| 摘要 |
A system comprising a drilling vessel, a riser connected to the drilling vessel, a drillstring within the riser, the drillstring extending into a borehole, a drill bit connectable to the drillstring, a pump system comprising an inlet in the riser and an outlet to the drilling vessel, and a pump controller adapted to control a pressure within the riser and the borehole by raising or lowering a fluid level within the riser. |
