Publications

The ‘easy reservoir’ paradigm sometimes has to be shifted into a more complicated setting, volcanic influenced deposit holds significant unlocked potential in some Indonesian Basins (e.g. Jatibarang Formation), despite being moderately understood and lacking analogue. This study is aimed to reveal the heterogeneity of volcanic influenced fluvio-braided stream, which was claimed as the ‘sandiest’ system, generalized as a uniform reservoir and the influence of volcanic events were poorly considered. An area of 800x700m of sand-gravely outcrop is exposed in the Brown Canyon Area, Central Java, by an active sandstone mining activities, providing the complete stratigraphic architecture of the volcanic influenced fluvio-braided stream. Since several spots are situated as hundreds of height and extremely steep slope, a Digital Outcrop Model (DOM) is established to deliver three-dimensional observation. Drone surface mapping and 120 detail measured-sections were collected by different data acquisition techniques: (1) manual stratigraphic measurement on the accessible area, (2) drone vertical logging on towers area and (3) telephotogrammetry logging on steep slope area. The study reveals north-eastern depositional trend with sediment source derived from the Proto-Ungaran volcanic system. The succession found were 1) black-greenish shale as the oldest unit beneath an erosive pyroclastic, 2) channel complexes with some channel features and overlaid by 3) channelcComplexes with poorly sorted laharic conglomerate as the contact, followed by braided stream beds which were channelized in several ways. Variable discharge concept is introduced in this study. Multi scenarios geocellular model were utilized, in order to have a wide range of channel presence probability. Connectivity measurement shows high number of channel communication, however the presence of tuffaceous beds and gravel beds are indicated to provide reservoir barriers. The findings from this study hopefully will provide valuable insights in exploring such kind of volcanic influenced braided stream reservoir.