There is not much correlation between sand content and P-wave impedance in faulted basins, and the prediction results cannot be guaranteed. Due to sedimentary facies control, there is inconsistency between sand content and low frequency trend of P-wave impedance, causing problems for seismic inversion modeling, which directly affects final seismic inversion results. The acoustic impedance increases with burial depth. When the same layers of sand and shale formation endure different compaction, the acoustic impedance values will be different. Therefore, The seismic inversion modeling of faulted basin is different from that of conventional basins. The authors built an inversion model using uncompact sandstone percentage, directly compensating for the low frequency trend of the inversion model. In addition, the model's intermediate frequency is similar to P-wave impedance, ensuring that the inversion results are converged correctly. The final results of the inversion can be used directly as sandstone percentage. The aforementioned method was applied to Liaohe Beach in the Bijialing region and obtained optimistic lithology inversion effects:the results were correlated well with the depositional facies map and with lithology in the well borehole. The inversion results can be used to define the sand body horizontally and can separate sand bodies vertically, which is very difficult on conventional seismic section. Therefore the inversion results played an important role in reservoir prediction.
Key words
sandstone percentage curves /
modelling /
inversion /
Bijialing region
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Funding
Supported by Project of National Natural Science Foundation (No. 41430322)
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