Page 69 - test2

to flow into the space occupied by the lower density fluid. No “u‐tube” flow of
the 14.3 ppg mud from the casing to the annulus occurred on October 7,
158
indicating that hydrocarbons were not present in the annulus.

After the BOP stack was recovered from the seabed, pictures taken from
the DDII relief well rig of the hanger and seal assembly showed no erosion. Had
hydrocarbons flowed up the annulus, the outside of the hanger and seal
assembly likely would have shown effects of erosion due to hydrocarbon flow.

Because the evidence does not support the theory that hydrocarbons
flowed up the annulus, the Panel concluded that the nitrified cement slurry used
in the annulus likely did not fail.

Scenario 2: Production Casing and Related Components from above the Top
Wiper Plug at 18,115 feet

Under this scenario, hydrocarbons would have flowed from the reservoir
through the crossover joint of the tapered casing string, into the well and up the
riser to the rig. The Panel considered the crossover point to be a possible source
of flow because it was manufactured separately from the other tubular elements
in the well. If hydrocarbons had flowed in this path, it would mean that the
annular cement isolating the hydrocarbon zones at the production interval had
failed and the casing had failed at the crossover joint. These failures would have
resulted in hydrocarbon flow out of the well and up the riser. This scenario is
depicted in Figure 7 below:

158 “U‐tubing,” or reverse flow, occurs when fluids flow in the reverse direction and back up the
inside of the casing. The “u‐tube effect” is the practice of putting a dense slugging pill (mud that
is more dense than the mud in the drill pipe and the wellbore annulus) into the drill pipe in order
to pull a dry string. The pill is pumped to the top of the drill string to push mud downward, out
of the pipe, thus keeping the upper strands of the pipe empty.

64