公开(公告)号：WO2019014431A1

公开(公告)日：2019-01-17

申请号：PCT/US2018/041789

申请日：2018-07-12

Applicant: BP CORPORATION NORTH AMERICA INC.

Inventor： FLORES, Rafael ,  FONTENOT, Hunter ,  HOWES, Thomas B. ,  KAHN, David

IPC: E21B33/076 ,  E21B43/12 ,  E21B47/01 ,  E21B21/00 ,  E21B21/08

CPC classification number: E21B33/076 ,  E21B21/001 ,  E21B21/08 ,  E21B43/12 ,  E21B47/01

Abstract: A method for drilling a wellbore includes pumping a drilling fluid from a drilling vessel (102) into a wellbore through a drillstring (142) extending through a marine riser (106) into the wellbore with a surface pump (112). The marine riser (106) extends from the drilling vessel (102) to a subsea blowout preventer (104). The method also includes pumping the drilling fluid from a first annulus (146A) in the riser (106) to a second annulus (146B) in the riser (106) with a subsea pump (126) positioned between the blowout preventer (104) and the drilling vessel (102). The first annulus (146A) is disposed below the second annulus (146B). Further, the method includes adjusting a pump rate of the subsea pump to control the amount of backpressure trapped in the wellbore.