Black Gold from the bowels of Earth - Petroleum
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Black Gold from the bowels of Earth - Petroleum
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Description - How is formed

Oil, petroleum, hydrocarbon — these words are defined one component -petroleum or crude oil.
Fossil fuels are those energy sources that formed from the remains of once-living organisms. They include oil, natural gas, coal, and fuels derived from oil shale and tar sand. The differences in the physical properties among the various fossil fuels arise from differences between the starting materials from which the fuels formed and changes to those materials after the organisms died and were buried within the layers of the earth. Petroleum means rock-oil, and comes from the Latin petra, meaning rock or stone, and oleum, meaning oil. 

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Petroleum or crude oil, is a naturally occurring flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface.


A fossil fuel, it is formed when large quantities of dead organisms, usually zooplankton and algae, are buried underneath sedimentary rock and undergo intense heat and pressure.



Liquid petroleum, or oil, comprises a variety of liquid hydrocarbon compounds; compounds made up of different proportions of the elements carbon and hydrogen. There are also gaseous hydrocarbons (natural gas), in which methane is the most common component. Hydrocarbon mixtures usually also contain minor amounts of nitrogen, oxygen, and sulfur as impurities.

Petroleum formation occurs by various hydrocarbons combining with certain minerals such as sulphur under extreme pressure. Modern day scientists have proven that most if not all petroleum fields were created by the remains of small animal and plant life being compressed on the sea bed by billions of tons of silt and sand several million years ago.

                 how_petroleum_crude_oil_is_formed  how_petroleum_crude_oil_is_formed


how_petroleum_crude_oil_is_formed_                     how_petroleum_crude_oil_is_formed

When small sea plants and animals die they will sink, they will then lie on the sea bed where they will decompose and mix with sand and silt. During the decomposition process tiny bacteria will clean the remains of certain chemicals such as phosphorus, nitrogen and oxygen. This leaves the remains consisting of mainly carbon and hydrogen. At the bottom of the ocean there is insufficient oxygen for the corpse to decompose.


The production of a large deposit of any fossil fuel requires an even larger initial accumulation of organic matter, which is rich in carbon and hydrogen. Another requirement is that the organic debris be buried quickly to protect it from the air so that decay by biological activity or reaction with oxygen will not destroy it. Microscopic life is abundant over most of the earth’s oceans. When these organisms die, their remains can settle to the sea floor. There are also underwater areas near shorelines, such as on many continental shelves, where sediments derived from continental erosion accumulate rapidly. In such a setting, the starting requirements for the formation of oil are satisfied; there is an abundance of organic matter rapidly buried by sediment. Oil and most natural gas are believed to form from such accumulated marine microorganisms.


The partially decomposed remains from the prehistoric life  will form a large, gelatinous mass, which will then slowly become covered by multiple layers of sand, silt and mud. This burying process takes millions of years, with layers piling up one atop another.
As the depth of the sediment build up increases the weight of the sand and silt pressing down on the mass will compress it into a layer which is much thinner than the original.
Finally, when the depth of the buried decomposing layer reaches somewhere around 10,000 feet the natural heat of the earth and the intense pressure will combine to act upon the mass. The end result, over time, is the formation of petroleum.


Some natural gas deposits that are not associated with oil may form from deposits of plant material buried in sediment. As burial continues, the organic matter begins to change. Pressures increase with the weight of the overlying sediment or rock; temperatures increase with depth in the earth; and slowly, over long periods of time, chemical reactions take place. These reactions break down the large, complex organic molecules into simpler, smaller hydrocarbon molecules. In the early stages of petroleum formation, the deposit may consist mainly of larger (heavy) hydrocarbons, which have the thick, nearly solid consistency of asphalt.

As the petroleum matures, and as the breakdown of large molecules continues, successively “lighter” hydrocarbons are produced. Thick liquids give way to thinner ones, from which lubricating oils, heating oils, and gasoline are derived.  In the final stages, most or all of the petroleum is broken down further into very simple, light, gaseous molecules—natural gas.  Most of the maturation (cooking) process occurs in the temperature range of 50° to 100° C(approximately 120° to 210° F). Above these temperatures, the remaining hydrocarbon is almost entirely methane (natural gas); with further temperature increases, methane can also be broken down and destroyed.

