Extracting a list of users who both received and opened a transactional Welcome email

Hello,

Every step of the way we have been encountering errors here.  We are trying to export a list of customers that have both received and opened a Welcome email.  We can query the data in both the Recipients and Tracking Log tables, but we cannot seem to intersect the audience and the Export activity does not seem to do anything.  Any help with how to approach this problem?

Thank you, in advance.