Chavez is many things, but he's not an idiot.
The positioning of American forces in Columbia does not bode well for peace in the region.
And of course, as reported here:
"There were 80 billion barrels (13×10^9 m3) of conventional oil reserves in Venezuela as of 2007, the largest oil reserves of any country in South America."
Let's see if I have the formula correctly. Foreign oil reserves, plus a government the US doesn't particularly like, equals... vigorous US attempts at destabilization of that government, including military confrontation, if the US thinks it can get away with it.