注入气类型对沥青质沉积影响实验研究OA北大核心CSTPCD

In order to clarify the deposition characteristics of asphaltene under different injected gas media,the asphaltene deposition measurement experiments under the injection of N2,CH4 and CO2 were carried out by using developed high-temperature high-pressure visual asphaltene deposition measurement device,and the effects of injected gas type and gas pressure on the mass fraction,deposition rate and particle size of asphaltene deposition were quantitatively evaluated.The results show that under the same injected gas pressure(9 MPa)and mole fraction(10％),When injecting CO2,the mass fraction of crude oil asphaltene deposition is the highest(0.086％),followed by CH4(0.067％),and the lowest(0.04％)when injecting N2,which is similar to the deposition amount without gas injection(0.035％).The deposition rate of asphaltene increases first and then decreases with the increase of oil and gas contact time.The average particle size of asphaltene aggregates is 4.4 μm and 7.3 pm under the action of CH4 and CO2,and the average parti-cle size is 2.2 μm and 1.7 pm respectively with injection of N2 and without gas injection.N2 has the least impact on asphaltene deposi-tion,while CO2 has the greatest impact on asphaltene deposition,and the impact of CH4 is between the two.The thermodynamic model of asphaltene can accurately predict the mass fraction of asphaltene deposition when injecting three gas media,with an error of less than 18.2％compared to experimental results.