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Most oil fields today are mature, and the majority of the reservoirs in the Middle East are carbonate rocks characterized by high temperature high salinity (HTHS), heterogeneous mineral composition, and natural fractures. Enhanced oil recovery (EOR) methods are used for boosting oil recovery from the aged reservoirs beyond primary and secondary recovery stages. Nevertheless, it can be a challenging task to employ EOR techniques in these aged carbonate reservoirs. This is because carbonate reservoirs have mixed-to-oil-wet wettability with temperatures exceeding 85 °C and salinity of over 100,000 ppm, which renders secondary EOR-methods such as waterflooding ineffective. Therefore, even though carbonate reservoirs contain 60–65% of world's remaining oil, with immense intrinsic economic prospects, the oil recovery process from carbonate reservoirs remains a considerable challenge. Chemical-EOR (cEOR) techniques, like SP based cEOR, have shown marked promise in improved oil recovery, mainly from clastic reservoirs with medium temperature and salinity, unlike carbonate reservoirs. During SP-floodings, the surfactants get adsorbed due to the mineral composition of the carbonate rocks, and polymer degradation occurs due to HTHS conditions. Consequently, new surfactants and polymers have been structurally conformed and tested to improve their robustness and related recovery efficacy. For instance, Guerbet alkoxy-carboxylate surfactants demonstrated good stability at temperatures over 100 °C and salinities up-to 275,000 ppm, yielding tertiary recovery of 94.5% and low adsorption of 0.086 mg/g of rock. The cationic Gemini surfactants, zwitterionic or amphoteric class of surfactants are also suitable for HTHS carbonates. Besides, effective biosurfactants sourced from plant such as, soy, corn, etc., are non-toxic and readily biodegradable. The hydrophobically associating polyacrylamide (HAPAM) and its modified nanocomposite derivative can act as replacement surfactants, due to their wettability altering and robust characteristics. Novel polymers viz., NVP-based, novel smart thermoviscosifying polymers (TVP), soft microgel, and sulfonated polymers, are also relevant to HTHS carbonate applications. Xanthan gum, scleroglucan, and schizophyllan biopolymers have been noted to resist HTHS and low permeability conditions, requiring lower concentration and having low adsorption. Recent surfactant-polymer (SP) formulations also can be applicable for HTHS carbonates with excellent ternary recoveries (93.6%) and minimal retention (0.083 μg/g of rock). Such low retention values suggest low surfactants cost with minimal environmental impact. Moreover, several successful field applications in carbonates were conducted in preceding years; however, the performance of some novel surfactants under HTHS carbonates is yet to be fully understood. Hence, this comprehensive review aims to provide renewed perspectives on surfactant and polymer optimizations for field applications in HTHS carbonates. A list of recommendations is presented as guidelines for efficient SP-flooding designs. This critical literature appraisal furnishes an array of potential manifestations for successful field application of SP-flooding in HTHS carbonates, which holds both economic and environmental feasibility. [Display omitted] [ABSTRACT FROM AUTHOR]

• We model CO 2 source-sink matching for decarbonizing India's electricity. • Domestic and Middle East CO 2 storage sites are explored for optimized matching. • International matching with enhanced oil recovery enhances economic feasibility. • CO 2 shipping could expand the potential of CCUS in India's climate mitigation. India is the third largest CO 2 emitter in the world and the ascending trend has not shown clear signs of leveling off. Electricity generation is the most important contributing sector. This paper examines the role of CO 2 capture, utilization and storage (CCUS) in decarbonizing India's electricity. We build a source-sink matching optimization model and unlike previous research, include transport by ship to overseas CO 2 storage sites. We initialize the model with open-source data on power sector emissions and sinks to work out the least-cost solutions for achieving various CO 2 matching scenarios. CO 2 can be captured in fossil-fuel-fired power plants in India, while the utilization and storage could be either within or beyond the country's border. We assess the potential chain of shipping CO 2 to the Middle East for enhanced oil recovery and CO 2 storage. The economics of such international CCUS chains may affect the role of CCUS in India's decarbonization scenarios. We provide first order estimates of costs and conditions to make such a proposition attractive. The model is available with an open-source license and is customizable to include additional sources, onshore and overseas sinks, and shipping terminals. [ABSTRACT FROM AUTHOR]