Enterprise Edition is all you need.
Data Guard is a feature of Oracle Database Enterprise Edition and does not require
1-10 from Oracle® Data Guard Concepts and Administration 11g Release 2 (11.2) E10700-02
2.3.2 Oracle Software Requirements
Oracle Data Guard is available only as a feature of Oracle Database Enterprise Edition. It is not available with Oracle Database Standard Edition.
Same doc - E10700-02
Licensing Data Recovery Environments