Wettability effects on capillary pressure, relative permeability, and. Mahdiyar shiraz university, aban91 1 slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Capillary pressure is the most fundamental rockfluid property in multiphase flow, just as porosity and permeability are for single phase flow in oil and gas reservoirs. Capillary pressure and saturation height model concepts for reservoir petrophsyics course is a vilt virtually instructor led training delivered in real time. Capillary pressure and relative permeability correlations. Ph pressure difference between injectors and producers neglecting near wellbore pressure losses in field units. Some systems are strongly waterwet, while others are oilwet or neutrally wet. Measurement of capillary pressure curves at reservoir conditions. Chapter 3 capillary pressure and relative permeability.
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. Although capillary pressure studies or potentially a lack thereof do not necessarily sit at the root of this particular oil spill, capillary pressure measurements yield crucial information for understanding reservoir properties that could have influenced the engineering decisions made in the deepwater horizon event. Capillary pressure and saturation height model concepts. Additionally capillary pressure was found to lead to bubble point suppression, reduction in oil density and viscosity, and increase in gas density and viscosity.
This, and the related gas and water saturations are controlled by capillary pressure. Pc capillary pressure difference between leading and lagging layers use capillary pressure at sw 50%. The capillary pressure is dependent on the interfacial tension, pore size, and wetting angle. Laboratory experiments have been developed to simulate the displacing forces in a reservoir in order to determine the magnitude of the capillary forces in a reservoir and, thereby, determine the fluid saturation distributions and connate water saturation.
One parameter expresses the pore size distribution and hence the curvature of the pc curve, the other the actual level of the capillary pressure, i. The capillary pressure curve is different for these two processes, as shown in the illustration at the right. Role of induced and natural imbibition in frac fluid. It can be inferred from information that indicates the height of a transition zone, such as well log. Capillary pressure curve, simulation, hysterises, water coning, well production. Capillary pressure an overview sciencedirect topics. Capillary pressure free download as powerpoint presentation. Modelling relative permeabilities and capillary pressures.
The prediction of reservoir initial fluid saturations. Not accounting for increased capillary pressure in small pores can lead to inaccurate estimates of ultimate recovery, and of saturation pressures. Capillary pressure reservoir analogue a series of mercury injection capillary pressure measurements from the grand mesa area, garfield county were analyzed, to create the capillary pressure model. Simulation of petroleum reservoir performance refers to the construction and operation of a model whose behavior assumes. Determining water saturation from capillary pressure in. By contrast, a heterogenous reservoir will have a family of rock types, each with its own capillary pressure curve. Pdf dynamic effect of capillary pressure in low permeability. Capillary pressure curves directly determine the irreducible water saturation.
For waterwet reservoirs, several expressions may be used to cor relate capillary pressure, or height above the free water level, with the water saturation. This difference reflects the ease of invasion by a wetting fluid. Wettability and capillary pressure petroleum reservoir. Averaging the experimental capillary pressure curves for scaling up to the reservoir condition in the imbibition process. Tsypkin and claudio calore institute for problems in mechanics, russian academy of sciences. Most capillary pressure graphs show only the drainage curve. These equations show that capillary pressure increases with greater height above the free surface and with smaller capillary size. Oil migrating into an oilwet reservoir would display a different saturation profile. During waterflooding, these forces may act together with frictional forces to. The course also covers the statistics of the spatial distribution of these properties and illustrates the benefits of using them.
Capillary pressure and relative permeability vary by 1 the pore surface properties including wettability, endpoint saturations and contact angle, and. Proceedings, twentyfourth workshop on geothermal reservoir engineering stanford university, stanford, california, january 2527, 1999 sgptr162 capillary pressure influence on water vaporization in geothermal reservoirs george g. Two series of capillary drainage tests porous plate method were performed with. Pdf the dynamic effect of capillary pressure in oilwater twophase percolation flow in low permeability reservoirs was investigated by. Petrophysicists will use capillary pressure curves as the basis for deriving a water saturation versus height relationship for a reservoir. Capillary pressure data are important because the capillary is the primary force beside gravity, viscous, diffusive and applied forces that control fluid flow and distribution in the reservoir rock.
In this chapter, capillary pressure and relative permeability behavior of unconsolidated sands of the j1 and j2 reservoirs at bullwinkle are characterized and modeled. Averaging the experimental capillary pressure curves for. Pore sizes can be on the order of nanometers for shale and tightrock formations. Capillary pressure and relative permeability correlations for transition zones of carbonate reservoirs article pdf available august 2017 with 697 reads how we measure reads. Figure 7 shows different capillary pressure curves of each rock type in the svk reservoir. The first two of these are the porosity of the reservoir rock, which defines the total volume available for hydrocarbon. Reservoir rock typically contains the immiscible phases. Capillary pressure is one of input data in reservoir simulation process which should be considered in history matching procedures. Crains petrophysical handbook capillary pressure pc. Effect of capillary pressure on phase behavior in tight.
