RE: earlier question by MikeDB concerning the notion that this well may have penetrated the Moho, may prove the russian hypothesis of abiotic petroleum, may kill the Peak Oil Hypothesis, Etc…
[QUOTE=MikeDB;37184]I hate to quote myself, but has anyone here given this any thought?[/QUOTE]
MikeDB,
I suspect the reason you have gotten no response to your questions is twofold. First, most of the folks following this blog are offshore marine community, not the geology community, so the expertise to comment intelligently on geologic themes is probably thin. Second, the small minority of us who do have a geologic background consider the kinds of ideas you are mentioning to be so long disproved that they are not worth distracting the main threads of this discussion about the safety of deepwater drilling. But for the sake of the rest of the audience, who may never have seen the arguments, let me summarize the key points against your various notions.
Did the well penetrate the Moho?
The answer is definitively NO. The Moho is the boundary between the crust, made up of rocks dominated by quartz and feldspar minerals, and the underlying mantle, made up of rocks dominated by olivine. The chemical differences between crust and mantle result in fundamental differences in the physical properties of the rocks, such as the difference in seismic velocity which was first documented by Mr. Mohorovicic more than a century ago. This boundary typically sits from 3.5 to 6 miles below the top of the oceanic crust, which itself sits below all the thick pile of sediments in the Gulf of Mexico which are roughly 10 miles thick at the well site. The well didn’t even get half way through the sediments overlying the crust, so the 4 miles covered by the well (roughly 1 through water and another 3 through sediments) obviously did not penetrate the Moho, which is probably still more than 10 miles below the bottom of the well.
The abiogenic hypothesis for the origin of petroleum.
This was a popular idea back in the 50’s and was strongly advocated by the ruling authorities of the russian geological community. Since the late 50’s and early 60’s the onset of the revolution in geologic thinking due to the theory of plate tectonics has largely swept aside most of the original arguments, but there are still a few diehard advocates who will go to their graves clinging to the idea (much as there are still advocates of the expanding earth hypothesis even after satellite telemetry has definitively disproved the notion). For those reading this blog who are not familiar with the debate, the currently accepted biogenic theory for the origin of petroleum states that petroleum is generated from the breakdown of organic matter trapped in sediments under the influence of the high pressures and temperatures imposed by burial. In essence, the alternative abiogenic theory suggests that a significant fraction of petroleum has its origins in methane trickling out of the mantle. The scientific evidence for the biogenic theory is abundant, ranging from the strong correlation of worldwide petroleum discoveries to proximity to organic rich source rocks, to a strong correlation of the degree of burial of those source rocks to the chemistry of the resulting petroleum generated, to precise chemical fingerprint matching between many oils and the source rocks which generated them, to geochemical fossils which can be dirctly tied back to exotic organic molecules in the evolutionary progression of species which died to produce the organic matter. The evidence is far greater than it would be possible or appropriate to review in this blog.
As far as I can gather, the abiogenic theory rests on a series of “Yeah, but…” statements attempting to refute the prevailing biogenic theory. The major points typically raised are that traces of methane are seen in the mantle, petroleum is occasionally found in the crystalline rocks of the crust underneath the sediments, and petroleum occasionally is found below the source rocks from which they could be sourced. All of these are true, but none of them are anything like the “smoking gun” to kill the biogenic theory that abiogenic proponents suggest. The traces of methane found in mantle rocks are real, but are in miniscule quantities and their carbon isotopic signatures do not match those found in petroleum. The presence of petroleum beneath the source rocks, whether in deeper strata or in the underlying fractured basement rocks, is also not a contradiction of their biogenic origin. The conversion of buried organic matter to petroleum creates added volume (solids converting to liquids and gases) and results in elevated fluid pressures. As we’ve seen vividly demonstrated in the recent top kill operation, when you increase pressure at a point the fluids are forced both upwards and downwards. If the upward path is easier, then most of the flow will go that way (as seen in the recent top kill attempt). If the upward path is impeded, as would be the case if strongly impermeable rocks overly the source beds (or in the case of the top kill, if the junk shots had succeeded in plugging the pipes), then fluid will be driven downward. Even if one were to accept one or more of these “Yeah, but…” arguments as support for an alternative to the biogenic theory, you would still be scientifically obliged to explain how all of the massive evidence in favor of a biogenic origin can be explained by your alternative. I have yet to hear anyone even attempt this with an abiogenic theory. As for all the gas coming from the current blowout having any bearing on the biogenic/abiogenic debate, the gassy oil seen here is exactly what traditional basin modelling, based on a biogenic origin for petroleum, would predict at these depths.
Could this well disprove the Peak Oil hypothesis?
I doubt it. In a nutshell, the Peak Oil hypothesis states that petroleum is a finite resource that was built up over geologic time and at some point, unless our consumption stops growing and starts to fall, we will be unable to find and/or produce as much of it as we consume. The peak of discovery of oil in the US happened back in the 70’s and for the world happened in the late 80’s. However, due to the long lag time between discovery and production, which often stretches to many decades for giant fields, and also due to the discovery of methods to squeeze more oil out of existing fields, the peak in production comes significantly later. But Pak Oil production has clearly already happened in the US and may currently be happening for the rest of the world. As for natural gas, we are currently experiencing a boom in production as liquified natural gas technology allows formerly trapped gas already discovered in remote places to be delivered to market. This has also been boosted by recent advances in our ability to extract gas from tight shales onshore, which was previously thought to be unrecoverable. But both of these are not new discoveries and simply reflect technology improvements to allow more to be extracted from what’s already been found. This spike in gas production will be a blip on the larger trend of rising and then falling production of total petroleum. In the long run we have no choice as a species but to find alternative ways to generate energy if we hope to maintain even our current standard of living, never mind lift the third world up to the standards enjoyed currently by the developed world. The other side of the peak will not be a sudden catastrophe as the last drop is extracted, but rather a long progression of rising prices for petroleum products as the cost of the advanced technology to produce more of the currently unextractable remaining resource continues to rise. Sadly, the fight to control that dwindling resource is likely to have more impact on most individuals than the actual market price. And the risks taken to extract it will only grow.
While I would personally love to talk about geology issues ad nauseum, I suspect this is not the appropriate forum. I have said my piece and will leave it there. Thanks for those who were interested. Sorry to those who weren’t.