Bultreys, Tom

Cnudde, Veerle

Van Hoorebeke, Luc

English

Ghent University Academic Bibliography

8th International Conference on Porous Media & Annual Meetingpage 1/2Assessing the influence of microporosity on imbibition in complex porestructures with multi-scale pore network modelsPresenter: Tom BultreysContact Author: Tom BultreysAUTHORSTom Bultreys 1, Luc Van Hoorebeke 2, Veerle Cnudde 31 UGCT/PProGRess, Ghent University, Krijgslaan 281 S8, 9000, Ghent, BE2 Prof. Dr., UGCT/Radiation Physics, Ghent University, Proeftuinstraat 86, 9000, Ghent, BE3 Prof. Dr., UGCT/PProGRess, Ghent University, Krijgslaan 281 S8, 9000, Ghent, BEABSTRACTUnderstanding the relative permeability behavior of complex geological materials during imbibition isan important challenge in e.g. petroleum engineering, environmental engineering andCO2-sequestration. While image-based pore network models have helped to understand how thepore-scale properties influence this behavior, specially adapted multi-scale models are needed toperform such simulations on rocks with wide pore size distributions. In previous work, we havedeveloped a multi-scale image-based pore network model, which takes unresolved microporosity intoaccount by adding special links (micro-links) with upscaled microporosity properties to the classicalnetwork description (pores and throats) [1]. Here, we present rules to simulate imbibition in suchnetworks under different wettability scenarios.Compared to drainage, the filling sequence during imbibition is more complex, as snap-off andcooperative pore filling have to be taken into account. In our model, the saturation and fluidconductivities of the microporosity at each point in the simulation are encoded in capillary pressureand relative permeability curves which are provided as input. Thus, an adequate network descriptionof the microporosity is required to assess these curves under the prevailing wettability conditions. Thisnetwork description can for example be obtained by performing high-resolution imaging experimentson the microporosity.To describe the filling sequence of the multi-scale network as a whole, the connectivity of both fluidphases (e.g. oil and water) in the microporous links is taken into account. Macropores can be filledwith the invading fluid through neighbouring microporosity if it percolates through the microporosity.During waterflooding in the water-wet case, the invasion capillary pressure at which this happens isgenerally controlled by the geometry of the macropore. During waterflooding under oil-wetconditions, the invasion capillary pressure is instead controlled by the microporosity, and a percolationtheory approach is used to determine through which micro-links water percolates first. Furthermore,microporosity can also provide an escape path for the defending phase if this phase percolates throughit. We thus also take the defending phase’s connectivity into account at the prevailing capillarypressure, which can affect the network’s trapping behaviour.In this work, we show how quasi-static, multi-scale pore network models can be used to incorporateinformation from multiple scales, and we illustrate how this approach can be used to investigate theinfluence of microporosity on relative permeability and resistivity index behavior during imbibition.The validity of the model is tested by comparing results to network models with individual micropores[2] and by treating networks extracted from micro-computed tomography scans of rocks with complexpore geometries (e.g. carbonates).REFERENCES[1] T. Bultreys, L. Van Hoorebeke, V. Cnudde, "Multi-scale, micro-computed tomography-based pore8th International Conference on Porous Media & Annual Meetingpage 2/2network models to simulate drainage in heterogeneous rocks", Adv. Water Resources. (2015) 78,36–49.[2] A. Mehmani, M. Prodanovi?, "The effect of microporosity on transport properties in porousmedia", Adv. Water Resources. (2014) 63, 104–119.GRAPHICS

Assessing the influence of microporosity on imbibition in complex pore structures with multi-scale pore network models

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Assessing the influence of microporosity on imbibition in complex pore structures with multi-scale pore network models

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