ARRANGEMENT AND METHOD FOR REGULATING BOTTOM HOLE PRESSURES WHEN DRILLING DEEPWATER OFFSHORE WELLS

摘要

An arrangement and a method to control and regulate the bottom hole pressurein awell during subsea drilling in deep waters: the method involves adjustment ofa liquid/gasinterface level in a drilling riser up or down. The arrangement comprises ahigh pressuredrilling riser and a surface BOP at the upper end of the drilling riser. Thesurface BOP hasa gas bleeding outlet. The riser also comprises a BOP, with a by-pass line.The drillingriser has an outlet at a depth below the water surface, and the outlet isconnected to apumping system with a flow return conduit running back to a drillingvessel/platform.