NEW YORK (Karvy) -- Key Energy Services (KEG - Get Report), Lufkin Industries (LUFK) and PAA Natural Gas Storage (PNG) were among the top gainers last week, while Comstock Resources (CRK), Helix Energy Solutions (HLX - Get Report), and Cobalt International Energy (CIE) topped the losers' list.

Key Energy, the world's largest provider of onshore well service rigs, jumped 10.1% last week, hitting 52-week highs on Friday. Last month. Chairman and CEO Dick Alario said, "December's activity should also benefit from two rigs that have gone to work in Bahrain and from the addition of two rigs to our existing contract in Colombia. We expect to finish the year with five rigs working in Colombia, and we believe that market will yield additional opportunities for Key. Overall, 2011 looks promising in each of our international markets."

Lufkin, a global supplier of oil and power transmission products, peaked to 52-week highs on Friday, gaining around 6.9% last week. PAA Natural Gas Storage advanced 6.5% on the drop in natural gas rig counts. The company is engaged in acquisition, development, operations, and commercial management of natural gas storage facilities.

Acergy ( ACGY), an offshore engineering and construction contractor, rose 6.4%, reaching 52-week highs on Friday. Analysts at Collins Stewart upgraded the stock to buy form hold.

Ensco ( ESV), an international offshore contract drilling company, gained 5.7% last week reaching 52-week highs on Friday. Analysts at Citigroup raised the stock's price target to $55 from $50, assigning a hold rating. Weatherford International ( WFT) and Precision Drilling ( PDS) advanced around 6.3% and 5.5%, respectively.

CGG Veritas ( CGV), the world's largest seismic surveyor of oilfields, rose 5.1% last week on the recent uptrend in oil prices, which will likely increase oil producers' spending. On Monday, the stock was upgraded to outperform from underperform at Exane BNP Paribas.

Forest Oil ( FST), a Denver-based oil and gas company, climbed 4.8% last week after the company filed an initial public offering for its Canadian operations, Lone Pine Resources.

SandRidge Energy ( SD), a natural gas and oil company, gained 4.7% last week. The stock was assigned a buy rating at Ladenburg Thalmann. The company announced the sale of 40,000 net acres in Texas' Permian Basin, a transaction accretive to net asset value, according to analysts at JPMorgan.

Baker Hughes ( BHI), an oilfield services company, gained 4.3% last week.

Among other winners, Penn West Energy Trust ( PWE), TransAtlantic Petroleum ( TAT), Seacor Holdings ( CKH), Western Gas Partners ( WES) and EXCO Resources ( XCO) were up 4.4%, 4.3%, 4.2%, 4.1%, and 3.7%, respectively.

Among losers, Comstock Resources, a gas-focused explorer, plunged 10.9% last week on a downtrend in natural gas prices. The company forecasts higher exploration and development budget, and production for 2011. In addition, Comstock plans to shift its focus to high-liquids content.

Helix Energy, an international offshore energy company providing reservoir development solutions and contracting services, lost around 9% last week. Last Tueaday, Gardon Ahlat, a company director, sold 42,412 shares. Cobalt International Energy, an oil-focused exploration and production company, dipped around 8.6% last week.

GT Solar ( SOLR) declined around 7.7% on news that Germany may cut solar incentives in mid-2011. Meanwhile, JA Solar Holdings ( JASO) and Trina Solar ( TSL) declined 5.1% and 6.3%, respectively.

Carbo Ceramics ( CRR) trimmed around 6.1%, after analysts at Howard Weil downgraded the stock to market perform from market outperform.

Similarly, Transocean ( RIG), an international provider of offshore contract drilling services for oil and gas wells, dropped 4% last week after Morgan Stanley downgraded the stock to equal-weight from overweight on increasing uncertainty related to a Department of Justice lawsuit. Analysts see 2011 earnings at risk, due to the delay in recovery for older jackup/floaters.

Among other losers, Ecopetrol ( EC), Gran Tierra Energy ( GTE), Energy Transfer Equity ( ETE), Complete Production Services ( CPX), and NuStar GP Holdings ( NSH) fell 6.4%, 5.7%, 5.6%, 5.1%, and 5%, respectively.

This commentary comes from an independent investor or market observer as part of TheStreet guest contributor program. The views expressed are those of the author and do not necessarily represent the views of TheStreet or its management.