Successful Drilling of First CBM Horizontal Wells in Indonesia Through Meticulous Drilling Design and Geomechanical Analysis

Abstract

Drilling horizontal wells in soft formations can pose significant risks that require careful planning and execution. During 2014, Virginia Indonesia Co. Limited (Vico) successfully completed two surface-to-inseam horizontal wells to appraise coalbed methane (CBM) production potential on their Sanga Sanga license in East Kalimantan, Indonesia. Both wells passed through soft shales and coals that exhibited breakouts in offset wells, in addition to heavily depleted zones exhibiting large fluid losses in an area well known for shallow gas blowouts. Geomechanical analysis of information from nearby offset wells was used to determine the mud-weight window and fluid properties required to effectively manage these conditions. The results were incorporated into the preliminary well design and planning, and with model matching carried out in real time while drilling operations were underway, any deviations in wellbore integrity were managed as they arose. The drilling success was, in large part, a result of extensive preplanning and a regimented approach to how the wells would be drilled and any instability dealt with promptly. In addition, real-time monitoring that identified deviations from model-based predictions provided invaluable information for planning subsequent wells. The methodical approach to planning and execution of these wells led to their successful completion, with the results potentially reshaping the Indonesian CBM and energy industry.