Identification of lithology and fluid content using simultaneous inversion in the “IM” field of the North Sumatra Basin

Abstract

The “IM” field is an oil and gas exploration field located in the North Sumatra Basin. It was previously identified that in this field hydrocarbons were found in the form of gas condensate. This study aims to characterize the reservoir in terms of lithological distribution and fluid content. The research includes carbonate reservoir targets located in Middle Miocene Malacca Limestone. The data used in this study are 3D seismic data and two wells data. The simultaneous inversion method is applied to process data so that research objectives can be achieved. The simultaneous inversion method produces Acoustic Impedance (Zp), Shear Impedance (Zs). The results show that in the gas reservoir the acoustic impedance (Zp) value is around 16542 - 18917 (ft/s*g/cc) and the shear impedance(Zs) is around 8375 (ft/s*g/cc) while in the water reservoir the acoustic impedance (Zp) value is around 21292 - 23667 (ft/s*g/cc) and the shear impedance (Zs) is around 18500-20525 (ft/s*g/cc). The results showed that the reservoir distribution has a North West-South East orientation.