(214e) Innovative Design, Performance Assessment, and Deployment Strategies of a Novel Modular Reactor for One-Step Liquid Fuel Production from Stranded Natural Gas

The crude extraction process faces a challenge in monetizing the low-volume associated gas that prevails in the oil reservoirs. The absence of an economically feasible technique and supporting infrastructure has negated the formulation of a viable solution for utilizing this associated gas; thereby leaving it stranded. ~9 MT/day of stranded natural gas (SNG) is flared from one reservoir, resulting in ~25 MT/day of CO₂ emissions. Growing emphasis on limiting greenhouse gas emissions and the necessity to find a robust solution to tackle SNG opens an avenue for developing modular technologies that can be deployed directly near the gas well and can convert SNG to value-added products while reducing carbon emissions. Liquid fuel (LF), a high-density energy carrier, is one such value-added product that can be obtained from SNG. It is easy to transport and can directly support the existing energy infrastructure. 9 MT/day of SNG has the potential to produce ~70 barrels/day of LF while co-generating ~75 kW of electrical power. This work proposes a single reactor modular unit that converts SNG to value-added LF. With the development of a novel catalyst in one of our previous works that can enable a tunable H₂:CO ratio and can sustain long-term operation under high pressure without deactivation, the proposed modular reactor can negate the requirement of complex syngas clean-up units and multiple gas compressors. The novel reactor configurations consist of a multi-tubular packed bed setup divided into three intermediate sections: a mixed reforming section, a section for heat exchange, and a Fischer-Tropsch (FT) section. Mixed reforming of SNG uses CO₂ and steam to produce high-quality syngas (H₂:CO = 1.7), which in turn can be used to produce liquid fuels in the FT section of the reactor. The heat exchange section assists in increasing the efficiency of the process by facilitating heat integration within the process streams. This process provides inherent CO₂ utilization and converts pressurized SNG to easy-to-transport LF that can be processed to manufacture motor spirit, diesel, jet engine fuels, and feedstocks for the petrochemical industry. System-level thermodynamic evaluation was conducted using ASPEN Plus software to process ~9 MT/day of SNG by taking multiple plausible cases of reactor configuration, heat integration, and electricity co-generation. Based on the process evaluation and comprehensive techno-economic analysis, a ~56.9% reduction in CO₂ emissions as compared to SNG flaring can be achieved along with an LF minimum selling price of $3.46/gal for steady-state processing of the feed at 100% capacity. Further, in order to account for the depleting volume of SNG in the reservoir and the requirement to strategically implement the dynamic allocation of these modular units in a real oil basin, a real-life case study was constructed for the Bakken oil field. A mixed-integer quadratic programming (MIQP) problem is formulated to determine the optimal deployment and scheduling of our novel modular plants across gas reservoirs to maximize the net present value (NPV) over a 20-year planning horizon. In addition to the nominal case analysis, we also conducted a sensitivity study to assess the impact of key parameters, including carbon pricing, market prices, and variable operating costs. This work establishes the design feasibility of a novel, economically viable, modular technology along with its optimal deployment strategy integrated with a real-life sensitivity analysis for upgrading SNG to value-added liquid fuels while reducing greenhouse gas emissions.