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) 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) 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) increased 3.6% after Citi raised the stock to hold from sell.

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

Superior Energy Services ( SPN) 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), Complete Production Services ( CPX), Noble Energy ( NBL) and Holly Energy Partners ( HEP) 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) fell 9%, Swift Energy ( SFY) reduced 8.9%, Oasis Petroleum ( OAS) pared 8.2% and Occidental Petroleum ( OXY) declined 7.7% for the week.

Valero Energy ( VLO) 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) 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) trimmed 6.6% and 6.5%, respectively.

Rosetta Resources ( ROSE) 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) and Suncor Energy ( SU), closing the week down around 6%.