Flow behaviour in the presence of wettability heterogeneities

The effect of heterogeneities on miscible and immiscible flood displacements in 2D bead packs in quadrant form, 2 × 2 block heterogeneity, with either a permeability or a wettability contrast is the subject of this paper. The physical processes occurring during miscible and immiscible flow and displacement within permeability and wettability quadrant bead pack models have been studied experimentally. This geometry occurs in a number of situations relevant to hydrocarbon production: particularly faults where adjacent rocks have large permeability contrasts with rapid changes, in the laboratory with core butting, in reservoir simulation where grid blocks have different permeability and in reservoirs having near-wellbore damage problems. The model quadrants 1-4, had 1 and 4 and 2 and 3 with identical properties, either in permeability or wettability. Reported are complete unit mobility miscible displacements, then the effects of viscosity differences (mobility modifiers) and finally immiscible displacements on displacement patterns for initial linear injection. The experiments demonstrate that nodal flow occurs for both miscible and immiscible flow, but for immiscible flow there are boundary effects due to capillary pressure differences created by water saturation changes or wettability contrasts which can leave patches of isolated fluid within a quadrant. The displacement patterns for the different models and fluids change significantly with the viscosity and wettability changes, particularly for the immiscible displacements. This is due to the changing capillary pressure between the quadrant blocks as the water saturation change. These are difficult to address in numerical modelling but should be accounted for. Other 6 R. A. Dawe, C. A. Grattoni effects include coupling of all physical processes governing the flow through the node (viscous, interfacial, gravity etc. forces) and creations of microzones of trapped residual oil. Our displacement patterns can therefore be a valuable verification benchmark tool for numerical modelling and a calibration data source for those wishing to simulate the effects of capillary pressure under differing wettability conditions and for those investigating upscaling modelling procedures. However, the possible loss of physical reality when averaging must always be considered.

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“…Some wettability contrast experiments have been reported by Caruana and Dawe (1996a). Here we complete the sequences.…”

Section: Wettability Contrastmentioning

confidence: 89%

Experimental displacement patterns in a 2 × 2 quadrant block with permeability and wettability heterogeneities—problems for numerical modelling

Dawe

Grattoni

2007

Transp Porous Med

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“…The fact that nearly all the samples that are investigated in the lab are heterogeneous (Huppler 1970) and that these heterogeneities are not representative of the full range of heterogeneities in the reservoir are strong source of uncertainty. As noted by a number of authors, relative permeability is indeed dependent on the wettability of the rock (Caruana and Dawe 1996), flow directions (Honarpour et al 1986;Crotti et al 1998), and heterogeneities (Crotti et al 1998). All these factors can be different in the lab and in the field, either because the rock sample investigated can have different properties (wettability), the way the experiments are performed does not coincide with the actual injection (flow directions) or because the heterogeneities of the lab sample are not representative of the reservoir.…”

mentioning

confidence: 95%

An Experimental Study on the Influence of Sub-Core Scale Heterogeneities on CO2 Distribution in Reservoir Rocks

2009

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This article presents the results of CO 2 /brine two-phase flow experiments in rocks at reservoir conditions. X-ray CT scanning is used to determine CO 2 saturation at a fine scale with a resolution of a few pore volumes and provide 3D porosity and saturation maps that can be use to correlate CO 2 saturations and rock properties. The study highlights the strong influence of sub-core scale heterogeneities on the spatial distribution of CO 2 at steady state and provides useful relative permeability data on a sample originated from an actual storage site (CO2CRC-Otway project, Victoria, South-West Australia). Two different samples tested, although different in nature, present strong heterogeneities, but differ in the detail of the connectivity of high porosity layers. In both samples, the results of the investigations show that sub-core scale heterogeneities control the sweep efficiency and may cause channeling through the porous medium. In one of the samples, CO 2 saturation appears uncorrelated to porosity close to the outlet end of the core. This observation is understood as a result of the position and the orientation of high porosity layers with respect to the inlet face of the core. Finally, in the operating conditions of the two experiments, the saturation maps demonstrate that gravity does not play a major role since no detectable buoyancy driven flow is observed.

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“…In beadpack models with heterogeneities end effects at a permeability boundaries was often found. Gradually as the displacing saturation increased there could be a breakthrough and change in flow path (Roti and Dawe 1993;Grattoni 1998, 2008;Caruana and Dawe 1996).…”

Section: Discussionmentioning

confidence: 98%

“…Experiments have also been conducted with the surfaces of the model being oil-wet (Caruana 1997;Caruana and Dawe 1996). The location of the two fluids is now reversed from the waterwet case.…”

Section: Effect Of Wettabilitymentioning

confidence: 99%

Microscale Visual Study of End Effects at Permeability Discontinuities

Dawe

Caruana

Grattoni³

2010

Transp Porous Med

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The physical effect of multiphase fluid distribution and flow at permeability boundaries has not been fully investigated, particularly at the pore scale (1-100 µm), although such behaviour can significantly affect the overall scaled-up reservoir trapping capacity and production performance. In this article, microscale physical models have been used to qualitatively study the pore scale flow events at permeability boundaries, both high to low and vice versa, to gain a better understanding of the role of these boundaries and water saturation on multiphase displacement behaviour at the pore scale. We have used etched glass models of stripes of large and small (a factor of two) pores with circular matrix. Capillary pressure, which is the controlling parameter is itself dependant on pore size and its spatial distribution, the magnitude of the interfacial tensions and the wettability between the fluids and the solid surface of the models. Sometimes, the only way the non-wetting fluid can penetrate the boundary is through a fortuitous leakage, whereby the presence of an initial saturation reduces the controlling capillary pressure. Examples are demonstrated including mechanisms of end-effects and how capillary boundary resistance (due to capillary forces) can be broken down and fluid movement across the boundary can develop. These micromodel experiments show vividly that connate water can assist in these processes, particularly oil trapping and leakage of water across a permeability boundary.

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Flow behaviour in the presence of wettability heterogeneities

Cited by 34 publications

References 11 publications

Experimental displacement patterns in a 2 × 2 quadrant block with permeability and wettability heterogeneities—problems for numerical modelling

Experimental displacement patterns in a 2 × 2 quadrant block with permeability and wettability heterogeneities—problems for numerical modelling

An Experimental Study on the Influence of Sub-Core Scale Heterogeneities on CO2 Distribution in Reservoir Rocks

Microscale Visual Study of End Effects at Permeability Discontinuities

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