T or E

There are, in fact, deep petroleum reservoirs which have been presumably pumped "dry" (typically 40% of oil in place) and then refilled with new petroleum from much further down in the Earth. The oil companies like to keep this fact on the QT.

A number of elements occur within petroleum, which are inconsistent with plant and animal composition. And a number of elements in plants and animals are not present in petroleum.

Nickel and Vanadium are quite common in petroleum but have no apparent metabolic use in living tissue. Sulfur exists in petroleum to as high a level as 7%. How much sulfur is in living tissue? (Aside from skunks)

Petroleum has nowhere as high level of Nitrogen as in living tissue. And much of tissue is Oxygen; what happened to that?

The case for abiotic petroleum is quite strong. And what mechanism would place vegetable matter several miles below the surface? Adds on TV have dumbed down the issue.



Gregg Wilson

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">The reason I bring this up is because he thinks that the conventional "accretion model" for the formation of the planets is necessary to his theory, because if the Earth was originally a ball of molten rock, all hydrocarbons would have been oxidized.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
The existence of diamonds at the surface of the earth, the isotopic composition of the carbon in these diamonds, and their emplaced occurrences being limited to unusual geologic structures known as Kimberlite diatremes, is clear evidence that the Earth contains considerable amounts of primordial, unoxidized carbon. While this does not speak directly to the question of “hydrocarbons,” it does indicate that unoxidized carbon was present within the Earth from a time at, or near, to its formation.

A diamond is pure carbon, in an isometric crystal that can only form, and is only stable, at pressures and temperatures that exist no closer to the Earth’s surface than at mantle depths of at least 120-150km. For diamonds to exist at the surface, pieces of this isometric crystalline carbon must have been transported from such depths extremely rapidly — in those rare, explosive erruptions that bore narrow, funnel-shaped “pipes” (diatremes) from mantle depths directly to the surface, filled with a rock type unique to such pipes, known as “Kimberlite.” Essentially all diamonds are found within Kimberlites, or in alluvial deposits weathererd from Kimberlites.

Rapid decompression and cooling is necessary for the diamond crystal form to survive at near-surface conditions. Rapid cooling is necessary because diamonds are unstable at surface pressure, but their conversion to graphite — the crystal form of pure carbon at low pressure — occurs so slowly at near-surface temperatures that diamond crystals, rapidly cooled, remain in existence for geologically interesting time intervals. Slower decompression and/or cooling results in the diamond transforming into graphite. Indeed, many igneous rocks that formed at great depth contain inclusions of graphite — in some cases these inclusions fill voids with shapes typical of diamond crystals.

That the carbon in diamonds is not of biological origin is indicated by its ratio of carbon-12 to carbon-13. Biological reactions, such as photosynthesis, slightly favor the lighter 12C isotope, so biogenic carbon is depleted in 13C relative to “standard carbon” — the standard being “PDB,” a particular marine limestone. (Marine limestones — CaCO3 — make a good standard because their carbon isotope ratios have remained remarkably uniform throughout geologic time.) In the geochemistry literature, depletion of 13C by more than 30 parts per thousand is generally taken to indicate carbon of biological origin, whereas depletion of 13C by smaller amounts, or enhancement of 13C, are taken to indicate a non-biological origin. On this basis, the carbon in diamonds is uniformly “non-biogenic,” with 13C depletions ranging from 0 to the high 20s of parts per thousand.

MAF



When you find yourself on the side of the majority it is time to reform. -- Mark Twain

There is abundant evidence for abiogenic origin of petroleum and natural gas, especially if one starts from the empirical (field) evidence itself, rather than attempting to interpret said field evidence in the context of conventional “fossil fuel” theories. A brief summary of major items supporting abiogenic origin includes:

1. Most petroleum and natural gas deposits occur along lines or arcs of regional scale, typically following tectonically-significant crustal structures or boundaries. The occurrence of petroleum deposits in such regions is NOT confined by smaller-scale elements such as stratigraphic levels or sedimentary rock units. The apparent rarity of petroleum in non-sedimentary rocks is a result of sampling bias — few exploratory wells are started into anything but sedimentary rocks, and when the drill encounters the non-sedimentary “basement” rocks, the well is usually abondoned.

