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watched it for 30 minutes and we had no flow.” Chris Pleasant testified that,
237
“[d]uring the negative test we didn’t see any – anything flow back.”
The crew apparently dismissed the phenomenon of the pressure
differential on the drill pipe and kill line as a “bladder effect” or annular
compression. Kaluza attempted to explain the bladder effect in an email sent on
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April 25.
I believe there is a bladder effect on the mud below an annular preventer
as we discussed. As we know the pressure differential was approximately
1400 – 1500 psi across an 18 ¾” rubber annular preventer, 14.0 SOBM plus
16.0 ppg Spacer in the riser, seawater and SOBM below the annular
bladder. Due to a bladder effect, pressure can and will build below the
annular bladder due to the differential pressure but can not flow ‐‐‐ the
bladder prevents flow, but we see differential pressure on the other side of
the bladder.
On April 27, Mike Zanghi, BP vice president for drilling and completions,
forwarded Kaluza’s description of the so‐called bladder effect to O’Bryan, who
responded as follows:
239
236 Ezell testimony at 282.
237 Testimony of Chris Pleasant, Joint Investigation Hearing, May 28, 2010, at 118.
238 BP‐HZN‐MBI00262896.
239 Id.
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