The Earth Story

Geology and Nomenclature: Why some names kick ass

I always appreciate a clever name or at least one that is descriptive of the object at hand. A firm favourite is roche moutonnée, a glacial feature which literally translates as ‘rock sheep’ due a pockmarked surface that resembles a particularly ragged sheep’s fleece.

So what other cool names are out there? I’ve compiled a short list of my favourites below but if you know of others feel free to enlighten us in the comments!

Petroleum – comes from the Latin petra meaning ‘rock’ and oleum meaning oil. Literally means rock oil.

Ammonite – derived from the name of the Egyptian god Amon who was often depicted with ram horns or a full ram’s head. It was thought that the fossils looked like his tightly coiled horns!

Protolith – comes from the Ancient Greek protos meaning ‘first’ and the word lithos meaning ‘stone’ or ‘rock’. Literally translates to first rock, a very apt name as it is used to describe a metamorphic rocks original rock type before transformation.

Metamorphic – Comes from the Greek meta which means ‘change’ and morph which translates as ‘form’. The ‘-ic’ indicates that we are talking about the ‘nature of changing form’ whereas ‘-osis’ would suggest we are talking about the ‘process of changing form’.

Sedimentary – thought to be derived from the Latin word sedimentum meaning ‘settling’.

Igneous – derived from the Latin word ignis which means ‘fire’. The suffix ‘-eous’ means ‘composed of’ meaning igneous literally translates as ‘composed of fire’.

Echinodermata – Groups of animals with radial symmetry including starfish, sea urchins and sea lillies. Comes from the Greek echinos meaning ‘hedgehog’ and derma meaning ‘skin’ to describe fossilised sea urchins as their spines reminded geologists of a hedgehogs.

Dinosaur – derived from the Greek deinos meaning ‘terrible’ and sauros meaning ‘lizard’. It was used to convey a sense of appreciation for the size and magnificence of the fossils.

Reference: http://membean.com/wrotds/morph-shape

Further Reading: http://www.britannica.com/EBchecked/topic/21208/Amon

Image Credit: www.paleoart.com

Continental Crumple Zone: Zagros

The Arabian tectonic plate and the Eurasian plate meet in continental collision at the Zagros mountain range in southwest Iran. The Zagros are among the world’s most seismically active mountains, formed as a “fold-and-thrust” belt around 1500km long and 300 km wide. Part of the Alpine-Himalayan belt, Earth’s crust is shortening at up to 9 mm per year at the Zagros Mountains, accommodated as both thrust faults in the basement rocks and folds in the overlying sediments.

This Landsat image shows a small part of the Zagros Mountains, bordered to the southwest by the Persian Gulf. The crests of anticlines rise up, formed as closed folds. They are expressed as mountain ridges running NW-SE, like a crumple zone as the crust shortens SW-NE. Recent sediments that run off the anticline ridges hide the synclines between them. They fill the valleys, seen here with their meandering rivers.

The Zagros anticlines are famous as petroleum sources. Impermeable layers of shale and marl in the folded sediments trap hydrocarbons in reservoir limestones and sandstones beneath. The oil and gas rises and is trapped at the crests of the anticlines. The accumulated petroleum reservoirs represent a significant fraction of the world’s oil and gas reserves.

~SATR

Image: Landsat 7 image of the Mand River and town of Konari within the Zagros Mountains of western Iran (credit: USGS/NASA)

Links:

Talebian & Jackson, (2004) doi:10.1111/j.1365-246X.2004.02092.x

McQuarrie (2004) doi:10.1016/j.jsg.2003.08.009

Petroleum in quartz Unusual inclusions these, and they have the added bonus of making the usually inert quartz glow in UV light since crude oil fluoresces (for an explanation of this phenomenon see http://tinyurl.com/kebod3b). They form when hot hydrothermal fluids rich in silica flow in oil containing rocks and precipitate there in pores and gaps, forming crystals such as this Herkimer diamond type pair with petroleum trapped in the cavities within the crystal. This specimen comes from Pakistan, and measures 3.6 cm across. Loz Image credit: http://betweenarockandaheartyplace.blogspot.com/2012/02/quartz-with-petroleum-inclusions.html

Asphalt

According to the US Department of transportation, 90% of the paved surfaces in the United States are held together using one material – asphalt. Asphalt is a thick hydrocarbon rich substance that is a solid at room temperature but can flow over long timescales or at high temperatures – see the legendary “pitch drop” experiments here: https://tmblr.co/Zyv2Js1HpF_qe.

