#Origin of petroleum?
7 messages in this thread
Mike,
Ran across this string while catching up on at 20megs of unread messages.
Anyone say anything about continued oil accumulations in extant reservoirs? A
prof in a Louisiana U. published a theory and supporting data from several old,
abandoned fields that are now re-charged with hydrocardons. It seems that
resersoir rock which is close enough to source rock can become re-pleted in 10
to 20 yrs.
People asked, "Well, if it accumulates that quickly, where does all the excess
go once a reservoir is full? It seems that shales are not as impermeable as
once thought. There is a distinct halo of hydrocarbons around and above a
reservoir. The halo forms a "chimney". Hydrocarbons leak off at an astounding
rate. Ergo, much of the unrefined "oil spill" material in (for example) the
world's oceans that can not be traced to a spill is indeed from natural
sources.
As for the organic source of hydrocarbons, I routinely estimate financial
recoverables from source rock via remote sensing (using electric, nuclear, and
acoustic signal sources) of in situ rock and rock-fluid's physical
characteristics. I have been on site for recovery of source rock material and
have been involved of recovery of formation material which is in the process of
out-gassing and seeping oil (it is called "pop") as it is inspected at the
surface. Advanced technologies are available for measuring pop and gasssing of
rock. I have held the organic material in my hand and watched it pop and spit.
The samples have been from 5,000feet to 22,500feet subsurface. The technologies
are called mudlogging, wireline logging, and petrophysical core measurments. My
company provides advanced neural network and fuzzy logic hybrid systems for
evaluation of the economic potential of (among other items) organic source
rock. Paleontologists (we call them bug counters) look at the organic material
and classify and date the material. What I am saying is that there exists an
entire scientific industry engaged in identifying and measuring the physical
maturity of organic source rock for the purpose of estimating the worth of a
reservoir. It *has* to make money. Wells currently cost $0.5million to
$15+million to drill and complete. On average, only one in eight (1/8) wells
are a success. Thus, if there was "nothing to" the idea that organic source
rock yeilds oil, or if there was another and better (more correct) explanation
for the origins of hydrocarbons, then I would venture to guess that there would
be kazillions of bucks thrown at the problem of identifying and understanding
that xxx source of hydrocarbons.
If any of this was already covered, I am sorry for repeating.
-JB
Hi Jeff! Many thanks for your most informative post!!
>> As for the organic source of hydrocarbons, I routinely estimate financial
recoverables from source rock via remote sensing (using electric, nuclear, and
acoustic signal sources) of in situ rock and rock-fluid's physical
characteristics. <<
Would that be the new ACME pocket nuke demo charge? Or do you wait for a
holocaust?? <VBG – seriously, how do you use nuclear sensing??>
>> … It *has* to make money. Wells currently cost $0.5million to
$15+million to drill and complete. On average, only one in eight (1/8) wells
are a success. Thus, if there was "nothing to" the idea that organic source
rock yeilds oil, or if there was another and better (more correct) explanation
for the origins of hydrocarbons, then I would venture to guess that there would
be kazillions of bucks thrown at the problem of identifying and understanding
that xxx source of hydrocarbons. <<
This is clearly convincing that it is a "given" in the industry. But are you
able to supply any more details on just how they are known, and/or work on the
assumption, that it is organic in origin. Did you snag any of the earlier
posts on this thread? (They're probably gone by now.) Basically asking for
more precise details of how they came to that conclusion and how they rule out
some potential confounders. All from an armchair perspective — I am not
trying to argue the earth is flat, I'm just trying to see to what level petrol
being from organic origins is "proven" by letting the findings and, the
theories they generate, speak for themselves.
Is any of this making sense. It is of course important in the abstract to say
that's the working assumption of everyone in the business. But it doesn't
actually fill in the blanks of why. And I'm not sure you can; we may in fact
be best served by one of the bug counters, if one were to show up around here.
Thanks!! – Mike
>>Did you snag any of the earlier posts on this thread?<<
Nope. Sorry if I repeat.
>>more precise details of how they came to that conclusion and how they rule
out some potential confounders.<<
Every organic "ooz" has a chemical "fingerprint" comprised of ratios of atoms
which are found in various organic materials, and ratios of molecules of
different types. What plants and animals were present during deposition, what
fluids present, atmostpheric conditions, etc., all go into making the
fingerprint. There is a further fingerprint as a result of what is called
diagenesis, or chemical changes to the rocks after burial. Geochemistry is a
well grounded and mature science. The rocks and fluids all interact during
diagenesis in ways that are controlled by geochemical processes and
understandable via that science. Everything is predictable. You got the
original stuff, you got the energy and forces applied as a function of time,
you got the washing action of subsurface migratory fluids …. add 'em all up
in your organic chemistry equation and *presto* you have only one possible
fingerprint of oils that can be "cracked" from the source rock. Lo *AND*
behold, you look around near the organic source rock and *there it is*!! Some
oil (or gas) with just the right fingerprint for it to have come from that
particular source rock. Other possible sources? Nope. There are too many
coincidental trace atoms (primarily vanadium and gadolinium, but others exist)
that have nothing to do with oil, per se, in both the source and the product of
that source. There can be no other source from which the observed mix of
molecules in thier respective fingerprint encarnations could have been cooked
up. Add to that the new papers published by a Louisiana U. Prof showing the
re-charging of known, depleted reservoirs close to source rock, where the
fingerprint of the source rock matches the fingerprint of the oils produced in
the reservoirs up to initial depletion and now matches the oils produced today
after recharging. Any other explanation for the source of the oils besides the
most available one (the organic source rock) must thus be discarded as being
overly "energetic" in its untold and most probably dubious mechanisms.
