Read the actual article by Lefsrud and Meyers. in Organizational Studies.  The people that responded to the APEGA survey that they analyzed  were 84% engineers,  15.6% geologists and geophysicists, and 0.4% technologists.  BTW, this was a self selecting survey so the results can in no way be used to claim representation of any larger group.  Given that oil sands dwarf all other mining considerations in Alberta with coal the next biggest, and given it was a self selecting survey I think the author's conclusion that they were analyzing people in the petroleum industry are pretty valid, but there could also be some respondents from the coal industry.