Integration of 3D seismic attributes and well logs for Asmari reservoir characterization in the Ramshir oilfield, the Dezful Embayment, SW Iran

3D seismic attributes and well logs were used to estimated porosity and water saturation in the Asmari Formation in the Dezful Embayment, SW Iran. For this purpose, at first, the 3D seismic volume was inverted base on the model, to obtain acoustic impedance cube. Afterward, the impedance and other attributes extracted from seismic volume were analyzed by multiple attribute regression transform and neural networks to predict porosity and water saturation between wells. Then linear or non-linear combinations of attributes performed for porosity and water saturation prediction. The result shows that the match between the actual and predicted porosity and water saturation improved; using only a single attribute to the derived multi attribute transforms and neural networks model. Based on the results of neural networks, the highest cross-correlation was observed between seismic attributes and the observed target logs between seven wells in the study area. Based on our study, the cross-correlation between actual and predicted porosity and water saturation increased and reached 93% and 90% respectively in the case of using probabilistic neural networks (PNN). Finally, according to the cross-validation results, PNN neural networks are used for porosity and water saturation prediction. We carry out porosity and water saturation slicing from the Asmari Formation for display lateral and vertical heterogeneities, and the result provided a reliable picture from subsurface formations. Porosity maps distribution shows the western portion of the structure is highly porous and should be considered for further exploration and development purposes. A possible reason for this high porosity in the western portion of the studied formation is the presence of sand layers, especially in zone 2.Note that sand volume increased towards west and northwest in direction of shadegan and Ahvaz fields and decreased towards east and southeast to Rag-e-Sefid field. Based on the result between acoustic impedance and core, changes in acoustic impedance were related to changes in the geological nature of the Asmari reservoir in the field. Accordingly, seismic inversion is a powerful tool for studying the details of lithology and sedimentary facies.