稠油蒸汽吞吐热裂解行为研究

Study on the thermal cracking of heavy oil during steam soak

为探讨稠油热采降黏机理，对国内3种典型稠油——草桥稠油、辽河稠油及新疆轮古稠油在蒸汽吞吐过程中发生的热裂解行为进行了室内研究．用GSHA型高压反应釜模拟热采时的井下条件，分别考察了温度、时间、加水量对3种油样热降黏效果的影响．结果表明：3种稠油在蒸汽吞吐过程中重质组分均会发生热裂解，实现永久性降黏；在250～300℃之间，稠油开始发生裂解；在同一温度下，时间越长，降黏效果越好；在同一时间下，温度越高降黏效果越好，温度与时间具有互补性；3种稠油在同一温度下降黏规律相同，可以用同一公式表示；水的存在对稠油裂解有影响，当加入的水完全汽化时为最佳．

In order to discuss heavy oil viscosity-reducing mechanism in thermal recovery process,the thermal cracking behaviors of three typical heavy crude oils from Caoqiao oilfield in Shengli,Liaohe olfield,Lungu oilfield in Xinjjiang in steam soak are investigated respectively in laboratory.The downhole condition in thermal recovery is simulated in GSHA high-pressure autoclave.The effects of reaction temperature,reaction time and water content on their viscosity-reducting results are studied.The results show that the heavy components in three kinds of heavy oil begin cracking when the reaction temperature reaches to 250～350 ℃; at the same reaction temperature,the longer the reaction time,the better the viscosity-reducing results; in the same period of time,the higher the reaction temperature,the better the viscosity-reducing results; at the same reaction temperature,the three heavy oils have the same viscosity-reducing rule,which can be expressed by a formula; there is the best viscosity-reducing result when water all transforms steam in the high-pressure autoclave.