Two decades ago, geologists knew the U.S. was sitting on vast reserves of natural gas, locked in shale rock located deep below the earth’s surface. What they didn’t know was that these hard-to-produce resources would one day become the pathway towards greater U.S. energy independence.
Fast forward to the 21st century: Advancing exploration and drilling technologies have enabled oil and gas exploration and production companies to economically tap these previously inaccessible resources. In fact, according to many sources, it is estimated that U.S. reservoirs contain enough natural gas to meet America’s needs for nearly 100 years, a projection that has profound economic and geopolitical implications.
When gas is liquid
While the media are doing their part to spread the news about the North American energy transformation, one important chapter is sometimes overlooked: the virtual explosion in the production of natural gas liquids (NGLs). NGLs (ethane, propane, butanes and natural gasoline) can exist in a liquid state at underground pressures and then become gaseous at normal atmospheric pressure. The mixture of these liquids and methane gas are collectively referred to as “wet” or “rich” natural gas.
NGLs are found in natural gas (comprised primarily of methane and known as “dry” gas) and to a lesser extent in crude oil. NGLs include heavier hydrocarbons – compounds of hydrogen and carbon – that have slightly different combinations of those two elements in their molecular makeup. They are a very valuable byproduct of natural gas processing. (Other valuable hydrocarbons, such as heptane, hexane, octane and kerosene are obtained in the fractional distillation of petroleum.)
The product of decomposed matter, hydrocarbons come in different molecular lengths and constructs, from straight chains, to chains with branches, to complete rings. When broken down over time, hydrocarbons form crude oil or natural gas. Depending on the pressure and temperature in which they exist, hydrocarbons may be gaseous, liquid, semisolid or solid, according to how many carbon atoms they contain and whether they are under pressure or at atmospheric conditions. Propane and butane, for example, are liquids under pressure but are gases at atmospheric conditions.