New Orleans , Louisiana ( CNN ) -- BP said Sunday that it is `` pleased '' with how the operation to place a new cap on its ruptured undersea well is proceeding . Officials hope the containment cap will stop oil from gushing into the Gulf . But while robots replace the old cap , crude is flowing freely . The procedure -- expected to take four to seven days -- continued to progress Sunday as crews worked to position a transition spool over the gushing well to prepare for the new connection , according to BP 's Senior Vice President Kent Wells . `` We 're pleased with how it 's going , '' Wells said , but cautioned that the operation , which began Saturday with the removal of the old cap , is only in its second day . Robots removed six giant bolts from the apparatus early Sunday so that the new cap could be positioned . If successful , the effects of the containment cap operation could halt the oil gusher that started April 20 after a deadly explosion on the Deepwater Horizon rig in the Gulf of Mexico . But officials have said the new containment cap would be a temporary fix , and the permanent solution would still be completion of a relief well . There are two relief wells under construction . Wells said Sunday that one of the relief wells could intercept the ruptured well as early as the end of July . `` We 're feeling very good about how we 've positioned that well , '' he said . The other relief well is expected to be completed in August . The old cap had been diverting about 15,000 barrels a day ( 630,000 gallons ) to a ship . BP still is recovering an additional 8,000 to 9,000 barrels a day ( 336,000 to 378,000 gallons ) through a line connected to another vessel , the Q4000 . `` As we start to ramp up the additional containment capacity , we should see less and less flow , '' Wells said . The Helix Producer recovery vessel is expected to begin collecting oil Sunday evening , Wells said , and officials hope to reach its full collection capacity of 20,000 to 25,000 barrels ( 840,000 to 1.5 million gallons ) per day within three days . Over the next two to three weeks , 60,000 to 80,000 barrels ( 2.52 million to 3.36 million gallons ) a day should be collected as part of the containment process , Wells said . Scientists estimate that 35,000 to 60,000 barrels of oil are spewing daily from BP 's breached well . BP says there will be a period of decreased oil and gas capture from the wellhead during the cap replacement . It said another recovery vessel , the Q4000 , `` should continue to capture and flare oil and gas . '' There will be other recovery vessels and skimmers deployed . Two more oil skimmers were added to the Gulf Sunday bringing the total to 48 collecting an oil and water mix from the surface , BP officials said . And another 15 burns were conducted in calm seas . `` It was a good day in trying to contain the oil that made it out to the surface , '' Wells said . Wells also said there will be `` significant measurement capability '' added to the new cap so officials can get a good idea of the flow rate . BP said in a statement that the new cap `` should improve containment efficiency during hurricane season by allowing shorter disconnect and reconnect times . '' Retired Coast Guard Adm. Thad Allen said Friday that the new cap would allow responders to collect more accurate oil flow data and that , once the switch is complete , the resulting capacity to contain oil `` will be far greater than the capabilities we have achieved using current systems . ''
NEW : Crews position transition spool to prepare for new connection . NEW : New recovery vessel expected to begin siphoning oil Sunday evening . BP : Cap replacement is proceeding as planned . Old containment cap removed from Gulf well . Switch will take another 3 to 6 days , during which oil will flow unimpeded .