De-Risking Exploration Well in A Mature Basin, Jabung Block, South Sumatra Basin: Application of Avo Analysis in A Sub-Unconformity Play

The Late Oligocene to Late Miocene reservoir as well as basement in Jabung block has been proven filled by hydrocarbon. One of the unexplored intervals in this block is the sub-unconformity (Pre-TAF) play as angular unconformity, which is older than the Lower Talang Akar Formation (LTAF). However, this play has many risks, for instance in the geometry and quality of the reservoir. To de-risk the play, this study proposes to characterize the reservoir by Amplitude Variation with Offset/Angle (AVO/AVA) method for a better understanding of reservoir conditions. Rock physics analysis and AVO forward modeling provide information about reservoir quality. Moreover, the AVO attribute gives reservoir geometry. This study finds that Pre-TAF play reservoir is categorized AVO class 2 with negative value in both intercept and gradient, which indicates good reservoir quality similar to LTAF oil and/or gas reservoir. Several channels are well identified by the P*G AVO attribute that is distributed from basement high in Southwest to basin depocenter in Northeast NEB field. As the result of this study to prove the potential of Pre-TAF play, we are proposing EXPL-Plan-1 well as a play opener to unlock hydrocarbon in this interval.