btcrecover as suggest by nc50lc would be the best way to do this if it was possible, but it almost certainly isn't I'm afraid.
18 scrambled words in an unknown position gives 18! combinations = 6.4*10
15 combinations. Here's a post I made a few months ago with some rough benchmarks:
Even assuming you can rent hardware which can test 1 million combinations a second, then you are still looking at over 200 years to exhaust the search space. The amount of hardware you would need to rent to solve this in a reasonable amount of time will almost certainly cost orders of magnitude more than whatever coins you have in that wallet. Do you have any other possible way of narrowing down the search space or confirming the location of some of the other words?
I will still give btcrecover a try, even if it sounds as there is no hope... Fortunately there are not that many coins on the wallet. Not even 1 btc