NEW YORK ( TheStreet) -- Tesoro ( TSO), National Oilwell Varco ( NOV) and Dresser-Rand Group ( DRC) showed strength this past week, while InterOil ( IOC), Lufkin Industries ( LUFK) and Exterran Holdings ( EXH) saw substantial declines.Tesoro led the pack of energy winners last week by gaining 16.2%. National-Oilwell Varco rose 14.8% after Standpoint Research initiated coverage on the stock with a buy rating and a price target of $74, which is 26% greater than current levels. Dresser-Rand Group increased 12.1% after Tupi and Guara awarded the company a compression equipment and services contract valued nearly $700 million. The deal includes up to 80 Datum compressor trains that will be installed on eight floating, production, storage and offloading (FPSO) vessels. Valero Energy ( VLO) improved 11.2%. Last week, the company completed the purchase of Murphy Oil's ( MUR) refinery and related logistics assets at Meraux for $325 million along with crude oil inventories valued $260 million. Yingli Green Energy Holdings ( YGE) was up 10.6% after research analysts at Bank of America/Merrill Lynch initiated coverage on the stock with a buy rating. Eni SpA ( E) increased 9.5%. The company announced last week it has reached an agreement with French power group GDF Suez to acquire a 10.4% stake in Elgin-Franklin gas condensate fields for $804.5 million. Halliburton ( HAL) appreciated 9.2%. The company has completed the acquisition of Multi-Chem Group announced initially in September. Solar companies ReneSola ( SOL) and LDK Solar ( LDK) gained 9.9% and 9%, respectively, while JA Solar Holdings ( JASO) rose 5.6%. Noble Energy ( NBL) added 6.3% at the close last week. The company has finalized its joint venture partnership with Consol Energy ( CNX) for the development of Marcellus Shale assets in Southwest Pennsylvania and Northwest West Virginia, the U.S. InterOil shed 12.8%, emerging the top loser this past week. Lufkin Industries fell 11.4%. Last week, the company reported preliminary unaudited financial results for the third quarter of 2011. Based on the financial data, the company expects to report third-quarter revenue in the range of $225 million to $235 million, vs. the previous guidance of $230 million to $250 million, and earnings per diluted share between 55 cents and 60 cents, compared with the earlier view of $0.72 to $0.82. Exterran Holdings dropped 9.6% last week.