2. Petroleum occurrences also show disregard for particular rock units and ages in the vertical dimension, similar to the areal disregard mentioned in (1). Petroleum tends to be found in all rock units of sufficient porosity, including non-sedimentary units, below the first reservoir level. This is sometimes known as “Koudryavtsev’s Rule” — after Nikolai Koudryavtsev, the eminent Soviet Union-era petroleum geologist who initiated the research into abiogenic petroluem science that led to the discoveries of many of the enormous petroleum fields of the former Soviet Union.

3. Methane (natural gas) deposits occur in significant amounts at locations where biogenic origin is improbable, such as the rift valleys of the mid-ocean ridges, massive bodies of intrusive, igneous rock, and impact structures where the impactor struck precambrian, igneous rocks.

4. Helium, which is neither produced nor concentrated by biologic processes, is universally present in petroleum and natural gasses, while being rare or absent in other mineral deposits in the petroleum-bearing regions. The isotopic signature of this helium is uniform over broad regions, independent of the stratigraphy, ages, and alleged sources of the various petroleum deposits therein, which points to a common origin, deep within the mantle. Furthermore, this helium tends to be enriched in helium-3 (“cosmogenic helium”) to greater than atmospheric abundance — which suggests a primordial source, as the helium originating from alpha decay of radioactive atoms in crustal rocks is almost exclusively helium-4 (“radiogenic helium”).

5. Metalic trace elements in petroleum are more consistent with a deep-Earth origin than with origin from local, biogenic debris. In addition to the excellent points made by Gregg in an earlier post to this topic, a fact that I consider quite significant is that the trace occurrence of elements in petroleum tends to be uniform over large areas (e.g. vanadium enrichment is typical of petroleum from South America), and tends NOT to match the compositions of the reservoir rocks.

6. The ratios of carbon-12 to carbon-13 observed in natural methane far exceed, in both directions, the range of ratios generally attributed to biological processes.

The only substantial evidence that points toward biogenic origin of petroleum (but not of methane) is the presence of organic molecules that are produced by biological processes or occur from the breakdown of such bioproducts. Indeed, this was the evidence that originally convinced me of biogenic origin when I was a geology student (early 1970s). However, this evidence is equally consistent with petroleum that originates from biological debris or with petroleum made up of primordial hydrocarbons that have been contaminated with biogenic molecules. Most of the debate over the origin of petroleum took place when the only known sources of such molecules were at the Earth’s surface. Since the discovery that a vast community of hyperthermophillic organisms — many of which metabolize hydrocarbons — living within the crust, and possibly down into upper levels of the mantle, a non-surface source of the biological molecules had been identified. In fact, bacteria and archaea have been found in petroleum samples taken from depths of over 4km, and molecules that almost certainly originated in the cell membranes of such organisms have been found in every petroleum sample that has been tested for their presence.

Therefore, the most plausible concept is that petroleum is comprised primarily of primordial hydrocarbons effusing from within the Earth’s mantle, and, on the way up, these hydrocarbons serve as the food/energy source for communities of microorganisims, whose bodies are the source of the bioproducts observed in the petroleum. While methane is almost certainly a major component of these primordial hydrocarbons, it is unclear whether it is the only component. Thomas Gold maintains (see <i>The Deep Hot Biosphere</i>, ISBN 0-387-98546- that the liquid hydrocarbon molecules form from methane under conditions of the upper mantle. C. Warren Hunt argues (see <i>Expanding Geospheres</i>, ISBN 0-9694506-1-3) that petroleum is produced by these microorganisms, using the primordial methane as the feedstock. The detailed studies by followers Koudryavtsev into the conditions of thermodynamic stability of hydrocarbon molecules (see www.gasresources.net/toc_StatMech.htm ) favor abiogenic formation within the mantle.

In closing, I would like to suggest that the non-acceptance of the abiogenic theory among western geologists has a similar basis to the non-acceptance of anything but big-bang cosmology among mainstream astronomers — a lack of published evidence favoring the alternatives, maintained by an observation and publication system that rejects such contrary evidence (as discussed, for astronomy, by Halton Arp in <i>Seeing Red</i>).

The abiogenic origin of petroleum is widely accepted among geologists in countries of the former Soviet Union — but most of their professional literature is published in Russian, and rarely read in the west. (For an excellent set of papers in English by Ukranian and Russian petroleum geologists see www.gasresources.net/ ).

