system according to  claim 26 , wherein the hydraulic fluid control system comprises a pressure sensing mechanism to sense the pressure within the throughbore of the system housing and further comprises a hydraulic fluid source capable of providing pressurised hydraulic fluid. 
     
     
         29 . The subsea rotating control device (RCD) system according to  claim 28 , wherein said hydraulic fluid control system comprises a wireless fluid pressure signal transmission system. 
     
     
         30 . The subsea rotating control device (RCD) system according to  claim 16 , wherein the locking devices are configured such that in use, in the locked configuration, the respective two RCD seals and the said annular seal cannot move relative to the system housing and in the unlocked configuration the respective two RCD seals and the said annular seal can move relative to the system housing.