Study of the contact angle of water droplet on the surface of natural K-feldspar with the combination of Ar+ polishing and atomic force microscopy scanning

Wettability is a key property of a reservoir rock, which can significantly affect the distribution and transportation of fluids (gas, oil, water, etc.) in reservoir pores which are constructed with various minerals. As for sandstone reservoirs, quartz and feldspar are the common minerals of the framework. However, the study on the wettability of feldspar is much less than that of quartz probably due to the strong heterogeneity and complex composition of natural feldspar minerals. In this study, a method for measuring the contact angle of water droplet on a natural mineral surface is proposed by combining argon ion polishing technique with atomic force microscopy scanning (Ar+-AFM method). Compared with the traditional optical goniometer measurement, this method can apparently reduce the influence of heterogeneity on the wettability of K-feldspar surface and yield more consistent contact angle data. (C) 2021 Elsevier Ltd. All rights reserved.