Oil

I was wondering that since we have taken such large quantities of oil out of the ground is it possible that if there is large seismic activity in the areas where the drilling occured could there be a problem with the land collapsing into these massive empty caverns? or is it too deep for it to matter?

By large, there aren't actually caverns.  Oil is generally found in porous rock under pressure and even travels through these pores upwards due to pressure.  When tapped, this subterranean pressure forces the oil out of the well.  If the pressure drops off too much for the well to be useful, they inject fluids - water, usually - into well to push the oil up.

Meanwhile, the same downwards pressure that turned whatever decomposed into these hydrocarbons in the first place is still pushing down and filling in gaps wherever it can.  No matter how much oil comes out of a well, the rate from that small pipe is not enough to outstrip the force over a volume of earth being pushed downwards.