Theoretical investigation of heterogeneous wettability in porous media using NMR

Abstract

It is highly important to understand the heterogeneous wettability properties of porous media for enhanced oil recovery (EOR). However, wettability measurements are still challenging in directly investigating the wettability of porous media. In this paper, we propose a multidimensional nuclear magnetic resonance (NMR) method and the concept of apparent contact angles to characterize the heterogeneous wettability of porous media. The apparent contact angle, which is determined by both the wetting surface coverage and the local wettability (wetting contact angles of each homogeneous wetting regions or wetting patches), is first introduced as an indicator of the heterogeneous wettability of porous media using the NMR method. For homogeneously wetting patches, the relaxation time ratio T1/T2 is employed to probe the local wettabiity of wetting patches. The T2 − D is introduced to obtain the wetting surface coverage using the effective relaxivity. Numerical simulations are conducted to validate this method.

One- and Two-Dimensional NMR in Studying Wood–Water Interaction at Moisturizing Spruce. Anisotropy of Water Self-Diffusion

“…It is important to know how wetting the wood affects porous microstructure and how to find suitable methods for estimation of pore-water interactions and water transport during changing moisture of wood [3][4][5][6][7][8][9]. Different methods including those based on the phenomenon of nuclear magnetic resonance (NMR spectroscopy and NMR Imaging) have been applied and developed to monitor wettability and saturation of different porous materials with water [1,4,[11][12][13][14]. For instance, different NMR techniques (spin-spin relaxation time (T 2 ) as a function of saturation, spin-lattice relaxation time (T 1 ) NMR dispersion, T 2 shift, NMR diffusion and T 1 /T 2 ratio) have been probed for 2 of 14 wettability measurements on chalk, rock, sandstone, coal [14][15][16][17].…”

“…For instance, different NMR techniques (spin-spin relaxation time (T 2 ) as a function of saturation, spin-lattice relaxation time (T 1 ) NMR dispersion, T 2 shift, NMR diffusion and T 1 /T 2 ratio) have been probed for 2 of 14 wettability measurements on chalk, rock, sandstone, coal [14][15][16][17]. Because NMR signal is sensitive to the interaction of liquid with solid surface, it is considered to be a suitable candidate for determination of wettability [11,12,[14][15][16]. Advantages of magnetic resonance methods are associated with quickness of measurement, and the result of the measurement (diffusion coefficient D and T 1 and T 2 relaxation times) can be obtained in real time [16].…”

“…Therefore, in practice, information about wettability from NMR data obtained can be extracted if the NMR parameters (T 1 , T 2 or D) have been already obtained and treated for proper analysis [14][15][16]. Considering the wettability as the interaction between the molecules of liquid and a solid surface, an intensity of these solid-water interactions can be clarified from the value of the T 1 /T 2 ratio [11,12,16]. The ratio of spin-lattice relaxation time to spin-spin relaxation time is supposed to test the local wettability.…”

“…The ratio of spin-lattice relaxation time to spin-spin relaxation time is supposed to test the local wettability. Using the effective relaxivity, the authors of Reference [12] consider the T 2 -D data for obtaining the wetting surface coverage.…”

Crude Oil Adsorbates on Calcite and Quartz Surfaces Investigated by NMR Spectroscopy

“…Wang et al [35] introduced a multidimensional NMR method to characterize the heterogeneous wettability that may be present in porous media. The method was validated with computer simulations.…”