the wellbore was ten barrels the kick will expand substantially as the kick moves up the choke line 24 to the surface the choke line 24 unit volume in the present example 0 0197 bbl ft thus in a system in 10 000 feet water depth the total choke line volume is 197 barrels fig1 shows the surface choke 44 being operated to keep bottom hole pressure constant as the kick fluid is discharged through the choke 44 a typical indication that bottom hole pressure is constant is a constant drill string pressure as shown by sensor dpp fig1 shows restarting the mud return pump 38 the valves 34 36 to the mud return pump 38 inlet are opened and the valves 30 32 to the choke line 24 are also open the intake pressure set point on the mud return pump 38 measured by sensor spp is set to match the existing pressure at the mud return pump 38 intake the valves 30 32 to the choke line 24 are then closed fig1 shows connecting one of the other auxiliary lines e g the kill line 22 to the choke line 24 using bypass lines or internal passages the bop stack 16 the valves 30 32 at the base of the choke line and the kill line 18 20 are then opened sea water is pumped from the surface down the kill line 22 back up the choke line 24 such pumping displaces the kick fluid.