The New Albany Shale

No two shale plays are the same. Shale can differ from region to region and within the same play. The rock within the New Albany in the Illinois Basin varies throughout the basin. This shale has been drilled for decades, but with horizontal drilling and fracturing, production is now possible.

The New Albany Shale formed about 350 million years ago in a shallow sea that once covered the eastern half of the U.S. It has a 100-foot thick pay zone of shale covered by gray-green shale, which distinguishes it from other plays. Currently, wells are 250 to 2,000 feet deep, and the gas extracted is a mixture of biogenic and thermogenic in origin. It contains up to 160 trillion cubic feet of in-place gas.

This was one of the first unconventional plays produced in the U.S. The rock that makes up the New Albany has natural fractures that complicate the hydraulic fracturing process. Despite this difficulty, booms were experienced in Illinois, Indiana and Kentucky—the three states that contain the New Albany.

History

The New Albany Shale is located in the Illinois Basin, which is contained within Southwestern Indiana, Wes-tern Kentucky and Illinois (except the northern-most part).

Drilling in the shale dates back to the 1800s when oil was accidentally discovered during drilling for saltwater. The saltwater was important to early settlers for preserving food and was also critical to the agricultural industry in the area. Once operators began drilling for oil, they discovered that natural gas was within the reservoirs, as well.

Illinois

The first drilling in Illinois occurred in 1853 with two wells near Champaign. Modest oil was also recovered in Clark County, Ill., in the 1860s. In 1866, the Clark County Petroleum and Mining Company set its headquarters in Marshall, Ill., and began drilling.

At this time, casings were not used, and water seepage prevented the deeper oil from making its way to the surface. Production was poor.

At the beginning of the 1900s, well casings began to be used, solving the water issues. However, operators had no way to accurately know where to drill—hitting a reservoir was more a matter of luck.