9781422285596

13 Chapter One: How Natural Gas Formed

These valuable areas of natural gas and petroleum oil are known as gas fields and oil fields. They do not exist as large “bubbles” of gas or “lakes” of oil, with rocks around. They are held in the cavities or pores in the rock, just as a sponge holds water. Porous rocks where this happens include sandstones and types of limestone with relatively big particles, called coarse-grained sandstones. Shales also contain enormous amounts of gas and oil. Shales have smaller or finer grains, so they hold their contents more tightly, which is why high-pressure cracking or fracking is needed to extract the natural gas and oil. Where and When Natural Gas Formed For millions of years, large areas of North America were covered by seas and oceans. Here the conditions were suitable for natural gas and petroleum oil formation. The main regions for natural gas were the Canadian Arctic Islands; the Northern Frontier of northwestern Alaska and the adjacent Northwest Territories; eastern Canada’s Atlantic states; the Rockies North American Gas Fields The vast Marcellus Shale gas fields cover an area of more than 100,000 square miles (260,000 square kilometers) in Pennsylvania and West Virginia, and into bordering Ohio, New York, Maryland, and Virginia. It probably contains more than 100 trillion cubic feet (2.8 trillion cubic meters) of natural gas in its shale rocks (some estimates go much higher). Almost as much is in the Haynesville Shale gas fields, with an area of about 10,000 square miles (26,000 square kilometers) in southwestern Arkansas, northeastern Texas, and northwestern Louisiana.

Natural gas drilling operation in Haynesville, Louisiana.