Second Round Interview

I received an email from Halliburton about 3 weeks ago saying i qualify for 2nd round interviews for the Field Engineer job. But i haven't heard back since. how long do they usually take to get back to a person about a position? I sent an email saying thank you and asking if i could do anything on my end to speed it up

I did the same interview a year ago, it took 1 month between the 2 interviews, but it was in France and in a different economic context ;) just don't hesitate to contact them again and again and again...
Good Luck