Imbibition Model Studies on Water-Wet Carbonate Rocks

Parsons, Robert W.; Chaney, P.R.

doi:10.2118/1091-pa

Cited by 45 publications

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“…This observation has been reported by other authors in experiments with countercurrent imbibition (Parsons and Chaney, 1964;Zhang et al, 1996;Leventis et al, 2000). This pattern is regarded as consequence of nonequilibrium effects Patzek, 2004, Le Guen andKovseck, 2006).…”

Section: Resultssupporting

confidence: 88%

Estimation of Dynamic Relative Permeability and Capillary Pressure from Countercurrent Imbibition Experiments

Schembre

Kovscek

2006

Transp Porous Med

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Direct laboratory measurements of in situ water-phase saturation history are used to estimate relative permeability and capillary pressure functions. The magnitude of so-called nonequilibrium effects during spontaneous imbibition is quantified and, if significant, these effects are incorporated within the estimation technique. The primary constraint employed is that curves must increase or decrease monotonically; otherwise, no predetermined functionality is assumed. The technique is demonstrated using water saturation profile histories obtained for diatomite (a low-permeability and high-porosity rock). Results indicate that nonequilibrium effects detected at laboratory scale in low-permeability rocks influence the estimation of unsteady-state relative permeability and capillary pressure.

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Section: Resultssupporting

confidence: 88%

Estimation of Dynamic Relative Permeability and Capillary Pressure from Countercurrent Imbibition Experiments

Schembre

Kovscek

2006

Transp Porous Med

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“…An important parameter in the model is the capillary back pressure (CBP) at the open face. The existence of the CBP was mentioned by Parsons and Chaney (1966), but its effect is usually omitted in analyses of the imbibition process. The CBP is determined by the largest pores at the surfaces where oil is produced as droplets (Li et al 2006;Mason et al 2009;Unsal et al 2009).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Viscosity on Relative Permeabilities Derived from Spontaneous Imbibition Tests

et al. 2014

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Spontaneous imbibition experiments are usually carried out on All Faces Open or One End Open cores and this severely limits the information that can be obtained because imbibition can be approximately described with a square root of time function, which involves only a single variable. Two Ends Open with one end in contact with the brine and the other end in contact with oil (at the same pressure) offers much more varied behaviour because imbibition is partly co-current and partly counter-current. Previously, an analysis and experiments were described for primarily co-current imbibition when the viscosities of the oil and brine were close to equal. Small deviations from the square root of time relationship allowed parameters such as the capillary back pressure (bubble pressure) to be determined. In the present paper, the situation when the oil is significantly more viscous than the brine is analysed and compared with experiments. The results show that counter-current imbibition continues for almost the entire imbibition period. They also show that the relative permeability to oil behind the front varies as the viscosity ratio is changed. Very viscous oil gives higher relative permeability than less viscous oil. ACross-sectional area of cylindrical core (m 2 ) D Parameter involved in the ratio of co-current to counter-current production of non-wetting phase k nw Co-current relative permeability to the non-wetting phase ahead of the imbibition front k * nw Counter-current relative permeability to the non-wetting phase behind the imbibition front k w Co-current relative permeability to the wetting phase behind the imbibition front K Rock permeability (m 2 ) L core Length of cylindrical core (m) P c,f Capillary pressure at the imbibition front (Pa) P c,o Capillary back pressure at the core face in contact with wetting phase (Pa) P w,f Pressure in the wetting phase at the imbibition front (Pa) P nw,f Pressure in the non-wetting phase at the imbibition front (Pa) P nw,pt (t)Pressure in the non-wetting phase measured at the pressure port at time t q nw Co-current flow of the non-wetting phase (m 3 /s) q * nw Counter-current flow of the non-wetting phase (m 3 /s) q w Co-current flow of the wetting phase (m 3 ) S wi Initial wetting phase saturation S wf Wetting phase saturation behind the front t Time for the front to reach distance X f from the core face in contact with the wetting phase (s) V nw (t)Cumulative volume of oil produced co-currently at time t (m 3 ) V * nw (t) Cumulative volume of oil produced counter-currently at time t (m 3 ) V w (t)Cumulative volume of water that has entered the core co-currently at time t (m 3 ) V * w (t) Cumulative volume of water that has entered the core counter-currently at time t (m 3

