Performing an underreamed gravel pack in a hot, overpressured reservoir is difficult. Underreaming fluid must be non-damaging, provide hole stability and cleaning, and generate a filter cake that can be removed. The gravel pack must be designed to minimize filter cake removal and gravel/formation sand intermixing. Successful underreamed gravel packs have been accomplished in normal pressure environments, but they have not been attempted in overpressured environments because of the associated difficulties.
This paper describes: 1) Displacement procedures used to clean the casing and protect the open hole, 2) Non-damaging underreaming fluid system which meets drilling and completion requirements, 3) Gravel pack design that minimizes gravel/formation sand intermixing, 4) Post gravel pack acid stimulation to remove the underreaming-fluid filter cake, 5) Gravel pack log, and 6) Well performance.