Fluid Saturations

Introduction

By definition, the fluid saturation for a particular fluid is the fraction of pore volume occupied by that fluid, and is considered an intensive property.

A subsurface pore can contain any number of components (whether water, gas, oil or specific compositions likes CO2 and Hydrogen). However, regardless of the subsurface fluids, the components must fill the entire pore.

Basic Equations

Oil Saturation

Gas Saturation

Water Saturation

By definition:

In the example below, provided by Chinook Consulting Services, shows different levels of Bitumen saturation in the Athabasca Oil Sands, from Alberta, Canada.

Typical Values

A general review of the literature suggested that in conventional oil reservoirs, typical values of oil saturation range between 65% and 85%. Certain oil reservoirs have a gas cap with measurable gas saturation. Dry gas
reservoirs generally have high saturation of natural gases, namely, methane, ethane, and heavier components. Examples of oil, gas, and water saturations are show below:

The numbers in this table are very appropriate and should be used as a general guide.

References:

• Satter & Ghulam, Reservoir Engineering The Fundamentals, Simulation, and Management of Conventional and Unconventional Recoveries, 2016.