Ivanova Anastasia, Mitiurev Nikolai, Cheremisin Alexey, Orekhov Anton, Kamyshinsky Roman, Vasiliev Alexander
Skolkovo Institute of Science and Technology, Moscow, 121205, Russia.
Curtin University, Perth, WA, 6845, Australia.
Sci Rep. 2019 Jul 23;9(1):10667. doi: 10.1038/s41598-019-47139-y.
Effective production of oil from carbonate reservoirs often requires the application of improved oil recovery technologies such as waterflooding. However, conventional waterflooding in carbonates usually results in low hydrocarbon recovery as most of these formations exhibit a complex pore throats structure and are mostly oil-wet. Therefore, improved insight into the causes of hydrophobic wetting behavior of such reservoirs is important for understanding the fluid distribution, displacement and enhancing recovery processes. The characterization of fluid-rock interactions is, however, challenging with existing laboratory methods, which are typically based on macroscale (mm) observations. In this experimental study, an advanced imaging technique, namely environmental scanning electron microscope, was applied for the comprehensive investigation of microscale (µm) wettability variations in carbonate rocks covered with organic layers. For the first time, the presence of organic layers on the sample was proved using energy dispersive X-ray mapping. Furthermore, the chemical bond of this layer and carbonate rock surfaces was determined using the transmission electron microscopy and electron energy-loss spectroscopy. The thickness of layer was estimated by using image processing software. These findings show that the application of combined microscopic techniques reveals important details about the reason of hydrophobic wetting properties of real carbonate rocks.
从碳酸盐岩储层中有效开采石油通常需要应用诸如注水等改进的采油技术。然而，碳酸盐岩中的传统注水通常导致烃类采收率较低，因为这些地层大多具有复杂的孔喉结构且大多为油湿。因此，深入了解此类储层疏水润湿行为的成因对于理解流体分布、驱替以及提高采收率过程至关重要。然而，用现有的通常基于宏观尺度（毫米）观测的实验室方法来表征流体 - 岩石相互作用具有挑战性。在本实验研究中，一种先进的成像技术，即环境扫描电子显微镜，被用于全面研究覆盖有有机层的碳酸盐岩中微观尺度（微米）的润湿性变化。首次使用能量色散X射线映射证明了样品上有机层的存在。此外，利用透射电子显微镜和电子能量损失谱确定了该层与碳酸盐岩表面的化学键。通过使用图像处理软件估计了层的厚度。这些发现表明，联合微观技术的应用揭示了真实碳酸盐岩疏水润湿特性原因的重要细节。
