Deferring the oil tax cash credits was the only action Governor Walker could take. He deferred the maximum amount allowed by law.  

Read the version of HB247 that Governor Walker introduced last January. 
http://www.akleg.gov/PDF/29/Bills/HB0247A.PDF

It contains MAJOR oil tax reforms. For instance, look at Sec. 26. AS 43.55.028(e), on page 19. Subsection 6 would limit tax credit payouts to $25 M per year per company.

The House passed the bill by a wide margin. It didn't make its way out of the Senate Finance Committee. Never had a floor vote.