A novel MPD setup has been tested and used at the Kvitebjørn field in the North Sea to make possible the drilling of 8.5″ holes through reservoirs with heavily depleted zones. A central part of the concept has been to use an advanced dynamic flow and temperature model in combination with an automatic choke system to control open hole pressure very accurately.

The paper describes briefly the operations, and discusses challenges and experiences related to making these complex components work reliably together.

The system has proven its potential for minimal variations in pressure at a given open hole position, with accurate automatic pressure control in wells were margins are very small, smaller than frictional pressure losses added when circulating at drilling rate.

This paper focuses in particular on the use of an advanced transient model for automatic choke regulation. Other aspects of the operation are described in more detail elsewhere, see Refs. 1-3. Challenges exceeded expectations, but after a test period with many improvements based on trial and error inside cased hole, the 8 1/2″ sections were drilled successfully with good pressure control.

Keywords:
Upstream Oil & Gas, well control, pwd pressure pwdpressure calcpwdpres-calcchokepre chokepre, rotation, flow rate, annular pressure drilling, calculation, well 2, Bjørkevoll, automatic choke system
Subjects:
Drilling Operations, Pressure Management, Well control
Copyright 2008, IADC/SPE Drilling Conference
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