Prediction and Estimation of Capillary Pressure for Wettability and Wettability Variations Within Reservoir

Derahman, Mohd. Nawi; Zahoor, Muhammad Khurram

doi:10.2118/117799-ms

Cited by 3 publications

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“…The most recent of these proposals are those of Morrow [5], Graue et al [6], and Derahman and Zahoor [7]. These indexes are designed to show a continuous variation from the preferential oil-wet to the preferential water-wet systems.…”

Section: Introductionmentioning

confidence: 99%

“…In 2008, Derahman and Zahoor demonstrated a method of calculating the permeability using capillary pressure curves measured by mercury injection [7]. A tortuosity factor in the model was earlier introduced and the method was modified by representing capillary pressure curve as a power law function of the wetting phase saturation [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Wettability Effects on Capillary Pressure, Relative Permeability, and Irredcucible Saturation Using Porous Plate

Falode

Manuel

2014

Journal of Petroleum Engineering

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An understanding of the mechanisms by which oil is displaced from porous media requires the knowledge of the role of wettability and capillary forces in the displacement process. The determination of representative capillary pressure ( ) data and wettability index of a reservoir rock is needed for the prediction of the fluids distribution in the reservoir: the initial water saturation and the volume of reserves. This study shows how wettability alteration of an initially water-wet reservoir rock to oil-wet affects the properties that govern multiphase flow in porous media, that is, capillary pressure, relative permeability, and irreducible saturation. Initial water-wet reservoir core samples with porosities ranging from 23 to 33%, absolute air permeability of 50 to 233 md, and initial brine saturation of 63 to 87% were first tested as water-wet samples under air-brine system. This yielded irreducible wetting phase saturation of 19 to 21%. The samples were later tested after modifying their wettability to oil-wet using a surfactant obtained from glycerophtalic paint; and the results yielded irreducible wetting phase saturation of 25 to 34%. From the results of these experiments, changing the wettability of the samples to oil-wet improved the recovery of the wetting phase.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Wettability Effects on Capillary Pressure, Relative Permeability, and Irredcucible Saturation Using Porous Plate

Falode

Manuel

2014

Journal of Petroleum Engineering

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Determining Wettability of Fractured Carbonate Reservoirs

Bakhshi

Torab

2015

Nat Resour Res

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Correlation for Prediction and Estimation of Capillary Pressure to Account for Wettability and Wettability Variations Within Reservoir—Part 2

2009

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Wettability plays an influential role in fluid flow behavior within a reservoir. Despite of its importance, it is not usually given the required significance during simulation studies. Different types of wettability may exist or co-exist within a reservoir which may change with the passage of time, depending on the prevailing conditions within a reservoir and also on the fluids which are injected for the purpose of enhanced oil recovery. In order to account for the effect of such wettabiliy variations on fluid flow behavior, a set of correlations have been developed to estimate capillary pressure, when the data from the core at extremely water-wet conditions is known. In this paper the developed set of correlations are further modified, so that they can be used quite effectively, when the capillary pressure data for any wettability conditions is known. Introduction Wettability can be defined as the ability of a liquid to coat the rock surface. It ranges from extremely water wet to extremely oil wet. Wettability can be expressed in a qualitative and as well as in quantitative way. However, expressing it in a quantitative way is frequently used, because of its better way of representation (Zahoor et. al., 2009). In a quantitative way it can be expressed in terms of contact angle, but it gives the wettability of that point/area only and the other way of its representation is by using wettability index, which is considered even better, as it gives average wettability, based on pressure vs. saturation change within a core (Zahoor et. al., 2009). Wettability index ranges from +1(0°) to -1(180°) for strongly water wet to strongly oil wet rock respectively. When one is known the other can be calculated by taking cosine or inverse cosine, i.e, W.I = Cos(?) Effect of Wettability on Fluid Distribution and Capillary Pressure Wettability controls the location/ distribution of a fluid within a reservoir. If the rock is water wet, the water will occupy the small pores while the oil will occupy the larger pores and vice versa (Pirson, 1958; Raza et. al., 1968; Donaldson et. al., 1971). So, the displacement of wetting phase which have relatively high force of adhesion with the rock surface and occupies the small pore spaces, requires higher displacement pressure to initiate the displacement process. Experiments conducted by Killins et. al.(1953), shows the behavior of capillary pressure curve under strongly water wet to strongly oil wet conditions as shown in figs 1 to 4. Before initiating the displacement process, the phase to be displaced is continuous, so when the displacement process initiates, it can be displaced efficiently at quite uniform pressure, which is slightly increasing (this behavior depends on the type of fluids involved, and core properties, depending on it, comparatively higher increasing pressure may be required for displacement). With the passage of time as the respective phase saturation is reduced, it becomes discontinuous, so further increase in pressure is required to continue the process (Anderson, 1987). With further decrease in saturation, this phase discontinuity increases, thus requiring even greater pressure, to continue the displacement process. When the capillary pressure curve becomes almost vertical, it is the time when no further displacement can take place and the saturation at this point is known as residual saturation of the displaced phase (Anderson, 1987). Based on this phenomenon, capillary pressure curve can be divided into three parts, namely (Derahman and Zahoor, 2008):

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Prediction and Estimation of Capillary Pressure for Wettability and Wettability Variations Within Reservoir

Cited by 3 publications

References 0 publications

Wettability Effects on Capillary Pressure, Relative Permeability, and Irredcucible Saturation Using Porous Plate

Wettability Effects on Capillary Pressure, Relative Permeability, and Irredcucible Saturation Using Porous Plate

Determining Wettability of Fractured Carbonate Reservoirs

Correlation for Prediction and Estimation of Capillary Pressure to Account for Wettability and Wettability Variations Within Reservoir—Part 2

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