Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada.
Sci Rep. 2017 Jun 28;7(1):4347. doi: 10.1038/s41598-017-04239-x.
Low-permeability (unconventional) hydrocarbon reservoirs exhibit a complex nanopore structure and micro (µm) -scale variability in composition which control fluid distribution, displacement and transport processes. Conventional methods for characterizing fluid-rock interaction are however typically performed at a macro (mm) -scale on rock sample surfaces. In this work, innovative methods for the quantification of micro-scale variations in wettability and fluid distribution in a low-permeability oil reservoir was enabled by using an environmental scanning electron microscope. Live imaging of controlled water condensation/evaporation experiments allowed micro-droplet contact angles to be evaluated, while imaging combined with x-ray mapping of cryogenically frozen samples facilitated the evaluation of oil and water micro-droplet contact angles after successive fluid injection. For the first time, live imaging of fluids injected through a micro-injection system has enabled quantification of sessile and dynamic micro-droplet contact angles. Application of these combined methods has revealed dramatic spatial changes in fluid contact angles at the micro-scale, calling into question the applicability of macro-scale observations of fluid-rock interaction.
低渗透（非常规）储层具有复杂的纳米孔隙结构和微米级的组成变化，控制着流体的分布、驱替和输运过程。然而，用于描述流体-岩石相互作用的常规方法通常是在岩石样品表面的宏观（mm）尺度上进行的。在这项工作中，通过使用环境扫描电子显微镜，实现了定量分析低渗透油藏中润湿性和流体分布微观变化的创新方法。通过控制水的冷凝/蒸发实验的实时成像，可以评估微液滴接触角，而与低温冷冻样品的成像相结合的 X 射线映射则有助于评估连续注入流体后的油和水微液滴接触角。首次通过微注入系统注入的流体的实时成像，实现了对固着和动态微液滴接触角的定量分析。这些组合方法的应用揭示了在微观尺度上流体接触角的显著空间变化，这对宏观尺度上观察流体-岩石相互作用的适用性提出了质疑。
