Chapter 7 Natural Gas and Natural Gas Liquids

Abstract

Publisher Summary This chapter provides an overview of natural gas and natural gas liquids. Natural gas is principally composed of methane with decreasing amounts of ethane, propane, and heavier components. It normally is partially or completely saturated with water vapor and may contain inert gases such as nitrogen and helium, and acid gases such as carbon dioxide, hydrogen sulfide, and mercaptans. Sales gas specifications for natural gas include one or more of the factors—water content, hydrocarbon content, heating value, specific gravity, acid gas content, temperature, and pressure. Natural gas liquids can be classified as (1) ethane, (2) liquefied petroleum gas (LPG), or (3) natural gasoline. The LPG is normally restricted to propane and butane or mixtures with small amounts of ethane and pentane being present as impurities. Natural gasoline is considered to consist of pentane and heavier hydrocarbons, but the term is also applied to mixtures of LPG and pentanes plus. The most common impurity in natural gas requiring treatment is water. Produced gas may be processed and injected back into the formation from which it is produced. Additional gas from other formations may also be injected to supplement the gas produced from a given oil zone.