烟道气对稠油油藏理化性质影响特性研究

Effect of flue gas on physical and chemical properties of heavy oil reservoir

在稠油原位燃烧开采过程中,会产生大量含有氮气、二氧化碳和少量氧气的烟道气。烟道气渗透进入未燃烧区与稠油混合,不仅会降低稠油的黏度还会对油品产生影响。研究了不同温度下烟道气(N_(2)+CO_(2)+O_(2))对辽河齐-40区块稠油改性作用。利用气相色谱、红外光谱、热重分析了烟道气对原油理化性能的改性机理。结果表明,烟道气对稠油具有增容降黏的作用,随温度的升高,烟道气在稠油中的溶解度先增加后降低,体积因子则受溶解度和热的双重作用随温度的升高而增加;在100℃时降黏率最大,为9.84%。由于烟道气中少量的残余氧,会与稠油发生低温氧化作用,因此会增加稠油中沥青质含量,造成最终结焦量由原本的5%增加至14%。该结果为现场稠油火驱方案设计提供技术依据。

In the process of in-situ combustion exploitation of heavy oil,a large amount of flue gas containing nitrogen,carbon dioxide and a small amount of oxygen will be produced.The flue gas infiltrates into the unburned zone and mixes with the heavy oil,which not only reduces the viscosity of the heavy oil,but also affects the oil.The effects of flue gas(N_(2)+CO_(2)+O_(2))on heavy oil modification in Qi-4o block of Liaohe Oilfield were studied at different temperatures.The modification mechanism of flue gas on the physical and chemical properties of crude oil was analyzed by gas chromatography,infrared spectroscopy and thermogravimetry.The results showed that the flue gas has the effect of increasing capacity and reducing viscosity of heavy oil.With the increase of temperature,the solubility of flue gas in heavy oil first increases and then decreases,while the volume factor increases with the increase of temperature due to the dual effects of solubility and heat.The viscosity reduction rate reaches the maximum of 9.84%at 100℃.Because a small amount of residual oxygen in flue gas will oxidize with heavy oil at low temperature,it will increase the asphaltene content in heavy oil,resulting in the final coking increase from 5%to 14%.The results provide a technical basis for the design of heavy oil fire flooding scheme.