Revealing crucial effects of reservoir environment and hydrocarbon fractions on fluid behaviour in kaolinite pores

Zhao, Rixin; Xue, Haitao; Lu, Shuangfang; Greenwell, H. Chris; Erastova, Valentina

Abstract

The adsorption interactions of hydrocarbons and clay surfaces are crucial to understanding fluid behaviour within shale reservoirs and to mediating organic pollutants in soils. These interactions are affected by the diversity of complex hydrocarbon components and the variations in environmental conditions. This study examines the interactions between kaolinite clay, featuring two distinct basal surfaces, and an array of hydrocarbons. We assess the impact of various molecular structures, functional groups, and environmental conditions (focusing on the reservoir temperature and pressure ranges) on the adsorption selectivity, surface packing, molecular alignment and orientation, and diffusion of hydrocarbons. Analyses of molecular interaction energies provide a quantitative elucidation of the adsorption mechanisms of hydrocarbons on the different kaolinite surfaces. Our findings suggest that molecular configuration, functional group properties, and spatial effects dictate the distribution patterns of hydrocarbons for the different kaolinite surfaces. The differences in the interaction energy between various hydrocarbons with kaolinite reveal the adsorption strength of different hydrocarbons in the order of asphaltenes > heteroatomic hydrocarbons > saturated hydrocarbons > aromatic hydrocarbons. Furthermore, we observe that the adsorptive characteristics of hydrocarbons on kaolinite are highly temperature-sensitive, with increased temperatures markedly reducing the adsorption amount. Beyond a certain threshold, the effect of pressure rise on the fluid behaviour of hydrocarbons is non-negligible and is related to molecular packing and reduced mobility. Simulation results based on actual geological characteristics demonstrate notable adsorption disparities among hydrocarbon components on different kaolinite surfaces, influenced by competitive adsorption and clay surface interactions. Polar surfaces are predominantly occupied by heteroatomic hydrocarbons, whereas on non-polar surfaces, asphaltenes and heavy saturated hydrocarbons develop multi-layer adsorption structures, with molecules aligned parallel to the surface.

Citation

Zhao, R., Xue, H., Lu, S., Greenwell, H. C., & Erastova, V. (2024). Revealing crucial effects of reservoir environment and hydrocarbon fractions on fluid behaviour in kaolinite pores. Chemical Engineering Journal, 489, Article 151362. https://doi.org/10.1016/j.cej.2024.151362

• Journal Article Type: Article
• Acceptance Date: Apr 15, 2024
• Online Publication Date: Apr 16, 2024
• Publication Date: 2024-06
• Deposit Date: May 15, 2024
• Publicly Available Date: May 15, 2024
• Journal: Chemical Engineering Journal
• Print ISSN: 1385-8947
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 489
• Article Number: 151362
• DOI: https://doi.org/10.1016/j.cej.2024.151362
• Public URL: https://durham-repository.worktribe.com/output/2440602