The number of permits for development and exploratory wells includes both crude oil wells and natural gas wells. In 2012, the number of development permits issued dropped by 53 percent offsetting the 50–percent increase the previous year. The number of exploratory permits issued increased 20 percent from the number of permits issued in 2011.
In 2011, the number of development permits issued jumped 50 percent while the number of exploratory permits issued was steady at 75 although was 2 permits less than in 2010. In 2010, the number of development permits issued nearly doubled and the number of exploratory permits issued more than doubled with the rise of the crude oil price. In 2009, the number of permits issued fell to levels which hadn't been seen since 2004. This was a drop in both permit categories of nearly 80 percent from 2008. An increasingly favorable economic environment in 2008, which included high crude oil prices, had driven up the number of drilling permits issued. Drilling permits issued for exploratory wells nearly doubled in 2008 from 2007 whereas drilling permits issued for development wells increased 13 percent. Development well permits had tripled in 2007 from 2006. The number of both types of permits peaked in 1981 with development well permits reaching 374 and exploratory well permits reaching 354.