>>how do you use nuclear sensing??<<
Chemical and electrical sources attached to metal tubes (2 to 5 inches in
diameter) filled with computer equipment, sealed against 20,000+psi pressure
and 350 deg f temperature are lowered on miles-long cables down drilled holes
(8 to 12 inches diameter). Chemical sources produce moderate energy (ca. 3 Mev)
neutrons and gamma rays that leave the tool, bang around in the formation, and
finally return to the tool detectors for measurement (energy, time, numbers).
The measured signals are encoded and sent up the cable for recording and
processing at the surface, or transmission via satellite to the "home" office
for perusal and processing. Electrical sources use deuterium and tritium
(charged particles) in high voltage, staged electrical discharge-like ramps to
crash these atoms together and cause high energy (14 Mev) neutron production.
The neutrons interact with tool, borehole, and formation materials, slowing
down to thermal levels. They are then absordbed by various materials and
produce gamma ray radiation time and energy spectra. From all of these
measurments it is possible to compute elemental abundances of hdyrogen, carbon,
oxygen, calcium, gadolinium, etc., void space in rocks (holes in which the oil
and gas exit), mineral types and abundances, fluid types and abundances, fluid
flow characteristics, and rock mechanical properties (these last two require
electrical and acoustic measurments to really be performed properly). The
radioactive sources used are extremely dangerous if you were to hold them in
your hand, but proper shielding and operating proceedure reduces risk to very
small indeed. Companies like the electrical sources better because if an
accident occurrs and you loose a source in the hole or stick a tool in the hole
then all you have to do to render the source inactive is pull the cable off the
tool at what is called the weak-point (a specially designed connection which
allows the engineer to break the link between tool and cable should the need
arise. Don't worry about the chemical sources ….. there are extreme saftey
measures required by the government to control and monitor source loss and
recovery operations. It doesn't happen often, but when it does there are enough
saftey proceedures and container-strength requirements that there has never
been any real problem in all the years of use ….. and in the overall scheme
of things, the sources may be dangerous to a person's hand, but the amounts of
material in any one tool is pretty small. Even so, the government acts like its
a 3 Mile Island when talking about this type of stuff. And I guess it is a good
idea, really, because by over reacting they ensure that not one atom of
unwanted material ever has a chance of harming anyone. So these technologies
are quite useful and extremely safe. After a measurement is produced and
evaluated, the data is merged with data from acoustic recodings of explosions
set off on the surface (siesmic cross-sections or lines). The size of the
reservoirs is able to be deduced from processing of many such lines. Also, the
physcial properties of the rocks and fluids in those reservoirs can be
estimated based upon many well measurement records, called logs, together with
those lines. This is how you tell not only where any oil/gas might be in a well
you just drilled, but you also can predict the economics of recovery based upon
these measurments (nuclear and otherwise).
Is that more than you ever wanted to know about petrophysical well logging and
data processing?
<<fingerprint of the source rock matches the fingerprint of the oils produced
in the reservoirs up to initial depletion and now matches the oils produced
today after recharging.>>
Interesting thread, Jeff! The above statement, particularly, is something I
hadn't run across before. It is interesting that a formation will recharge in
a time scale that we can measure. How substantial is this recharging? My very
basic, 15 year old geology training made me believe that these oil-bearing
deposits were ancient and "fermented to completion" if you will, and once they
were pumped dry and maybe flushed once or twice to catch the crude that didn't
come to the surface the first time, they were empty. Can you in fact go so far
as to identify a formation that is aching to produce oil or gas but has not yet
done so; or to go a step further, look at a producing formation and say, "Hmm,
this may produce even better later on" or "This one will recharge and this one
won't"…?
Regards, ed
>>My very basic, 15 year old geology training made me believe that these
oil-bearing deposits were ancient and "fermented to completion" if you will,
and once they were pumped dry and maybe flushed once or twice to catch the
crude that didn't come to the surface the first time, they were empty.<<
Me, too. That's what caught my eye about the abstract I read. I am trying to
locate the author and publication. I have a viedo someone lent me of one of the
3D reservoir fluid flow models generated either by that same prof or at that
same converence. Very spiffy stuff!!
>>How substantial is this recharging?<<
I asked the same question, but not in quite this nice a fashion. My tone was
… how shall we say, somewhat derisive. Perhaps jeering. It seems that the
charging is complete under the right conditions and can be accomplished in as
few as about 20 years.
>>Can you in fact go so far as to identify a formation that is aching to
produce oil or gas but has not yet done so; or to go a step further, look at a
producing formation and say, "Hmm, this may produce even better later on" or
"This one will recharge and this one won't"…?<<
Apparently so. I'm sure the model will be hotly debated, but the fact that
there's new oil in some of them thar Louisiana fields is undeniable ….
especially when someone is trucking the monetary gains from production in these
"depleted" fields to the bank.
-JB
<<That's what caught my eye about the abstract I read. I am trying to locate
the author and publication. I have a viedo someone lent me of one of the 3D
reservoir fluid flow models generated either by that same prof or at that same
converence. Very spiffy stuff!!>>
Lemme know. This is new and interesting.
Ed,
>>Lemme know.<< show nuf', podna!