Willy, those rules appear to state that wells of 2,000' to 5,000' must be 660' apart, or 8 wells per 640 acre section. that would be one well for each 80 acres. Deep wells appear to be on 160 acre spacing.
For 1,500 acres, that's 18 wells, and we already have 4 shallow wells, so 14 more of the 20 shallow wells can be drilled.