posted on Jun, 14 2010 @ 04:03 AM
Here is some basic science for those of you who think the well head
or casing will burst yet again spewing massive pools of oil into the sea.
1) Drill casing used in deep sea drilling has a compressive strength of
between 60,000 to 140,000 PSI (i.e. S-140 alloys). There are other
strength measurements but general drill pipe strength is based upon
two axes which is Tensile Strength (i.e. Bend until catastrophic metal
fracture or until plastic failure) and Compressive Strength (i.e. Press
until catastrophic metal fracture or until plastic failure).
There are also peak load and average load calculations
used to determine the workload a particular steel alloy will take
when used as well-bore casing and which include a number of factors
such as torsion, bend, compressive and shear forces which NEED
to be taken into account when you're drilling through multi-strata
formation rock and/or other substances such as salt, sulphurous
(i.e. corrosive) compounds or heated/pressure activated formations
that may suddenly MOVE because of intrusion by a well-bore or by
upwelling of lower formations due to magmic pressure.
2) These "strength" measurement allow us to determine the extremes
that any well casing can handle before it fails. What has been the problem
with BP and many OTHER players in the drilling industry is that they
have insufficiently computer modelled the EXTREMES of formation behaviour
upon stressed well casings AT THE EXTREMES of those well-casing
load capacities. The blowout happened because they just didn't foresee
that the extremes of the blow-out preventers would be reached and/or
surpassed. They probably THOUGHT they could get away with 80,000 PSI
alloys when they really needed 140,000 PSI alloys for both well casings
and blowout preventer modules.
3) Catastrophic failure is ...well....CATASTROPHIC!
It's both hard and EXPENSIVE to TEST to the extremes and since
the act of drilling is expensive, MOST companies do the basic
computer modelling BUT NEGLECT to TEST at the MINIMUM and
MAXIMUM strength values for any well device or casing...ergo...
they stick their head in the sand and HOPE that the drilling follows
a general "Standard Model" that is really just a comparison
against what has happened before. The problem with that attitude
is that compiling what has happened before is just "Statistics" which
models what GENERALLY or PROBABLY will happen but DOES NOT
model what will EXPLICITLY or SPECIFICALLY happen during a
particular drill operation. So BP basically put on their blinders
and started to drill EXPECTING things to go smoothly as they
probably HAD DONE BEFORE! However drilling in this specific
instance caused an exceeding of MANY maximums when it
came to the forces that were present within the formations
AND thus upon the materials USED to perform the drilling...ergo
the blow-out preventers failed because the alloys used in them
weren't strong enough and that the drilling of relief wells MAY WELL
FAIL AGAIN because they're using 120,000 PSI well casing
when they need 140,000 PSI (i.e. S-140 alloys) capable materials.
4) Thinking ahead...In Canada it is ILLEGAL to drill an oil or gas well
without filing an EXTENSIVE catastrophic failure plan in place for
dealing with rupture of well-bores and dangerous formation behaviours.
Why the USA does NOT have such a legal requirement is beyond me!
SOME companies already have well caps ready-built to be shipped
wherever just in case a head blowout DOES occur and while 5000 feet
underwater IS different than on-ground blowouts, the emergency
response machinery AND plans should have ALREADY been in place
and BP has definitely dropped the ball here!
5) Lack of extensive computer modelling and seismic surveys.
Using another company's example, SHELL OIL has a supercomputer
or four in London that do NOTHING BUT oil & gas reservoir and
strata-formation behaviour modelling.
BP is a very big company with a few BILLION dollars at it`s disposal,
a few 16,000 processor Linux grid processing systems are CHEAP
compared to just 30 days of drilling....WHY in the name of Heaven
did BP NOT HAVE an extensive seismic survey AND formation behaviour
model in place BEFORE drilling even began. A few thousand hours of
drill simulation modelling would have FORESEEN what would happen
if all the variables were plugged in correctly into a wide area deep-bore
Where are those drilling simulations? Where are the seismic surveys?
Who did those surveys and/or formation models? What variables
were included? Did BP even HAVE such a drilling simulation in place?
If not, then that was one of the biggest Crimes of the Century
and BP should be VASTLY PUNISHED for incompetence.
Hindsight is always 20/20 ... BUT .... to me, it seems that
SOMEONE is trying to coverup that they took SHORTCUTS
because of cost & time pressures.
ON a technical note, the well casing will eventually collapse
on itself because of basic formation pressure which will
eventually exceed the compressive strength of the well casing
as it is corroded by the drilling muds and sulphurous compounds
mixing together. The problem is that this could take more than
a year OR that the ejection pressures of the oil outflow COULD
WELL EXCEED the compressive forces of the surrounding
wellbore formations to PREVENT the natural well sealing
that SHOULD happen. Even relief wells might not do the trick
because the well-casing used in THOSE WELLS might not be strong
enough to hold the pressure of the formation`s oil outflow OR that the
formation has too many soft & hard spots which will exceed the
relief wellbore casing's ability to remain rigid and will bend past
the tensile strength of the casing because one formation is "hard"
and another "soft" causing excessive shearing or bending effects
upon the drill pipe as individual strata layers are punctured.
I see a whole lot of variables and NOT ENOUGH modelling of
probable drilling extremes and formation behaviours...ergo...this
is going to go on for 6 months or more. They need to dump
a whole lot of REALLY BIG & REALLY HEAVY pre-cast and
pre-stressed well caps rather than use explosives which might
shatter the formation....or they COULD try to drill MANY shallow
relief wells to inject corrosive or weakening compounds near the
casing and into wellbore formation walls to cause a "natural" wellbore
collapse which will eventually seal the well.
We'll have to wait and see.....
[edit on 2010/6/14 by StargateSG7]