APPLICATION OF STOCHASTIC SEISMIC INVERSION AND SEISMIC STRATIGRAPHY FOR MAPPING LTAF THIN SAND RESERVOIRS IN THE COMPARTMENTALIZED UNTUNG FIELD, JABUNG BLOCK, SOUTH SUMATRA
Untung Field located in the Jabung block, South Sumatra basin, to be exact, about 50 km southeast of Jambi City. This study focuses on the Lower Talang Akar formation (LTAF), based on well data, this formation deposited in three types of environments; Braided River, Meandering Channel, and Anomos...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/69105 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Untung Field located in the Jabung block, South Sumatra basin, to be exact, about
50 km southeast of Jambi City. This study focuses on the Lower Talang Akar
formation (LTAF), based on well data, this formation deposited in three types of
environments; Braided River, Meandering Channel, and Anomostosing Channel or
Coastal Plain. LTAF compartmentalized into three compartment due to the major
fault that divides Untung Field. The target reservoir in the LTAF is thin sandstone
intercalate by coal, it is difficult to identify by the seismic data only. Therefore, a
geostatistical approach is needed by performing a stochastic inversion to analyze
the LTAF reservoir in the Unutng field in order to be able to resolve thin layers of
sandstone and see the direction of the distribution of deposition.
This study was used 3D Pre-Stack Time Migration (PSTM) seismic data, with 64
data wells and two wells for validation. Based on the tuning thickness analysis, the
thickness of individual sandstones in the LTAF is below the vertical seismic
resolution, with the stochastic inversion, the unresolved sandstone can be resolved.
The stochastic inversion process carried out with 30 realizations and 150
iterations. From these results the best realization is selected based on the smallest
error map value with a percentage of truth 83.6%. In this study, the results of the
stochastic inversion focus on the density 3D volume where the density can best
separate the lithology of sandstone, shale, and coal. The density value used is based
on the results of sensitivity analysis. In addition, the direction of deposition of the
reservoir is Northeast – Southwest and North-South. By integrating seismic
stratigraphy and stochastic inversion results, channel fill and floodplain sediment
patterns can be seen as facies of the LTAF reservoir. |
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