Automated Reservoir Characterization of Carbonate Rocks using Deep Learning Image Segmentation Approach

The objective of this study is to develop a systematic and novel workflow for the automated and objective characterization of carbonate reservoirs with the help of deep learning architectures. An image database of more than 6,000 carbonate thin- section images was generated using the optical microscope and image augmentation techniques. Five features, namely clay/silt/mineral, calcite, pores, fossils, and opaque minerals, were identified with the help of manual petrography of the thin sections under the microscope. A total of four deep learning models were developed, which included U- Net, U- Net with ResNet34 backbone, U- Net with Mobilenetv2 backbone, and LinkNet with ResNet34 backbone. The Ensemble model of U- Net + ResNet34 and U- Net + MobileNetv2 yielded the highest intersection over union (IoU) score of 75%, followed by the U- Net + ResNet34 model with an IoU score of 61%. The models struggled with class imbalance, which was very prominent in the image database, with classes such as fossils and opaques considered to be rare. The statistical analysis of the relative errors revealed that the major classes play a more important role in increasing the final IoU score as opposed to the common understanding that the rare classes affect the model performance. The novel workflow developed in this paper can be extended to real carbonate reservoirs for time efficient, objective, and accurate characterization.