Petroleum Reservoir Engineering Practice

Chapter 3. Reservoir Fluid Saturations

3.1 Introduction

The pore spaces in reservoir rocks are occupied by fluids. In petroleum reservoirs, the fluids are usually water and hydrocarbons. The relative volumes of water and hydrocarbons in the pore volume of the reservoir rock are designated as saturations. Water saturation in the reservoir rock is the fraction of the pore volume occupied by water. By the same definition, hydrocarbon saturation in the reservoir rock is the fraction of the pore volume occupied by hydrocarbons. The sum of the water and hydrocarbon saturations in the reservoir rock is equal to unity. This relationship can be expressed simply as:

(3.1)

In Eq. (3.1), S_h = hydrocarbon saturation, fraction; and S_w = water saturation, ...