The present invention provides drilling systems for drilling subsea wellbores. The drilling system includes a tubing that passes through a sea bottom wellhead and carries a drill bit. A drilling fluid system continuously supplies drilling fluid into the tubing, which discharges at the drill bit bottom...http://www.google.es/patents/US6648081?utm_source=gb-gplus-sharePatente US6648081 - Subsea wellbore drilling system for reducing bottom hole pressure
Subsea wellbore drilling system for reducing bottom hole pressure
