The wells in Soka field in onshore South Sumatra, Indonesia are drilled through a fractured carbonate reservoir (Baturaja formation) where severe circulation losses and kicks while drilling are commonplace. Drilling in one of the wells in the field, Soka 2006-1 was suspended for two years due to total losses combined with gas kicks. Almost two months were spent after total loss of circulation was experienced trying to control and drill Soka 2006-1 to no avail. The well was plugged and abandoned on July 2006 with the intention of returning to it and finishing it once an appropriate approach can be developed to address the drilling issues that were encountered.

The approach chosen for re-entry operations in Soka 2006-1 was a managed pressure drilling (MPD) technique called Pressurized Mud Cap Drilling (PMCD). A rotating control device (RCD) is the main component used in PMCD operations, the objective of which is to eliminate the non-productive time (NPT) associated with drilling when loss – kick scenarios occur.

A new well, Soka 2006-6, was also planned to be drilled in the area using the same technique, but with the addition of a downhole isolation valve that was to be installed and cemented together with the last casing string above the section where losses are expected. The casing valve allows for safer and faster tripping operations and more importantly, can serve as a downhole lubricator that will help facilitate the running of the completion assembly in PMCD mode. A casing valve could not be installed in Soka 2006-1 as the casing string above the loss zone was already in place.

This paper describes the planning and implementation of the PMCD technique in both the Soka 2006-1 and 2006-6 wells and discusses the results of the drilling operations. Furthermore, it explains how drilling in PMCD mode allowed re-entry operations in Soka 2006-1 to reach the target depth in less than a day after total loss of circulation was again experienced, and how the completion assembly was run and cemented in PMCD mode.

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