Description Houston-based, with North and South American properties, and energy focused, Houston American Energy explores for and produces oil and natural gas, primarily in Colombia, but also along the US Gulf Coast. In 2008 the company reported proved reserves of 18.8 million cu. ft. of natural gas and about 213,000 barrels of oil. Of its 5,360 gross acres of proved developed leasehold, about 30% is in Colombia. The bulk of the balance is in Louisiana and Texas, although the oil and gas independent also holds some acreage in Oklahoma. President and CEO John Terwilliger owns 31% of Houston American Energy; director Orrie Tawes, 12%.