The effects of clay minerals on imbibition in shale reservoirs

A team of researchers from the China University of Petroleum, led by Dr. Yuxuan Xia, has published a comprehensive review in Capillarity, exploring the dual effects of clay minerals on imbibition in shale reservoirs. The study delves into how clay minerals, through their unique structures and properties, can either promote or hinder imbibition by influencing micro-fracture formation, pore throat reduction, and osmotic pressure.

The team published their work in Capillarity (DOI: 10.46690/capi.2025.01.02) on January 9, 2025.

The review highlights that clay minerals, such as montmorillonite, illite, and kaolinite, can significantly impact imbibition through mechanisms like hydration swelling and osmotic pressure. These minerals can either enhance permeability by creating micro-fractures or reduce it by blocking flow paths due to swelling and migration. The study also emphasized that capillary forces are commonly considered the main mechanism for fluid displacement during imbibition. However, the diffuse double layer of clay minerals can form a "semipermeable membrane" with selective permeability under the influence of surface adsorption and diffusion movements. This "semipermeable membrane" allows water molecules to pass through but restricts the passage of salt ions. The resulting osmotic pressure, therefore, also serves as a significant driving force for imbibition and should not be overlooked.

Dr. Xia stated, "Given the high clay mineral content in shale, future research should focus on two key aspects: the threshold of clay mineral content and the resulting osmotic pressure. In-depth exploration of these factors will advance the sustainable development and utilization of shale oil and gas resources."

This research not only advances the scientific understanding of capillary-driven phenomena in shale reservoirs but also provides practical insights for the oil and gas industry, particularly in the context of hydraulic fracturing and water injection strategies.

Other contributors include Lipeng Wang, Han Wang, Xuanzhe Xia and Fangzhou Zhao from State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing; Ryan Masoodi from School of Design and Engineering, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
 

This work was supported by the National Natural Science Foundation of China (Nos. 42302143, 52404048).

About Author

Corresponding Author: Yuxuan Xia, Ph.D., postdoctoral fellow, has long been engaged in research on the characterization of unconventional reservoir structures and seepage mechanisms. He has published 9 papers as the first/corresponding author, one of which has been selected as an ESI highly cited paper. He has successively presided over the National Natural Science Foundation of China Youth Science Fund and the Postdoctoral General Fund, and won the second prize of the Natural Science Award of the Science and Technology Award of the Petroleum and Chemical Automation Industry in China.