Be sure all of your PreReqs are installed Prior to running commandline install

(dotNetFx40_Full_x86_x64.exe, NDP40-KB2468871-v2-x64.exe, SDI_APS_Drivers.exe, vcredist_x64.exe)

- for silent INSTALL of Petrel is as follows: (just list all of the features your users have requested after ISFeatureInstall= 

%INST%\PetrelSuite.exe ISFeatureInstall=Petrel2012,Petrel,SDI,CoordinateSystemManager,RDR,PetrelStudioAdmin,AdobeAir,PetrelHelp,PetrelDesktop,Iswt,Drilling,Production /silent

- for silent UNINSTALL use the following commandline:

%INST%\PetrelSuite.exe /remove /silent /debuglog

NOTE: if your upgrading an existing version of Petrel 2012, you might not be able to run the /silent switch, and might just need to run PetrelSuite.exe and click the Upgrade button to continue.