Publications

In 2004, Medco E&P Indonesia initiated an integrated study, survey, and exploration drilling campaign to prove heavy oil resources in South Sumatra covering an area of approximately 525 km2. During 2011-2012, five exploration wells were drilled with continuous coring specifically for heavy oil evaluation. Laboratory cores analysis from those exploration wells proves there is a significant heavy oil resource in the Tb-Tl structure. The heavy oil accumulation occurs in relatively shallow two formations: the Telisa Formation (depth 50–200 ft) and the Talangakar Formation (depth 175–400 ft). Petrophysical evaluation is quite difficult especially for water saturation (Sw) determination due to meteoric water infiltrate of the reservoir. The aim of the static model study was to characterize the Tb-Tl structure heavy oil reservoirs and to estimate Original Oil in Place (OOIP). The main challenges to building a reliable static model in the exploration stage are sparse two-dimensional seismic and well data. The results have a wide range of uncertainty, therefore several factors that assure commercial development have also been considered, including minimum net thickness, Sw multiplier for areas where depletion is known to be significant, and exclusion of the upper flow unit in the Telisa Formation, which is already depleted. Depositional facies are distributed deterministically and are based on both regional geology and local observations. Lithofacies are distributed based on a truncated Gaussian simulation technique and a probability distribution that was related to geological concepts and data from observations of cores and well logs. The water saturation model is generated using a J-Function, after finalizing transition zone analysis for three rock types determined from lithofacies distributions within various zones in the model. Although uncertainties exist, the OOIP estimation result is thought to be reasonable for initiation of a pilot project plan of the field.