The imbibition process plays a crucial role in the development of shale reservoirs, particularly during the volume fracturing and water injection development phases. This process significantly influences the production capacity of shale and also serves as a essential parameter for assessing reservoir performance. Clay minerals contribute to the formation of numerous micro-pores and micro-fractures, exhibit strong plasticity and are prone to swelling. The unique structures and properties of clay minerals have a profound impact on shale imbibition. This review analyzes the effects of clay minerals on imbibition from different perspectives, finding that the effect is closely related to the total amount of clay minerals, as well as to specific mineral types and content. Clay minerals exhibit a dual impact on imbibition, which can either facilitate imbibition by promoting micro-fractures formation or hinder it by reducing pore throats and migrating to block flow paths due to swelling. While capillary action is usually considered the main mechanism for fluid displacement during the imbibition, the osmotic pressure formed by clay minerals can also serve as a driving force for imbibition, positively contributing to shale oil and gas recovery. This review aims to provide a comprehensive understanding of the role of clay minerals on the imbibition, providing a theoretical foundation and practical guidance for future research and efficient development of shale reservoirs.

Design of hygiene products such as sanitary napkins, diapers, etc. is heavily dependent on the liquid absorption performance of fabrics. As fibres swell upon liquid absorption, their liquid absorption performance changes. Understanding the flow through porous media under swelling conditions has important implications for product design and has yet to be elucidated fully. The goal of our research was to study the effect of fibre swelling experimentally. Cotton is selected as the test fabric as it is commonly used in most hygiene applications. Under swelling conditions, the effect of swelling on individual fibres, porosity, permeability, and performance of the cotton fabric is analysed. Findings showed that upon water absorption, the fibre diameter increased by 10%, porosity decreased by 11%, and permeability decreased by 60% under fully swollen conditions. The porosity reduction is also predicted analytically using the data obtained from the fibre swelling measurements. In contrast, predictions of commonly used analytical models showed only a 30% reduction in the porosity. To correct this, two new correction factors to account for effects of inter-fibre interactions on the total swelling rate of fabric are proposed. The performance measures of cotton samples under swelling conditions indicated that advancement of the flow front on the lower face was more dominant than the upper face of the sample possibly related to gravity. These experimental data improve our understanding of wicking flow which can help to improve the design of hygiene products and to develop more realistic computational fluid dynamics models.