It sounds like you haven't setup your driver correctly.
In standalone/configuration/standalone.xml (or domain or whatever you are using) there is a subsystem node with {code:xml}<datasources><datasource jndi-name=...>{code} (you may build an entry for your datasource here which should use the name mentioned later -- likely {code:xml}<driver>ORACLE</driver>{code}) there should also be (in that same subsystem node) {code:xml}<datasources><drivers><driver>{code} nodes (at least one should already exist by default with name="h2", you now need to add one with name="ORACLE" or whatever you prefer -- to be used in the above {code:xml}<datasources><datasource><driver>{code} node).
Note: The name attribute may not work if you put punctuation marks in it as some of those appear to be treated special (like ".").