How to find the applied patches between the two R12 EBS systems

Hi,

We're using Oracle Ebusiness suite R12 (12.1.3). We normally apply a lot of patches to non-production system, and most of the time we merge those patches when we apply. Some of those patches are not applied to production system. We regularly refresh the non-production from production. We need to find out all the patches applied to non-production and apply them for each refresh. The question is: how to get the list of the patches applied to non-production and not in production? We considerred comparing ad_applied _patches, and ad_bugs. However, ad_applied_patches doesn't list the merged patches. ad_bugs lists all the bugs, not just the applied patches.