Publications

The Tangguh fields, located in the Bird’s Head region of West Papua, are currently producing ~2.1 Bcf of gas per day and have become the largest gas producing fields in Indonesia. More than 50 exploration, appraisal and development wells have been drilled in Tangguh, including 10 development wells as part of the Tangguh Train 3 project during the 2019 - 2022 period. Several drilling challenges have been experienced by those wells with WDA-06/ST-1 experiencing particularly severe problems.

Tangguh is considered as an extremely challenging area to drill wells. The shallow interval is prone to risks associated with shallow gas. The underlying Miocene-Eocene aged karstified limestone interval is prone to total losses and instability, while the deeper Paleocene-Mesozoic interval is characterized by overpressure. Among those sequences, the Miocene-Eocene aged karstified limestone presents the most severe drilling challenges (excessive torque and drag, borehole instability, losses, pack off, stuck pipe) and account for the majority of Non-Productive Time in most wells.

WDA-06/ST-1 was the sixth development well drilled from the WDA platform in the Wiriagar Deep Field, targeting the Jurassic reservoir. The original hole experienced several instances of stuck pipe caused not only by drilling through the Miocene-Eocene aged karstified limestone while on total losses, but also by the sub-optimal attack angle when penetrating faults. Poor seismic data quality resulted in significant seismic interpretation uncertainty for the well design. Bottom Hole Assembly had to be cut following the final stuck pipe event which led to the side-track of the original borehole. The well was eventually safely drilled to the target depth.

Prominent learnings from this well include trajectory optimization to avoid penetrating faults and caves within the same depth interval and understanding optimal angle of intersection with faults. Incorporating these learnings has led to a substantial improvement in the drilling performances of subsequent wells in the Tangguh area.