Déjà 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.”
Let us understand what a positive test is. That is where they had pumped in drilling mud that was filling the hole and being kept in the hole by the pressure of the oil from the blown out formation trying to get into the well. 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. On the 4th of August 2010 their static kill was achieved at 13.2 pounds per gallon 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.
A negative 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. 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 appears now to be 12742 psi. If the mud density had been 17 pounds per gallon, 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. 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.
On the 5th of August cement was pumped in. BP engineers say they have stopped the oil and gas pressure from entering the well. Does the pressure gauge now read zero?
Let us all hope that it is true.
13. 2 pounds per gallon of mud weight is not a high mud weight. 17 or 18 pounds would be more indicative of a high pressure well.
Was the pressure always this low or has it fallen off over the last 105 days as the oil and gas has been depleted?
An alternative idea would be that 12742 psi was coming in at the base of the well but that 5742 psi was escaping out into one of the low pressure oil and gas horizons higher up in the well, leading to only 7000 psi being recorded.
I would imagine that this second scenario would be more difficult to seal than the first scenario as more open porous structure would be found.
If this well can be easily sealed with cement now, then either BP has bungled their way through the last 105 days or the pressure has dropped drastically to allow the cement to seal this blowout well.
WHAT DOES THE PRESSURE GAUGE READ NOW?
Chris Landau
August 6, 2010
chrislandau@yahoo.com
christianjlandau@yahoo.com
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