Houston-based BP Prudhoe Bay Royalty Trust, a grantor trust operating in the U.S., currently holds an overriding royalty interest in the prolific Prudhoe Bay oil field located on Alaska's North Slope. Boasting a sprawling 12 by 27-mile terrain, the Prudhoe Bay field covers roughly 150,000 gross productive acres and has been in operation since the 1980s. The BP Prudhoe Bay Royalty Trust, incorporated in 1989, enables investors to benefit from the oil field's profits.