Few oil stocks would be safe if crude falls $20 to $30 a barrel. Independent exploration and production companies like Devon Energy (DVN), Apache (APA) and XTO Energy (XTO) could get hit hard because they're up sharply in the past year.

Few oil stocks would be safe if crude falls $20 to $30 a barrel. Independent exploration and production companies like Devon Energy (DVN), Apache (APA) and XTO Energy (XTO) could get hit hard because they're up sharply in the past year.

Few oil stocks would be safe if crude falls $20 to $30 a barrel. Independent exploration and production companies like Devon Energy (DVN), Apache (APA) and XTO Energy (XTO) could get hit hard because they're up sharply in the past year.

Bernstein's McMahon estimates Exxon could earn $12 share in 2009, versus the current consensus of $9, if oil holds $130 and natural gas averages $11 per thousand cubic feet; it is now around $13. This suggests Exxon, at 86, may be trading for just seven times estimated '09 profits.

The majors, including ExxonMobil (XOM), Chevron (CVX) and ConocoPhillips (COP), might hold up better because they have refining and related businesses like chemicals, whose profitability isn't directly linked to crude and natural-gas prices.

Conoco and Chevron also could earn far more than the current '09 consensus under the same oil and gas scenario, Bernstein estimates

Some of the biggest oil companies, notably ExxonMobil, Royal Dutch Shell (RDS/A) and BP (BP), have badly lagged in the past year. BP, for one, has been beset by problems, including a troubled joint venture in Russia.

McMahon favors BP, Royal Dutch and Marathon Oil (MRO).