It is worth remembering that petroleum geology developed in response to expansion of the petroleum industry, not the reverse. The petroleum industry began from attempts to enhance the availability of an accessible resource — initial drilling for oil took place near the sites of natural petroleum seeps. For the western hemisphere, this started in 1859, near Titusville, Pennsylvania. For the eastern hemisphere, this started in 1840, near Grozy, Chechnya — a location that has been in the news recently for (not completely) unrelated reasons.

The expansion of the oil industry during the remainder of the 19th century occurred using discoveries made by essentially random drilling. For example, in the late 19th century, roughly one in six “wildcat” wells drilled in the “oil patch” of the central USA struck oil or natural gas. It was not until the productivity of such random drilling began to decline that oil companies began investing in geological research. The data available to geologists attempting to develop a theory of petroleum formation came from existing drilling records — almost all of which was from holes drilled into sedimentary rocks of paleozoic or mesozoic age. Given the continued success finding oil fields in such (relatively soft) sedimentary rocks, there was little incentive to pursue drilling into (relatively hard) igneous or metamorphic rocks. To see how this attitude pervades US petroleum orthodoxy, one needs to look no farther than the definition of “basement rock” in <i>Dictionary for the Petroleum Industry</i> 3rd Edition, 2001, published by the Petroleum Extension Service of the University of Texas at Austin:

“<b>basement rock</b> n: igneous or metamorphic rock, which seldom contains petroleum. Ordinarily, it lies below sedimentary rock. When it is encountered in drilling, the well is usually abandoned.”

(BTW, this already shows some progress! In the 2nd edition of this dictionary the phrase “... which seldom contains petroleum” read “... it does not contain petroleum.”)

With exploratory wells being abandoned as dry holes when the basement is encountered, there was essentially no data on the existence of petroleum in igneous (or precambrian sedimentary) rocks availabile to the geologists who theorized on the origin of petroleum — is it any wonder that the theories tended to emphasize a near-surface source for the contained carbon as biological debris?

MAF

When you find yourself on the side of the majority it is time to reform. -- Mark Twain

Mr. Fischer has nailed the issue. I certainly have no more to add.

Gregg Wilson

MAF,

Does an abiotic origin for petroleum affect depletion rates? Is it really possible that wells are being "refilled," as Gregg suggests? I find this hard to believe. I mean, if Texas has refilled, why aren't the oil companies pumping the oil there? Petroleum may very well be abiogenic, but it still seems that world production is levelling off or falling.

Emanuel

Emanuel:
There is no doubt that SOME petroleum reservoirs are refilling from deeper levels. What remains unclear are questions such as how common is such refilling, whether such refilling can take place at anything approaching the rates of production, and how extensive are the deeper reserves from which the refilling occurs. There are many oil fields that have produced far in excess of their estimated reserves, although the older the field, the more likely that the reserve estimates were, at least in part, to blame. It is also certain that many petroleum reservoirs are not refilling, especially the type of isolated reservoirs known as stratigraphic traps.

There is one case where the refilling of a shallow reservoir from deeper levels was actually observed: the Eugene Island 330 field in the Gulf of Mexico south of Morgan City, Louisiana. Production at this field began in the early 1970s. In the early 1990s, a research project using "4D seismic" (3D seismic imaging plus time-series analysis) was able to image an upward flow replenishing the shallower, producing pool from a deeper, unexplored level. There were quite a few publications on this about 10 years ago. A small article which mentions Eugene Island 330 is available online is at:
www.pnl.gov/er_news/08_95/er_news/oil1.kb.html

There are also numerous oil fields where reservoir pressure has not dropped at the rate expected due to the production levels, and some form of recharge is a likely explanation. These fields are mostly located along continental margins, where conditions are excellent for upslope migration of petroleum, and/or at locations were deep faults or impact structures have created fractures that extend to the base of the crust.

World petroleum production is not declining, although it is not expanding fast enough to keep pace with increasing demand. It is very hard to gauge what is happening to world "proven reserves" both because of the fields that maintain higher reservoir pressures than expected, and because the reserve figures published by many countries are highly suspect (especially 3rd-world oil producers in need of international credit and OPEC members seeking larger production quotas).

Even if the deep levels, from which oil field recharge is occuring, contain many trillions of barrels of petroleum, it is unlikely that recharge alone can maintain adequate production from near-surface reservoirs. It will be necessary to explore and produce directly from deeper levels, which requires development of improved deep drilling and hard-rock imaging technologies.

MAF

When you find yourself on the side of the majority it is time to reform. -- Mark Twain