Because asphalt is able to flow at high temperatures, the chemistry of an asphalt mix needs to be tuned to the local climate. Asphalt grades for local areas are based on the average yearly high and low temperatures over decade long periods. Average road lifetimes are expected to be nearly 20 years. But, if asphalt isn’t appropriately tuned to the local temperatures, roads will degrade more rapidly than expected. A highway like this one in Death Valley has to be built for higher temperatures. building this road to those temperature levels is more expensive than building roads for colder climates, and if the roads aren’t built for the right temperature they will fail and crumble sooner than expected. The average expenditure on road repair by governments per year is about $40 billion dollars, so if roads are even a few percent less reliable than predicted, the total cost is going to be in the billions per year.

A new paper published in the journal Nature Climate Change by researchers from Arizona State combined construction records with weather records from the last decade and found that, largely due to temperature changes in the past decade, up to 35% of roads are constructed for temperatures below those actually observed. Most of these roads are in areas that no longer get as cold at night as expected. This misfit is exactly what would happen if temperatures were increasing due to increasing greenhouse gases in the atmosphere, which have the strongest warming effect at night.

As of right now, this difference in temperatures is likely leading to road degradation costs on the order of tens of millions of dollars per year to repair and replace roads early. Teaming these analyses with climate models to predict how the weather will change with continued greenhouse gas buildup and warming leads the scientists to suggest that by the latter half of the 20th century, maintaining current roads will cost more than a billion dollars extra per year nationwide if asphalt remains a primary ingredient and roads are constructed based on historic temperature baselines.

-JBB

Image credit: tsaiproject https://flic.kr/p/grfUyz

Original paper: https://www.nature.com/articles/nclimate3390_ _

Watch for the bubbles in this enhydro quartz - they move around as they turn the crystal.

CLEANING UP OIL SPILLS WITH COTTON

The April 20, 2010 explosion on the BP Deepwater Horizon drilling platform dumped more than 200 million gallons of crude oil into the Gulf of Mexico and killed 11 people; the catastrophe also created far-reaching environmental consequences that are still observed to this day. There have been many ideas proposed for cleanup since the disaster. They ranged from chemical oil dispersants such as the controversial Corexit, to breakdown by bacteria native to the Gulf, and even included rebuilding damaged oyster reefs and dunes in the region. According to a new study published in the journal Industrial & Engineering Chemistry Research, low-grade cotton may be another viable option in cleaning the devastation caused by oil spills.

According to the researchers involved in the study, low micronaire cotton, which is a very low-quality type of the material, is very effective at absorbing oil. This cotton is grown in West Texas, and represents about 10% of the cotton crop. Since it does not take in dye as well as some other forms of cotton, it is not often used on a wide scale for clothing production. The substance is more effective at oil absorption than higher-quality cotton and synthetic cotton-like materials. A 0.45 kg (1 lb) piece of this cotton can take in more than 13.6 kg (30 lbs) of oil. The material is finer in texture than other types of cotton, so it has more fiber packed per unit area. This helps the oil stick to its surface, and even helps the cotton absorb the oil; when it absorbs the oil, it swells. In addition, the cotton is waxy, which helps it to repel water when picking up the oil. This uptake technique is excellent for removing crude oil from wetland environments like the Gulf of Mexico. Crude oil is challenging to remove due to its high density and its release of toxic fumes. Since this cotton is able to easily remove this type of petroleum, it may be an option for cleaning future spills.

