Abstract Oil recovery from carbonate reservoirs is low because of their complex nature which is characterized by the presence of high permeability streaks/fractures, broad pore size distribution and oil-wet/mixed wet state. The presence of high permeability streaks/fractures causes the injected fluid to bypass the low permeability pores that contain a high percentage of producible oil. One of the most effective and promising methods to control the fluid bypass is fluid diversion using chemical agents where a chemical agent is placed in the high permeability zone to block the path for the subsequent fluid, which ultimately diverts the injected fluids to the less permeable and oil-containing region. In this work, we investigate the potential use of cellulosic nanocrystals (CNC) for fluid diversion applications. Upon contact with brine, the nanosized CNC particles agglomerate to form micron size flocs showing a viscosity increment of an order at reservoir shear rates. In our core flooding experiments, the permeability of carbonate core decreased from 2827 mD to 127 mD when a CNC dispersion of 3000 ppm was injected. Injection of pre-equilibrated de-ionized water following CNC injection showed that the permeability reduction is permanent signifying the stability of CNC agglomerates in high temperature-high salinity environments. The blocking of high permeability zones due to the agglomeration of CNC particles results in fluid diversion. This improves the sweep efficiency and allows the injected fluid to come in contact with the oil. This is the first application of CNC in the area of fluid diversion for high temperature and high salinity fractured carbonate reservoirs which are present in the Middle East.

中文翻译：

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绿色添加剂在提高石油采收率中的应用：纤维素纳米晶在碳酸盐岩油藏中作为流体导流剂

摘要 碳酸盐岩储层具有高渗透条纹/裂缝、宽孔径分布和油湿/混湿状态等复杂性质，其采油率低。高渗透条纹/裂缝的存在导致注入的流体绕过含有高百分比可生产油的低渗透孔隙。控制流体旁路的最有效和最有前途的方法之一是使用化学试剂进行流体分流，其中将化学试剂放置在高渗透区以阻塞后续流体的路径，最终将注入的流体转向渗透性较低的流体。含油区。在这项工作中，我们研究了纤维素纳米晶体 (CNC) 在流体分流应用中的潜在用途。与盐水接触后，纳米尺寸的 CNC 颗粒聚集形成微米尺寸的絮凝体，在储层剪切速率下显示出一个数量级的粘度增加。在我们的岩心驱替实验中，当注入 3000 ppm 的 CNC 分散体时，碳酸盐岩岩心的渗透率从 2827 mD 降低到 127 mD。CNC 注入后注入预平衡的去离子水表明渗透率降低是永久性的，这表明 CNC 团聚体在高温高盐环境中的稳定性。由于 CNC 颗粒的聚集导致高渗透区的阻塞导致流体转向。这提高了波及效率并允许注入的流体与油接触。