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“…At the open face the pressure in the wetting phase is zero but the pressure in the non-wetting phase is not zero because the non-wetting phase forms bubbles as it exits the rock. Although its existence has long been recognised (Parsons and Cheney 1966), the inclusion of the effective capillary pressure at the open face is not part of the standard analysis, it being introduced by . For cylindrical tubes, the capillary pressure is related to permeability by the Leverett (1941) relation:…”

Section: Of All-faces-open Imbibition With Results From Linear and Ramentioning

confidence: 99%

Spontaneous Counter-Current Imbibition into Core Samples with All Faces Open

et al. 2008

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Counter-current imbibition occurs when brine spontaneously displaces oil from a very strongly water-wet rock. Experiments are usually carried out on cylindrical core plugs which have all of their faces open, mainly because this is easiest to do and also because it appears to give the most reproducible results. The flow patterns are complex, but a reasonable approximation can be obtained by assuming piston-like advance of fronts from the radial outer face and both flat ends. This separates the flow pattern into two types: linear imbibition into cones and radial imbibition into the surrounding toroid ring. Production versus time curves have been calculated for cylinders of varying aspect ratios and other core shapes. The analytical results confirm the experimental observation that sample shape does not have much effect on the shape of the production versus time curves. Bearing in mind the inherent variability of experimental results for individual core samples, the differences would be difficult to detect in experiments. The time for imbibition to be completed scales as the characteristic length. The function given by Ma et al. (J Pet Sci Eng 18:165-178, 1997) requires only a small correction factor for agreement with the analytical result. The present analysis makes straightforward the comparison of results from the complex flow condition 123 200 G. Mason et al. of all-faces-open imbibition with results from linear and radial experiments. A comparison is made with published results. Nomenclature a L toroid − L cone (m) A Area (m 2 ) A f Area of the displacement front (m 2 ) A i Area open to imbibition in the ith direction (m 2 ) A R Area of the cylinder at a general radius, R(m 2 ) b L cone /R max C spread Factor determined by the breadth and shape of the pore size distribution d Core diameter (m) f Fraction of the core filled K Permeability (m 2 ) k rnw Relative permeability of the non-wetting phase k rw Relative permeability of the wetting phase L c Characteristic length (m) L cone Length of a cone (m) L core Core length (m) L c,Ma Characteristic length calculated from Ma's equation (m) L f Distance from the open face to the front for the cone (m) L max Length of the core for linear imbibition (m) L toroid Length of the toroid (m) M Mobility factor (Pa −1 s −1 )n Total number of surfaces open to imbibition P c Capillary pressure (Pa) P cf Capillary pressure at the imbibition front (Pa) P co Capillary pressure at the open face (Pa) P nw Pressure in the non-wetting phase (Pa) P w Pressure in the wetting phase (Pa) q nw Flow of non-wetting phase (m 3 /s) q w Flow of wetting phase (m 3 /s) q R w Flow passing through the surface of the cylinder, radius R (m 3 /s) R f Radial distance of the front from the axis (m) R end Radius of the final position of the front for the shorter toroid (m) R core Core radius (m) R sphere Radius of spherical core (m) S wf Wetting phase saturation behind the front S wi Initial wetting phase saturation t Time (s) t D Dimensionless time t end Time when imbibition ceases (s) t f Time when ...

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Imbibition Model Studies on Water-Wet Carbonate Rocks

Cited by 45 publications

References 0 publications

Estimation of Dynamic Relative Permeability and Capillary Pressure from Countercurrent Imbibition Experiments

Estimation of Dynamic Relative Permeability and Capillary Pressure from Countercurrent Imbibition Experiments

The Effect of Viscosity on Relative Permeabilities Derived from Spontaneous Imbibition Tests

Spontaneous Counter-Current Imbibition into Core Samples with All Faces Open

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