Use of glass bubbles in low-density fluids, Tambun field drilling program, Indonesia

The Tambun Field in Indonesia was initially developed in the 1990s to exploit oil reserves from the Baturaja Formation (BRF). Since the initial drilling program, reservoir pressure in the field has steadily declined from more than 2,600 psia to less than 1,970 psia resulting in severe circulation losses and an increase in non-productive time (NPT) during drilling and completion programs. The use of hollow glass microspheres, commonly known as glass bubbles—a low density additive (LDA)—in ultra-low density drilling fluids (< 0.9 g/cc) is a novel approach in addressing this issue. A seven-well managed pressure drilling and completion exercise was undertaken by P.T. Pertamina EP Jawa region in the first half of 2010 under challenging drilling conditions in this low-pressure, high-permeability carbonate reservoir. The glass bubble mud system was selected because it would reduce or eliminate lost circulation and stuck pipe problems, reduce formation damage, eliminate the need for post drilling stimulation and give early analysis of reservoir behaviour and production rates. This paper describes the front-end engineering design, project management, risk mitigation, detailed engineering and design, operational results and lessons learnt from this project.