The files created by Exporter's CSV Export feature are 100% compatible with JIRA CSV file import wirzard so you can import issues into any JIRA project or JIRA instances.
To avoid errors during import process we recomend you to include (at least) the next fields:
- Issue ID
- Parent ID
- Status (if you want to continue that issues with its flow)
- Issue type
Custom fields can be imported as they are exported on the CSV (All) option. This is a powerful option, so you can import a lot of custom data from it.