"If this transaction is made, we would seek to raise up to $400 million in a share issue," said Sven Boerre Larsen, who heads TGS's business development and acquisitions team.
PGS in a separate statement on Friday said it would consider the offer for its so-called multiclient data library, which TGS announced late on Thursday.
(Reporting by Terje Solsvik, editing by Gwladys Fouche)