Google Inc. searches for the idea that once helped propel oil prices to nearly $150 per barrel have dwindled to almost nothing, according to a Sanford C. Bernstein analysis. The theory that oil prices would have to rise as supply inevitably declined gained hold on popular imaginations in the mid- to late 2000s, but has since languished in internet obscurity, as new discoveries and technology, including the shale revolution that helped push U.S. oil production to a 40-year high, have ensured plentiful amounts of crude in recent years.