BP: Pressure tests indicate Gulf well sound

History tells us not to pop the cork yet but so far so good.

SAN FRANCISCO (MarketWatch) -- 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.