3D Visualization to Study the Effect of Wettability Alteration on Fluid Distribution at the Pore

摘要

Fluid mobility in porous media is highly affected by the fluid distribution and fluid wettability condition inside the pore space. Fluid wetting the rock tends to have a lower mobility compared to the non-wetting fluid. In petroleum engineering applications, changes in the wetting characteristics of the rock-fluid system can have a significant effect on well productivity. One example is condensate blocking, where the liquid condensate accumulates in high saturation near the wellbore due to the strong liquid-wetting, resulting in reduced gas mobility. Previous studies have shown that altering the wettability towards a gas-wetting state can enhance liquid mobility and reduce the accumulation in the near-wellbore region. Changes in the rock Wettability are usually studied either through contact angle measurements at the core scale, or through studies on the changes in fluid mobility characteristics. However, some researchers have been skeptical as to whether a state of gas-wetting can be achieved at the pore scale. In this work, we conducted an experimental study where we altered carbonate rock wettability from liquid-wetting to gas-wetting. This was achieved using a fluorinated polymer treatment. A new experimental setup was used combining a high resolution computed microtomography (MCT), to acquire 3D images of the rock-fluid system at pore scale. Pore spaces in the order of 50 to 200 micrometer were scanned at a resolution of 2 micron in order to visualize the liquid-air interface. The results show that the polymer treatment changed the distribution of liquid and gas inside the pore space. Liquid appears to be wetting the rock surface when the rock is in its original conditions. The studies in this area are important to improve the productivity of gas condensate reservoirs where liquid accumulates, decreasing the production of the well. It is evident from our work that achieving a state of gas-wetting at the pore scale is possible. 3D visualization is a very important tool to help us quantify the success of the polymer treatment and the uniformity of the surface coating. In order to conduct a similar study at higher temperature and pressure conditions, a visual cell is under design and will be discussed in future work