SAGD (steam-assisted gravity drainage) has been proven as an effective technology to enhance heavy oil/bitumen recovery. The main shortcoming of this method is its inefficiency, a result of high water and energy consumption. As a solution to SAGD efficiency improvement, we propose the addition of chemicals resulting in higher recovery and reduced steam consumption. The objective of this paper is to screen new generation chemicals as additives and study the mechanisms and optimum injection strategies. This screening was achieved through Hele-Shaw-type macroscopic visual experiments. We previously screened a wide variety of chemical additives for steam flooding. As a continuation of this work, these chemicals were tested for SAGD conditions using a new visual experimental design where the optimal injection strategies were identified, eventually providing a reference for the selection of chemical additives for field applications. Eleven conventional and new generation chemical additives (heptane, biodiesel, dimethyl ether, LTS-18, Tween 80, Span 80, Novelfroth 190, ionic liquid [BMMMIM BF₄], silicon dioxide nanoparticle, DES 9, and DES 11) were selected based on both their strong thermal stability and enhanced oil recovery capability. The recovery improvement mechanisms for the different chemical additives and different injection strategies were identified through flow characteristics, emulsifying ability, viscosity reduction capability, and wettability alteration. Simultaneously, the mechanisms were studied from a macro perspective via analyzing areal sweep efficiency and microscopic oil displacement efficiency together with observing the images acquired during the process. Three different injection strategies were applied for each chemical: (1) chemicals were injected at the beginning, (2) in the middle, and (3) at the end of the steam injection. The chemical additives played different roles in recovery improvement, and different chemical addition strategies yielded different mechanisms. Heptane exhibited extraordinary characteristics with maximum “steam saving” (34.52%) when the middle injection strategy was applied, and maximum ultimate oil recovery (64.75%) was obtained for the end injection strategy due to the ability to reduce the viscosity of heavy oil by dissolving around the chamber edge. Steamflooding with Novelfroth 190 showed an excellent performance for the middle and end injection strategies because of its ability to develop rapid oil drainage “channels”. The addition of surfactant LST-18 presented the ability to improve the EOR by forming emulsions. Additionally, the distributions of the steam chamber in the Hele-Shaw cell were different because of the changed flow characteristics when the same chemical additive was injected at different times, thus showing the ability to reduce viscosity and form emulsions with different strengths.

中文翻译：

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使用新一代化学物质的蒸汽辅助重力排水注入提高重油采收率

SAGD（蒸汽辅助重力排水）已被证明是提高重油/沥青采收率的有效技术。这种方法的主要缺点是效率低下，这是高耗水和高能耗的结果。作为提高SAGD效率的解决方案，我们建议添加化学品以提高回收率并减少蒸汽消耗。本文的目的是筛选新一代化学品作为添加剂，并研究机理和最佳注射策略。该筛选是通过Hele-Shaw型宏观视觉实验完成的。之前，我们筛选了用于蒸汽驱的多种化学添加剂。作为这项工作的延续，我们使用新的视觉实验设计对这些化学品的SAGD条件进行了测试，确定了最佳注射策略，最终为选择现场应用的化学添加剂提供参考。十一种常规和新一代化学添加剂（庚烷，生物柴油，二甲醚，LTS-18，Tween 80，Span 80，Novefroth 190，离子液体[BMMMIM BF₄根据它们的强热稳定性和增强的采油能力，选择了二氧化硅纳米粒子，DES 9和DES 11）。通过流动特性，乳化能力，粘度降低能力和润湿性改变，确定了不同化学添加剂和不同注射策略的回收率改善机理。同时，通过分析平面扫油效率和微观驱油效率以及观察过程中获得的图像，从宏观角度研究了这些机理。每种化学药品采用三种不同的注入策略：（1）在蒸汽注入开始时注入化学药品，（2）在中间注入，（3）在蒸汽注入结束时注入。化学添加剂在提高采收率方面起着不同的作用，不同的化学添加策略产生不同的机理。庚烷表现出非凡的特性，当采用中注入策略时，具有最大的“蒸汽节省”率（34.52％），并且由于能够降低重油粘度，最终注入策略的最终油回收率最高（64.75％）。围绕腔室边缘溶解。使用Novelfroth 190进行蒸汽驱，由于具有快速排油“通道”的能力，因此在中端注油策略中表现出出色的性能。加入表面活性剂LST-18可以通过形成乳液来改善EOR。此外，由于在不同时间注入相同的化学添加剂时流动特性发生了变化，因此Hele-Shaw池中蒸汽室的分布也有所不同，