Where it can be found - Deposits
According to the International Energy Agency's Oil Market Report unconventional oil includes the following sources:
   Oil shales
   Oil sands-based synthetic crudes and derivative products
   Coal-based liquid supplies
   Biomass-based liquid supplies
   Liquids arising from chemical processing of natural gas.


Based on data from OPEC at the beginning of 2011 the highest proved oil reserves including non-conventional oil deposits are in Venezuela (20% of global reserves), Saudi Arabia (18% of global reserves), Canada (13% of global reserves), Iran (9%)


The majority of petroleum source rocks are fine-grained sedimentary rocks (like shale), from which it would be difficult to extract large quantities of oil or gas quickly. However, oil and gas are able to migrate out of their source rocks into more permeable rocks over the long spans of geologic time. Most people have the incorrect notion that there are underground “lakes” of oil.

The oil industry has helped feed this misconception by talking about oil “pools.” The truth is that virtually all the oil is contained in tiny holes in solid rock. These holes, or pores, are filled with water, gas, or oil. But if the holes are not connected, then oil can’t flow out of the rock. The ability of liquid to flow through the pores is permeability. So, in addition to high porosity, which allows the rock to hold large amounts of oil, the rock must have good permeability, which allows oil to flow quickly out of the rock. A rock with good porosity and permeability is a reservoir rock. Mostoils and all natural gases are less dense than water, so they tend to rise as well as to migrate laterally through the water-filled pores of permeable rocks



Why the Petroleum-crude oil it can be found in some areas more than others?

If we look hundreds of thousand of year ago, and even millions we notice a lot of tectonic activities on all Earth surface and constantly some of the actual ground (including underwater ground from oceans and sea’s) where expose to prehistoric water and then suddenly water retreat due to fragmentation and movement of the continents.
So, what we see today on Grand Canion and Texas area where several times under the ocean water for many millions of years making ideal place for microorganisms, plantcton or big mammals to form a crust on the bottom of prehistoric oceans.In time and due to dramatic tectonic activity which can be seen into the Grand Caninon , water retreat leaving what we known today as Colorado Plateau.

Petroleum is formed  when small sea plants and animals die and will sink, they will then lie on the sea bed where they will decompose and mix with sand and silt.This process is a long one and ast for milion of years.

Acually the Earth as we know it today was not like this 250.000.000 years ago.


A big continet called Pangea was formed in the begining.

After millions oy years (around 90.000.000 ago) the continents start to split giving birth of some of the shape which we know today.But the movment of continents was not stoppend, still contiuing even today.



Evidences of this incredible powerful process we can find todai in Venezuela, were we can see some of the oldest rocks formations on Earth as well with evidence of imens stress which tectonic plates have been subjected to enormous stress, creating breath taking landscapes.





 Many times during glaciation process and Ice Age large land surface were covered by ice, and then slowley water came floding vegetation and burring animals with.

Proves of water covering different surfaces on the Earth we can find in Grand Canion rocks but also in Sahara making scientiest drawing the conclusion (and with other geological evidences) taht long time ago Sahara and Grand Canion were togheter.


Grand_canion_under_water   grand_canion_was_part_of_sahara_desert

Grand Canion 90.000.000 ago under the water


saw fish skeleton in sahara


Millions of year ago Sahara region (Nordic countries of Africa along with Irak, Iran, Kuwait) were under the water

Therefore is these regions particularely when proper conditions were met, covered vegetations and animals by the waters could start up the process of petroleum - oil forming.


Colorado Plateau is unique on diversify of hydrocarbures and oil deposit or minerals
The rocks of the Colorado Plateau are a source of oil and a major source of natural gas. Major petroleum deposits are present in the San Juan Basin of New Mexico and Colorado, the Uinta Basin of Utah, the Piceance Basin of Colorado, and the Paradox Basin of Utah, Colorado, and Arizona.


