Preparation And Evaluation Of Carbon Dioxide Emulsion For Replacement Of Natural Gas Hydrate

Natural gas hydrate is one of the most promising energy sources in the 21st century,and major countries in the world have invested a lot of resources in research.In this paper,the preparation and stability evaluation of CO₂emulsion were studied in the CO₂emulsion mining technology involved in mining.The essential properties of CO₂make most surfactants unable to form stable CO₂emulsions.Through the experimental screening,the liquid surfactant CO₂emulsion was prepared by using the green surfactant alkyl glucoside?APG?.The main research contents are as follows:?1?In the sapphire kettle,the effect of APG on the stability of CO₂emulsion was investigated by the delamination time of the emulsion under the operating conditions of284.5 K and 5.2 MPa.The results show that APG has broad application prospects in the preparation of CO₂emulsion.The suitable dosage of APG is about 3 wt%of the aqueous phase.The binary aqueous system was analyzed with 3 wt%APG to determine that the phase transition point of the CO₂/H₂O emulsion and the H₂O/CO₂emulsion was between 15 vol%and 17.5 vol%.Two surfactants,fatty alcohol polyoxyethylene ether?AEO?and sodium bis?2-ethylhexyl?sulfosuccinate?AOT?,were tested.In order to investigate the applicability of CO₂emulsion in the field of seabed hydrate mining,CO₂storage,etc.,the performance of surfactant in brine was investigated.The experimental results show that APG can be used as a surfactant to prepare a CO₂liquid emulsion with or without Na Cl.After the addition of 1.0 wt%Na Cl and 3 wt%APG to the CO₂emulsion,the phase inversion point became high.In contrast,the anionic surfactant AOT is ineffective in saline solution.?2?The stability of CO₂emulsion was evaluated by micrometer using PVM and FBRM.The effects of particle size distribution on the emulsion particles under different conditions were investigated.The experiment found that higher pressure and lower temperature are beneficial to the uniform distribution of emulsion particles.An increase in water cut will result in a reduction in the small size of the emulsion,but at the same time has little effect on the distribution of the large particle emulsion particles.The addition of salt and the increase in shear strength cause the particle size distribution curve of the emulsion particles to move toward the small particles.