It is dependent upon pore geometry, wettability, fluid distribution, and fluid saturation history. Analysis and evaluation of oilwater relative permeability curves. Aug 20, 2017 a sizable oil reserves are held in a thick oilwater capillary transition zones in the carbonate reservoirs, but it is an ongoing challenge to accurately describe the relationship between capillary pressure, relative permeability and oilwater saturation due to the complex wettability variation, pore geometry and heterogeneity throughout the reservoir column. In this chapter, capillary pressure and relative permeability behavior of unconsolidated sands of the j1 and j2 reservoirs at bullwinkle are characterized and modeled. A sizable oil reserves are held in a thick oilwater capillary transition zones in the carbonate reservoirs, but it is an ongoing challenge to accurately describe the relationship between capillary pressure, relative permeability and oilwater saturation due to the complex wettability variation, pore geometry and heterogeneity throughout the reservoir column. Such data are crucial for the estimation of productivity, ulti mate recovery, formation injectivity and planning various engineering operations, includ ing eor and diagnosing formation damage.
Relative permeability relative permeability is the ratio of the effective permeability of a fluid at a given saturation to some base permeability. Relative permeability hysteresis in porous media applied. The twophase curves represent the end curves when either the gas saturation or water saturation equals zero. The maximum relative permeabilities, kro max, krw,max, and krg,max, are between 0 and 1. Relative permeability value generally varies from 0 to 1 and in the case of three phase permeability, the sum is always less than 1, which means that. Relative permeability curves fundamentals of fluid flow. Comparative analysis of relative permeability models with. Relative permeability as measured in laboratory basic input to all reservoir simulation work. Relative gas permeability k rg data for lowpermeability sandstones have been reported in numerous studies thomas and ward, 1972. A number of researchers report that viscosity does not affect relative permeability at all, while others say that it does. Effects of viscosity on relative permeability fundamentals.
Diamagnets are materials with a magnetic permeability less than. The two sets of pvt data shown in table 2 table 3 were used for this reservoir. The xcurve describes relative permeability as a linear function of saturation k rl s l 1. Relativepermeability data are essential for almost all calculations of fluid flow in hydrocarbon reservoirs. Relative permeability, petrophysics lecture 5, petroleum. Therefore, the oil relative permeability curve begins at zero gas saturation.
Introduction hysteresis refers to irreversibility or path dependence. We can characterize the gas flow aspect of permeability jail by examining the properties of gas relative permeability curves for lowpermeability rocks. These four relative permeability curves were presented in two groups. Relative permeability k r functions are among the required data for simulation of multi phase flow in porous media. When the reservoir temperature is below the wax appearance temperature wat, wax would precipitate in the oil phase as wax crystals, which could increase the oil. Relative permeability petroleum reservoir permeability. To generate relative permeability curves, displacing phase minimum saturation gas and water is varied from 0 to 0. The number of relative permeability curves that can be generated when measuring steadystate relative permeability at different velocities and values of ift will be large, inasmuch as relative permeability is known to change with ift and has been reported to. Relative permeability measurements are conducted on core samples in a laboratory and are both timeconsuming and. Imbibition oil relative permeability curves may exhibit a. If a single fluid is present in a rock, its relative permeability is 1. Does not account for saturation gradients within the grid block. The relative permeability is the ratio of the permeability of a specific medium to.
When a wetting and a nonwetting phase flow together in a reservoir rock, each phase follows separate and distinct paths. Factors affecting pseudo relative permeability curves. Chapter 3 capillary pressure and relative permeability. Crains petrophysical handbook relative permeability. Relative permeability is important for estimating the flow of reservoir fluids. An overview article pdf available in journal of petroleum technology 408.
Threephase relative permeability can be generated from the twophase relative permeability curves of the oilwater system and the relative permeability curves of the gasoil system. Based on the results presented herein, it is suggested that the. Imbibition oil relative permeability curves may exhibit a characteristic. Vertical oil water drainage relative permeability curves for a fractured and vugular. Since the experimental conditions under which the experimental data presented above were obtained violate the assumption of weldge, johnsonbosslernaumann jbn method, and other explicit relative permeability methods, empirical correlations are used to generate the relative permeability curves for the different flow processes. Based on the actual production of oilfields, two classification methods are proposed to optimize the relative permeability curves, and the two methods are combined.
Relative permeability is further discussed in chapter 8. Determination of relative permeability curves in the arbuckle. Relative permeability curves have been obtained for three fluid systems having interfacial tensions of the order of 50, 0. Petropedia what is imbibition relative permeability. The distribution of the two phases according to their wetting characteristics results in characteristic wetting and nonwetting phase relative permeabilities. Relative permeability and capillary pressure defines relative permeabilities as dimensionless functions of saturation with values generally ranging between 0 and 1. The reinjection of produced gas in these high permeability. A study of the effect of relative permeability and residual oil. Relative permeability correlation for mixedwet reservoirs. The shape of the wateroil relative permeability curves depends on the rock type and pore structure.
