Reservoir Characterization and Quantitive Interpretation (QI) Using 3D Seismic and Well Logs Data of Mishrif Formation a Case Study Southern Iraq

Abstract

Seismic reservoir property is one of the most important components of the seismic interpretation analysis. The research describes a successful use of a model-based seismic inversion tool and probabilistic neural network (PNN) to post-stack 3D seismic data for the identification of hydrocarbon reservoir zones within the Mishrif Formation. It represents an important formation in Iraq geologically and economically. The objective of this work is to evaluate reservoir characterization and increase the method to obtain better information about reservoir characterization by enhancement and assessment of petrophysical properties of Mishrif Formation such as (P-wave, effective porosity, density, and water saturation). Well logging data, well tops and 3D seismic were used as input to achieve the goal of this along with Petrel and Hampson Russel (The strata and emerge modules). Two horizons were picked in the Two-Way Travel Time (TWT) domain and converted to depth maps by using average velocity of wells. The TWT and depth maps of the Mishrif and near Ahmadi formations show highly developed structures in the southwest and southeast, with a N-S axis, and generally dipping toward the NW. The results of the acoustic impedance horizon units within the Mishrif Formation showed low acoustic impedance values, with higher values observed at the crest and on the northern sides of the N–S anticline axis, as well as in the southwestern part. The final results of the merged and horizon slices of P-wave data showed low velocity, high effective porosity, low water saturation, and low density within the reservoir units of the Mishrif Formation, with improved values observed at the crest, on the northern sides of the N–S anticline axis, and in the southwestern part. Two carbonate buildups within the Mishrif Formation were identified, and seismic attribute analysis was used to determine the boundaries of these buildups and to estimate their reservoir characteristics. The findings from the carbonate buildups and horizon slices revealed low acoustic impedance, low density, low P-wave velocity, high effective porosity, and low water saturation values. Based on all results and attribute analyses, it is recommended to drill an exploration well targeting the stratigraphic carbonate buildup located in the southwestern part of the 3D seismic survey area of the X Oilfield.