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By Cassandra Sweet Of DOW JONES NEWSWIRES SAN FRANCISCO (Dow Jones)--BP PLC (BP, BP.LN) said Friday that preliminary test results indicate that a new cap on the broken oil well in the Gulf of Mexico is keeping the oil underground in a reservoir that was probably depleted more than initially thought. No oil has visibly leaked out of the well since the cap was sealed Thursday and the pressure in the well is high enough to indicate that the well isn't leaking, said BP Vice President Kent Wells. Preliminary seismic surveys indicate that the seafloor around the well hasn't ruptured, although more surveys, by BP and government scientists, are underway to ensure that no oil or gas is leaking from the well or the seafloor, Wells said. "There is no evidence that the well does not have integrity," Wells said, speaking during a teleconference. He added that BP and government scientists won't draw any conclusions until more testing and measurements are done. Temperature measurements show that no oil is coming out of the well, Wells said. When oil and gas were flowing through the well, they heated up the well bore, but after the hydrocarbons were sealed under the cap, the temperature of the well bore dropped to the same level as the seawater around it, Wells said. Acoustic sensing surveys and sonar scanning also have turned up no evidence that oil is flowing from the well or the seafloor, Wells said. Still, more data are needed, he said. The pressure in the well is about 6,700 pounds per square inch, Wells said. That level is high enough to show that an oil leak is unlikely, but low enough to make scientists wonder whether there could be a hidden leak somewhere or whether the reservoir beneath the seafloor has simply been depleted as oil has gushed out over the last three months, Wells said. While BP scientists believe the pressure reading is a result of a lower reservoir level, they're pressing on with measurements to rule out any other factors he said. BP officials said earlier this week that they were hoping the pressure in the well would exceed 8,000 pounds per square inch. U.S. Coast Guard Adm. Thad Allen, the federal response commander, said earlier Friday that the optimal pressure level was 7,500 pounds per square inch, but that more testing would show whether the current level is sufficient. -By Cassandra Sweet, Dow Jones Newswires; 415-439-6468; cassandra.sweet@dowjones.com (END) Dow Jones Newswires July 16, 2010 19:58 ET (23:58 GMT)