Reservoir Characterization & Dynamic Modeling in Dahab Field, Sirte Basin - An Integrated Approach

Abstract Reservoir characterization and modeling is an important step in developing and operating oil and gas fields. Proper reservoir characterization requires acquiring, analyzing, and integrating all the data and tools to build a comprehensive understanding of a reservoir and its properties. Advanced reservoir simulation models used for predicting future reservoir performance and efficiently exploiting the oil and gas reserves can only be relied on if the reservoir behavior is well understood. In this paper, an integrated reservoir engineering analysis approach is presented. The analysis approach comprises using historical production and injection data, pressure behavior and historical trends, reservoir fluid analysis from different reservoir zones, well log data, and core analysis to properly characterize the reservoir behavior. Reservoir engineering-driven understanding coupled with information from Seismic and geological data was integrated and used for building a robust 3D Geological model. Well Test analysis, waterflooding schemes analysis, and Material balance calculations came in agreement with the inputs/outputs from the different other disciplines. The Dahab field has two fluid regions in the reservoir which explains the change in the GOR behavior over time. Special Core Analysis data (SCAL) indicated that the reservoir permeability is in the same order of magnitude (between 10 and 70 md with an average of 20 md) and the analysis shows three distinct rock types and was represented by three Relative permeability sets and 3 J functions for model initialization. The waterflood analysis was inconclusive (immature waterflood). It has been concluded that water injection has a pressure impact and arrests the declining pressure. The dynamic model initialization shows OOIP is in line with Material balance calculation and the first reservoir dynamic simulation runs showed that the reservoir characterization is properly captured, and models are reliable. Therefore, the main goal in reservoir characterization and modeling is to construct reliable reservoir models that can assist decision-makers in improving field development strategies. The more consistent the model is with the available data, and the more accurate that data is, the more correct the model's predictions will be. This holistic approach helped to ensure the reservoir characterization and modeling were properly captured, making the models more reliable for informing critical field development decisions.