Study On Solvent Extraction Experiment And Mechanism Of VAPEX In Heavy Oil Reservoir

As a new heavy oil recovery technology,vapor extraction(VAPEX)has been proposed in recent years.Compared with the conventional heavy oil recovery process,VAPEX has the advantages of lower energy consumption,higher utilization efficiency,better economic benefit and environmental friendliness.In addition,the injected solvent also has obvious effect on the upgrading of heavy oil.Therefore,solvent extraction is a heavy oil recovery technology with broad potentiality in the current environment of rich heavy oil resources.In this paper,aiming at the problems of limited heating radius of steam huff and puff and low oil recovery efficiency in heavy oil exploitation in Block X of Shengli Oilfield,the basic properties of heavy oil including group components are determined.By comparing the structure and properties of crude oil before and after extraction,the viscosity reduction and upgrading effects of different solvent systems on heavy oil were evaluated,and the corresponding solvent combinations and their proportions were screened out.The extraction effects of solvent under different reservoir temperature and pressure were discussed.The formulation and operating conditions of solvent extraction were summarized.The injection process and influencing factors of solvent in the extraction process were carried out,and the basic principle of solvent extraction for enhancing oil recovery was studied.The experiments of asphalt deposition after solvent extraction were carried out,and the mechanism of solvent extraction de-asphalting was expounded.The influencing factors of solvent injection de-asphalting and the damage to reservoir after asphalt deposition were studied.By comparing the properties of crude oil before and after extraction,such as group composition and viscosity-temperature relationship,the viscosity reduction and upgrading ability of heavy oil by solvent extraction were studied and the suitable solvent system was 90%propane+10% n-hexane.The optimal injection conditions of solvent were optimized and experimental results showed that the optimal injection mode of n-hexane and propane was gas-liquid co-injection,The experiment also proves that solvent extraction has the best recovery effect for heavy oil recovery in the middle stage of water injection development(oil saturation is 40%).Under lower temperature and pressure,the asphalt deposition is small,and the reservoir damage is also low.