BP: 50 percent is really 10 percent, right?

BP's latest attempt to shut off the Deepwater Horizon gush has not the greatest chance of success:

After several failed attempts to divert or block the well, BP's latest attempt involves cutting the broken riser pipe, making it spew as much as 20 percent more oil into the water for days while engineers try to position a cap over the opening.

Eric Smith, an associate director of the Tulane Energy Institute, said the strategy had about a 50 to 70 percent chance to succeed. He likened it to trying to place a tiny cap on a fire hydrant.

So, if it doesn't work, the 20 percent increase in the gush will be permanent? Adding yet more plumes to the already existing ones BP claims don't exist.

Ultimately, we have to look at BP's claim it can shut off the Deepwater Horizon gush with relief wells, by August. Is that believable? It took 10 months to shut off the huge 1979 Mexican well blowout. Yes, technology has advanced in 31 years, but that was a shallow-water well.

So, instead of two months, should we say four? Six? Or like Mexico 1979, 10 months? And, 10 months of a gush increased by 20 percent?