At the height of production, the Piceance Basin in western Colorado could produce 1 billion cubic feet of natural gas daily--about 2 percent of all U.S. gas production. And, despite falling prices, Texas-based Exxon Mobil Corp. is ramping up drilling in the bowl-shaped basin, which spans 6,000 square miles in five counties. The company has leased some 300,000 acres of largely federal land that contains about twice the amount of gas consumed in the United States annually, according to The Houston Chronicle . As one analyst puts it, "Exxon is very bullish on natural gas globally, not only in the U.S., and they are putting their money where their mouth is." Some gas producers have backed off of natural gas in Colorado because prices have fallen from a high last year of $13 per million British thermal units to $3.50. Williams Energy, which is also operating in western Colorado and the Piceance, is not one of those producers. The company recently invested $350 million to expand operations, reports the Grand Junction Sentinel .