Hi Michael,
Please follow below steps you will get "WRTTP" Field in BI also.
go RSA6 Tcode in your Source system ( SAP R/3) --> find your data source in RSA6 --->
Keep cusrsor on your Data Source and click on change mode --> then you will see all the fields related data source in that sap screen, there you can see "WRTTP" Field also.
There is a "Hide field" Column is trhere. Just you can UN Check Check box of "Hide Field" column related to your "WRTTP" Field.
then activate that data source from Source system.
next go to your BI System , replicate yor data source in BI System.
Now you will definetly see your "WRTTP" Filed also in your BI.
Finally you need to collect transport from Source system while activating the data source,
That Transport you need to send Quality and Production system.
then only you can see this same filed in both Quality and Productions Systems.
Please find below screen shot for reference:
Regards,
Nagaraju K