Characterisation of unconventional reservoirs in NE Java based on the brittleness index, permeability, mobility, and transmissibility

Shale hydrocarbons are sources of oil and gas trapped in shale rock formations which are rich in organic material. Oil and gas reservoirs can be detected by knowing the characteristics of the rocks. This study attempts to determine whether permeability, mobility, transmissibility, and the brittleness index (BI) can be used for identifying unconventional reservoirs. The research area includes the geological formations in the OD Field of the NE Java basin. We perform acoustic impedance seismic inversion on 48 two-dimensional seismic sections and we analyse well logs from three wells (namely M-1, M-2, and M-3). The results obtained show that wells M-1, M-2, and M-3 have small permeability, mobility, and transmissibility parameters. The distribution of the BI values is 0.46-0.54 falling within a less brittle category. The Kujung formation has a BI value of 0.46-0.76 falling within a low brittle category. The Ngimbang formation has a high BI value of 0.52-0.82 with a brittle category.