Coal - Major coal deposits are being mined in the Colorado Plateau in Utah, Arizona, Colorado, and New Mexico, though large coal mining projects, such as on the Kaiparowits Plateau, have been proposed and defeated politically. The ITT Power Project, eventually located in Lynndyl, Utah, near Delta, was originally suggested for Salt Wash near Capitol Reef National Park. After a firestorm of opposition, it was moved to a less beloved site. In Utah the largest deposits are in aptly named Carbon County. In Arizona the biggest operation is on Black Mesa, supplying coal to Navajo Power Plant.


Gilsonite and uintatite - Perhaps the only one of its kind, a gilsonite plant near Bonanza, southeast of Vernal, Utah, mines this unique, lustrous, brittle form of asphalt, for use in Oil shale- There are large deposits of oil shale, primarily in the northeastern Colorado Plateau Beside Golf of Mexico, Colorado Plateau, and North Africa, large oil (especially natural gases) are in North Russia and Venezuela.
Venezuela is also one of the important “player” on oil market and roughly a third of GDP, around 80% of exports, and more than half of government revenues.

Since the discovery of oil in the early 20th century, Venezuela has been one of the world's leading exporters of oil, and it is a founder member of OPEC.  
The Venezuelan oil producer PDVSA wholly owns its United States-based subsidiary, Citgo and attributes a large percentage of its wealth to oil sales from the United States Venezuela has some of the largest oil and natural gas reserves in the world, and consistently ranks among the top ten world crude oil producers. Compared to the preceding year another 40.4% in crude oil reserves were proven in 2010, allowing Venezuela to surpass Saudi Arabia as the country with the largest reserves of this type.


The country's main petroleum deposits are located around and beneath Lake Maracaibo, the Gulf of Venezuela (both in Zulia), and in the Orinoco River basin (eastern Venezuela), where the country's largest reserve is located. Besides the largest conventional oil reserves and the second-largest natural gas reserves in the Western Hemisphere, Venezuela has non-conventional oil deposits (extra-heavy crude oil, bitumen and tar sands) approximately equal to the world's reserves of conventional oil.

How is extracted

  • Ground extraction
  • Deep sea extraction
  • Sand extraction

The exploitation of bituminous deposits and seeps dates back to Paleolithic times. The earliest known use of bitumen was by Neanderthals, some 40,000 years ago. Bitumen has been found adhering to stone tools used by Neanderthals at sites in Syria. After the arrival of Homo sapiens, humans used bitumen for construction of buildings and water proofing of reed boats, among other uses. In ancient Egypt, the use of bitumen was important in creating Egyptian mummies—in fact, the word mummy is derived from the Arab word mumiyyah, which means bitumen.



In ancient times, bitumen was primarily a Mesopotamian commodity used by the Sumerians and Babylonians, although it was also found in the Levant and Persia.
The area along the Tigris and Euphrates rivers was littered with hundreds of pure bitumen seepages. The Mesopotamians used the bitumen for waterproofing boats and buildings. In North America, the early European fur traders found Canadian First Nations using bitumen from the vast Athabasca oil sands to waterproof their birch bark canoes. In Europe, they were extensively mined near the European city of Pechelbronn, where the vapour separation process was in use in 1742.

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The name tar sands was applied to bituminous sands in the late 19th and early 20th century. People who saw the bituminous sands during this period were familiar with the large amounts of tar residue produced in urban areas as a by-product of the manufacture of coal gas for urban heating and lighting. The word "tar" to describe these natural bitumen deposits is really a misnomer, since, chemically speaking, tar is a human-made substance produced by the destructive distillation of organic material, usually coal.



Since then, coal gas has almost completely been replaced by natural gas as a fuel, and coal tar as a material for paving roads has been replaced by the petroleum product asphalt. Naturally occurring bitumen is chemically more similar to asphalt than to tar, and the term oil sands (or oilsands) is more commonly used in the producing areas than tar sands because synthetic oil is what is manufactured from the bitumen. Oil sands are now an alternative to conventional crude oil.

