NEW YORK (TheStreet) - Weatherford Interantional (WFT), Cabot Oil & Gas (COG), Helix Energy Solutions (HLX) and Cameron International (CAM) were top performers this week, while SunPower (SPWRA), Cobalt International Energy (CIE) and Whiting Petroleum (WLL - Get Report) eroded substantial value.

Among the advancers this week, Weatherford International topped the charts, gaining 14% as equity analyst William Conroy at Pritchard Capital Partners raised the stock to buy from neutral with a target price of $29 per share.

Helix Energy Solutions rose 8.4% on the week after reporting profit. The second-quarter 2011 EPS stood at 39 cents per share compared to net loss of 82 cents in the corresponding quarter of 2010.

Cameron International rose 6.5% after the company posted better-than-expected results and raised its 2011 guidance. Revenue and EPS for the second quarter stood at $1.65 billion and 66 cents, respectively. The company observed a 72% jump in orders during the quarter over the same quarter prior year.

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Cabot Oil & Gas advanced 6.3%.

EQT ( EQT - Get Report) rose 3.6% after better-than-expected results. Net income was $77.5 million, topping the estimated $63.5 million. EPS stood at 51 cents.

Range Resources ( RRC - Get Report) increased 3.6% after Citi raised the stock to hold from sell.

SandRidge Energy ( SD - Get Report) advanced 2.9% for the week.

Superior Energy Services ( SPN - Get Report) moved up 2.6% as the company has raised its 2011 EPS guidance to $1.96 to $2.16 per share vs. the earlier guided $1.62 to 2.02 per share.

Among other movers, Williams Companies ( WMB - Get Report), Complete Production Services ( CPX), Noble Energy ( NBL - Get Report) and Holly Energy Partners ( HEP - Get Report) added around 2%.

SunPower was the top lagger, shedding 15%. The company reported higher-than-forecast net loss. Stifel Nicolaus equity analyst at Jeff Osborne has downgraded the stock to sell from hold.

Cobalt International Energy shed 14.2%.

Whiting Petroleum declined 10.6% as BMO equity analyst Philip Jungwirth downgraded the stock to market perform from outperform with a target price of $65 per share.

GT Solar International ( SOLR) retreated 9.9% as Credit Agricole Securities equity analyst Mark Heller has downgraded the stock to underperform from outperform with a target price of $16 per share.

Among other movers, Carbo Ceramics ( CRR - Get Report) fell 9%, Swift Energy ( SFY) reduced 8.9%, Oasis Petroleum ( OAS - Get Report) pared 8.2% and Occidental Petroleum ( OXY - Get Report) declined 7.7% for the week.

Valero Energy ( VLO - Get Report) erased 7.6% as the company's second-quarter profit missed analysts' estimates on higher-than-expected losses at its Canadian refinery.

RPC Inc ( RES - Get Report) and Talisman Energy ( TLM) erased 7.5% and 7.1%, respectively.

Advantage Oil & Gas ( AAV) shed 6.7%.

Suntech Power Holdings ( STP) declined 6.7% as Deutsche Bank equity analyst Eric Cheng has downgraded the stock to hold from buy with a price target of $6.2 per share.

Newfield Exploration ( NFX) and Cheniere Energy Partners ( CQP - Get Report) trimmed 6.6% and 6.5%, respectively.

Rosetta Resources ( ROSE - Get Report) lost 6.3% after receiving a downgrade to neutral from positive with a price target of $60 per share from Susquehanna equity analyst Gray Peckham.

Also on the downside were Denbury Resources ( DNR - Get Report) and Suncor Energy ( SU - Get Report), closing the week down around 6%.