Source of Petroleum

Crude situation

The crude oil price had reached its all time high of (higher then that of during the 1971 oil crises) US$135 per barrel on 22 May 2008. The oil industrial analysts forecasted that it may reach to levels of US$150 to US$200 per barrel in due course of time.

The causes for this price hike is widely speculated for various reasons like production loss in recent years (post 2003 middle-east political situation), depleting oil reserves, drastic increase in fuel consumption in recent years, increasing demand, from expanding economies, mainly in China and India.

But till what period we are assured of getting the oil even if we are ready to pay higher price for it?

Oil depletion is the inescapable result of extracting and consuming oil faster than it is naturally produced, because the formation of new natural petroleum is a continuous geologic process which takes millions of years. No one knows for sure when the long-term decline of oil reserves will begin, or what the consequences will be. The Hubbert peak is an influential theory concerning the long-term rate of conventional Petroleum (and other fossil fuel) extraction and depletion.

United States geophysicist M. King Hubbert, created a model from known oil reserves world-wide, and proposed the theory. The concept of passing the peak-point, so that society is on the downward side of the oil supply curve, is also referred to as Peak oil or the end of cheap oil. By most projections, this point has already been passed or is about to be at some point between the years 2007 and 2010, although by United States government prediction, world consumption of oil will increase to 98.3 million barrels a day in 2015 and 118 million barrels a day in 2030.

Oil depletion occurs in a predictable fashion based on geological principles and engineering practices which apply in varying degrees to all oil fields. The shape of the decline curves can vary depending on particular circumstances and government policies, but all oil fields decline over time, and the geological and operational mechanisms involved ensure the fields will decline in a relatively predictable manner.

In theory, Oil wells would follow an exponential decline curve. Produced at their natural rates, oil wells will start off by producing at a high rate and then will decline rapidly from that rate and eventually level off at a low rate of slow decline. There are many exceptions to this, some dictated by operational procedures at the surface (the typical Saudi Arabia well does not decline in this manner for example) and others dictated by allowable restrictions, such as oil wells in Louisiana.

Example of US
Oil production in the United States has followed the theoretical Hubbert Curve in a general fashion. U.S. oil production reached its peak in 1970 and by the mid-2000s it had fallen half way down the production curve to a level last seen in the 1940s. In 1950, the United States produced over half the world's oil, but by 2005 that proportion had dropped to about 8%.

World oil production has followed a typical exponential growth curve, which has continued to grow for over a century with only a few dips, but the experience of the United States decline has caused many people to question how long the world can continue to produce steadily increasing amounts of oil. As of the mid-2000s, all of the world's oil producing countries except Saudi Arabia was producing at maximum capacity.

Industry observers and proponents of the peak oil theory have pointed to the similarities between the global production curve in mid-2000s and that of the United States in the 1970s, which peaked without warning and started to decline.

Results of oil depletion
The effects of such a oil shortage would depend on the rate of decline and the development and adoption of effective alternatives, ongoing as you read this. If alternatives were not forthcoming, it has been speculated that the numerous products produced with oil would become scarcer, leading to at the very least lower living standards in developed and developing countries alike, and possibly in the worst case to the collapse of the entire international banking system, which could not hope to sustain itself without the prospect of growth[citation needed]. The political situation may change dramatically, with potential wars between countries over access to dwindling supplies. Accordingly, inequalities between various countries and regions of the world may become exacerbated.

Economic growth and prosperity since the industrial revolution have, in large part, been due to increased efficiencies in the use of better and higher concentrations of energy in fossil fuels. The use of fossil fuels allows humans to participate in takedown, which is the consumption of energy at a greater rate than it is being replaced. Some believe that decreasing oil production portends a drastic impact on human culture and modern technological society, which is currently heavily dependent on oil as a fuel and chemical feedstock. For example, over 90% of transportation in the United States relies on oil.

Since the 1940s, agriculture has dramatically increased its productivity, due largely to the use of chemical pesticides, fertilizers, and increased mechanisation. Pesticides rely upon oil as a critical ingredient, and fertilizers require natural gas. Farm machinery also requires oil. Arguing that in today's world every joule one eats requires 5-15 joules to produce and deliver, some have speculated that decreasing supply of oil will cause modern industrial agriculture to collapse, leading to a drastic decline in food production, food shortages and possibly even mass starvation.

A more modest scenario, assuming a slower rate of depletion and a smooth transition to alternative energy sources could cause substantial economic hardship such as a recession or depression due to higher energy prices.

But the oil reserves of our planet will vanish suddenly?
Let’s get to the basics first.

Petroleum Oil is a naturally occurring, flammable liquid found in rock formations in the Earth consisting of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds. It is found in porous rock formations in the upper strata of some areas of the Earth's crust. There is also petroleum in oil sands (tar sands).

Formation of petroleum occurs from kerogen pyrolysis, in a variety of mostly endothermic reactions at high temperature and/or pressure.

