Kodiak Oil & Gas Corp., an independent energy company, is engaged in the acquisition, exploration, exploitation, development, and production of crude oil and natural gas in the Rocky Mountain region of the United States. Its oil and natural gas reserves and operations are primarily focused in the Williston Basin of North Dakota. As of December 31, 2012, the company had estimated proved reserves of 138.3 million barrels of oil; and 174.0 billion cubic feet of natural gas. It markets and sells crude oil and natural gas primarily to purchasers that have access to nearby pipeline facilities, refineries, or other markets. The company was formerly known as Columbia Copper Company Ltd. and changed its name to Kodiak Oil & Gas Corp. in September 2001. Kodiak Oil & Gas Corp. was incorporated in 1972 and is headquartered in Denver, Colorado.