Modular mud lift pump assembly

Abstract

A method and system for lifting drilling mud from subsea to a drilling vessel, which uses a pump having a body with a chamber, and a bladder in the chamber. The bladder attaches to the body and defines water and mud sides in the chamber. A mud inlet valve allows mud into the mud side of the chamber; which moves the bladder into the water side and urges water in the water side from the chamber and through a water exit valve. Pressurized water enters the chamber through a water inlet valve, which in turn pushes the bladder and mud from the chamber through a mud exit valve. The bladder separates the mud and water as it reciprocates in the chamber. The travel of the bladder in the chamber is controlled to prevent damage from contact with the chamber.

What is claimed is: 
     
         1 . A system for lifting drilling fluid from a subsea wellbore comprising:
 a drilling riser having a return flow of the drilling fluid;   a subsea module coupled with the drilling riser and having piping, and that is transportable to the drilling riser on a vessel having a capacity that is less than a capacity of a rig used in conjunction with the drilling riser;   a riser module coupled with the drilling riser and having controls, and that is transportable to the drilling riser on the vessel; and   a pump module coupled with the drilling riser, and having a pump that is in fluid communication with the drilling fluid in the drilling riser via the piping in the subsea module and that is in communication with the controls in the riser module, and that is transportable to the drilling riser on the vessel.   
     
     
         2 . The system of  claim 1 , wherein the pump module comprises a first pump module, the system further comprising a second pump module that is symmetric and interchangeable with the first pump module. 
     
     
         3 . The system of  claim 2 , wherein each pump module comprises three pumps. 
     
     
         4 . The system of  claim 3 , wherein each pump comprises a housing, a water space in the housing, a mud space in the housing that is in pressure communication with the water space, a bladder mounted in the housing having a side in contact with the water space and an opposing side in contact with the mud space, and that defines a barrier between the water and mud space. 
     
     
         5 . The system of  claim 1 , wherein the pump module, the subsea module, and the riser module each have a weight less than 50 metric tons. 
     
     
         6 . The system of  claim 1 , wherein the piping in the subsea module includes a portion for bypassing the pump module. 
     
     
         7 . A method of lifting drilling fluid from subsea comprising:
 providing a pump module having a series of pumps;   providing a riser module having controls for the pump module;   providing a subsea module having piping;   forming a mud pump kit by coupling together the pump module, riser module, and subsea module;   coupling the mud pump kit with a subsea riser;   flowing mud from the riser to the pump module via the subsea module; and   lifting the mud to above sea surface by pressurizing the mud with the pumps in the pump module.   
     
     
         8 . The method of  claim 7 , wherein the pump module comprises a first pump module, the method further comprising providing a second pump module that is symmetric with the first pump module, so that the first and second pump modules are interchangeable. 
     
     
         9 . The method of  claim 7 , wherein the pump module, the subsea module, and the riser module are transported individually to a drilling riser on the sea surface with a vessel having a limited capacity. 
     
     
         10 . The method of  claim 7 , further comprising providing a spare pump module, and replacing the pump module with the spare pump module. 
     
     
         11 . The method of  claim 7 , wherein the pump module is controlled with the controls from the riser module. 
     
     
         12 . The method of  claim 7 , further comprising bypassing mud flow around the pump module and through the subsea module. 
     
     
         13 . A method of lifting drilling fluid from subsea comprising:
 providing first and second pump modules that are symmetric to one another, each of the pump modules having a series of pumps;   providing a riser module having controls for the pump modules;   providing a subsea module having piping;   individually transporting the first pump module, the second pump module, the riser module, and subsea module on a vessel and to an offshore rig;   forming a mud pump kit by coupling together the pump modules, riser module, and subsea module on the offshore rig;   coupling the mud pump kit with a subsea riser that is operated in conjunction with the offshore rig;   flowing mud from the riser to the pump modules via the subsea module; and   lifting the mud to above sea surface by pressurizing the mud in the pump modules.   
     
     
         14 . The method of  claim 13 , further comprising providing a spare pump module, and replacing one of the first or second pump modules with the spare pump module. 
     
     
         15 . The method of  claim 13 , wherein the controls in the riser module include a processor and hydraulic power units, the method further comprising using the processor to selectively open and close valves provided with the pump modules.