Methods and apparatus for drilling with a multiphase pump

A method of transporting cuttings from a subsea wellbore, comprising:

• urging the cuttings in a fluid slurry from an annular area in the wellbore to a pump assembly in fluid communication with the wellbore;
• utilizing the slurry to operate at least one plunger member of the pump assembly in a first direction;
• and utilizing a power fluid to operate the at least one plunger in a second direction, thereby pumping the slurry towards the surface of the sea.

A method of reducing equivalent circulating density in a subsea wellbore, comprising:

• pumping a fluid through a drill pipe from a surface of water to a drill bit in a wellbore;
• circulating the fluid and cuttings to the top of the wellbore;
• and adding energy to the fluid and cuttings with a multi-phase pump, thereby urging the fluid and cuttings to the surface.

A sub-sea fluid pumping system, comprising:

• a pair of substantially counter synchronous fluid pumps locatable adjacent a sub-sea wellbore and in fluid communication with an annulus therein;
• at least one fluid path for communicating wellbore fluid between the annulus and the fluid pumps;
• and at least one power fluid line for providing power fluid to the fluid pumps.

A sub-sea fluid pumping system, comprising:

• a pair of substantially counter synchronous fluid pumps disposed on a riser pipe at a location between a surface and a sea floor, whereby the fluid pumps are in fluid communication with an annulus of a sub-sea wellbore;
• at least one fluid path for communicating wellbore fluid between the annulus and the fluid pumps;
• and at least one power fluid line for providing power fluid to the fluid pumps.