By Steve Gelsi

Shares of natural gas producers led gains in the energy sector, which drew strength from steady oil prices, a discovery by Anadarko Petroleum Corp. (APC) and analyst upgrades, as the broad market struggled back from opening losses.

The Amex Oil Index rose 0.3% to 781, with shares of refining giant Valero Energy Corp. (VLO) and Hess Corp. (HES) up nearly 3% each. The Amex Natural Gas Index rose 1.3% to 306, with Southwestern Energy Co.(SWN) up 4% to $29.86.

The Philadelphia Oil Service Index rose 2.6% to 112.

Crude oil futures rose 14 cents to $45.66.

Anadarko Petroleum shares rose 5% to $34.65 after the company announced an oil discovery at its Tweneboa-1 offshore well in Ghana.

"Tweneboa is an outstanding discovery and continues our success in Ghana," the company said. "We believe there is significant additional upside as we conduct appraisal activity closer to the perceived core of this stratigraphic trap, where a thicker reservoir section is mapped."

The well was drilled, logged and cased to a depth of approximately 11,790 feet, and is being deepened to further assess additional prospective hydrocarbon-bearing zones.

Halliburton Co. (HAL) jumped 7% to $16.16 after FBR upgraded the oil-service giant to outperform from market perform.

Drill-ship maker Transocean Ltd. (RIG) rose 3.7% to $52.99, also following an FBR upgrade to outperform from market perform.

Pritchard Capital Partners said Monday that Baker Hughes Inc.'s (BHI) rig count fell by 73 rigs last week to 1,170 rigs, down by 861 rigs or approximately 42% from the 2,031-rig peak set in September of last year. The 42% decline is outpacing those of the 1983 cycle, the 2001-2002 cycle, and the 1997-1998 cycle, Pritchard said.

Shares of Baker Hughes rose 5% to $28.

Total SA (TOT) said its Total Upstream Nigeria Ltd. (Tupni) unit started production earlier than expected on a major project off the shore of Nigeria. The Akpo Deep Offshore Field is one of the largest deep offshore projects ever undertaken and will be the largest brought on stream in 2009, Total said.

The ramp up of production to 175,000 barrels per day of condensate and 320 million standard cubic feet per day is expected to be reached during the summer. Total holds a 24% interest in the Akpo OML 130 block, alongside partners including Nigerian National Petroleum Corp., South Atlantic Petroleum of Nigeria, Cnooc Ltd. of China (CEO) and Brazil's Petrobras (PBR).

Total shares fell 1.3% to $45.18 in early U.S. trade.

-Steve Gelsi; 415-439-6400; AskNewswires@dowjones.com