In addition to being effective at picking up and absorbing oil, the cotton is biodegradable. The cotton’s usefulness is also beneficial for cotton farmers, since it provides a use for an otherwise discounted crop. Its low environmental impact as well as its economic benefits may make low micronaire cotton a viable option for further Gulf of Mexico cleanup and for future devastation from oil spills.

-Jeanne K.

Photo courtesy of Petty Officer 3rd Class Patrick Kelley on Defense Video & Imagery Distribution System, via Flickr Creative Commons. The photo shows a worker cleaning oily waste on Elmer’s Island, which is west of Grand Isle, Louisiana. The photo was taken on May 21, 2010.

References: http://pubs.acs.org/doi/abs/10.1021/ie4005942

http://today.ttu.edu/2013/05/low-grade-cotton-brings-top-value-in-oil-spill-cleanup/

http://www.sciencedaily.com/releases/2013/05/130516123659.htm

http://blog.nwf.org/2011/06/gulf-restoration-tour-finishes-on-a-high-note/

http://www.nwf.org/What-We-Do/Protect-Habitat/Gulf-Restoration/Oil-Spill.aspx

For more information on studies conducted to clean the BP Deepwater Horizon leak, please see: https://www.facebook.com/photo.php?fbid=504622866265429&set=pb.352857924775258.-2207520000.1369168675.&type=3&theater

For more information on wildlife affected by the BP Deepwater disaster in the Gulf of Mexico, please see: https://www.facebook.com/photo.php?fbid=501285109932538&set=pb.352857924775258.-2207520000.1369168719.&type=3&theater

Sale is probably no longer going on so don’t contact the poster...but neat. Glowing quartz crystal, due to inclusions trapped inside it that fluoresce. 

Geology and Nomenclature: Why some names kick ass

I always appreciate a clever name or at least one that is descriptive of the object at hand. A firm favourite is roche moutonnée, a glacial feature which literally translates as ‘rock sheep’ due a pockmarked surface that resembles a particularly ragged sheep’s fleece.

So what other cool names are out there? I’ve compiled a short list of my favourites below but if you know of others feel free to enlighten us in the comments! Petroleum – comes from the Latin petra meaning ‘rock’ and oleum meaning oil. Literally means rock oil.

Ammonite – derived from the name of the Egyptian god Amon who was often depicted with ram horns or a full ram’s head. It was thought that the fossils looked like his tightly coiled horns!

Protolith – comes from the Ancient Greek protos meaning ‘first’ and the word lithos meaning ‘stone’ or ‘rock’. Literally translates to first rock, a very apt name as it is used to describe a metamorphic rocks original rock type before transformation.

Metamorphic – Comes from the Greek meta which means ‘change’ and morph which translates as ‘form’. The ‘-ic’ indicates that we are talking about the ‘nature of changing form’ whereas ‘-osis’ would suggest we are talking about the ‘process of changing form’.

Sedimentary – thought to be derived from the Latin word sedimentum meaning ‘settling’.

Igneous – derived from the Latin word ignis which means ‘fire’. The suffix ‘-eous’ means ‘composed of’ meaning igneous literally translates as ‘composed of fire’.

Echinodermata – Groups of animals with radial symmetry including starfish, sea urchins and sea lillies. Comes from the Greek echinos meaning ‘hedgehog’ and derma meaning ‘skin’ to describe fossilised sea urchins as their spines reminded geologists of a hedgehogs.

Dinosaur – derived from the Greek deinos meaning ‘terrible’ and sauros meaning ‘lizard’. It was used to convey a sense of appreciation for the size and magnificence of the fossils.

Reference: http://membean.com/wrotds/morph-shape

Further Reading: http://www.britannica.com/EBchecked/topic/21208/Amon

Image Credit: www.paleoart.com

Seismic Interpretation: Learning to Read between the Lines

Ever wondered how geologists study rocks buried thousands of metres below the surface? Or how oil and gas companies find hydrocarbons when drilling under the sea floor? The answer lies in the study of subsurface reflections known as seismic. These surveys have revolutionised our understanding of underlying strata and have been instrumental in many of the world’s oil and gas discoveries.

