NGINX directed logging

I'm running a drupal multi-site and I want to write to a particular access log file based on the url that comes in. Catch: in the same server block.

I have 1 server block that is handling multiple urls (the drupal multi-site) drupal handles what content is served. I what to test for the urls and have nginx write the access record to a log file associated to that particular url without having to write several server blocks. Is there a way to do this ?

Thanks