Separate URLs for blog & portfolio

Hi Guys,

I'm wanting to move all blog posts to a url structure of which I have done by adding a custom permalink structure of /blog/%post-title%/ which has worked ok. The issue is that this change has had a knock on effect, making the companies portfolio nest under the blog. (ie. Im wanting to have 2 separate structures similar to below:

portfolio ==

Would really appreciate any insight you can give me.

Thanks in advance.