## What is water saturation in oil and gas

30 Jul 2009 Porosity×Irreducible Water Saturation=Constant Rieke, III, eds., 1972, Oil and Gas Production from Carbonate Rocks: Elsevier, New York,. Water Saturation. Fengqi Wang. Province Key Laboratory of Unconventional Oil and Gas Reservoir and Development, Northeast Petroleum. University, Daqing 21 Feb 2016 Gas saturation (Sg) = Vg ÷ Vp. Oil saturation (So) = Vo ÷ Vp. Water saturation (Sw ) = Vw ÷ Vp. Total saturation of fluid is equation to 1, therefore 9 Apr 2019 Oil initially in place (OIIP) is the first estimate of the size of deposit prior how porous the rock surrounding the oil is, how high water saturation might Original gas in place (OGIP) is again the same volumetric calculation but

## The residual oil saturation quantity is the saturation achieved after an infinite number of pore volumes of the displacing fluid have flowed through a particular portion of reservoir rock. To define residual oil saturation, the displacement method and the type, volume, direction and velocity of the displacing fluid must be known.

Gas cap drive (right) pushes oil down, but water saturation does not change until the gas that replaced the oil is also produced. If there is no aquifer, both situations produce only by expansion drive - in this case water saturation does not change unless a water flood is imposed by the field operator. Water saturation (S w) determination is the most challenging of petrophysical calculations and is used to quantify its more important complement, the hydrocarbon saturation (1 – S w).Complexities arise because there are a number of independent approaches that can be used to calculate S w.The complication is that often, if not typically, these different approaches lead to somewhat different S There are few published guidelines for gas permeability endpoints. As an approximation, the residual oil saturation to gas is usually similar to the residual oil saturation to water. Because gas is a nonwetting phase, the relative permeability to gas at S org is usually greater than 0.5. Among the challenges in water saturation and hence oil saturation calculations are the accuracy of the applied model and the accuracy of its input parameters. The residual oil saturation quantity is the saturation achieved after an infinite number of pore volumes of the displacing fluid have flowed through a particular portion of reservoir rock. To define residual oil saturation, the displacement method and the type, volume, direction and velocity of the displacing fluid must be known.

### Water saturation (S w) of a reservoir is a function of height above free water (h) and pore type. S w interpretations should be made accounting for h, r 35, and pore throat size distribution in the reservoir. The Archie equation is the most widely used method of determining S w.. See also. Determining water saturation; Interpreting water saturation; Archie equation

Water saturation (S w) determination is the most challenging of petrophysical calculations and is used to quantify its more important complement, the hydrocarbon saturation (1 – S w).Complexities arise because there are a number of independent approaches that can be used to calculate S w.The complication is that often, if not typically, these different approaches lead to somewhat different S There are few published guidelines for gas permeability endpoints. As an approximation, the residual oil saturation to gas is usually similar to the residual oil saturation to water. Because gas is a nonwetting phase, the relative permeability to gas at S org is usually greater than 0.5. Among the challenges in water saturation and hence oil saturation calculations are the accuracy of the applied model and the accuracy of its input parameters. The residual oil saturation quantity is the saturation achieved after an infinite number of pore volumes of the displacing fluid have flowed through a particular portion of reservoir rock. To define residual oil saturation, the displacement method and the type, volume, direction and velocity of the displacing fluid must be known.

### The saturation point is the maximum amount of dissolved water an oil will hold. It is dependent on temperature. As temperature increases, the saturation point of any given oil will decease at a relatively linear rate, as seen in the graph below.

Gas cap drive (right) pushes oil down, but water saturation does not change until the gas that replaced the oil is also produced. If there is no aquifer, both situations produce only by expansion drive - in this case water saturation does not change unless a water flood is imposed by the field operator. Water saturation (S w) determination is the most challenging of petrophysical calculations and is used to quantify its more important complement, the hydrocarbon saturation (1 – S w).Complexities arise because there are a number of independent approaches that can be used to calculate S w.The complication is that often, if not typically, these different approaches lead to somewhat different S There are few published guidelines for gas permeability endpoints. As an approximation, the residual oil saturation to gas is usually similar to the residual oil saturation to water. Because gas is a nonwetting phase, the relative permeability to gas at S org is usually greater than 0.5. Among the challenges in water saturation and hence oil saturation calculations are the accuracy of the applied model and the accuracy of its input parameters.

## Summary During gas injection, bypassing of oil is common because of gravitational, viscous, and/or heterogeneity effects. The oil in the bypassed regions can

oil-saturated but water-wet rock into a beaker of water and it will spontaneously imbibe a significant quantity of water and expel oil. Strictly speaking, the term imbibition refers to an increase in the saturation of the wetting phase, whether this is a spontaneous imbibition process or a forced imbibition process such as a Water saturation is an important parameter used in reservoir modelling, as it gives an idea of the percentage of the pore spaces occupied by water and oil or gas and hence the total amount of hydrocarbon present in the pore spaces of the reservoir. In an oil or gas reservoir there is always some water (which you generally do not want to produce) in the pore space and therefore wettability is an important rock characteristic to understand. In general, wettability is determined by looking at a core sample through a microscope and applying a drop of oil or water to the rocks surface and observing it's shape. The water between the gas and oil is called "top water" by the oil explorationist, to distinguish it from the "bottom water" below the oil. Either or both of the gas and top water zones may be missing in this region. The moral of the tale is that gas crossover can be misleading.

2 Department of Exploration, Egyptian Petroleum Research Institute, Egypt and saturation percentage especially in gas/water transitional zones. 1. I'll then discuss the issue of consistency between water saturation and porosity Since oil and gas reservoirs occur at a variety of different temperatures and At each depth, the reflectivity of a shale/oil-sand interface decreases moderately with increasing water saturation; whereas, the reflectivity of a shale/gas-sand (resistivity) model for saturation and obtain water saturation by measuring on match the oil, water and gas saturations calculated from the capillary-gravity The fraction of water in a given pore space. It is expressed in volume/volume, percent or saturation units. Unless otherwise stated, water saturation is the fraction of formation water in the undisturbed zone.The saturation is known as the total water saturation if the pore space is the total porosity, but is known as effective water saturation if the pore space is the effective porosity.