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

摘要

An arrangement and method for controlling and regulating bottom hole pressure in a well during subsea drilling in deep water involves adjustment of a liquid/gas interface level in a high pressure drilling riser up or down to change the slope and offset of the pressure gradient in the well. The arrangement may include a surface BOP and gas bleeding outlet at the upper end of the drilling riser, a lower BOP with a by-pass line, and an outlet at a depth below the water surface that is connected to a pumping system with a flow return conduit running back to a drilling vessel or platform.