Wetting mechanism and alteration of nano-sized shale pores: Insights from contrast variation small angle neutron scattering

Tao Zhang, Qinhong Hu, Yufeng Xiao, Gergely Nagy, Shengyu Yang, Bao Yuan, Hanqiu Jiang, Yubin Ke, Qiming Wang

Research output: Contribution to journalArticlepeer-review

Abstract

Wettability of tight shale is crucial for fluid flow and mass transport process in energy geosciences. However, understanding the interfacial chemistry and wetting mechanisms at sub-nano-pore scales remains a formidable challenge. In this study, the Contrast Variation technique of Small Angle Neutron Scattering (CV-SANS) is employed to investigate shale's interfacial chemistry using reagents that possess a range of different polarities, including water, n-decane, toluene, and dimethyl methanamide. Through five different experimental strategies, we have demonstrated a successful modification of shale wettability, ranging from enhancement, weakening, to reversal. Delving into the mechanisms, we illustrated the crucial role of pre-existing liquid films in these changes, where the uniquely co-existing polar and non-polar functional groups in dimethyl methanamide acted as a conduit for interfacial chemistry adjustments. Furthermore, a solvent immersion led to matrix dilation as well as liberation of residual oil-occupied pores, resulting in altered pore size distributions, with hydrogen bonding playing a significant role in the polar groups. Interestingly, despite shale exhibiting a stronger affinity for oil over water, hydrophilic solvents induced more substantial dilation than lipophilic ones. Collectively, this work elucidates the dynamic change of interfacial chemistry via the configuration of polarity using chemical reagents, and the CV-SANS technique underscores its invaluable utilities in decoding the interfacial wettability traits in nanopore space of shale.

Original languageEnglish
Article number125962
JournalJournal of Molecular Liquids
Volume413
DOIs
StatePublished - Nov 1 2024

Keywords

  • Contrast variation
  • Interfacial chemistry
  • SANS
  • Shale
  • Swelling
  • Wettability

Fingerprint

Dive into the research topics of 'Wetting mechanism and alteration of nano-sized shale pores: Insights from contrast variation small angle neutron scattering'. Together they form a unique fingerprint.

Cite this