No, you may only spend surges to gain threat from a successful attack (2 surges for on threat).
Descent base rules, page 10:
Using Power Surges (Overlord): For every two surges the overlord player rolls during an attack, he gains one threat token. Any unused surges are lost.
and clarified in the FAQ:
Q: Under what circumstances can the overlord receive threat for rolling surges on an attack roll?
A: The overlord may spend two surges on each attack roll to gain one threat. He may do this on any attack that hits a hero. This represents a change from previous FAQ rulings on this subject.
In addition, the Dark Priests get a attack bonus (+range and +damage) when they roll surges.
Surges do not add movement or upgrade power die. You are getting confused with threat. The OL may use threat during an outdoor encounter for additional movement or power dice. This is due to the fact that the OL does not get any cards during encounters.