Underbalanced perforation can substantially reduce formation damage and improve the efficiency of production operation. The field in question is a giant oil field in Southwest Iran, with over 350,000 bbl/day production rates. Reservoir X is the main reservoir of the field and includes 139 horizontal wells out of the total of 185 production wells drilled in the field. Despite its technical difficulties, under-balance perforation has been proven to result in high productivity ratios and has been shown to reduce workover costs if appropriately conducted. Therefore, this study investigated a customized underbalanced tubing conveyed perforation to enhance oil production. First, post-drilling formation damage was estimated using Perforating Completion Solution Kits. Next, high-density guns (types 73 and 127) with high melting explosives were selected based on the reservoir and well specifications. By conducting a sensitivity analysis using schlumberger perforating analyzer program, shot angles of 60 ${}^{\circ }$ and 90 ${}^{\circ }$, shot densities of 16 and 20 shots per meter, perforation diameters of 8 and 10 mm, and helix hole distribution were selected as optimized perforation parameters and resulted in productivity ratios up to 1.18. The current study provides a case study of applying a combination of two previously proven technologies, tubing convoyed and underbalanced perforation, in Iran’s giant oilfield. The method used and the outcome could be used to analyze the efficiency of applying the technology in other green or mature fields.

Unconventional reservoir resources are important to supplement energy consumption and maintain the balance of supply and demand in the oil and gas market. However, due to the complex geological conditions, it is a significant challenge to develop unconventional reservoirs efficiently and economically. At present, unconventional reservoirs are extensively studied, covering a wide range of areas, with special attention to the multiscale characterization of pore structures and fracture networks, description of complex fluid transport mechanisms, mathematical modeling of flow properties, and coupled analysis with multiphysics fields. This work briefly describes the multiscale and multiphysics influences on fluids in unconventional reservoirs, and the modeling and simulation work conducted to analyze them, with the aim to provide some theoretical basis for enhanced recovery from these geo-energy resources. The present article also aims to enhance the community's knowledge of other potential utilizations associated with some unconventional reservoirs, specially related to environmentally-driven projects, including permanent greenhouse gas storage and cyclic underground energy storage.

Underground hydrogen storage has been recognized as a key technology for storing enormous amounts of hydrogen, thus aiding in the industrial-scale application of a hydrogen economy. However, underground hydrogen storage is only poorly understood, which leads to high project risk. This research thus examined the effect of caprock availability and hydrogen injection rate on hydrogen recovery factor and hydrogen leakage rate to address some fundamental questions related to underground hydrogen storage. A three dimensional heterogeneous reservoir model was developed, and the impact of caprock and hydrogen injected rate on hydrogen underground storage efficiency were analysed with the model. The results indicate that both caprock and injection rate have an important impact on hydrogen leakage, and the quantities of trapped and recovered hydrogen. It is concluded that higher injection rate increases H ${}_2$ leakage when caprocks are absent. In addition, lower injection rates and caprock availability increases the amount of recovered hydrogen. This work therefore provided fundamental information regarding underground hydrogen storage project assessment, and supports the decarbonisation of the energy supply chain.

Fully understanding the mechanism of pore-scale immiscible displacement dominated by capillary forces, especially local instabilities and their influence on flow patterns, is essential for various industrial and environmental applications such as enhanced oil recovery, ${\mathrm{CO}}_{\mathrm{2}}$ geo-sequestration and remediation of contaminated aquifers. It is well known that such immiscible displacement is extremely sensitive to the fluid properties and pore structure, especially the wetting properties of the porous medium which affect not only local interfacial instabilities at the micro-scale, but also displacement patterns at the macro-scale. In this review, local interfacial instabilities under three typical wetting conditions, namely Haines jump events during weakly-wetting drainage, snap-off events during strongly-wetting imbibition, and the co-existence of concave and convex interfaces under intermediate-wet condition, are reviewed to help understand the microscale physics and macroscopic consequences resulting in natural porous media.