Characteristic and mechanism of marine-continental transitional shale hydration: a case study on disaggregated shale in Guizhou Province, South China

• Published in: Arabian journal of geosciences Vol. 15; no. 6
• Main Authors: Zhang, Baoxin, Li, Wuzhong, Yang, Yiming, Fu, Xuehai, Shen, Yulin, Deng, Ze
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.03.2022; Springer Nature B.V
• Subjects: Adsorption; Deformation; Disaggregation; Drilling; Drilling fluids; Earth and Environmental Science; Earth science; Earth Sciences; Exploitation; Hydration; Illite; Illites; Moisture; Montmorillonite; Montmorillonites; Natural gas exploration; Oil and gas exploration; Original Paper; Permian; Potassium chloride; Reduction; Sedimentary rocks; Shale; Shale gas; Shales; Specific surface; Surface area; Surface chemistry; Swelling; X-ray diffraction; China; Guizhou China; Hydration; Clay mineral; Marine-continental transitional shale; Guizhou Province; Shale gas
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-022-09789-7

Several properties of shale reservoirs change after absorbing water due to hydration, which increases the difficulty for shale gas exploration and exploitation. The Permian marine-continental transitional shale with different hydration degrees in Guizhou Province, China was collected to clarify the characteristics and mechanism of shale hydration in this study. The deformation induced by moisture adsorption, X-ray diffraction (XRD), and other experiments were conducted. The results show that the high-degree hydrated shale cores are seriously disaggregated. The larger the moisture adsorption capacity means the higher hydration degree. The shale swells after absorbing moisture, and the deformation ranges from 808 to 9145 uε. The swelling of the high-degree hydrated sample can reach 10 times of that of the unhydrated sample within the same time. While the pore volume and specific surface area decrease, and the maximum reduction of specific surface area is 26.69%. Compared with the unhydrated transitional shale, the essential reason for shale hydration is the higher illite-montmorillonite mixture content. When replacing clean water with 3% (mass fraction) KCl solution, the swelling reduces to between 633 and 8634 uε. The reduction in the swelling of the high-degree hydrated samples is greater than that of the other samples, which demonstrates that shale hydration prevention may be achieved by adding a certain concentration KCl solution to the drilling fluid. Graphical abstract Highlights 1) The disaggregation characteristics of transitional shale with different hydration degrees in the western Guizhou Province, China, were compared. 2) The shale hydration characteristics were demonstrated using reproduced samples, which has practical significance for gas exploitation. 3) Compared with the unhydrated transitional shale, the reason for shale hydration was illustrated. 4) The measures for shale hydration preventionwere discussed.