Publications

Kerisi oil field (Kerisi) is located in Block B in the South Natuna Sea in a water depth of about 308 ft. Kerisi was discovered in December 1990, by Well Kerisi 1-A, with gas shows in the Upper Gabus (UG) and Lower Gabus (LG) reservoirs and some oil shows in the LG reservoir. Drilling of Kerisi-3 and Kerisi-4 wells in 2001 found a significant amount of oil contained within the UG reservoirs. The finding prompted the accelerated development of Kerisi and the nearby Hiu gas field. Both fields are satellite fields to the Belanak field. Kerisi has been a success story. Eight producers (including three horizontal wells) and one injector were optimally placed by utilizing seismic attributes and MWD/LWD technology. Successful drilling and completions provided good well productivities, allowing production to be maintained at a plateau rate of 50,000 BPD of oil and condensate for about a year before decline commenced. The average annual oil rate decline was 43% in 2009 and is expected to slow down to 38% in 2010. To mitigate the future decline and improveestimated ultimate recovery (EUR), optimization efforts, infill drilling and improved oil recovery processes have been evaluated. With gas injection at 50 MMSCFD, optimal gas lift, and two infill wells as currently planned, the base oil recovery could be improved by 31%. It could be improved by another 43% if waterflood and immiscible wateralternating- gas injection (IWAG) were implemented. The waterflood feasibility study is ongoing while IWAG and miscible wateralternating- gas injection (MWAG) need further detailed subsurface evaluation.