【作者】 杜庆军；

【导师】 陈月明；

【作者基本信息】 中国石油大学 ， 油气田开发工程， 2008， 博士

【摘要】 我国对石油能源的需求日益增长,而石油勘探的难度不断增加,提高已开发油田的原油采收率日趋重要。泡沫驱油技术以泡沫独特的性质,能够有效地提高原油采收率,是一种正处于迅速发展阶段的新型三次采油技术。然而,泡沫驱油体系在多孔介质中的渗流机理十分复杂,准确合理地认识和描述其渗流特征和驱油机理是决定该体系具有更强的油藏适应性和矿场增油效果的关键问题。开展泡沫驱油渗流特征的基础研究具有重要的现实意义和理论价值。本文利用比较先进的美国TEMECO公司的泡沫驱替实验系统进行了无油模型和含油模型中单一泡沫和强化泡沫驱油体系渗流特征的物理模拟研究,讨论了气液比、注入方式、聚合物及渗透率等参数对泡沫封堵效果的影响。分别建立了基于分流理论的解析模型和基于泡沫组分物质的量守恒的描述强化泡沫驱渗流的数学模型,提出了由具有明确物理意义的参数确定的泡沫生成速度、自然破灭速度、遇油破灭速度表征模型,并进行了数值模拟研究。首次提出强化泡沫驱实验参数的多级拟合研究思路,达到了尽可能地降低或消除待定参数的多解性,实现物理模拟和数学模拟有机结合的目的。在此基础上,研究了泡沫生成速度、自然破灭速度、遇油破灭速度的分布及运移机制,描述了泡沫在多孔介质中渗流的分区规律,系统分析了强化泡沫驱油渗流特征。以气相中泡沫浓度表征泡沫稳定性,讨论了泡沫稳定性的影响因素,分析了强化泡沫驱油效果与泡沫稳定性的关系,认识了高效强化泡沫驱油机理,有助于进一步完善和发展泡沫驱渗流理论,改善强化泡沫驱效果,从而提高原油采收率。研究结果表明:强化泡沫体系中聚合物通过降低遇油破灭速度起到复合增效作用,增强泡沫遇油稳定性,大幅提高原油采收率。无油条件下,泡沫在多孔介质中具有活塞式驱替特征;含油条件下,泡沫驱替过程中存在生长区、稳态区、衰减区三部分。从驱油机理来看,泡沫驱是动态平衡过程,前缘破灭泡沫能够由后续稳定泡沫不断补充,后续水驱阶段泡沫仍能够稳定存在并向前推进。注泡沫阶段主要是以“调剖”机理为主,在纵向上扩大了波及体积;含水恢复阶段以“增加平面波及面积”机理为主。在诸多油藏参数和注入参数中,影响泡沫驱增油效果较明显的依次为段塞长度、原油粘度、气液比、注入时机等;影响泡沫稳定性的依次是气液比、聚合物浓度、变异系数等。更多还原

【Abstract】 With the ever-increasing demand of petroleum energy in China and difficulty of exploration, enhancing the developed oil fields oil recovery became more and more important. Foam flooding, as the rapidly developed and novel tertiary oil recovery technique, could effectively enhance oil recovery for its special characteristics. However, the seepage mechanism of foam displacement system in porous media was very complicated and the correct and reasonable understanding and description of seepage characteristics and displacement mechanism was the key problem of reservoir adaptability and oil increment effect. The fundamental study of foam seepage characteristics was of practical importance and theoretical value.The physical simulation study of foam flooding and enhanced foam flooding displacement systems was conducted in both oil-free and oil-bearing models with the aid of advanced foam displacement experiment system of TEMECO company in the United States. The effects of gas/liquid ratio, injection mode, polymer and permeability on foam plugging effect were discussed. Analytical model based on fractional flow theory and mathematical model describing enhanced foam flooding based on molar weight conservation of foam component were established respectively. Formulations with definite physical meanings such as foam generation rate, natural coalescence rate and oil-contacting coalescence rate were developed and numerical simulation was conducted. The multistage matching approach of enhanced foam flooding experiment parameter was first put forwarded, which eliminated or decreased the multiplicity solutions of undetermined parameters as much as possible and achieved the combination of physical simulation and mathematical simulation. Then the distribution of generating rate, natural coalescence rate, oil-contacting coalescence rate and the foam migration characteristics were studied , the partition pattern of foam migration in porous media was described and the seepage characteristics of enhanced foam flooding was systematically analyzed. Foam concentration in gas phase was used to characterize the foam stability and the influencing factors of foam stability were discussed. The relation between displacement effect of enhanced foam flooding and foam stability was analyzed and the displacement mechanism of enhanced foam flooding was brought into cognition, which was conducive to the improvement and development of foam flooding filtration theory and improvement of enhanced foam flooding effect and ultimately enhanced oil recovery.It was indicated that polymer in the enhanced foam flooding system have compound effect by means of decreasing oil coalescence rate, which strengthened foam stability and enhanced considerably oil recovery. The displacement characteristic of foam was characterized as piston-like displacement under the oil-free condition. The foam displacement process could be divided into three parts: growth zone, steady state zone and decay zone under oil-bearing condition. Foam flooding was a dynamic equilibrium process from the aspect of displacement mechanism. The front coalescence foam could be replaced by subsequent stable foam and the foam could still be stable and advance in the process of follow-up water flooding. Profile control mechanism played the main role in foam injection stage, which expanded vertical sweep volume. The enlargement of plane sweep area mechanism dominated in the stage of water cut recovery. The reservoir and injection influencing factors of foam flooding effect were listed in proper order as follows: plug length, oil viscosity, gas/liquid ratio and injection timing. The influencing factors of foam stability were successively gas/liquid ratio, polymer concentration and variation coefficient.更多还原