The effects of a single emulsifier octylphenol ethoxylate 10 (OP?10) and its compounding system on emulsion stability, rheology and the effect of organic bases on the interfacial tension were investigated. The results show that the optimal binary composition is as follows: The mass fraction of OP?10 is 1% and the mass fraction of sodium oleate (YSN) is 0.6%.The optimum compounding method can produce stable emulsion with thick oil, and the viscosity can be reduced from 1 168.22 mPa?s to 57.57 mPa?s, with the viscosity reduction rate of 91.03% and the water separation rate of 21.33%. The organobase triethanolamine (TEOA) can reduce the interfacial tension of the compounded system to the 10^-2 mN/m level.

The Bohai Sea is very rich in heavy oil reserves. At present,the thermal recovery rate is so low that the potential for tapping the potential is huge. It is of great practical significance to discuss the feasibility of gas injection exploitation in offshore heavy oil field. Through gas injection expansion experiments and multiple contact experiments, the effects of different gas injection media (CO₂,N₂,natural gas) on heavy oils with different viscosities in the Bohai Sea (general I?1, general I?2?A, general I?2?B) the solubilization,expansion,viscosity reduction effect and mixing mechanism.The experimental results show that the compatibility of CO₂ and heavy oil is better than natural gas and better than N₂, the viscosity reduction rates of CO₂ to the three types of heavy oil are 78%,85%,and 90%,respectively,and the viscosity reduction rates of natural gas to the three types of heavy oil are 29%, 69%,and 62%, respectively. CO₂ injection is more suitable for general I?2?B heavy oil, and natural gas injection is more suitable for general I?2?A heavy oil; the results of multiple contact experiments show that the mass transfer mechanism of CO₂ flooding is dominated by dissolution and condensate, the mass transfer mechanism of N₂ flooding is dominated by extraction and extraction, and the mass transfer mechanism of natural gas flooding is the condensate?extraction balance; in addition, the theoretical minimum miscible pressures are all greater than 43.00 MPa, so it is difficult to form miscible at the displacement front. The research results can provide important basis and technical support for gas injection to enhance oil recovery in Bohai heavy oil fields.