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Applied Seismic Reservoir Characterization to Distinguish Coals and Sandstone Reservoir of Southwest Betara Field, South Sumatra Basin, Indonesia

Alamsyah, Muhammad N.; Handono, Bambang W.; Fitrianto, Teguh
Jabung Exploitation, PetroChina International Jabung Ltd., Jakarta, Indonesia.

Seismic reservoir characterization of a 3D seismic and well data has been applied to 60 km2 of seismic over Lower Talang Akar Formation sand reservoirs intervals in Southwest Betara Field of Jabung Block, South Sumatra Basin, Indonesia. The field has produced oil since first production in late 2005 from the sandstone-A reservoirs. The main problem on this field is well distributed of coals on sandstone-A reservoirs interval which affecting seismic reflectivity and shows the ambiguity between coals and sandstone-A reservoir. The objectives of this study are to delineate sandstone-A reservoir distribution laterally by using seismic reservoir characterization methods and to compare the result with previous study.

The sensitivity analysis from log data, seismic multi-attribute and amplitude attribute study has been carried out to solve this problem. Results from crossplot analyses of well data indicate that the coals can be identified and distinguished over and between the sandstone reservoirs by using pseudo log Gamma Ray Index (GRI) within certain cut-off value. By using this pseudo log GRI and generating multi-attribute analysis with linear regression, the GRI volume has been created. Based on this GRI volume, the lateral distribution of sandstone-A reservoir and coals can be created separately by using amplitude attributes of RMS Amplitude, Threshold Value and Sum of Negative Amplitude. These attributes can be used to delineate the paleo depositional environment of sandstone-A reservoir and coals in Southwest Betara Field.

The distribution maps are showing the delineation of sandstone-A reservoirs and coals with NW-SE direction, which is consistent with well data. By comparing these data to the previous study, the result of latest study has been successfully differentiates the sand reservoir and coals, also defines both in laterally distribution within Southwest Betara Field.


AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012