The seismic section below is from offshore Morocco and comprises numerous reflections representing changes in the subsurface. Contrary to popular belief the different reflections do not necessarily reflect changes in lithology (rock type), and are in fact the product of changing densities and velocities between two horizons.

For example, if a seismic wave hits the surface between a shale and a sandstone, then the differences in acoustic impedance (density x velocity) of the two layers will cause a reflection. The stronger the difference between the two layers the stronger (and brighter) the reflection will be. Going from a hard rock to a soft rock will produce a negative reflection (in most cases blue) whereas a transition from soft to hard will give a positive (normally red) response.

However, a seismic wave hitting a cemented horizon within a sandstone (the pore space being infilled with cement increases the velocity and the density of the rock) will also create a reflection, despite the rock type remaining the same.

Furthermore, because the reflection strength and polarity are dependent on the relationship between the two layers there is no hard and fast rule as to what lithologies are being imaged without well data or prior knowledge of the area.

Looking at the seismic section below you can see that the data has been annotated with the time in seconds along the vertical axis. This is the time it takes for a reflection to reach a horizon and return to the surface, and is called the Two Way Travel Time (TWTT). In areas of very complex geology or where companies wish to increase the accuracy TWTT can be converted to depth, removing any artifacts produced by velocity anomalies.

So what does seismic tell us? It can highlight structures within the subsurface such as faults or folds, as well hinting at the environment of deposition. With this it is possible to start narrowing down the lithologies involved and a rough geological history can be constructed. As can be seen below an entire cross section through the geology can be inferred, although this takes time, practice and a fair bit of patience!

References: http://aapgbull.geoscienceworld.org/content/94/5/615.abstract

Further Reading: http://www.aapg.org/publications/news/explorer/column/articleid/2471/what-is-seismic-interpretation http://140.115.21.141/download/courses/sequence_strat/10_seismic_stratigraphy.pdf

Image Credit: Dunlap et al, 2010 http://aapgbull.geoscienceworld.org/content/94/5/615.abstract

