The temperature of the oil coming from the wellhead
might be sub-freezing, due to the dissolution of methane from the
liquid oil as it flows upward from its deep, high-pressure
reservoir. Perhaps cold enough to cause seawater to
freeze.
The drop in temperature when dissolved gases come out of
solution can be seen if a bottle of carbonated soft drink is
chilled to 0C, or a few degrees less, and then opened. An ice
slurry will form in the liquid, a slurry thick enough to block
the pouring of soda from the bottle.
In early May when the 100-ton containment dome failed to
capture the flow of oil and gas, the failure was attributed to
the spontaneous and rapid formation of methane hydrate.
However, an article from the Lawrence Livermore National
Laboratory, "Methane Hydrate: A
Surprising Compound," suggests that methane hydrate is
difficult to synthesize, which implies that hydrate formation
might be slow in nature. In addition, though the article does not
say it, it seems plausible that the process of hydrate formation,
because it entraps gas molecules that might would otherwise be
moving rapidly, would be exothermic and therefore self-limiting
with respect to rate of hydrate formation.
An alternative explanation for the failure of the containment
dome involves ordinary water ice, which formed when the already
cool sea water encountered, inside the small volume of the
containment dome, a sub- freezing plume of gas and oil coming
from the wellhead. That is conjecture, that the plume would be
that cold, but here is the basis for thinking it:
When gas comes out of solution from a liquid, as happens when
the aforementioned bottle of chilled carbonated soft drink is
opened and CO2 comes out of solution, the process of dissolution
involves the release of fast-moving molecules of carbon dioxide,
which means that the temperature of the liquid left behind would
get lower.
The flow rate of gas from the wellhead is reported to have
been between
110,000 and 480,000 cubic meters per day. That's presumably
at STP. Compare that to ~6,500 to ~13,000 cubic meters of oil
per day (40,000 to 80,000 barrels of petroleum per day coming
from the wellhead [my estimate] at ~6.3 barrels per cubic
meter).
Clearly, gas is coming out of solution from the oil. It seems
likely that the gas was dissolved in the petroleum prior to being
emitted from the wellhead, especially when it was deep in the
well and in the reservoir itself. Similar to carbonated water, it
is methanated petroleum.
The gaseous portion must come out of solution from the liquid
portion as the petroleum rises to the wellhead from its deep
reservoir; that is, the dissolution happens because of the
pressure decrease as the flow moves from the deep reservoir to
the wellhead. In addition, the turbulent interaction of the oil
with the wall of the pipe would further provoke dissolution, just
as shaking a soft drink can or bottle causes the CO2 to come out
of solution. It is plausible to assume that the temperature of
the oil flow decreases as the gas portion comes out of
solution.
It follows, given the >80 days of oil and gas flow, that the
well itself and the adjacent rock, out to several meters
laterally, might be at a sub-freezing temperature.
It would interesting to secure a mesh grating over the top of
the wellhead when the relief well is joined to the main well, and
then to inject fresh water so as to form an icy slurry that might
at least slow the flow as it clogs the mesh.
Or, with such a grating securely in place, the earlier idea of
a "junk shot," but from the relief well, might impede the flow;
and the addition of fresh water might slow it yet further,
perhaps stopping it completely long enough for heavy mud and/or
concrete to be injected into the deepest portions of the well,
below where the relief well intersects it.
Send comments to Bob
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