Eagle Ford is one of the biggest shale plays in the country. This play offers a large amount of both oil and natural gas. This shale extracts about 1.2 million barrels of oil every single day. In addition to this, the drilling helps extract well over 6 billion cubic feet of natural gas each day. Four companies make up about 45 percent of the drilling that happens here. This is a large area of land, covering over 400 miles in length.