Scorecard to Asses Risk Level of Upside Potential, Case Study in South Sumatera Basin

South Sumatra Basin has been a source of oil and gas since the early 1900s. It was regarded as one of Indonesia’s most productive hydrocarbon producers since then. Based on a long history of oil and gas field located in South Sumatra Basin, those fields were categorized as mature field ( Aprilian, et al, 2003 ). In addition, South Sumatra Basin is an inverted post-arc tertiary basin, which has a complex evolution history from late Eocene-Oligocene extension to late Miocene and Pliocene compression (Carrilat, et al., 2013). Meanwhile, hydrocarbons are derived from early Eocene to late Oligocene source rocks. It started to move 2 or 3 million years ago which then charging the reservoir rock. There are five formations in South Sumatra basin—Lahat Formation, Talang Akar Formation, Batu Raja Formation, Muara Enim Formation, and Air Benakat Formation. These formations have been proven as containing hydrocarbons ( Figure 2 ). Since it is critical for maintaining oil and gas production, Pertamina recently outlined a new methodology for assessing upside potential in South Sumatera Basin. The focus-study areas are Prabumulih-Limau anticlinorium and South Prabumulih.