催化空气驱技术低温氧化催化机理及油藏适应性

Low-temperature oxidation catalysis mechanism and oil reservoir adaptability of catalytic air flooding technique

注空气采油技术是提高原油采收率的重要方式之一。针对轻质油藏注空气采油技术现场应用安全问题,以3种原油为研究对象,开展了低温氧化催化机理及油藏适应性研究。首先,采用静态低温氧化催化实验对催化剂进行优选;其次,运用氧化动力学结合热重-红外联用(TG-FTIR),分析低温氧化催化机理;最后,通过长氧化管填砂模型动态氧化实验,研究催化剂油藏适应性,优化催化剂应用条件。研究结果表明:铜、铁、锰和钴等过渡金属的有机盐具有优异的低温氧化催化效果及较好的普适性,可以加快不同原油低温氧化(LTO)反应进程,优选环烷酸钴为原油低温氧化反应催化剂。环烷酸钴能够激发原油及其四族组分(SARA)低温氧化反应活性。以芳香分为例,加入环烷酸钴前后LTO反应活化能由35606J/mol减小至19849J/mol,降幅高达44.3%。环烷酸钴对原油及其SARA组分加氧和断键反应催化作用明显。油田现场应用注空气技术时推荐采用催化剂/空气交替段塞注入,对于水驱见水油藏,应在产水率<30%时转催化空气驱。催化空气驱技术在储层温度低于90℃的轻质油藏中应用潜力更大。

The air injection oil recovery technique is one of the important ways to improve oil recovery efficiency.In view of the safety problems during field application of air injection technique in light oil reservoirs,a study of low-temperature catalytic mechanism and oil reservoir adaptability was conducted on three types of crude oil.Firstly,the catalyst was optimized by static low-temperature oxidation catalysis experiment;secondly,low-temperature oxidation catalysis mechanism was analyzed by oxidation kinetics in combination with thermogravimetry-Fourier transform infrared spectroscopy(TG-FTIR);finally,oil reservoir adaptability was investigated and the catalyst application conditions were optimized through the dynamic oxidation experiment based on the sand-packed model of long oxidation tube.The results show that the organic salts of transition metals such as copper,iron,manganese,and cobalt have excellent low-temperature oxidation catalytic effect and better universality,and can speed up the low-temperature oxidation(LTO)reaction process of different crude oil,so that cobalt naphthenate is optimized as the catalyst for low-temperature oxidation of crude oil.In fact,cobalt naphthenate can stimulate the LTO reactivity of crude oil and its saturates,aromatics,resins,and asphaltenes(SARA)fractions.Taking aromatics for an example,the activation energy of LTO reaction before and after adding cobalt naphthenate is dropped from 35606 to 19849 J/mol,decreased by 44.3%.Besides,cobalt naphthenate has an obvious catalytic effect on oxygen addition and bond-breaking reactions of crude oil and its SARA fractions.Therefore,catalyst/air alternate slug injection is recommended when the air injection technique is applied in the oilfield.For water-flooding reservoirs,catalytic air flooding shall be adopted instead when the water production rate is lower than 30%.It can be seen that the catalytic air flooding technique applied in light oil reservoirs below the temperature of 90℃has a great application potential.