Abstract:

In order to investigate the chemical reaction mechanisms of in-situ heavy oil upgrading during supercritical water flooding, batch reactor experiments were conducted to study the transformation of fraction distribution of upgraded heavy oil products in supercritical water at 380—420℃. The results showed that the vacuum residue content was significantly reduced after upgrading, while the content of various light components increased. Increasing the reaction temperature or extending the reaction time enhance the upgrading effect but also intensify coke formation. Based on the experimental results, a six-lumped kinetic model was established, revealing that reaction temperature has a significant impact on the reaction equilibrium. At 380℃, light fractions and gas are mainly produced from the cracking of vacuum residue, whereas at higher temperatures, vacuum gas oil and atmospheric gas oil sequentially tend to convert into lighter fractions. Integrating the kinetic model, reservoir numerical simulations were performed to evaluate the actual oil recovery performance of supercritical water flooding. The results indicate that at temperatures above 400℃, supercritical water flooding exhibits high efficiency of oil recovery. The content of light fractions in the produced oil increases with temperature. However, the effect of in-situ upgrading remains constrained due to the effects of fluid heat and mass transfer.

Key words: supercritical water, petroleum, reaction kinetics, in-situ upgrading, numerical simulation

摘要：

为探究超临界水注采中稠油原位转化的反应机制，通过反应釜实验探究了380~420℃时稠油在超临界水中改质产物的变化规律。结果表明，改质后减压渣油显著减少，各轻质组分含量增加；提高反应温度及延长反应时间能深化改质效果，但也使结焦加剧。基于实验结果，建立了6集总反应动力学模型，发现反应温度对反应平衡方向具有显著影响，380℃时轻质组分以及气体主要由减压渣油裂解产生，在更高温度下，减压瓦斯油与常压瓦斯油趋于向更轻质组分转化。结合动力学模型，通过油藏数值模拟研究了超临界水驱油的实际开采效果，结果表明在400℃以上时超临界水驱油效率较高，升温能提高采出油中轻质组分含量，但受流体传热传质影响，原位改质效果有一定限制。

关键词: 超临界水, 石油, 反应动力学, 原位改质, 数值模拟