I was told I need to reach 30k sat to say goodbye to captcha, either with a deposit or any other mean (roll, lottery, referral, etc)
You were told wrong. Read the two posts in this thread previous to yours for the correct answer.
No, 30,000 is the withdrawal minimum. As has been stated many times in this thread captcha is removed when your balance is double your total free roll winnings.
go deposit and ur captcha will be gone.. 
what? are you sure? how many deposit does it take to get rid off the captcha?This question has been answered multiple times in this forum thread, but here's the answer once again:
To remove the captcha you should deposit a Bitcoin amount equal to the amount of your free roll earnings. You can see your current free roll earnings by clicking "Stats" and then "Personal Stats". For example if you earned 0.001 BTC from free rolls, you should deposit 0.001 BTC to your FreeBitco.in BTC deposit address and the captcha will be removed. My advice is to deposit a bit more, because if you continue with free rolls, the earning from free rolls will soon become more than the deposited amount and the captcha may return. Please someone correct me if something in my answer is wrong.
Close enough to being correct. A simpler way of putting it is that you need a balance of double your total free roll earnings. You don't have to deposit it, you can win it from gambling or earn it from referrals as well.
Please at least read at least a few posts back before posting incorrect information.
and I can tell you you need to be above the withdrawal threshold and have at least double your free roll earnings to have the captcha removed based on experience. If you want proof make a new account and send some coins to it but under the withdrawal threshold and you will still have to do the captcha to claim. It isn't something I can easily prove with my account though since I am passed 15k free roll earnings which means I will always be above the 30k threshold with double the earnings.