Now the company is having to move on to even more difficult operations, where the likelihood of making things worse increases even as the chances of success fall. Its next ploy is to try to cut the broken pipe through which the oil is being emitted, and to lower a dome to capture most of the black sticky liquid and siphon it off. But this is likely to increase the flow by a fifth, at least in the short term, and even if it works, will not shut it off completely.