Energy giant, BP, says it is conducting several hours of diagnostic tests ahead of the risky manoeuvering for plugging the devastating oil leak in the Gulf of Mexico. The company said, the tests were in preparation for the so-called "top kill" operation to seal the leaking oil well,about a kilometer and a half under water. They say the method involves attaching a series of tubes to a massive valve that sits atop the well on the sea floor. Kent Wells, a senior vice president for BP, says surface ships will then pump large amounts of heavy mud down to plug the well. Ultimately when enough mud is pumped, the flow will stop, he said. BP officials and oil experts have been studying the plan for weeks to ensure the method is likely to succeed and not make the problem worse. The whole exercise is expected to take 24 hours. President Obama is expected to announce tomorrow proper safety requirements for off-shore oil drilling. An Adinistration official told the Associated Press, the steps are likely to include stringent inspection of oil riggs. The President is expected travel to the Lousiana coast on Friday to review efforts seal the disastrous spill. Meanwhile, family members and colleagues held a memorial service for 11 workers who died on the drill rig Deepwater Horizon, when it exploded and sank last month. The crew had nearly finished drilling the well when the blow out occurred. At the time of the accident, 126 people were on the rig. The other 115 were evacuated, with a few people suffering minor injuries.