Crucial negative pressure test, on BP blowout well, taking place before our eyes.
A negative pressure test on the BP Blowout Well is more valuable than a positive pressure test.
DejÃ vu for the 20th of May 2010
On the 14th of July 2010, I wrote for OPED News the following paragraph:
"Mark Hafle, BP's senior drilling engineer testified to the MMS on May 28, 2010 that the well had lost integrity and that thousands of barrels of mud had been lost down this well during drilling. This meant that the formation integrity had blown out. Reports at the hearings in May also indicated that the LOW positive pressure tests on the day of the blowout on April 20, 2010 had passed but the negative pressure tests had failed, so the well was not properly sealed. This happened within a few hours of the blowout.
The cement-casing structure is compromised. The well had ballooned out and the formation had blown out, long before the blowout occurred."
What is a positive pressure test?
That is where the drilling contractor and roughnecks pump drilling mud into the well. This drilling mud fills the hole and by the mud's density, keeps the oil and gas from the blown out formation from being able to enter into the well. The density of the mud (mudweight) exceeded the pressure of the oil and gas and there appeared to be no loss of mud into the formation, or they said there was no loss or they were not monitoring the loss correctly. That test was successful on the day of the blowout. So if you finely balance the pressure of oil and gas coming in against the pressure of drilling mud you are pumping in you get a Static Kill (no movement). On the 4th of August 2010 their static kill was achieved at 13.2 pounds per gallon mudweight. No movement either in or out of oil or mud. If you were to increase the mud density in order to increase the pressure, above the 13.2 pounds per gallon (0.694 pounds per square inch per linear foot increase with depth) or 12742 psi at the bottom of the well (18360 feet), the drilling mud would flow out the well into the formation.
So just before the static kill began, we know that their pressure gauges were reading about 7000 psi. Where is the missing pressure of 5742 psi going? It is not entering the well. It was not measured by their pressure gauges.
A negative pressure test is when you remove the drilling mud and replace it with air or water.
This is what they did on the day of the blowout. They removed the drilling mud and replaced it with water. The casing cement structure did not hold and oil and gas rushed in to cause the blowout.
So the positive test only tells us what pressure we need to maintain in the hole in order to put cement in to seal the well and keep the oil and gas out. That pressure appeared to be 12742 psi. If the mud density had been 17 pounds per gallon while drilling, the pressure would have been 16457 psi at the bottom of the well.
Therefore we had 7000 psi coming into the well before the Static Kill.
12742 psi is not coming in. 5242psi is going somewhere?
The well is acting like a one way valve, resisting the true outside pressures from entering the well. The holes through the casing and cement must be relatively small. Oil and gas could only come in at 7000 psi, but it requires 12742 psi of mudweight or13.2 pounds per gallon of drilling mud density to achieve a static kill, that is, that pressure to force the oil and gas out into the formation.
On the 5th of August, 2010 cement was pumped in. BP engineers say they have stopped the oil and gas pressure from entering the well.