LONDON -- The FTSE 100 (INDEX: ^FTSE) is barely moving today and was just 20 points up at 5,674 points by around midday. While markets in general have been buoyed by the latest murmurings from the eurozone, BP's share-price slide has helped hold back the index of the U.K.'s biggest shares.

It's actually been a big day for oil and gas news in general, with companies from the various FTSE indexes moving in both directions. Here's a look at three that fell today.

BP (LSE: BP.L)
BP fell 4.3% to 425 pence after releasing second-quarter results that included a $5 billion charge for massive write-offs of a number of its U.S. assets. The writedown covers the falling value of its refineries in the U.S. and its shale gas assets, whose potential valuation is slumping, among others.

The oil giant's operational performance was substandard, too, with underlying profit of $3.7 billion, compared with $4.8 billion the previous quarter and $5.7 billion in the second quarter of the previous year. But at current price levels, the shares are on a forward dividend yield of 4.9% for this year and 5.5% next year, and the payouts should be well-covered by earnings. Unless those dividends are cut, BP shares are looking like a bargain.

Borders & Southern (LSE: BOR.L)
Borders & Southern's shares fell by 6.3% to 16.6 pence this morning after it announced it has reached the end of its 2012 drilling program. The explorer, operating in the region of the Falklands, has plugged and abandoned its Stebbing well and has passed on the use of the Leiv Eiriksson drilling rig to Falklands Oil and Gas, which will now use it for its own exploration program.

Exactly why the shares should fall today is anybody's guess; the Stebbings result was announced on July 16, when the shares crashed by 70%, and it was already known that this was the end of the drilling season. But that's the way oil explorer share prices often move.

Weir (LSE: WEIR.L)
Engineer Weir Group saw its shares fall 3.1% on the release of interim figures, which might seem strange on the back of a 29% rise in revenue to 1.3 billion pounds, a 27% rise in pretax profit to 226 million pounds, and an 11% hike in the interim dividend to 8 pence per share.

But although the firm's power and industrial divisions were strong, we learned of "the challenging pressure pumping market conditions faced by oil and gas," and that seems to have been enough to spook the market.

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