BP to start critical pressure test after fixing leak

After having fixed a leaking valve on the new sealing cap designed to stop the flow of oil from its blown-out Deep Water Horizon rig, BP said yesterday that it will start a twice-delayed critical pressure test to determine whether the biggest oil spill in history could be stopped temporarily.

BP had to delay the Mocondo oil well 'integrity test' after it detected a leak in the choke line. The choke hub was replaced on Wednesday night but the oil major said that there are intricate procedures to be completed before starting the tests.

By conducting the tests, BP wants to find out whether the pressure in the well is rising and holding, which would indicate that the well is not damaged and oil has stopped leaking.

The a minimum of six-hour duration of the test could extend up to 48 hours and the three-ram capping stack will be closed and all sub-sea containment systems will be temporarily suspended, effectively shutting in the well.

The integrity test involves slowly closing the new sealing cap's valves that were installed last this week, (See: BP places new sealing cap to stop oil spill, prepares for testing) entirely blocking the flow of oil. High pressure would denote a measure of success since it would indicate either none or only a single leak whereas, low pressures would suggest multiple leaks.

BP however cautioned that the sealing cap system has never before been deployed at these depths or under these conditions, and its efficiency and ability to contain the oil and gas cannot be assured.

BP will continue checking the pressure for 48 hours and if all goes well, then it will consult with the US government scientists on keeping the valves closed, thereby shutting the well - similar to putting a cap on a soft drink bottle.

But capping the well, if successful, will still be a temporary measure until BP's permanent solution of drilling of two relief wells that are expected completed by the middle of next month.