Seismic Reservoir Characterization of the Abadi Gas Field, Masela PSC Block, West Arafura Sea, Eastern Indonesia

This paper presents the results of seismic inversion work of the Abadi gas field in Masela PSC Block, West Arafura Sea, Eastern Indonesia. The field was discovered in 2000 and has undergone a series of reservoir characterization programs, which include seismic inversion, depth conversion and reservoir geology. The basic data sets for this study consist of 2,060km of 3D seismic, and well data of Abadi-1, Abadi-2 and Abadi-3. A discrepancy exists between velocity measurements in wireline logs and those in laboratory core sample measurements. It is essential to reconcile this discrepancy for calibration of seismic-inverted properties. A method of rock physics modeling was applied, first in order to correct the log data and secondly to optimize the seismic inversion. Quantitative relationships were identified between the seismic-inverted and petrophysical properties by the modeling. Intensive ultra-sonic measurements on core samples were conducted to properly calibrate the seismic-inverted properties. Seismic inversion was conducted for the 3D seismic data and the modeled sonic and density logs of the three wells. Three Elastic Impedance (EI) volumes were constructed from three reflection-amplitude-angle stacks. Based on the relationships between seismic-inverted and petrophysical properties, the EI volumes were converted into a total porosity volume and a lithology * Inpex Masela, Ltd. ** Japan Oil, Gas and Metals National Corporation *** Inpex Browse, Ltd indicator volume which discriminates sand and shale. The volumes indicate a 3D distribution of the sandy reservoir which is used as an input for dynamic simulation of the Abadi Field’s gas production. The seismic inversion provides high resolution lithological contrasts that correspond to stratigraphic boundaries. Reserve estimates of the Field and their uncertainty have been repeatedly updated based on the successive programs of the reservoir characterization study. Seismic data reprocessing and wavelet analysis are being conducted in order to improve the quality of both the seismic inversion and depth structure mapping for better reservoir characterization in the future.