注空气开发中稠油不同馏分氧化特性研究

Research on Oxidation Characteristics of Different Fractions of Heavy Oil in Air Injection Development

应用蒸馏法将原油分离为轻质、中质、重质3种馏分,通过FT-IR及TG-PDSC手段,对比稠油不同馏分的特征官能团,分析了注空气过程中其不同反应阶段的氧化特性。结果表明:轻质馏分官能团以直链烷烃为主,中质馏分官能团以含氧基团为主,重质馏分官能团以芳香环为主。轻质馏分蒸发阶段质量损失率最大,中质馏分主导低温氧化反应,对该阶段放热量贡献最大,重质馏分在高温氧化阶段质量损失及放热量最高。利用Coats-Redfern积分法计算低温氧化阶段活化能随馏分中轻质组分含量减少而增大,重质馏分活化能整体最高;对于稠油油样,重质馏分所占比例高,350℃以上重质馏分发生高温氧化对稠油提高采收率至关重要,350℃以下主要是轻质馏分和中质馏分参与低温氧化。稠油油藏注空气火驱开采应以快速实现重质馏分高温氧化为主要目标。

Crude oil was separated into light,medium and heavy fractions by distillation,the characteristic functional groups of different heavy oil fractions were compared by means of FT-IR and TG-PDSC,and their oxidation characteristics in different reaction stages in air injection development of heavy oil were analyzed.The results show that the main functional group of light fraction is straight chain alkane,the main functional group of middle fraction is oxygen-containing group,and the main functional group of heavy fraction is aromatic ring.The mass loss of light fraction is the fastest and the largest in evaporation stage,the middle fraction dominates the low-temperature oxidation reaction and contributes the most to the heat release of this stage,and the heavy fraction has the greatest mass loss and heat release in the high-temperature oxidation stage.The kinetic parameters are calculated using Coats-Redfern integral method,the low-temperature oxidation activation energy increases with the decrease of light component content in the fractions,and the activation energy of heavy fraction is the highest as a whole.The proportion of heavy fraction in heavy oil samplesis high.The high temperature oxidation of heavy fraction above 350℃is very important to enhanced oil recovery.Below 350℃,the light fraction and the medium fraction mainly participated in the low temperature oxidation reaction.Therefore,the main goal of air injection fire flooding in heavy oil reservoir is to realize high temperature oxidation of heavy fraction quickly.