Conventional crude oil is normally extracted from the ground by drilling oil wells into a petroleum reservoir, allowing oil to flow into them under natural  reservoir pressures, although artificial lift and techniques such as water flooding and gas injection are usually required to maintain production as  reservoir pressure drops toward the end of a field's life.



Because bitumen flow very slowly, if at all, toward producing wells under normal reservoir  conditions, the sands must be extracted by strip mining or the oil made to flow into wells by in-situ techniques, which reduce the viscosity by injecting  steam, solvents, and/or hot air into the sands.


These processes can use more water and require larger amounts of energy than conventional oil extraction, although many conventional oil fields also require large amounts of water and energy to achieve good rates of production.
It is estimated that approximately 90% of the Alberta oil sands are too far below the surface to use open-pit mining. Several in-situ techniques have been developed.

The search for oil and gas beneath the earth’s surface is a risky undertaking. Indeed it is quite a gamble to invest money in an exploration “wildcat” well, because there are so many unknowns involved in the analysis and study of the earth. A number of conditions must exist before an oil or gas accumulation can develop—hydrocarbons must have been generated and they must have migrated to a suitable location to be trapped. Geoscientists use several scientific and technical procedures to “predict” whether these conditions may have combined to create an oil or gas field, but the results are never guaranteed.



Not all exploration wells drilled result in the discovery of oil and gas. The success rate can vary from drilling five or ten exploration wells to achieve one successful producing well; it may take as many as 50 or 100 exploration wells to discover a “significant” new oil field. The risk is further increased by the high cost of drilling new wells. In 2002, the average cost of drilling a new well in the United States was nearly $1 million assuming a well depth of 5,000 feet (typical for onshore oil wells).  The high cost of finding new oil and gas fields demands that proper exploration work be completed before extensive drilling is started.

The use of exploration techniques to find oil and gas began nearly 150 years ago when Edwin Drake drilled the first successful oil well in Pennsylvania in 1859. Early oil explorers originally looked for oil in seeps and slicks along low places in river valleys and their adjoining creeks. Water wells with their occasional oil shows provided additional clues to the existence of petroleum beneath the earth’s surface.


It was during this early period that the term “wildcat well” was first used. In those days, the woods of Pennsylvania were full of wild cats (bobcats) and mountain lions.  At night, while oil drillers were working on their rigs, the wild cats often could be heard screaming in the woods.

As a result, the early exploratory wells drilled in this part of the country became known as “wildcat wells.” This term has been used throughout the history of oil exploration, and still refers to those wells that are drilled to find oil and gas in previously unexplored areas. The modern science of exploring for petroleum deposits combines methods of describing the geology that can be observed at the earth’s surface with sophisticated subsurface techniques that allow the geoscientist to visualize below the earth’s surface. Equally important as the techniques themselves, however, is their application to the general exploration process.

Most exploration goes through a typicalcycle or pattern, although more research is required to find new fields than locating extensions of older or existing ones. The exploration geologist’s first task is to choose a general area for exploration. In the United States, there are numerous locations, generally known as sedimentary basins, where major exploration activities are conducted.
The  Rocky Mountains have many large basins of sedimentary deposits that contain hydrocarbons. Geologists must choose a particular area or basin that they consider promising, and further define their target by making regional studies of the basin. They will identify the hydrocarbon traps or potential reservoirs using both surface and subsurface methods.

Incidents - The Deepwater Horizon oil spill (also referred to as the BP oil spill, the BP oil disaster, the Gulf of Mexico oil spill, and the Macondo blowout) was an oil spill in the Gulf of Mexico on the BP-operated Macondo Prospect, considered the largest accidental marine oil spill in the history of the petroleum industry, estimated to be between 8% and 31% larger in volume than the earlier Ixtoc I oil spill.





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Sources :

* Excerpts for Rock Talk Vol 7 No.2 Colorado Geological Survey  - Author : Jim Fausnaugh


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