'OraOLEDB.Oracle' provider is not registered on the local machine - Oracle Database Client 12C
From comment by Wernfried Domscheit:


  Have a look at this instruction to install both 32 bit and 64 bit on one machine: stackoverflow.com/questions/24104210/…. Note Oracle OLEDB provider is not included in Oracle Instant client, you have to install it separately or enable the corresponding option in Oracle Universal Installer.