Modified pumped riser solution

1. A riser assembly comprising:

a main body comprising a first end, a second end, a longitudinal axis, a first port, and a second port, the main body being configured to enclose a main body main passage which extends from the first end to the second end generally parallel to the longitudinal axis and to be mounted in a riser so that that the main body main passage forms a part of a main passage of the riser, wherein, the first port and the second port are configured to extend through the main body to connect the main body main passage with an exterior of the main body;

a tubular extending along the main body main passage;

a first sealing assembly arranged in the main body between the first port and the second port, the first sealing assembly being configured to provide a seal between the main body and the tubular so as to substantially prevent a flow of a fluid along the main body main passage around the tubular;

at least two diversion lines each of which extend from the first port in the main body to the second port in the main body; and

a pump arranged within each of the at least two diversion lines, each pump being configured to pump a fluid along a respective diversion line in which the pump is arranged,

wherein,

each pump is a hose diaphragm pump system which comprises at least two hose diaphragm pump heads and a drive motor, the drive motor being configured to simultaneously power the at least two hose diaphragm pump heads,

the main body further comprises an additional port which is arranged directly above the first sealing assembly, and

the riser assembly further comprises a booster line tie-in which is configured to extend to the additional port.

2. The riser assembly as recited in claim 1 , wherein,

each of the at least two diversion lines comprises a main portion which extends generally parallel to the longitudinal axis of the main body, and

each of the at least two diversion lines is arranged to abut on or be directly adjacent to the main body.

3. The riser assembly as recited in claim 1 , wherein each pump is a pump module which comprises at least two pumps which are arranged in parallel.

4. The riser assembly as recited in claim 1 , wherein each pump is a progressive cavity pump.

5. The riser assembly as recited in claim 1 , wherein each pump is a pump module which comprises two pumps which are arranged in series.

6. The riser assembly as recited in claim 1 , wherein each pump is configured to pump the fluid along the respective diversion line from the first port to the second port.

7. The riser assembly as recited in claim 1 , wherein each pump is configured to prevent a flow of the fluid along the respective diversion line from the second port to the first port.

8. The riser assembly as recited in claim 1 , wherein each of the at least two diversion lines comprises a separate first port and a separate second port.

9. The riser assembly as recited in claim 1 , wherein,

the main body further comprises a third port which is configured to connect the main body main passage to the exterior of the main body, and

further comprising:

a booster line configured to extend to the third port in the main body.

10. The riser assembly as recited in claim 1 , wherein,

the main body further comprises a fourth port and a fifth port, the fourth port and the fifth port each being configured to connect the main body main passage to the exterior of the main body, and

the first sealing assembly is arranged between the fourth port and the fifth port, and

further comprising:

a by-pass line configured to extend between the fourth port and the fifth port.

11. The riser assembly as recited in claim 1 , further comprising:

a second sealing assembly configured to provide a seal between the main body and the tubular so as to substantially prevent the flow of the fluid along the main body main passage around the tubular,

wherein,

the first port is arranged between the first sealing assembly and the second sealing assembly.

12. A riser assembly comprising:

a riser body comprising a first end, a second end, a longitudinal axis, a first port, a second port, and a third port, the riser body being configured to enclose a riser body main passage which extends from the first end to the second end generally parallel to the longitudinal axis, wherein,

the second end of the riser body is connected to a subsea blowout preventer which is suitable for mounting on a wellhead,

the first port and the second port are configured to extend through the riser body to connect the riser body main passage with an exterior of the riser body, and

the third port is configured to connect the riser body main passage to the exterior of the riser body;

a tubular configured to extend along the riser body main passage;

a first sealing assembly arranged in the riser body between the first port and the second port, the first sealing assembly being configured to provide a seal between the riser body and the tubular so as to substantially prevent a flow of a fluid along the riser body main passage around the tubular;

a second sealing assembly configured to provide a seal between the riser body and the tubular so as to substantially prevent the flow of the fluid along the riser body main passage around the tubular;

a diversion line configured to extend from the first port in the main body to the second port in the main body;

a pump arranged within the diversion line, the pump being configured to pump a fluid along the diversion line from the first port to the second port;

a riser booster pump; and

a booster line comprising a first branch, the booster line being configured to extend from the riser booster pump so that the first branch extends to the third port,

wherein,

the third port is arranged in the riser body between the first sealing assembly and the second sealing assembly or directly above the first sealing assembly.

