热自生CO_2吞吐中技术研究及其应用

Application and Research of Hot Self-generated CO_2 Technology in Steam Soaking

针对稠油油藏难开采、蒸汽吞吐效果差等一系列问题,提出了一种热自生CO2吞吐技术,该技术结合了蒸汽吞吐和气驱技术等多种方法,改善稠油油藏蒸汽吞吐效果,其主要机理是利用蒸汽加热生气剂,在地层中产生大量的气体（CO2、NH3等）,部分气体作用于原油,降低原油黏度;部分气体与原油发生反应极易形成混相驱,降低油水界面张力,从而达到提高采收率的目的。通过对优选出生气剂溶液反应前后比较可知,反应后溶液比反应前溶液的碱性增强（pH值8.26→9.7110.02）,有助于降低原油黏度、降低油水界面张力等。研究表明,热自生CO2吞吐技术可实现最大,降黏率达到76.7%,油水界面张力降低了54.77%,在蒸汽吞吐的基础上可进一步提高原油采收率,仅第5轮次最高可提高4.18%,充分体现了该技术的优势。现场试验分析表明,平均单周期投入产出比高达1.0：3.2,该技术在较大幅度提高原油产量下,具有较好的经济效益,为高效开发稠油提供了强有力的技术支持。

Hot self-generated CO2 technology is focused on the problems of recovery difficulty,poor effect of steam soaking and so on for heavy oil reservoirs.This technology combines steam flooding and gas flooding and improves the effect of steam soaking in heavy oil reservoir.Its main mechanism is the application of steam to heat blowing agent and generate a large volume of gases（including CO2,NH3,etc） in the formation.Some of these gases react with the oil to reduce the oil viscosity,others form miscible flooding to reduce water interfacial tension,so as to enhance oil recovery.An optimized selection of the heat blowing agents was performed.By comparing the difference of blowing agent solution before and after the reaction,we find that alkaline increases after the reaction（pH changes in value from 8.26 to 9.7110.02）,which is helpful to reduce oil viscosity and lower interfacial tension,etc.Studies indicate that Heat-generating CO2 flooding technology can get a maximum viscosity reduction rate of 76.7%;oil-water interfacial tension decreases by 54.77%,and further improve oil recovery by 4.18%in the5 th steam soaking.Single cycle input-output ratio averages 1.0：3.2,which shows a technical advantage toward conventional EOR method and a preferable economic profit.The field experiments found that the technique can greatly improve the oil production,which will provide a powerful technical supporting for the efficient development of heavy oil.