The Assessment of Sandstone Gas Reservoirs in T Gas Field, Bengal Basin, Bangladesh

Seismic inversion (both pre-stack and post stack) is nowadays a robust technique for mapping the reservoir properties especially in cases of sand reservoirs. If it is used in combination with the AVO will not only help in the detection of hydrocarbons but will also delineate its quantification. This study aims the assessment of the reservoir quality of the sandstones of the Titas Gas Field, Bengal Basin using post/pre-stack seismic inversion, AVO analysis and rock physics modeling. The target sand reservoir is subdivided into A, B, and C sand groups. The results of this study clearly distinguished the sandstone and shale of the reservoir units with the help of pre-stack and post-stack inversion analysis. It also demarcates the gas-bearing sandstones both in the shallow zone and target zone. In the target zone, the predicted gas-bearing sandstones have clear boundaries and a high coincidence rate with wells. The A sand group has thick sandstones with wide distribution, good connectivity and high porosity, so that a massive gas reservoirs has developed. The gas bearing zones were further confirmed via AVO analysis and through calibration with well logs data. The methodology presented in this paper a compact one for the full characterization of the reservoir properties from seismic data that may will help in similar other rock units worldwide.