Feet in 1 sq mi = 5280 * 5280
Cubic feet in an 800 foot thick sq mi
5280 * 5280 * 800 = 22,302,720,000 cubic feet
22,302,720,000 cubic feet in gallons
1 cubic feet = 7.48051945 US gallons
22,302,720,000 * 7.48 = 1.66835931 × 1011 US gallons
166,835,931,000 gallons
There's no way the oil producing sands are 50% permeable, maybe 25% if you're lucky.
166B gallons * .25 = 41.5B gallons
41.5B / 42 = .99 bbl per square mile 800 feet thick.
How many sq miles is this field???