This course teaches integrated reservoir characterization, from basic petrophysics through geostatistics. Because of the small pore throats and low permeability of shale reservoirs, capillary pressures affect both the primary and enhanced oil recovery. Modelling relative permeabilities and capillary pressures with hysteresis for reservoir simulation supervisor. Wettability effects on capillary pressure, relative. The determination of representative capillary pressure data and wettability index of a reservoir rock is needed for the prediction of the. Accumulation of hydrocarbon in a reservoir is a drainage process and production by aquifer drive or waterflood is an imbibition process. Johan romate shelltud problem background in petroleum reservoir engineering various techniques are used to enhance the oil recovery from a reservoir. A new method for construction of hysteresis capillary pressure relationships for use in reservoir simulation models is presented. What is the importance of feeding the reservoir simulator. The method is based on the experimental drainageimbibition bounding curves and the history of the saturation changes. Capillary pressure and relative permeability oilfieldwiki. The forces that hold these fluids in equilibrium with each other and with the rock are expressions of capillary forces. Saturation modeling in a carbonate reservoir using. Many capillary pressure correlations have been suggested in the literature,15 and they typically have two adjustable parameters.
Capillary pressure is also important in describing fluid flow from fractured reservoirs because capillary pressure controls the flow of fluids between the fracture and the rock matrix. Reservoir sw30% capillary pressure difference between these two swstates is 100s1,000s of psi. Capillary forces are one of effective parameters in hydrocarbon reservoirs which are notable in the porous media. The emphasis is on porosity, permeability, capillary pressure and relative permeability as they relate to flow. The importance of capillary pressure in reservoir studies is that many reservoir rocks can be approximated by a bundle of capillaries, with formation water being the wetting phase and hydrocarbons the nonwetting phase.
Figure 7 is a porositypermeability cross plot for the capillary pressure samples. Therefore the interactive effects between capillary pressure and rock deformation are observed in numerical results. Spe175074ms effect of large capillary pressure on fluid. Pdf capillary pressure measurement using reservoir fluids in a. Permeability predication by using capillary pressure data. Although steamwater capillary pressure is of central importance in geothermal reservoir engineering, it is nevertheless still poorly understood because of the difficulties involved in making. Capillary pressure,petrophysics lecture 4, petroleum. Gasoil capillary pressure measurements at reservoir conditions. Impact of capillary pressure and critical properties shift.
A homogenous reservoir rock can be represented by a single capillary pressure curve. As ancillary data for assessment of relative permeability. Capillary pressure two fluid system waterwet reservoir st. Capillary pressure data are used in reservoir engineering primarily for determining initial fluid contacts and transition zones. As ancillary data for assessment of relative permeability data. This characteristic can be measured from core samples analyzed in a laboratory setting and compared to other measurements taken in the field. The role of capillary pressure curves in reservoir. Representation of capillary pressure hysteresis in reservoir simulation. Wettabilities of reservoir systems are categorized by a variety of names. Pdf representation of capillary pressure hysteresis in. Capillary pressure is an important characteristic of rock that helps reservoir engineers determine where hydrocarbons and water are located in the subsurface. Porosity ranges from 5% to 14% and permeability from 0.
The capillary pressure in a hydrocarbon reservoir is a function of the difference between the pressure in the water and hydrocarbon phases. Such small pores can affect the phase behavior of insitu oil and gas because of increased capillary pressure. Be familiar with the concept of capillary pressure for tubes as well as porous media and be able to derive the capillary pressure relation for fluid rise in a tube. Bakken fluid phase properties were found to deviate from bulk behavior up till pore radii of approximately 100 nm. Reservoir properties geol493k porosity and permeability porosity. If you continue browsing the site, you agree to the use of cookies on this website. Evaluating capillary pressure of potential reservoir and seal rocks is important because capillarity controls. Pdf a capillary pressure model for geothermal reservoirs. Additionally, it extracts important reservoir quality information from the reservoirs saturationheight behavior and has practical applications in reservoir development such as. Capillary pressure cannot be measured directly in a reservoir. Mercury injection data, collected using wholecore samples, are used to. The reservoir elevation depth above the free water level may be converted to capillary pressure values through the application of the equation. Capillary pressure data are useful in characterizing rock types because it is an indication of pore throat size distribution within one rock type. After filling the capillary with buffer, the sample can be introduced by dipping the end of the capillary into the sample solution and elevating the immersed capillary a foot or so above the detectorside buffer reservoir.
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