摘要
利用蒸汽驱开发海上稠油，存在能耗高、热利用率低、效果差等问题。超临界多元热流体作为一种新兴的注入热介质，可有效解决上述问题。其主要成分为超临界蒸汽、超临界N2及CO2，是由有机废液在温度373.85～699.85 ℃、压力22.1～30.0 MPa的空气和超临界蒸汽环境中气化及燃烧而成。但是，目前国内外相关研究仍处于初级阶段，缺乏有效的物理模拟装置和方法，超临界多元热流体驱的可行性尚待进一步评估，其驱油特征及参数影响规律也不清楚。为此，文中首次利用自主研制的大型超临界多元热流体驱替实验装置，研究超临界多元热流体驱油过程，揭示了最终采收率变化、超临界多元热流体腔发育和剩余油分布等驱油特征，并阐明了超临界多元热流体注入温度及压力变化对开发效果的影响规律。研究结果表明：与蒸汽驱相比，采用超临界多元热流体驱油，最终采收率提高了13.06百分点，可有效降低稠油黏度，延缓突破时间，扩大波及范围，降低剩余油饱和度和热损失，是一种有效的海上稠油开发技术。随着注入温度的升高，超临界多元热流体波及范围增大，最终采收率提高，但同时焦炭产量增加；而注入压力的增加可改善驱替效果，并抑制焦炭生成。文中研究结果为海上稠油超临界多元热流体驱油的现场实施奠定了理论基础。
Abstract
Conventional steam flooding has some challenges such as high energy consumption, low heat utilization and poor performance during the development of offshore heavy oil reservoirs. The above challenges can be effectively solved by supercritical multiple-thermal fluids as a novel thermal agent. The main components of that are supercritical steam, supercritical N2 and supercritical CO2, which are produced by the gasification and combustion of organic waste fluid in the environment of air and supercritical steam at 373.85￣699.85 ℃ and 22.1￣30.0 MPa. Nevertheless, the correlational research at present, both domestically and internationally, remains at a preliminary stage because of a dearth of efficacious physical simulation setup and techniques. Further evaluation is required to determine the feasibility of utilizing supercritical multiple-thermal fluids, while the flooding characteristics and the influence of parameters remain unclear. In this paper, a self-developed large experimental setup was used to to examine the flooding mechanisms of supercritical multiple-thermal fluids. Through this investigation, the flooding characteristics, including change of oil recovery, development of the supercritical multiple-thermal fluids cavity, and residual oil distribution, were revealed. And the influence rule of injection temperature and pressure on development effect was clarified. The findings indicated that, in comparison to conventional steam flooding, the oil recovery ratio of supercritical multiple-thermal fluids flooding can increase by 13.06%. This technology can decrease effectively heavy oil viscosity, delay occurrence of breakthrough, expand sweep area and decrease residual oil saturation and heat loss, which is an effective development technology for offshore heavy oil reservoirs. In addition, the growing injection temperature can lead to an increase in both the sweep area and the oil recovery. However, it also results in an growing coke production. And an increase in pressure has a positive effect on oil recovery while controlling coke production. The research results lay the valuable theoretical basis for the practical application of supercritical multiple-thermal fluids in offshore heavy oil reservoirs.
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