Combination and stratigraphic traps may contribute with significant gas reserves in Bongkot Field, Gulf of Thailand. However, such stratigraphic play cannot be easily defined as conventional seismic interpretation provides mainly structural information. To identify stratigraphic prospects in this area, a seismic pre-stack inversion and reservoir characterization study was carried out. The input dataset consisted of 365 km2 of 3D seismic, six wells, and interpreted time horizons. Following seismic pre-conditioning and rock physics analysis, wavelet extraction and well-ties were performed for each individual well, considering every input angle stack. Constrained by input time horizons, low frequency models were built based on well log and seismic stacking velocity. Inversion parameters were tested; subsequently, final inversion results were subjected to Bayesian classification to obtain a litho-facies volume. In addition, multi-linear regression was used to derive elastic-petrophysical relationships, to generate petrophysical property volumes. The final results included inverted elastic properties, classified litho-facies, computed effective porosity and Vshale volumes. By analyzing these results, several channel and deltaic/sand lobe features could be observed throughout the study area. Connected sand-filled channels with high porosity were mainly observed in the shallow section, as sand distribution appeared sparser and more isolated with increasing depth. Also, the predicted reservoirs in the deeper section were mostly filled with gas, while shallower sand bodies were mostly filled with brine. This observation implied that the high net-to-gross reservoir distribution in the shallow section can be a key factor that hinders effective trapping of hydrocarbons at this level. Since reservoir distribution plays a key role in hydrocarbon trapping mechanism, upside stratigraphic potential was identified from isolated gas-filled channels, mapped from seismic inversion products, to implement a more successful field development strategy in a mature field.

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