重力超覆下气体连续"剥蚀"稠油边界层的驱油机制研究

In the process of heavy oil recovery by gas injection, there is the phenomenon of gravity override caused by density difference between oil and gas, overlapping gas denudates boundary layer of heavy oil continuously, thus gas generates physicochemical reactions with denuded heavy oil which contributes to the formation of foamy fluid(gas-in-oil dispersoid). This kind of process is similar to shaved noodles, and generates foamy fluid constantly which improves mobility of heavy oil significantly. So effective method of heavy oil cold production can be achieved. At present, experimental study has been conducted by compeletely blending gas with heavy oil in the PVT apparatus which ignore action mode, action process and action mechanism. The idea that gas denudates boundary layer of heavy oil has not yet been put forward at home and abroad, and denudation-style displacement mechanism has not yet been discussed and studied.By means of using physical simulation experiment and AUTOSCAN-II core scanning system and molecular diffusion theory synthetically, we will design and make the visual heterogeneous physical model simulating process of gas denudating oil, carry out the following research: visual denudation process, denudation mechanism, formation condition and applicable condition of foamy fluid, gas-in-oil dispersion theory and mathematical model, potential of EOR. On the basis of the above research, we will cognize displacement mechanism that gas denudates boundary layer of heavy oil under the condition of gravity override, and build the heavy-oil-cold-production model of “gas overlap -- denudation -- formation of foamy fluid”.

在稠油注气冷采过程中，由于气油密度差异极大，存在重力超覆现象，超覆气体连续“剥蚀”稠油边界层，然后气体与剥蚀下来的稠油形成泡沫流体（油包气弥散相），这种连续“剥蚀”稠油边界层的过程类似于“刀削面”，不断形成泡沫流体，显著改善稠油的流动性，实现稠油的有效冷采。目前国内外普遍将气体与稠油在PVT装置中完全混合后进行实验研究，忽略了气体与稠油之间的作用方式、过程与机理，尚未有人提出“气体剥蚀稠油边界层”概念，更未对“剥蚀”驱油机制进行研究。本项目将综合运用物理模拟实验、AUTOSCAN-II岩心扫描系统和分子扩散弥散理论，设计制作可视化非均质气剥油物理模型；开展剥蚀过程及机理、气体与被剥蚀稠油的泡沫流体形成及适用条件、油包气弥散理论与数学模型、提高采收率潜力的研究；在上述综合研究基础上，认知重力超覆下气体连续“剥蚀”稠油边界层的驱油机制，构建“气体超覆-剥蚀-形成泡沫流体”的稠油冷采模式。

摘要：根据国家自然科学基金项目（批准号：51574200）合同要求，本项目设计制作了可视化非均质物理模拟模型，模拟重力超覆下气体连续“剥蚀”稠油边界层的动态过程，通过注气剥蚀可视化实验，描述了气体剥蚀稠油的动态过程。筛选出了适合新疆油田九区92623和胜利油田枣1281-B油样的最佳的气体注入参数（注气类型、注气速度、注气压力和接触时间），对剥蚀后形成的泡沫油性能进行了性能评价和分析，开展了原油组成、注气类型、注气速度、注气压力和接触时间对形成稳定泡沫油的影响规律研究。建立了弥散相数学模型、泡沫生长模型，并通过数学模型得出原油粘度对泡沫油的影响规律。利用一维填砂管进行气体剥蚀稠油实验，测定了不同原油粘度和不同渗透率条件下气体剥蚀稠油形成泡沫流体的驱油效率，并研究了泡沫流体的驱油弹性能量、泡沫流体的流度、注入气的流度控制效果、泡沫流体物理化学渗流特征（滑脱效应、毛管效应孔隙结构和出砂）等对驱油效果的影响规律。本项目筛选出了适合稠油冷采的气体并确定适用的油藏条件，结合对气体超覆剥蚀、弥散、泡沫油、渗流规律的研究，建立了“气体超覆-剥蚀-形成泡沫流体”辅助稠油冷采的开采模式。