Experimental Study On The Effect Of Air - Flooding On Oil Oxidation And Its Influence On Phase

HPAI is one of the most developed technology of tertiary oil recovery, without being limited by the air supply and transportation. And it is effective, safe and low-cost. Unlike chemical flooding, the application of this technology is not affected by high temperature and high salinity reservoir as well as the impurities in water. It can not only mee the demand of gas injection of low permeability reservoirs, but also can satisfy the need of further improveing oil recovery after water flooding. HPAI has special displacement mechanism because of its flue gas formed after oxidation, heat effect and heavy oil cracking, leading to the difference of both phase behavior and displace mechanism from nitrogen injection.This paper focused on the formation crude oil in Dagang oil field to carry out the crude oil oxidation and the phase behavior study, aiming at providing air injection in Dagang oilfield with further theoretical support. The research content completed is as followed:(1) Through TG and DSC experiments, it has investigated and analyzed the oxidation kinetics as well as the calculation of the two phase of the activation energy (respectively15.86kJmol-1and219.61kJ·mol-1), as well as the calculation of the two phase of the activation energy that low temperature phase oxidation reaction occurs more easily.(2) During the oxidation of long tube experiments, the effect of different injection time, temperature and pressure on the oxidation reaction of crude oil was studied. The results show that the longer oxidation time, oxidation reaction more thoroughly; the higher the temperature and pressure, the more severe oxidation reacted. Oxidation reaction changed the composition of crude oil, making heavy component cracking for intermediate component and light component, thus influenced the phase behavior of crude oil.(3) According to DBR-PVT analysis system, the P-X phase diagram was drawn under the reservoir condition of air injection and low oxygen air. It is concluded that within a certain range, with the increase of gas injection, oil bubble point pressure was rising.(4) According to DBR-PVT analysis system, it has completed air injection and low oxygen air injection multiple-contact experiments. Analyzed the equilibrium gas and oil phase change of each composition. Owing to the existence and influence of oxidation reaction, which makes oil components and physical property change more apparent in multiple contact with air. Air injection and low oxygen air injection quasi ternary phase diagram are draw.The research of this paper for Dagang oilfield provides a theoretical reference and technical support. Research shows that HPAI is a development potential tertiary oil recovery technology.