Definition(s)
Pressurized Mud Cap Drilling
A drilling technique used to drill without returns while balancing a full annular fluid column by using a Light Annular Mud (LAM) cap maintained above an open-hole formation that is taking all injected (sacrificial) fluid and drilled cuttings assisted by surface pressure. The LAM density is chosen based on ability to make LAM and the desired surface pressure that can be maintained and observed. Periodically injecting more of the same fluid into the annulus provides a means to control the surface back-pressure within the operating limits of the RCD and/or riser system.
Source: ABS Guide for Classification and Certification of Managed Pressure Drilling Systems, September 2017. Global Standards
Pressurized Mud Cap Drilling
Variation of MPD, drilling with no returns to surface where an annulus fluid column, assisted by surface pressure, is maintained above a formation that is capable of accepting fluid and cuttings. A sacrificial fluid with cuttings is accepted by the loss circulation zone. Useful for cases of severe loss circulation that preclude the use of conventional wellbore construction techniques.
Source: IADC UBO / MPD Glossary, December 2011. Global Standards