储层介质环境对原油裂解生气影响的实验研究

Experimental study on the effects of reservoir mediums on crude oil cracking to gas

采用封闭黄金管高压釜体系,在恒温(365℃)、恒压(50 MPa)条件下模拟不同储层介质环境下原油的裂解生气过程。实验结果表明:(1)在模拟实验条件下,水、矿物基质对原油裂解具有促进作用,使得气体产率有所提高,其中气态烃产率大约提高1倍,H2、CO2产率也有所提高;(2)硫酸镁溶液的存在可导致原油热解体系发生明显的硫酸盐热化学还原反应(TSR),产生大量H2S气体,同时烃类气体产率也有大幅提高,气体干燥系数明显增大;气体碳同位素数据表明TSR反应使甲烷、乙烷、丙烷相对富集13C;(3)一定量氯化钠溶液的存在会促进TSR反应,使得气态烃与非烃产率明显提高,同时造成烃类气体碳同位素组成的偏重(富集13C),乙烷的增重尤其明显,最大变化可达4‰。因此,储层介质环境对原油裂解具有显著的影响,在利用气体化学和同位素组成对原油裂解气进行研究时需要考虑储层介质环境可能存在的影响。

The cracking of crude oil in different medium conditions was simulated by using a confined goldtube-autoclave system and a heating method of constant temperature ure （365 ℃） and constant pressure （50 MPa）. Theexperiment results show that： （1） Water and minerals can promote the cracking of crude oil and lead to obviousincrease of gas yields, in which gaseous hydrocarbon yield increases about 2 times and the yields of H2 and CO2also increase to some extent. （2） The adding of magnesium sulfate solution can trigger the thermochemical sulfatereduction （TSR） in this reaction system and lead to significant increase in the yields of hydrocarbon gases andnon-hydrocarbon gas, such as H2S. At the same time, TSR makes hydrocarbon gas become dryer and enriched in13C. （3） sodium chloride solution can promote the TSR, which leads to the yield increase of hydrocarbon gas andnon-hydrocarbon gas and the 13C-enrichment of gaseous hydrocarbons, especially for ethane, its ？13Cvariationreaching up to 4‰. Therefore, the influences of reservoir mediums should be taken into considerationwhen chemical and carbon isotopic compositions of gases were used into gas-source rock correlation.