Pore-scale Modelling of Wettability Alteration during 1 Primary Drainage 2 3

Content Provider	Semantic Scholar
Author	Kallel, W. Dijke, Marinus Izaak Jan Van Sorbie, K. S. Wood, Rachel
Copyright Year	2017
Abstract	19 While carbonate reservoirs are recognized to be weaklyto moderately oil-wet at the core20 scale, wettability distributions at the pore-scale remain poorly understood. In particular, the 21 wetting state of micropores (pores <5 μm in radius) is crucial for assessing multi-phase flow 22 processes, as microporosity can determine overall pore-space connectivity. While oil-wet 23 micropores are plausible, it is unclear how this may have occurred without invoking 24 excessively high capillary pressures. Here, we develop a novel mechanistic wettability 25 alteration scenario that evolves during primary drainage, involving the release of small polar 26 non-hydrocarbon compounds (e.g. alkylphenols, carbazoles) from the oil-phase into the 27 water-phase. We implement a diffusion and adsorption model for these compounds that 28 triggers a wettability alteration from initially water-wet to more intermediate–wet conditions. 29 This mechanism is incorporated in a quasi-static pore-network model to which we add a 30 notional time-dependency of the quasi-static invasion percolation mechanism. The model 31 qualitatively reproduces experimental observations where an early rapid wettability alteration 32 involving these small polar species occurred during primary drainage, preferentially near the 33 inlet. Interestingly, we are able to invoke clear differences in the primary drainage patterns by 34 varying both the extent of wettability alteration and the balance between the processes of oil 35 invasion and wetting change. Combined, these parameters dictate the initial water saturation 36 for waterflooding. Indeed, under conditions where oil invasion is slow compared to a fast and 37 relatively strong wetting change, the model results in significant non-zero water saturations, 38 even at high capillary pressures. This water trapping results from the removal of water 39 wetting films in the corners of angular pores. On the other hand, for relatively fast oil 40
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Alternate Webpage(s)	https://pureapps2.hw.ac.uk/ws/portalfiles/portal/15019834/2016WR018703Kallel.pdf
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article