During the well integrity test, the three ram capping stack is closed, effectively shutting in the well and all sub-sea containment systems – the Q4000 and Helix Producer systems – have been temporarily stopped.

Although it cannot be assured, it is expected that no oil will be released to the ocean during the test. Even if no oil is released during the test, this will not be an indication that oil and gas flow from the wellbore has been permanently stopped, BP said.

According to the company, information gathered during the test will be reviewed with the relevant government agencies, including the federal science team, to determine next steps.

During the well integrity test, operations on the first relief well have been temporarily stopped while the well was at 17,840ft as a precaution. Operations on the second relief well have been temporarily suspended at 15,874ft to ensure that there is no interference with the first relief well. The relief wells remain the sole means to permanently seal and isolate the well, the company said.