13. The riser assembly as recited in claim 12 , wherein the booster line further comprises a second branch which extends into the riser body main passage at the second end of the riser body.

14. The riser assembly as recited in 12 , wherein,

the riser body further comprises a fourth port and a fifth port, the fourth port and the fifth port being configured to connect the riser body main passage to the exterior of the riser body, and

the first sealing assembly is arranged between the fourth port and the fifth port, and

further comprising:

a by-pass line configured to extend between the fourth port and the fifth port.

15. A method of operating a riser assembly,

the riser assembly comprising:

a riser body comprising a first end, a second end, a longitudinal axis, a first port, a second port, and a third port, the riser body being configured to enclose a riser body main passage which extends from the first end to the second end generally parallel to the longitudinal axis, wherein,

the first port and the second port are configured to extend through the riser body to connect the riser body main passage with an exterior of the riser body, and

the third port is configured to connect the riser body main passage to the exterior of the riser body;

a tubular configured to extend along the riser body main passage;

a first sealing assembly arranged in the riser body between the first port and the second port, the first sealing assembly being configured to provide a seal between the riser body and the tubular so as to substantially prevent a flow of a fluid along the riser body main passage around the tubular;

a second sealing assembly configured to provide a seal between the riser body and the tubular so as to substantially prevent the flow of the fluid along the riser body main passage around the tubular;

a diversion line configured to extend from the first port in the main body to the second port in the main body;

a pump arranged in the diversion line, the pump being configured to pump a fluid along the diversion line from the first port to the second port;

a riser booster pump; and

a booster line comprising a first branch, the booster line being configured to extend from the riser booster pump to the third port,

wherein,

the third port is arranged in the riser body between the first sealing assembly and the second sealing assembly or directly above the first sealing assembly;

the method comprising:

operating the second sealing assembly to seal against the tubular; and

operating the riser booster pump to pump a fluid into the riser body main passage via the third port.

16. The method as recited in claim 15 , wherein,

the riser body further comprises a fourth port and a fifth port, the fourth port and the fifth port being configured to connect the riser body main passage to the exterior of the riser body, and

the first sealing assembly is arranged between the fourth port and the fifth port, and

the riser assembly further comprises:

an isolation valve arranged in the diversion line, the isolation valve being configured to move between a first configuration in which the isolation valve permits the flow of the fluid along the diversion line, and a second configuration in which the isolation valve substantially prevents the flow of the fluid along the diversion line, the isolation valve being arranged between the pump and the second port or between the pump and the first port;

a by-pass line configured to extend between the fourth port and the fifth port; and

a by-pass isolation valve configured to move between a first configuration in which the by-pass isolation valve permits a flow of a fluid along the by-pass line, and a second configuration in which the by-pass isolation valve substantially prevents the flow of the fluid along the by-pass line.

17. The method as recited in claim 16 , further comprising:

operating the first sealing assembly to seal against the tubular;

operating the isolation valve to substantially prevent the flow of the fluid along the diversion line; and

opening the by-pass isolation valve so as to permit the flow of the fluid along the by-pass line.

18. The method as recited in claim 16 , further comprising:

operating the first sealing assembly to seal against the tubular;

operating the isolation valve to permit the flow of the fluid along the diversion line; and

closing the by-pass isolation valve to substantially prevent the flow of the fluid along the by-pass line.

19. The method as recited in claim 16 , further comprising:

operating the first sealing assembly so that the first sealing assembly does not seal against the tubular;

operating the isolation valve in the diversion line to substantially prevent the flow of the fluid along the diversion line; and

operating the bypass isolation valve to substantially prevent the flow of the fluid along the bypass line.

20. The method as recited in claim 15 , further comprising:

operating the pump in the diversion line to pump the fluid along the diversion line from the first port to the second port.

21. The method as recited in claim 15 , wherein,

the riser assembly further comprises at least one of:

a pump module;

a choke arranged on the by-pass line; and

a rig mud pump, and,

the method further comprises controlling a riser pressure by at least one of:

modulating a speed of the pump module,

varying a rate of the riser booster pump,

relaxing or tightening at least one of the first sealing assembly and the second sealing assembly,

modulating the choke on the by-pass line to adjust a riser pressure, and

modulating the rig mud pump.