Multiphase Flow Under Heterogeneous Wettability Conditions Studied by Special Core Analysis and Pore-Scale Imaging

Zou, Shuangmei; Armstrong, Ryan T.

doi:10.2118/195577-pa

Cited by 15 publications

(12 citation statements)

References 61 publications

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“…The pressure gradient dP c /dx (kPa/mm) measured from Zou and Armstrong (2019) compared with dP c /dx (kPa/mm) determined from chain‐rule‐based and image‐based calculation in this study for mixed‐wet.…”

Section: Resultsmentioning

confidence: 96%

“…In Figure 7, the relative permeability results determined using

\frac{{italicdP}_{c}}{dx}

are compared with the experimentally measured relative permeability results from Zou and Armstrong (2019) for the same samples. Experimental data from Øren et al (1998) are also provided in Figures 7a and 7b as a baseline measurement for water‐wet Bentheimer sandstone.…”

Section: Resultsmentioning

confidence: 99%

“…To provide a better estimate of

\frac{{italicdP}_{c}}{dx}

, the nonlinear generalized reduced‐gradient method was used again to minimize Equation . In this case, however, the relative permeability is known from the results of Zou and Armstrong (2019) while the gradient is the adjustable parameter. The resulting gradient, as shown in Figure 8, is sharper than the experimentally measured values.…”

Section: Resultsmentioning

confidence: 99%

“…The experimental data is available from Zou et al (2018) and Zou and Armstrong (2019). All the figures in this work can be found in the supporting information S1.…”

Section: Data Availability Statementmentioning

confidence: 99%

“…Numerical simulations are also commonly used for correcting the capillary‐end effect (Qadeer et al, 1988). In the numerical simulations, relative permeability is corrected with experimental data, such as in situ saturation measurements and an independent measurement of capillary pressure (Cao et al, 2020; Qadeer et al, 1988; Wang & Sheng, 2018; Zou & Armstrong, 2019). These measurements are then history‐matched via numerical modeling, with the core outlet treated as a zero capillary pressure boundary.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Capillarity on Relative Permeability in Fractional Flows

Zou

Liu

Cai

et al. 2020

Water Resources Research

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The effect of capillary pressure on multiphase flow is described by the capillary pressure gradient term in the fractional flow equation. This term is typically neglected during core-flooding experiments, as it is not easily accessible. However, the capillary pressure is not constant during core flooding owing to a capillary pressure discontinuity at the core outlet. By imaging spatial fluid distributions under two-phase steady-state flow, we determine in situ phase saturations and capillary pressures from interfacial curvature measurements along an entire core, thus achieving the assessment of the capillary pressure gradient and its influence on multiphase flow. We demonstrate how the pore-scale capillary pressure gradient affects multiphase flow and, in turn, the core-scale relative permeability measurements. Further, an alternative approach to determining relative permeability from a single fractional flow experiment is proposed. The approach provides a range of relative permeabilities for a single fractional flow experiment and does not require capillary-end correction, as the formulation directly accounts for the effect of capillary pressure on the flow.

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Section: Resultsmentioning

confidence: 96%

“…In Figure 7, the relative permeability results determined using

\frac{{italicdP}_{c}}{dx}

Section: Resultsmentioning

confidence: 99%

“…To provide a better estimate of

\frac{{italicdP}_{c}}{dx}

Section: Resultsmentioning

confidence: 99%

“…The experimental data is available from Zou et al (2018) and Zou and Armstrong (2019). All the figures in this work can be found in the supporting information S1.…”

Section: Data Availability Statementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Capillarity on Relative Permeability in Fractional Flows

Zou

Liu

Cai

et al. 2020

Water Resources Research

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A Method to Correct Steady-State Relative Permeability Measurements for Inhomogeneous Saturation Profiles in One-Dimensional Flow

et al. 2023

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Traditionally, steady-state relative permeability is calculated from measurements on small rock samples using Darcy’s law and assuming a homogenous saturation profile and constant capillary pressure. However, these assumptions are rarely correct as local inhomogeneities exist; furthermore, the wetting phase tends to be retained at the outlet–the so-called capillary end effect. We have introduced a new method that corrects the relative permeabilities, analytically, for an inhomogeneous saturation profile along the flow direction. The only data required are the measured pressure drops for different fractional flow values, an estimate of capillary pressure, and the saturation profiles. An optimization routine is applied to find the range of relative permeability values consistent with the uncertainty in the measured pressure. Assuming a homogenous saturation profile systematically underestimates the relative permeability and this effect is most marked for media where one of the phases is strongly wetting with a noticeable capillary end effect. Relative permeabilities from seven two-phase flow experiments in centimetre-scale samples with different wettability were corrected while reconciling some hitherto apparently contradictory results. We reproduce relative permeabilities of water-wet Bentheimer sandstone that are closer to other measurements in the literature on larger samples than the original analysis. Furthermore, we find that the water relative permeability during waterflooding a carbonate sample with a wide range of pore sizes can be high, due to good connectivity through the microporosity. For mixed-wet media with lower capillary pressure and less variable saturation profiles, the corrections are less significant.

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