During marine oil–gas extraction, significant amounts of carbon dioxide (CO₂) gas are often produced. Effectively separating these associated CO₂ gases during extraction has become a critical technical challenge. Therefore, this paper aims to enhance the efficiency of CO₂ hydrate-based capture technology and conduct relevant research. The goal is to increase the driving force for hydrate formation by combining the traditional thermodynamic additive TBAB with pressure modulation and to improve the hydrate formation rate through the use of multiple kinetic promoters. This paper presents the initial investigation into the effect of the thermodynamic accelerator tetrabutylammonium bromide (TBAB) on the characteristics of CO₂ hydrate formation. The promotion effects of TBAB solutions with varying mass concentrations (3%, 5%, 7.5%, 10%) and reaction pressures (3 MPa, 4 MPa) were subjected to a systematic analysis, and the optimal conditions were identified as 4 MPa and a 5 wt% TBAB concentration. Subsequently, the impact of combining TBAB with kinetic promoters (SDS, nano Al₂O₃, L-methionine, L-leucine) on CO₂ hydrate generation characteristics was further investigated. In this paper, the effect of a single promoter on the generation characteristics of CO₂ hydrate was investigated, and the efficient carbon trapping ability of the complex promoter was verified, which provides theoretical support for the application of CO₂ trapping technology using the hydrate method.

To manage the interactions between wax and hydrate formation, a comprehensive understanding of the system’s thermodynamics and flow characteristics is essential. Wax and hydrates coexist under low-temperature and high-pressure conditions, mutually influencing each other both thermodynamically and kinetically. This study focused on two main aspects: how wax affects the rate of hydrate formation in the oil–water system and how hydrate formation influences the thermodynamics of wax crystal precipitation. The presence of wax decreased the rate of hydrate formation, especially at higher wax contents. In systems with high wax content, over 70% of wax precipitated before hydrate formation, leading to less precipitation within the hydrate formation temperature range. With low water content, there were more nucleation sites for wax crystals in the oil phase, resulting in a greater difference in precipitation rates among different wax contents. For water content greater than 10%, the differences in precipitation rates were less significant, indicating a diminished effect of water content on wax crystal precipitation rates. Hydrates’ hydrophilic nature had a limited impact on wax crystal nucleation and growth. Generally, wax crystals precipitate before hydrate formation, necessitating control measures for wax deposition during production processes.

Retained water associated with water-locking can restrict gas production in heterogeneous tight sandstones, and the activity and phase stability of many surfactant treatments are reduced under high-temperature, high-salinity (HTHS) conditions. In this study, a composite surfactant formulation, CSF-1, designed to lower gas–brine capillary resistance and adjust sandstone wettability under representative reservoir constraints, is reported. Its performance was evaluated using thermal aging, surface tension and contact angle measurements, geochemical compatibility tests, laser diffraction, SEM/EDS, and core flooding combined with stagewise low-field nuclear magnetic resonance (LF-NMR). CSF-1 remained macroscopically homogeneous after aging at 170 °C in 188.314 g/L hypersaline brine and retained low gas–brine surface tension when measured at 25 °C after aging. In core flooding tests, CSF-1 increased the apparent gas permeability from 0.203 to 0.388 mD relative to the SFW-saturated water-locked state, corresponding to a 91.1% improvement. One- and two-dimensional NMR measurements provided comparative relaxation domain evidence that CSF-1 promoted the removal and redistribution of relatively mobile and weakly restricted fluid signals and reduced residual signal clustering. The shortest T₂ relaxation domains were less affected. The absence of replicate core flooding and associated LF-NMR runs, together with the non-equivalent Ref-S comparison, precludes a statistically rigorous cross-agent performance ranking. These results support the laboratory water-locking mitigation potential under the tested conditions, without implying calibrated pore-size-resolved removal or field-scale confirmation.

Kinetic hydrate inhibitors (KHIs) have shown significant potential in preventing hydrate blockages and ensuring flow assurance by delaying hydrate nucleation and aggregation. However, the molecular mechanisms by which KHIs influence the early-stage growth and stability of hydrate fluids under oil and gas flow conditions remain insufficiently understood, limiting the optimization and development of more efficient formulations. In this paper, molecular dynamics (MD) simulations were employed to systematically investigate the regulatory effects of two representative KHIspolyvinylpyrrolidone (PVP) and polyvinylcaprolactam (PVCap)on gas hydrate prevention; and the interaction mechanism between the molecules was elucidated by combining molecular dynamics simulations with Density Functional Theory (DFT). Key parameters, including the number of cage structures, the water molecule ordering parameters, and the potential energy, were also analyzed to assess the inhibitors’ impacts on gas hydrate growth and fluid stability. The results reveal a triple synergistic mechanism involving site-blocking, mass transfer interference, and hydrogen-bond disruption, which provides a theoretical basis for the design and optimization of high-efficiency KHIs in the traditional fossil fuel transportation, particularly in oil and gas flowlines.