The problem is (surprise), Socialism! That's right! Because of the Mexican nationalization of its natural resources outside investment isn't allowed (maybe to a small extent). I read an interesting article a while back (sorry, don't have the link) comparing and contrasting Canada’s (Quebec?) natural resources policy to Mexico's. Both countries say the state owns the land and the resources under it but Canada allows private companies to extract if for them (a good ballance?). In Mexico, only they state is allowed to extract the oil. Therefore the technology needed to make their fields productive isn’t available and everyone suffers except for their corrupt politicians (in the finest Spanish tradition of course).