Publications

The Kutei Basin is bounded to the south by the Paternoster Platform and Adang flexural zone. In the last two decades, no exploration success has been recorded in the southern margin of the Kutei Basin, with wells drilled in the area mostly ending up as dry holes. Post-mortem analyses show trap and charge to be missing. The SIS-A#1 exploration well was drilled in the South Sesulu Block to test Middle to Late Miocene sandstone reservoirs. Early to Late Miocene shales were expected to be the source rock, as well as providing good intra-formational seals. Structural traps were formed by Early Miocene inversion. Although 3D seismic acquired in 2010 imaged the traps better than earlier attempts, trapping still became one of the major risks due to the location of South Sesulu in an area of high-intensity faults within the Adang flexural zone. Gas, rather than oil, was expected in the trap, since geochemical data from offset wells point to the source rocks being Type III kerogen. SIS-A#1 was drilled to a TD of 9,505 ft MD in a Middle Miocene section. The well penetrated good quality Middle to Late Miocene deltaic and upper slope sandstones with porosities up to 30%. SIS-A#1 flowed 17.5 MMcfd of dry gas in cased-hole tests from a Late Miocene sandstone.