Experimental and COSMO-RS Simulation Studies on the Effects of Polyatomic Anions on Clay Swelling

Md Tauhidur Rahman; Berihun Mamo Negash; Alamin Idris; Mohammad Islam Miah; Kallol Biswas

doi:10.1021/acsomega.1c03786

Experimental and COSMO-RS Simulation Studies on the Effects of Polyatomic Anions on Clay Swelling

ACS Omega. 2021 Sep 28;6(40):26519-26532. doi: 10.1021/acsomega.1c03786. eCollection 2021 Oct 12.

Authors

Md Tauhidur Rahman^{1

1}, Berihun Mamo Negash^{1

1}, Alamin Idris², Mohammad Islam Miah³, Kallol Biswas¹

Affiliations

¹ Department of Petroleum Engineering, Shale Gas Research Group (SGRG), and Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak Darul Ridzuan, Malaysia.
² Department of Engineering and Chemical Sciences, Karlstad University, 65188 Karlstad, Sweden.
³ Department of Petroleum and Mining Engineering, Chittagong University of Engineering and Technology, Chittagong 4349, Bangladesh.

Abstract

Ionic liquids (ILs) can play a vital role in clay swelling inhibition during hydraulic fracturing. Previous studies highlighted the effect of side-chain length attached to the cationic core and different anions possessing almost the same chemical properties on inhibition performance. However, polyatomic anions have the potential to superiorly inhibit swelling compared to monoatomic anions. In this study, three ILs, namely, 1-butyl-3-methylimidazolium chloride (BMIMCl), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF₆), were utilized to assess the effects of polyatomic anions on clay swelling inhibition. These performances were compared with the performances of a conventional inhibitor, potassium chloride (KCl). X-ray diffraction (XRD) testing was applied to check the mineral components present in the bentonite clay sample studied in this research. Clay swelling inhibition performance and rheological properties of these ILs were evaluated by the bentonite plate soaking test, linear swelling test, and rheological test. The swelling inhibition mechanisms were investigated through ζ-potential measurement, Fourier transform infrared (FT-IR) spectroscopy, and contact angle measurement. Moreover, COSMO-RS computer simulation was conducted to explain the inhibition mechanisms theoretically. The results demonstrated that BMIMPF₆ showed superior inhibition performance and reduced the swelling by 21.55%, while only 9.26% reduction was attained by potassium chloride (KCl). The adsorption ability on the bentonite surface through electrostatic attraction, higher activity coefficient, and less electronegativity of PF₆ ^- anion played a vital role in attaining such superior inhibition performance by BMIMPF₆.