As gas evolves in the reservoir or is added to a rock sample in a test, the oil premeability is reduced, but the gas does not necessarily flow until it reaches a critical gas saturation, s gc. The study of relative permeability and residual gas saturation at high. Capillary pressure and relative permeability correlations for. Wax deposition has always been a problem for the production of waxy crude oil. The total permeability is the product of the absolute and relative permeabilities. Relative permeabilities generated using a corey correlation with residual saturation of 0. Lowfrequency, real permeability, 00, as a function of. Moreover, relative permeability curves vary with different samples and so one set of relative permeability curves cannot represent relative permeability for all rock types in a reservoir. Researchers still havent reached a conclusion regarding the effect of viscosity on relative permeability. Analysis the distribution of the reservoir usable remaining oil and reservoir irreducible oil of different types of relative permeability curves. We can characterize the gas flow aspect of permeability jail by examining the properties of gas relative permeability curves for low permeability rocks. The reservoir system rock has a porosity of 30% and a permeability of 10 md r 35 1. On the normalization of relative permeability curves onepetro. This phenomena is illustrated for an oilwater case in figure 1.
Relative permeability of the nonwetting phase vs water saturation. Imbibition relative permeability is related to the capillary pressure curves. Typically, the shape of the kcurve is concave upward. Calculation of relative permeability allows comparison of the different abilities of fluids to flow in. Relative permeability is the ratio of effective permeability of a particular fluid at a particular saturation to absolute permeability of that fluid at total saturation. Variations in bounding and scanning relative permeability. Temfunction in analyzing relative permeability data is analogous with leverett jfunction in analyzing capillary pressure data. Mercury injection data, collected using wholecore samples, are used to evaluate insitu fluid capillary behavior. Frequencydependence of relative permeability in steel. The diagram in figure 2 shows relationships between relative permeability curves drainage and imbibition, capillary pressure, and fluid distribution in a homogeneous section of a reservoir system. The comparison of the resultant pseudo relative permeability curves are shown in fig. Oil relative permeability an overview sciencedirect topics. The hysteresis loops of the capillary pressure and the relative permeabilities form a consistent set.
Review on methods to obtain relative permeability data some time after breakthrough, in this time interval, the plot is a straight line whose slope is equal to the exponent in the relative permeability power law. In multiphase flow, it manifests itself through the dependence of relative. Shown is gas relative permeability left, oil relative permeability right and the gasoil relative permeability in the single phase region center. The relative permeability is the ratio of the permeability of a specific medium to the permeability of free space 0. Relative permeability three phase relative permeability. To measure wateroil relative permeability characteristics for very low interfacial tension systems as related to methods of improved oil recovery. Relative permeability functions are usually taken to be dependent on phase saturation. Capillary pressure curves play an important role in understanding the saturation distribution of fluids in hydrocarbon reservoirs and affect the multiphase flow of fluids as well as imbibitions through porous rocks. Pdf the deep water reservoirs are increasing areas of activities for the oil industry. The samples in one group were from same layer and same well, one for original relative permeability test and another for test by wetttability alteration agents. The relative permeability of a magnetic material, designated. Relative permeability is a concept used to convey the reduction in flow capability due to the presence of multiple mobile fluids. We call absolute or intrinsic permeability the one determined by the porous material alone.
Effect of flow direction on relative permeability curves in. Each of the two pvt data sets was used in all sets of crosssections. Variations in bounding and scanning relative permeability curves with different carbonate rock type. A number of researchers report that viscosity does not affect relative permeability at. Relative permeability relative permeability curves.
In a recent paper the normalization of imbibition, water oil, relative permeability curves has been presented as a step of a method for evaluating imbibition, gaswater, relative permeability curves from end point gaswater laboratory data. Generally, as the permeability of the rock increases, the k rw at s orw end point rises. Chapter 8 permeability and relative permeability of carbonate. It is generally a quite weak effect in most materials, although superconductors exhibit a strong effect. Relative permeability free download as powerpoint presentation. These expressions are often referred to as modified brookscorey relations, reflecting their similarity to the brookscorey expression for oil relative permeability. Be familiar with and be able to derive the purcellburdine relative permeability equations. Consequently, diamagnetism is a form of magnetism that a substance exhibits only in the presence of an externally applied magnetic field. It is asohelpful to present such plots on a semilog scale to expand the relativepermeability characteristics nea the endpoint saturation. Measurement and correlation of gas condensate relative. In multiphase systems relative permeability curves of each fluid phase i. The two most commonly used expression for relative permeability for homogeneous porous media are the xcurve and corey curve corey, 1954.
In 1956, corey and rathjens extended coreys earlier work. Pdf the effect of temperature and rock permeability on oil. The number of relative permeability curves that can be generated when measuring steadystate relative permeability at different velocities and values of ift will be large, inasmuch as relative permeability is known to change with ift and has been reported to vary with velocity when using condensing fluids. You should be also familiar with the laboratory techniques for measuring relative permeability. Permeabilityplane plot of experimental and modelled complex permeability. The relative permeability k curves are a function of water saturation s. Hysteretic relative permeability effects and reservoir. Relative permeability curves fundamentals of fluid flow in.
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