Try this,
string ConnectionString = "Data Source=(DESCRIPTION =(ADDRESS_LIST =(ADDRESS = (PROTOCOL = TCP)(HOST = @fill_IP)(PORT = @fill_Port)) ) (CONNECT_DATA = (SERVICE_NAME = @fill_servicename) (INSTANCE_NAME = @fill_InstanceName) (GLOBAL_NAME = @fill_DatabaseName))); user id=@fill_UserId; password=@fill_Password; Connection Timeout=360";
OracleConnection con = new OracleConnection(ConnectionString );
con.open();