Oracle apparently has several inter-related protocols used for sending SQL over the wire. Wireshark at one point had a short dissector for a small subset of these, but the code was very buggy and without a protocol reference there was little we could do with it.
See mailing list discussion: https://www.wireshark.org/lists/wireshark-dev/201303/msg00161.html
The old dissector is attached below for reference: it may be useful when reverse-engineering the protocol, but should not be used as-is in any way -- the code style is terrible and buggy:
Also perhaps worth noting: PortReference/Ports0to99 lists Oracle SQL*Net on TCP/UDP port 66.