Just busted Event #6 at the Borgata Winter Open and still unsure of my shove in this spot. I'm primarily a cash game player and would just like some feedback on my shove with this stack.We just returned from dinner break and I had been at this table about an hour before the break, after my last table broke (where I was all day). I do not believe I played more than 1 or 2 hands in that hour, so my image is definitely on the tighter side. 

We came back to 2000/4000 w/ a 400 ante. I have 73.5k (little over 18 bb). UTG accidentally throws in 4k as the second card is being dealt thinking he is in the BB. He tries to take it back, but the dealer says the 4k must stay in as he already has cards (not sure of the rule here?). He seems a little upset but does not call the floor for a ruling.

Antes 3,600

SB 2,000

BB 4,000 (has about 25 bb)

UTG 4,000 (calls mistakenly w 20 bb)

UTG+1 folds 

MP1 folds (most aggressive player w biggest stack)

(Hero) MP2 A  9  All In for 73,000

HJ folds (20 bb – new player)

CO folds (30 bb – limping a lot)

BTN (60+ bb – seemingly tight older man who looked to be getting hit w the deck in the hour I was there)

My reasoning was with 13.6k (about 19% of my stack) in the pot already and assuming 4k of it is dead money, I think I can pick up this pot uncontested pretty often. People might be thinking I'm making this play b/c of UTG calling mistakenly, but like I said no one had seen me get out of line and I'd played very few hands (was fairly card dead).

Long story short, is this a shove w/ 18-19 bigs and this dynamic? Fold? Raise to 10k? 

Also, what type of range should I be shoving here? Raising to 2-3x?

Results aren't important here, but the BTN called w/ AQ and I hit the rail. 

Thanks for your input!