克拉玛依风城油田稠油低温氧化过程

Low temperature oxidation process of heavy oil in Fengcheng Oilfield, Karamay

风城油田稠油胶质含量高,随着开采的不断深入,部分油井出现吞吐效果变差、含水率升高的现象。为提高克拉玛依风城区稠油油藏注空气采油过程的安全性,进行了低温氧化实验。实验模拟了克拉玛依风城稠油油藏压力(8 MPa),分别考察油样在不同温度(80～250℃)条件下的低温氧化过程,对火烧油层初始低温氧化阶段的油样物性变化、组分变化规律、气体变化进行研究。结果表明,低温氧化反应使稠油密度增加了2%,黏度增加0.72倍;IR分析表明,稠油与空气发生的低温氧化反应使含氧类官能团(-C=O、脂肪醚)的吸收强度明显增强;SARA组分活性强弱为:芳香分>饱和分>胶质,250℃反应后,沥青质增加较多;气体中N2含量基本没变,O_2含量由21%降至5%,CO、CH_4和CO_2气体含量升高,由键能法计算结果可知,每消耗1 moL的O_2平均放热量391.54～420.58 kJ。该研究为现场试验设计和应用提供了理论基础数据和技术指导。

The resin content of heavy oil in Fengcheng Oilfield is high. And as the exploitation of heavy oil in this area goes further, some oil wells present the problems of poor stimulation effect and high water cut. In order to improve the safety of air injection for oil recovery in heavy oil reservoirs in Fengcheng Oilfield Karamay, low temperature oxidation experiment was carried out. In the experiment , the low temperature oxidation situations of oil samples in different temperatures (80-250 ℃) were investigated under the simulated pressure (8 MPa) of heavy oil reservoirs in Fengcheng Block of Karamay. The physical property change, compositional change and gas change of oil samples in the initial low temperature oxidation stage of in-situ combustion were studied. It is indicated that due to the low temperature oxidation reaction, the density of heavy oil is increased by 2% and its viscosity is increased by 0.72 times. IR analysis results show that the low temperature oxidation reaction between heavy oil and air increases the absorption intensity of oxygenated functional group (-C=O and aliphatic ether) significantly. The activity of SARA compositions is ranked as aromatic>saturate>resin. After reaction at 250 ℃, the asphaltene content increases more. N2 content of the air is basically unchanged, O2 content decreases from 21% to 5%, and the content of CO, CH4 and CO2 increases. The calculation results by bond energy method shows that the average thermal discharge corresponding to the O2 consumption of 1 moL is 391.54-420.58 kJ. The research results provide the basic data for field experiment design and field application.