A phase inversion polymer coating to prevent swelling and spalling of clay fines in coal seam gas wells

Ge, Lei and Hamilton, Christopher and Febrina, Rahman Tasha and Rudolph, Victor and Rufford, Thomas E. (2018) A phase inversion polymer coating to prevent swelling and spalling of clay fines in coal seam gas wells. International Journal of Coal Science and Technology. ISSN 2095-8293

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We report a phase inversion polymer coating as a novel concept with potential to prevent clay swelling and fines generation in coal seam gas, or other petroleum, wellbores. Our approach uses polyethersulfone (PES) with N-methyl-2-pyrrolidinone (NMP) as a water-soluble solvent to form a dense, low-porosity film across the clay-rich interburden layers, but a porous and permeable membrane on coal seams. This contrasting behaviour occurs because the coal contains much more free water than the clay-rich interburden layers. We demonstrate the efficacy of the method to prevent clay spalling in immersion tests and under a flow of fresh water in a visual swell test apparatus. The clay-rich rocks studied were mudstone and siltstone, and these were dip coated in the PES/NMP solution. The uncoated mudstone swelled and broke apart quickly in the immersion test and visual flow test, but the PES coated rock samples were stable for 30 days. The coated rock and coal samples were characterised by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The morphology of coated mudstone and coated coal samples showed that the polymer formed a dense layer across the low-permeability mudstone, but an open porous structure on the coal surface. The effect of the coating on the permeability of KCl brine through coal was measured in a core-flood apparatus. Although the permeability of the coal showed some deterioration after coating, from (0.58±0.12) mD to (0.3±0.03) mD, these results demonstrate the potential of a smart polymer coating to prevent clay swelling while remaining permeable to gas and water on coal layers.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version made available under Creative Commons Attribution 4.0 International License.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials
Date Deposited: 18 Apr 2018 03:28
Last Modified: 15 May 2018 23:08
Uncontrolled Keywords: phase inversion polymer coating; coal seam gas, clay swelling
Fields of Research : 03 Chemical Sciences > 0303 Macromolecular and Materials Chemistry > 030304 Physical Chemistry of Materials
09 Engineering > 0914 Resources Engineering and Extractive Metallurgy > 091406 Petroleum and Reservoir Engineering
09 Engineering > 0904 Chemical Engineering > 090404 Membrane and Separation Technologies
Socio-Economic Objective: B Economic Development > 85 Energy > 8501 Energy Exploration > 850103 Oil and Gas Exploration
Funding Details:
Identification Number or DOI: https://doi.org/10.1007/s40789-018-0199-0
URI: http://eprints.usq.edu.au/id/eprint/33906

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