Publications

The offshore South West Java constitutes one of the few remaining frontier petroleum provinces of Western Indonesia. Open to the Indian Ocean, the area is subject to disruptive environmental conditions, lacks infrastructure for logistics support, and neighbors a protected national park. Although all previous exploration wells were located in the reach of Jack Up legs, operators opted for the use of high-cost floater rigs to drill this challenging setting. With the planned Cula-1 wildcat to be drilled in shallow water and down to 2400m-ss, is using a Jack Up rig feasible and can it be implemented successfully? A drilling risk assessment was performed at the Cula-1 planned location to constrain the uncertainties pertaining to i) the presence of shallow gas, ii) the Jack Up legs penetration, and iii) the environmental conditions. A seismic survey supported the absence of shallow gas at the legs location and along the wellbore. Based on drilling load estimation and soil boring results, the maximum legs penetration was forecasted with an acceptable value of 6m. A statistical assessment of sea and weather observations for the last 25 years established that a Jack Up rig operation, for a target shallower than 2500m-ss, would expose to minimum risk during the annual favorable environmental window of December-March. Cula-1 was eventually spudded early February 2016, in 65m water depth and using the Soehanah Jack Up rig. The operational phase lasted less than 2 months and within the approved budget. The environmental assessment was instrumental in getting it right the first time, avoiding any waiting on weather during rig mobilization and demobilization, and bringing efficiency during jacking up and jack down operation. No Lost Time Incident was experienced, drilling being even performed faster than planned, and the well delivered key geological inputs to the exploration team.