Glass micromodel

Figure 1. Micrograph of foam in a 1.1 pm, two dimensional etched-glass micromodel of a Kuparuk sandstone. Bright areas reflect the solid matrix while grey areas correspond to wetting aqueous surfactant solution next to the pore walls. Pore throats are about 30 to 70 /xm in size. Gas bubbles separated by lamellae (dark lines) are seen as the nonwetting "foam" phase.

Glass micromodels, in high P cell (Tohidi et al., 2002) Hydrate, gas, water phase distribution Yes P, T hydrate phase vs. time (min) Typically up to 5000 psi >50 pm channels Visual location of hydrate phase during growth... 

FIGURE 6.10 Schematic of the glass micromodel apparatus (a) and the micromodel pore network (b). (Reproduced from Tohidi, B., Anderson, R., Clennell, B., Yang, J., Bashir, A., Burgass, R.W., in Proc. Fourth International Conference on Gas Hydrates, Yokohama, Japan, May 19-23, p. 761 (2002). With permission.)... 

Micro-scale experiments involve the microscopic observation of flowing foams in etched-glass micromodels. Here the pore dimensions are typically on the order of hundreds of micrometers. Such experiments provide valuable and rapidly obtainable qualitative information about foam behaviour in constrained media under a variety of experimental conditions, including the presence of a residual oil saturation... 

The studies of Marsden et al. [162], Holm [164] and more recently of Trienen et al. [165], Ettinger and Radke [166,167], including the direct observations in a transparent etched-glass micromodels [158,168,169], have established that the bubble size is almost equal to the... 

Mast, in a pioneering 1972 paper, reported visual observations of foam flow in etched glass micromodels (37 ) His observations showed that some of the conflicting claims about the properties of foam flow in porous media were probably due simply to the dominance of different mechanisms under the various conditions employed by the separate researchers (37). Mast observed most of the various mechanisms of dispersion formation, flow, and breakdown that are now believed to control the sweep control properties of surfactant-based mobility control (37,39-41). 

This equation assumes a contact angle of zero, a good approximation for the glass micromodel used here where the oleic phase has been observed flowing through pore constrictions without forming contact lines. 

Soo and Radke (11) confirmed that the transient permeability reduction observed by McAuliffe (9) mainly arises from the retention of drops in pores, which they termed as straining capture of the oil droplets. They also observed that droplets smaller than pore throats were captured in crevices or pockets and sometimes on the surface of the porous medium. They concluded, on the basis of their experiments in sand packs and visual glass micromodel observations, that stable OAV emulsions do not flow in the porous medium as a continuum viscous liquid, nor do they flow by squeezing through pore constrictions, but rather by the capture of the oil droplets with subsequent permeability reduction. They used deep-bed filtration principles (i2, 13) to model this phenomenon, which is discussed in detail later in this chapter. 

Figure 2. Photomicrograph of foam in a transparent-glass micromodel A white scale marker at lower left corresponds to 100 pm. The leftmost black arrow marks a large liquid-filled pore connected to the foam-flow channel by a small pore-throat. The black arrow to the right of center indicates the growth of a wetting collar (11).

These macroscopic measurements of gas trapping are confirmed by visual observations in transparent etched-glass micromodels and bead packs (24—26, 41). Trapped foam severely reduces the effective permeability of gas moving through a porous medium by blocking all but the least resistive flow paths. Hence, trapped gas reduces the void volume of the porous medium available for flow. Thus, higher flow resistances are measured, and lower permeabilities to gas are computed. This trapped gas accounts for some, but not all, increased resistance to flow. 

The single layer glass bead model is a closer representation of a porous medium. This was used by Sharma to study toe foam drive process and Egbogah and Dawe to study toe size distribution of oil droplets. Mattax and Kyte used a network of etched capillaries to study fluid distributions under various wettability conditions. Davis and Jones studied the flow of foam in porous media using etched glass micromodels. A study of toe multiphase flow of oil and water di ersed in toe porous medium was carried out by Bonnet using an etched plastic micromodel. 

Meybodi, H.E., Kharrat, R., and Ghazanfari, M.H. 2008. Effect of Heterogeneity of Layered Reservoirs on Polymer Flooding An Experimental Approach Using Five-Spot Glass Micromodel. Paper SPE 113820 presented at the Europec/EAGE Conference and Exhibition, Rome, 9-12 June. DPI 10.2118/113820-MS. 

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