Biogenic theory
Most geologists view crude oil and natural gas as the product of compression and heating of ancient organic materials over geological time. Oil is formed from the preserved remains of prehistoric zooplankton and algae which have been settled to the sea (or lake) bottom in large quantities under anoxic conditions. Terrestrial plants, on the other hand, tend to form coal. Over geological time this organic matter, mixed with mud, is buried under heavy layers of sediment. The resulting high levels of heat and pressure cause the organic matter to chemically change during diagenesis, first into a waxy material known as kerogen which is found in various oil shales around the world, and then with more heat into liquid and gaseous hydrocarbons in a process known as catagenesis.

Geologists often refer to an "oil window" which is the temperature range that oil forms in—below the minimum temperature oil remains trapped in the form of kerogen, and above the maximum temperature the oil is converted to natural gas through the process of thermal cracking. Though this happens at different depths in different locations around the world, a typical depth for the oil window might be 4–6 km. Note that even if oil is formed at extreme depths, it may be trapped at much shallower depths where it was not formed (the Athabasca Oil Sands is one example).

Because most hydrocarbons are lighter than rock or water, these often migrate upward through adjacent rock layers until they either reach the surface or become trapped beneath impermeable rocks, within porous rocks called reservoirs. However, the process is not straightforward since it is influenced by underground water flows, and oil may migrate hundreds of kilometres horizontally or even short distances downward before becoming trapped in a reservoir. Concentration of hydrocarbons in a trap forms an oil field from which the liquid can be extracted by drilling and pumping.

Three conditions must be present for oil reservoirs to form: a source rock rich in organic material buried deep enough for subterranean heat to cook it into oil; a porous and permeable reservoir rock for it to accumulate in; and a cap rock (seal) or other mechanism that prevents it from escaping to the surface. Within these reservoirs, fluids will typically organize themselves like a three-layer cake with a layer of water below the oil layer and a layer of gas above it, although the different layers vary in size between reservoirs.

The vast majority of oil that has been produced by the earth has long ago escaped to the surface and been biodegraded by oil-eating bacteria. Oil companies are looking for the small fraction that has been trapped by this rare combination of circumstances. Oil sands are reservoirs of partially biodegraded oil still in the process of escaping, but contain so much migrating oil that, although most of it has escaped, vast amounts are still present—more than can be found in conventional oil reservoirs.

On the other hand, oil shales are source rocks that have not been exposed to heat or pressure long enough to convert their trapped kerogen into oil.

The biogenic origin of petroleum (liquid hydrocarbon oils) has recently been reviewed in detail by a few eminents who raise a number of objections.

Now comes the revolutionary theory…

Eugene Island is a submerged mountain 70-85 miles off the Louisiana coast in the Gulf of Mexico. The nearby oil field Eugene Island 330 is best known for its unusual depletion profile.

A significant reservoir of crude oil was discovered nearby in the late ’60s, and by 1970, a platform named Eugene 330 was busily producing about 15,000 barrels per day of high-quality crude oil. By the late ’80s, the platform’s production had slipped to less than 4,000 barrels per day and was considered pumped out. Done. Suddenly, in 1990, production soared back to 15,000 barrels per day.

However, the speculative figures are as: Production from Eugene Island had achieved 20,000 barrels per day by 1989; by 1992 it had slipped to 15,000 bbl/d, but recovered to reach a peak of 30,000 bbl/d in 1996. Production from the reservoir has dropped steadily since then.

The source of additional oil was analyzed as migrating through faults from deeper and older formations below. The oil contains biomarkers similar to those in other oils in the area.

Eugene Island 330 is often cited as a key example of something called as Abiogenic petroleum origin theory, which holds that petroleum reservoirs are continuously replenished from inorganic sources deep within the Earth.

Abiogenic theory
The theory of abiogenic petroleum origin holds that natural petroleum was formed from deep carbon deposits, perhaps dating to the formation of the Earth. The ubiquity of hydrocarbons in the solar system is taken as evidence that there may be a great deal more petroleum on Earth than commonly thought and that petroleum may originate from carbon-bearing fluids which migrate upward from the mantle.

Various abiogenic hypotheses were first proposed after advances in science in the nineteenth century.

Within the mantle, carbon may exist as hydrocarbon molecules, chiefly methane, and as elemental carbon, carbon dioxide and carbonates. The abiotic hypothesis is that a full suite of hydrocarbons found in petroleum can be generated in the mantle by abiogenic processes, and these hydrocarbons can migrate out of the mantle, into the crust until they escape to the surface or are trapped by impermeable strata, forming petroleum reservoirs.

Meteorites are believed to suggest the major composition of material from which the Earth was formed. Some meteorites, such as carbonaceous chondrites, contain carbonaceous material. If a large amount of this material is still within the Earth, it could have been leaking upward for billions of years.

Russian researchers performed the calculations of thermodynamic equilibrium and concluded that hydrocarbon mixes would be created within the mantle. Experiments under high temperatures and pressures produced many hydrocarbons.

Hydrogen gas and water have been found more than 6 kilometers deep in the upper crust. There is data in the western United States that aquifers from near the surface may extend to depths of 10 to 20 km. Hydrogen gas can be created by water reacting with silicates, quartz and feldspar, in temperatures in the 25° to 270 °C range. These minerals are common in crustal rocks such as granite. Hydrogen may react with dissolved carbon compounds in water to form methane and higher carbon compounds.

