岩石矿物对超稠油氧化动力学特征的影响分析

随着注蒸汽采油经济与环境成本的增加,注空气提高采收率技术越来越受到重视,原油氧化动力学基础研究对注空气采油技术研发具有重要意义。以新疆油田某区块超稠油为研究对象,采用等转化率法,在30~600℃条件下,实验获得了不同升温速率下的原油氧化失重曲线,并计算得到原油样品的氧化活化能,进而揭示了典型岩石矿物对原油氧化活化能的影响。研究表明,该原油及其人造油砂的氧化过程呈现三个阶段:1温度小于350℃且转化率在0~0.5的中、低温氧化阶段,活化能在50~80 kJ·mol-1;2温度在350~450℃之间且转化率在0.5~0.65之间的过渡阶段,活化能从80 kJ·mol-1上升到350 kJ·mol-1左右;3温度在450℃以上且转化率在0.6~1.0的高温氧化阶段,活化能初始维持在350 kJ·mol-1左右,随着转化率增加快速下降到150 kJ·mol-1并稳定;岩石矿物可降低原油氧化的活化能,高温氧化阶段活化能降低明显,中低温氧化阶段影响相对较小;蒙脱石对原油氧化动力学特征的影响在不同氧化阶段影响不同,与石英砂原油样品相比,中低温氧化初始阶段及高温氧化阶段,蒙脱石能进一步降低氧化反应活化能。

The Effects of Granular Materials and Clays on the Oxidation Kinetics of Extra Heavy Oil

The objective of this research is to investigate the oxidation kinetics of a typical extra heavy oil from Xinjiang oil field and the effect of granular materials and clays on the oxidation activation energy. Thermogravimetric data at different heating rate were obtained. Through the isoconversional method, activation energy curves of three samples (pure extra heavy oil, extra heavy oil with quartz sand, and extra heavy oil with quartz and clay) were acquired. All three samples exhibited similar patterns with three distinctive regions, known as low temperature oxidation (LTO), fuel deposition and high temperature oxidation (HTO). Results showed LTO activation energy varied from 50 to 80KJmol_-1, while activation energy increased sharply from 80 to more than 350 KJmol_-1 in fuel deposition region and HTO activation energy declined from about 350 to 150 KJmol_-1. A comparison between the activation energy curves revealed that in LTO smectite slightly reduced activation energy (only when conversion ranged from 0 to 0.2) and a significant reduction of activation energy due to the addition of quartz sand and smectite in HTO.