Reserves in 2008 a negative for energy cos-analyst

HOUSTON, Jan 5 (Reuters) - Investors betting the shares of oil and gas producers will extend recent gains may be disappointed as lower commodity prices and higher costs take a toll on 2008 energy reserves, an energy research firm said on Monday.

"We think investors are too complacent about year-end reserves, which will be a net negative/downside surprise for the group as a whole," Tudor, Pickering, Holt & Co Securities Inc wrote in a note to clients. "Reserves aren't a reason for investors to flee the sector, but they will be a reason for traders to buy or sell."

Year-end proven reserves are key because investors use them to calculate an energy company's net asset value, among other measures. But a sharp drop in oil and natural gas prices may prompt some companies to defer the development of oil and gas deposits.

On a year-over-year basis, crude oil prices fell to about $45 per barrel from about $96 per barrel, while natural gas prices dropped to $5.70 per thousand cubic feet from $6.80 per thousand cubic feet.

Companies that might see their stocks get a lift from their year-end reserve data include SandRidge Energy Inc (SD.N: Quote, Profile, Research), SW Energy Co SW.N, Carrizo Oil & Gas Inc (CRZO.O: Quote, Profile, Research) and Petrohawk Energy Corp (HK.N: Quote, Profile, Research), the note said.

Smaller companies with more oil-weighted assets or those with a largest percentage of proven undeveloped reserves or high operating costs will have the largest exposure to negative price revisions, the research firm said.

Rex Energy Corp (REXX.O: Quote, Profile, Research), Parallel Petroleum Corp (PLLL.O: Quote, Profile, Research), Berry Petroleum Co (BRY.N: Quote, Profile, Research) and Plains Exploration & Production Co (PXP.N: Quote, Profile, Research) will likely report the worst reserve results, according to Tudor, Pickering.

Other larger companies that may disappoint because their projects have longer lead times include Occidental Petroleum Corp (OXY.N: Quote, Profile, Research) and Noble Energy Inc (NBL.N: Quote, Profile, Research), the firm said. (Reporting by Anna Driver in Houston; Editing by Andre Grenon)