Publications

Yakin West and Yakin North are offshore oilfields located 8 km south of Balikpapan in East Kalimantan. Major production was established in 1984 and 1985 respectively, two years after initial discovery, from a total 17 new wells and 4 new platforms installed in 20 ft water depth, depleting reserves of 20 MMB over 335 acres. Relatively shallow depths (1800-5000 ft) of the multilayered sandstone reservoirs posed potential production problems through low reservoir pressures and unconsolidated formations.The current production level of 14,000 BOPD was made possible by innovations in completion techniques adopted during initial planning and development. Multi-zone (stacked) gravel-packs provide optimum and selective production, through isolation of each individual reservoir, and required sand control.A new MULTI-MODE concept was designed for submersible pump completions, extending the use of a Y-tool (traditionally as an appendage for pressure measuring devices) to allow a single tubing string to continue, alongside the pump, down into a multiple zone environment. Selectivity is achieved by (slick) wireline shifting of sleeves across each interval, separated by packer sealbore assemblies. The MULTI-MODE completion allows the same well to produce under flowing, pumping or gaslift conditions, with the transition from one mode to another accomplished by wireline, and provides flexibility of alternate producing modes in the event of pump failure. This decreases the potential frequency of workovers normally related to reservoir changes or pump failure.Five wells are completed as dud string completions, with stacked gravel-packs, into deeper reservoirs. All wells were predrilled with a jack-up rig and open-hole gravel-packed. After platform installation, testing, cased-hole gravel-packs and completions were subsequently performed at considerable cost-saving with a hydraulic workover unit.