This document addresses recommended practices for pressurized mud cap drilling (PMCD) from a floating rig with a subsea BOP stack. When massive lost circulation conditions are encountered, PMCD can be implemented to allow well construction operations to continue.
Although this document only addresses PMCD, most of the equipment described may also be used for the surface back-pressure (SBP) method of managed pressure drilling. However, much of the equipment used for SBP is not required for PMCD and is beyond the scope of this document.
The following methods, described briefly, are also used during lost circulation conditions, however, they are outside the scope of this document:
a) blind drilling (see 4.3.2),
b) continuous annular injection drilling (see 4.3.3),
c) floating mud cap drilling (see 4.3.4).