There will always be a PGS because they are Norwegian and the govt is a shareholder and will always want a Norwegian company with that expertise for them.
There may not always be a WesternGeco since Schlumberger is all about oilfield services - much more profitable than seismic.
There will always be a French exploration company , as there will always be a French oil company looking after France's energy needs.
The management went into RBS mode , buying everything they could when the oil price was getting ridiculously high.