At the Thirtieth Annual Sanford C. Bernstein Conference on May 29, 2014, EOG Resources CEO Bill Thomas indicated the company doesn't see another shale play of the same magnitude as the Bakken or Eagle Ford on the horizon.

According to Thomas, the Bakken and the Eagle Ford currently produce 75% of all horizontal oil production in the U.S., but he notes the two plays are beginning to mature, and their growth rates are beginning to slow.

Thomas' postulation about the Bakken and Eagle Ford, which is likely an accurate depiction, doesn't diminish the impact these plays have already had, or will continue to have on the oil and gas industry, and the U.S. economy. According to the EIA, production in the Bakken Shale has now exceeded the 1-million b/d mark. Recently, Continental Resources, the Bakken Shale's largest producer, released data showing the Bakken field of North Dakota and Montana reached the milestone of 1-billion bbls of cumulative light, sweet crude oil produced during first quarter of 2014.

Read more: Continental Resources: Bakken Hits 1-Billion Barrel Mark