My dad's worked sub-contract in Angola, wannabe, just before he retired. He's a retired petroleum engineer for Shell, but that assignment was sub-contract to Texaco, IIRC.
A lot of kidnapping there at the time. He basically didn't hang around much. Work, go back to compound, don't leave.
But yes, a colleague of his was kidnapped in Brazil years ago and even then, Shell brought in a negotiator and they were able to secure his release.
I'm surprised the kidnappers have not released their ransom demands, although perhaps they have and it's not been reported yet.
Perhaps they are already working with negotiators.