Good point about the competition of the survivors
as for the seven sisters , they were Esso ,Mobil ,Gulf oil ,Texaco ,Standard oil of California ,British Petroleum , and Shell
the first fives were the daughters of Standard oil , broken by law .
The daughters have now reunited back , that's a bit like the Japanese Zaibatsu broken by MacAthur during his rule there,
they have largely reunited back .
Sumitomo, Mitsui, Mitsubishi Nissan with Nomura added for good count ,while broken in independent companies kept working as single unit through their common "understanding " then reunited the working bits
something like" back to the future "
one must note the quite sudden appearance of the Asian giants ,
the Chinese corporations have deep pockets and a lot of heft in many country ,
they compete directly for reserves all over the world ,
national oil companies are a bit of a strange story , on the whole they don't seem to be able to cut the mustard outside their home advantage