Publications

South Saubi-1 well is a deepwater vertical exploration well recently drilled by Kangean Energy Indonesia (KEI) in Q3-2016. Narrow window between pore pressure gradient and fracture pressure gradient required 6 casing strings to be installed. Hole enlargement while drilling (HEWD) was applied to drill and enlarge simultaneously 17”x20” hole for 16” liner, 14-3/4”x17-1/2” hole for 13-3/8” casing, 12-1/4”x14-1/2” hole for 11-3/4” liner, and 10-5/8”x12-1/4” hole for 9-5/8” casing. Ball-drop-activated underreamers which had to be placed above LWD-MWD tools would leave 120-180 ft rathole remain not-enlarged. Additional trip is required to enlarge the rathole. Recently, flow-cycle-activated near-bit underreamers for 12-1/4”x14-1/2” and 10-5/8”x12-1/4” became available to be used in combination with ball-drop-activated underreamers to drill, enlarge, and reduce the rathole to ±18 ft in one run. At 12-1/4”x14-1/2” hole, integrated dual-underreamer was successfully used with RSS (Rotary-Steerable-System) to drill and enlarge the 1,411 ft section while correcting the hole deviation. Determining the working flow rate and pressure drop was important for keeping the RSS-pad working and full dual-underreamer arms opening. Another dual-underreamer was also successfully used to drill and enlarge 1,418 ft of 10-5/8”x12-1/4” hole in MPD (Managed-Pressure-Drilling) mode and set 9-5/8” casing to seal off Cepu-Shale. SWD (Seismic-While-Drilling) was utilized in BHA to identify the top Carbonate-Reservoir to minimize remaining Cepu-Shale when drilling the next carbonate section where total loss situation with PMCD (Pressurized-Mud-Cap-Drilling) was anticipated. Although the hole caliper was not measured in any of under-reamed sections, the fact that casing/liner were successfully run to bottom without any issue is the evidence of the good hole conditions as a result of underreamers. Integrated dual-underreamer in 2 hole sections at South Saubi-1 well proved saving 57 hrs rig time (~US$ 1,425,000 drilling cost) by eliminating dedicated hole-opening trips. This was the first application of integrated dual-underreamer in Indonesia.