One proposed mechanism by which abiogenic petroleum is formed was first proposed by the Ukrainian scientist, Prof. Emmanuil B. Chekaliuk in 1967. He proposed that petroleum could be formed at high temperatures and pressures from inorganic carbon in the form of carbon dioxide, hydrogen and/or methane.

This mechanism is supported by several lines of evidence which are accepted by modern scientific literature. This involves synthesis of oil within the crust via catalysis by chemically reductive rocks. A proposed mechanism for the formation of inorganic hydrocarbons is via natural analogs of the Fischer-Tropsch process known as the serpentinite mechanism or the serpentinite process.

Abiogenic theories reject the supposition that certain molecules found within petroleum, known as "biomarkers," are indicative of the biological origin of petroleum. They contend that some of these molecules could have come from the microbes that the petroleum encounters in its upward migration through the crust, and that some of them are found in meteorites, which have presumably never contacted living material, and that some can be generated by plausible reactions in petroleum abiogenically.

The hypothesis is founded primarily upon:
- The ubiquity of methane within the solar system
- The presence of hydrocarbons in extraterrestrial bodies including meteors, moons and comets
- Plausible mechanisms of abiotically chemically synthesizing hydrocarbons within the mantle
- Hydrocarbon-rich areas tend to be hydrocarbon-rich at many different levels
- Petroleum and methane deposits are found in large patterns related to deep-seated large-scale structural features of the crust rather than to the patchwork of sedimentary deposits
- Interpretations of the chemical and isotopic composition of natural petroleum
- The presence of oil and methane within non-sedimentary rocks upon the Earth
- The existence of methane hydrate deposits
- Perceived ambiguity in some assumptions and key evidence used in the orthodox biogenic petroleum theories
- Bituminous coal creation is based upon deep hydrocarbon seeps
- Inability to create petroleum-like material from organic material at the time the theories were created
- Surface carbon budget and oxygen levels stable over geologic time scales
- Biogenic theories do not explain some hydrocarbon deposit characteristics
- The distribution of metals in crude oils fits better with upper serpentinized mantle, primitive mantle and chondrite patterns than oceanic and continental crust, and show no correlation with sea water
- The association of hydrocarbons with helium, a noble gas
- Deep microbial hypothesis of hydrocarbon generation

And, more…
Biotic (microbial) hydrocarbons
The deep biotic petroleum theory, is similar to the abiogenic petroleum origin hypothesis.
This theory is different from biogenic oil in that the role of deep-dwelling microbes is a biological source for oil which is not of a sedimentary origin and is not sourced from surface carbon. Deep biotic oil is considered to be formed as a byproduct of the life cycle of deep microbes. Shallow biotic oil is considered to be formed as a byproduct of the life cycles of shallow microbes.

The Law of thermodynamics prohibits petroleum formation at low pressure and temperature. Petroleum is stable within earth's mantle at depths around 150-200 km. At low pressure levels (for instance sedimentary basins) may occur bacterial contamination that leave their fingerprints in oil. It's impossible to form petroleum from biogenic detritus.

Microbial life has been discovered 4.2 kilometers deep in Alaska and 5.2 kilometers deep in Sweden. Proponents of abiogenic petroleum origin contend that deep microbial life is responsible for the biomarkers (see below) that are generally cited as evidence of biogenic origin. A community of Archaea bacteria is thriving deep in the subsurface source of a hot spring in Idaho. Geothermal hydrogen, not organic carbon, is the primary energy source for this methanogen-dominated microbial community. This is the first documented case of a microbial community completely dominated by Archaea.

The presence of biomarkers in the extremely rare examples of Proterozoic oils and within oils found in Mesozoic and younger crystalline reservoirs, could be explained as coming from deep-dwelling bacteria.

The abiogenic theory of oil sees the role of deep microbes as providing these biomarkers as contaminants of abiogenic petroleum accumulations, not as products of plant and plankton detritus which have been converted to petroleum via orthodox biogenic processes.

The case for shallow bacterial life creating petroleum is apparent from circumstantial evidence at "tar seeps" in sandstone outcrops where live oil is encountered down-dip (e.g. Midway-Sunset field, San Joaquin Valley, California). Bacteria are considered to have "degraded" higher gravity oil to bitumens.

Extrapolation of bacterial degradation to still higher gravity oils and finally to methane leads to the suggestion that all petroleum up to tar and most of the carbon in coal are derivatives of methane, which is progressively stripped of its hydrogen by bacteria and archaea.


Conclusion
Currently there is little direct research on abiogenic petroleum or experimental studies into the synthesis of abiogenic methane. However, several research areas, mostly related to astrobiology and the deep microbial biosphere and serpentinite reactions, continue to provide insight into the contribution of abiogenic hydrocarbons into petroleum accumulations.


Similarly, research into the deep microbial hypothesis of hydrocarbon generation is advancing as part of the attempt to investigate the concept of panspermia and astrobiology, specifically using deep microbial life as an analog for life on Mars.

Let's hope that these researches gives some clear picture about the formation of the fuel, hence we all can decide upon using cars or carts in the future - till then happy travelling.