Geophysical Reservoir Characterization and Modeling of Marrat Carbonate Reservoir in Minagish Field, West Kuwait

Abstract As a part of an integrated field development study, comprehensive seismic interpretation, velocity modeling and inversion were carried out for the Minagish Marrat reservoir. The geophysical lithology-porosity effects were imaged and quantified for the first time, and used for detailed reservoir characterization and 3D geological modeling. Recently acquired 3D PSTM seismic data was used to interpret and refine the key horizons over the Minagish field. The multi-attribute analysis was used to quality control the horizon picking and to interpret the faults accurately, particularly since the data was contaminated with multiples. Advanced post-stack attribute analysis provided insights into the faults, fractures and matrix properties of the heterogeneous carbonate sequences to understand the reservoir architecture at all scales. Several velocity modeling scenarios with combination of wells and seismic velocity were evaluated to investigate the structural uncertainty for accurate depth conversion. A total of 57 key wells were used to build a robust velocity model from surface to 13,000 ft with an average accuracy of + 10 ft at the reservoir level. 3D PSTM seismic volume was used for post-stack acoustic impedance inversion to map the reservoir properties from seismic. The objective of one of the key rock physics analysis was to understand the mineral-elastic response of the reservoir rocks. Advanced well log data conditioning with rigorous quality control was performed on 22 wells used in the inversion process. Fully integrated core and well log derived mineralogy results were used to prepare sonic-density scatter plots to understand and calibrate the response in terms of mineralogy (e.g. clay, dolomite, and calcite) as well as lithofacies with varying porosity. This meticulous calibration resulted in good relative and absolute acoustic impedance transforms to derive porosity, which in-turn was used for modeling the reservoir properties in 3D geological model. This model has provided a strong base for horizontal and multilateral well placement as the results from recently drilled first horizontal well has shown excellent match with the model predicted reservoir structure, lithofacies and porosity.