Subject (Region)
- Iran17
- Utah17
- Canada16
- Gulf Coast (U.S.)16
- Nigeria16
- North Slope16
- Powder River Basin (Wyo. and Mont.)16
- Asia15
- Brazil15
- Louisiana15
- Mexico15
- New Mexico15
- Arctic National Wildlife Refuge (Alaska)14
- Developing countries14
- Russia14
- National Petroleum Reserve (Alaska)13
- West (U.S.)13
- Gulf Coast12
- Oklahoma11
- Arctic Ocean10