British energy company BP has said that subsea efforts continue to focus on progressing options to stop the flow of oil from the well through interventions via the blow out preventer (BOP) and to collect the flow of oil from the leak points.

The riser insertion tube tool (RITT) containment system was put into place in the end of the leaking riser on May 16. Operations began during the day to allow oil and gas to flow through the tool up to the drillship Discoverer Enterprise on the surface 5,000ft above.

Produced oil is being stored on the drillship while produced gas is being flared. It is expected that it will take some time to increase the flow through the system and maximize the proportion of oil and gas flowing through the broken riser that will be captured and transported to the drillship.

BP also continues to develop options to shut off the flow of oil from the well through interventions via the well’s failed BOP.

Plans continue to be developed for a ‘top kill’ operation where heavy drilling fluids are injected into the well to stem the flow of oil and gas, followed by cement to seal the well. Options have also been developed to potentially combine this with ‘junk shot’, the injection under pressure of a variety of materials into the BOP to seal off upward flow. Plans for deployment of these options are being progressed with the possibility of deployment in the next week or so.

BP said that it is continuing work on the first relief well, which began on earlier this month. The DDII drilling rig began drilling the second relief well on May 16. Each of these wells is estimated to take some three months to complete from the commencement of drilling.

Work continues to collect and disperse oil that has reached the surface of the sea. Over 650 vessels are involved in the response effort, including skimmers, tugs, barges and recovery vessels.

BP said that intensive operations to skim oil from the surface of the water have now recovered, in total, some 151,000 barrels of oily liquid. The total length of boom deployed as part of efforts to prevent oil reaching the coast is now almost 1.7 million feet, including over 400,000ft of sorbent boom.