Abstract: 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.

Abstract: A system for controlling sand has an expandable screen an an inner string to isolate the sand screen allowing for drilling fluids to be circulated to the bottom of the drilling assembly, before returning up the annulus in normal fashion. Both ends of the expandable screen are mount on an inner string. The inner string is integral with the internals of the bottomhole drilling assembly, allowing for retrieval thereof, including a pilot bit. Upon retrieval an isolation valve will close and seal thus providing sand control integrity in the well. Release from the sand screen will be by pumping a ball down the string and engaging this in a catcher to slim the sliding sleeve open, giving hydraulic access to the liner hanger and engaging slips in the previous casing. Further pressure will release the ball into a catcher, restoring communication through the drill string.

Abstract: A system for controlling sand has an expandable screen and an inner string to isolate the sand screen allowing for drilling fluids to be circulated to the bottom of the drilling assembly, before returning up the annulus in normal fashion. Both ends of the expandable screen are mounted on an inner string by means of a swivel and seals, the former allowing for drill string rotation and the latter ensuring that drilling fluids do not circulate to the inside of the screen. The inner string is integral with the internals of the bottomhole drilling assembly, allowing for retrieval thereof, including a pilot bit. Upon retrieval an isolation valve will close and seal thus providing sand control integrity in the well. Release from the sand screen will be by pumping a ball down the string and engaging this in a catcher to slim the sliding sleeve open, giving hydraulic access to the liner hanger and engaging slips in the previous casing.