Pioneer Natural Resources Company is an American energy company engaged in hydrocarbon exploration in the Cline Shale, which is part of the Spraberry Trend of the Permian Basin, where the company is the largest acreage holder. The company is organized in Delaware and headquartered in Irving, Texas. The company is ranked 333rd on the Fortune 500. As of December 31, 2019, the company had 1.135 billion barrels of oil equivalent (6.94×109 GJ) of proved reserves, of which 53% was petroleum, 25% was natural gas liquids, and 22% was natural gas. In 2019, the company produced 345 thousand barrels of oil equivalent (2,110,000 GJ) per day, of which 61% was petroleum, 21% was natural gas liquids, and 18% was natural gas.