Plains Exploration (NYSE:PXP): Standardized measure of discounted net cash flows increased 66% to $5.1B in 2011 from $3.1B in 2010. The 2011 PV-10 value increased 58% to $7.9B from $5.0B in 2010. The 2011 reserve replacement is 222% or 290% pro forma for asset sales.

The shares closed at $41.80, up $2.36, or 5.98%, on the day. Its market capitalization is $5.89 billion.

Canadian Natural Resource (NYSE:CNQ) Horizon oil sands plant in Alberta, a 110,000 barrel a day operation, is shut down following planned maintenance and repairs being performed could keep it off line for two to three weeks, reported Reuters, citing a source.

The shares closed at $38.74, down $1.76, or 4.35%, on the day. Its market capitalization is $42.41 billion.

Peabody Energy Corp. (NYSE:BTU), Anadarko Petroleum Corp. (NYSE:APC): 24.4% of U.S. electricity came from gas, versus 42.8% from coal, during the 12 months through November, whereas in 2008, the figures were 21.4% and 48.2%, respectively, reported The Wall Street Journal. A comparison to a decade ago, when gas contributed 17.9% versus 49.8% from coal, further underscores the way in which cheap natural gas continues to pressure coal use and, by extension, coal miners.

BTU shares closed at $37.41, down $1.4, or 3.62%, on the day. Its market capitalization is $10.13 billion.

APC shares closed at $87.21, up $4.34, or 5.24%, on the day. Its market capitalization is $43.43 billion.

Exxon Mobil Corporation (NYSE:XOM), Chevron Corporation (NYSE:CVX): In its monthly short-term energy outlook report, the U.S. Energy Information Administration said it expects the price of West Texas Intermediate crude oil to average about $100 per barrel in 2012, with data showing the market believes there is about a one-in-fifteen chance that the average WTI price in June will exceed $125 per barrel. For 2013, EIA expects WTI prices continuing to rise, reaching $106 per barrel in the fourth quarter of next year.

XOM shares closed at $86.34, up $0.59, or 0.69%, on the day. Its market capitalization is $408.73 billion.

CVX shares closed at $106.83, up $0.16, or 0.15%, on the day. Its market capitalization is $212.75 billion.

Halliburton Company (NYSE:HAL) has decided to phase out thousands of employee BlackBerrys (NASDAQ:RIMM) in favor of the iPhone (NASDAQ:AAPL), according to Apple Insider.

The shares closed at $37.00, down $0.4, or 1.07%, on the day. Its market capitalization is $34.05 billion.

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To contact the reporter on this story: Stella Mariz at staff.writers@wallstcheatsheet.com

To contact the editor responsible for this story: Damien Hoffman at editors@wallstcheatsheet.com

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