Sarafzadeh Pegah, Zeinolabedini Hezave Ali, Mohammadi Sahar, Niazi Ali, Ayatollahi Shahab
School of Petroleum and Chemical Engineering, Shiraz University, Shiraz, Iran.
Islamic Azad University, Dashtestan Branch, Borazjan, Iran.
Colloids Surf B Biointerfaces. 2014 May 1;117:457-65. doi: 10.1016/j.colsurfb.2013.12.002. Epub 2013 Dec 7.
During any microbial enhanced oil recovery process, both cells and the metabolic products of bacteria govern the tertiary oil recovery efficiency. However, very accurate examination is needed to find the functionality of these tiny creatures at different reservoir conditions. In this regard, the effect of cell structure on ultimate microbial recovery efficiency which is the most dominant mechanism based on the microorganism types (gram-negative or gram-positive) was systematically investigated. At the first stage, possible different active mechanisms using Bacillus stearothermophilus SUCPM#14 strain were tested using specially designed injection protocol, in situ and ex situ core flooding experiments, interfacial tension, viscosity, pH and Amott wettability index measurements. At the second stage, comparing functionality of B. stearothermophilus SUCPM#14 (a gram-positive type) with the previously examined strain namely Enterobacter cloacae as a gram-negative type, proposed this hypothesis that the cell structure significantly affects the interfacial behaviors. New designed protocols were utilized to check the individual effects of cells, bioproducts and interaction of these together on the oil/water and also fluids/rock interfaces. The final results showed that the cells of B. stearothermophilus SUCPM#14 adhere more into the oil/water interface compared to E. cloacae and change its rheological properties; e.g. its elastic properties which affect the ultimate microbial oil recovery efficiency. Eventually, contradicting results revealed that biosurfactant produced by E. cloacae was able to considerably reduce the interfacial tension and alter the wettability of the rock (to neutral conditions) while biosurfactant produced by B. stearothermophilus SUCPM#14 was not very effective.
在任何微生物强化采油过程中，细菌细胞及其代谢产物都决定着三次采油效率。然而，需要非常精确的检测来发现这些微小生物在不同油藏条件下的功能。在这方面，基于微生物类型（革兰氏阴性或革兰氏阳性），系统地研究了细胞结构对最终微生物采油效率的影响，这是最主要的机制。在第一阶段，使用特别设计的注入方案、原位和异位岩心驱替实验、界面张力、粘度、pH值和阿莫特润湿性指数测量，测试了嗜热脂肪芽孢杆菌SUCPM#14菌株可能的不同活性机制。在第二阶段，将嗜热脂肪芽孢杆菌SUCPM#14（革兰氏阳性类型）的功能与先前检测的阴沟肠杆菌菌株（革兰氏阴性类型）进行比较，提出了细胞结构显著影响界面行为的假设。利用新设计的方案来检查细胞、生物产物及其相互作用对油/水以及流体/岩石界面的单独影响。最终结果表明，与阴沟肠杆菌相比，嗜热脂肪芽孢杆菌SUCPM#14的细胞更多地附着在油/水界面上，并改变其流变特性，例如其弹性特性，这会影响最终的微生物采油效率。最终，相互矛盾的结果表明，阴沟肠杆菌产生的生物表面活性剂能够显著降低界面张力并改变岩石的润湿性（至中性条件），而嗜热脂肪芽孢杆菌SUCPM#14产生的生物表面活性剂效果不佳。