Oil FAQs Ever wondered how oil and whiskey are related? Curious as to whether we’re running out of oil? Are the oil majors hiding the fact that they can’t find any more oil? And where do you store your countries emergency oil in case of an apocalypse? All the answers and more are below: 1. Why is Oil measured in 42 US gallon barrels? America was one of the first countries to start producing oil and they needed a way to store and transport it. One of America’s big exports was whiskey and therefore the oil producers would use empty whiskey barrels to transport their crude. In truth any empty, water tight barrel would do but there were plenty of empty whiskey barrels to go around and people were more inclined to empty whiskey barrels than those filled with fish or other such delights. But why 42 gallons? This goes back to England’s King Richard III who decreed a wine puncheon to be an 84 gallon cask and a tierce as holding 42 gallons (159 litres). As a 42 gallon of crude weighed over 300 pounds (136.4kg) it was decided that a barrel any larger than this would be unmanageable and that any less would be uneconomic to transport. 2. Is the world running out of oil? This is a little tricky to calculate as some countries/companies will openly state their reserves, others will provide exaggerated figures and some will provide no data at all. However in 1993 there were 1041.4 Bbbl (billion barrels) of proved reserves globally, in 2003 that climbed to 1334.1 Bbbl and by 2013 the figure was 1687.9 Bbbl. Furthermore, predictions for when we would run out of oil have been surpassed multiple times. In 1874 it was predicted the world would run out of oil by 1878, in the 1970s it was predicted oil would run out in 2000 (30 years) and now it is predicted that we have enough conventional reserves (those that do not include unconventionals such as fracking, tar sands, heavy oils etc) to last another 50 years. This is predominantly down to better technology and a greater understanding of the geology in the subsurface. 3. Can companies replace their reserves at the rate they produce? This is also tricky; some companies focus on exploration, discovering new fields in areas where oil had yet to be found. Other companies, such as the oil majors, have reigned back on exploration for the last few years, focussing on maximising the output of their current fields. In 2013 BP had a reserves replacement ration of 0.77, described as being abnormally low as the company had succeeded in averaging above 100% in the last 20 years. Shell also saw problems in 2013 with its fourth quarter reserves replacement ratio only 0.44. As you can see this varies from company to company, with some companies replenishing their reserves faster than they produce and vice versa. 4. Do governments hoard emergency oil for a rainy day? Yes, you wouldn’t want to run out of oil half way through the apocalypse now would you? The American Government can store up to 727mmbol (million barrels) within four deep underground storage caverns that have been carved out of salt domes on the Texas and Louisiana Gulf Coasts. And America aren’t the only ones; according to EU legislation each EU country must hold oil stocks exceeding 90 days’ worth of imports ( for non-producing countries) or 61 days of daily consumption ( for oil producing countries). The UK government therefore requires companies producing, refining or selling oil within a useable form (as diesel, petrol, aviation fuel) to always have a certain percentage of those products on hold in case of emergencies. This means that a large proportion of the UK’s emergency reserves are actually held in stock tanks below petrol stations. References: http://aoghs.org/transportation/history-of-the-42-gallon-oil-barrel/ http://www.ft.com/cms/s/0/91b14e18-6b7a-11e2-8c62-00144feab49a.html#axzz3OhHm1g16 http://www.ft.com/cms/s/0/e37c4e64-8745-11e2-9dd7-00144feabdc0.html#axzz3OhHm1g16 http://energy.gov/fe/services/petroleum-reserves/strategic-petroleum-reserve#Current http://bit.ly/1BepH4o Further Reading: http://www.bp.com/content/dam/bp/pdf/Energy-economics/statistical-review-2014/BP-statistical-review-of-world-energy-2014-full-report.pdf

Who controls the oil price? In June 2014 the price for a barrel of Brent crude was $118 but today it is less than half that at $51.12. The big question is what has caused this drop and who, if anyone, controls the price in the future? The price of oil, like any commodity, varies according to demand and supply. When demand outstrips supply the price increases and vice versa. So how did the world go from a global deficit to a global surplus in just six months? For this there is no straight forward answer as governments and oil majors are often secretive of their intentions and future plans. The information below is purely a summary of ideas and concepts from business and financial analysts as well as some ex-industry employees. So, let’s start with demand: Global demand was set to continue increasing due to population growth and a greater consumption of oil from developing countries. However, Europe is still in the grip of a financial downturn and with the IMF predicting that the EU has a 40% chance of another depression demand from these countries has fallen. More importantly it has also fallen in rapidly developing countries such as China, leading to a decrease in global demand that bucks every predicted trend out there. In short in the last 6 months the world just hasn't been consuming as much oil as everyone thought it would. Then there is the conundrum of supply. The US oil boom has meant that America has almost ceased importing oil and has converted its refineries from import into export. This means there is a surplus of oil on the market, but this was not expected due to the growing unrest in the middle east. Wars in Libya and the conflicts caused by ISIS were predicted to cause countries such as Iraq and Libya to ‘go offline’ (stop producing oil). However, for quite some time this was not the case and it was only on the 14th December 2014 that Libya's main oil terminal finally ceased operations. So it’s a simple case of too much oil and too little demand? Unfortunately not, and this is where OPEC comes in. OPEC is a cartel of Oil Producing and Exporting Countries led by Saudi Arabia and including Algeria, Angola, Ecuador, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Venezuela and the United Arab Emirates. Since 1960 this cartel has effectively regulated the price of oil, cutting production when demand was low and increasing it when it rose. Each country receives a quota of oil to produce that is a percentage of that country’s total reserves. So why has OPEC not reigned in production to curb the falling oil price? Well this is where politics get involved and conspiracy theorists get excited. Here are three proposed reasons why OPEC has not cut production, and each one is as plausible as the next. 1) OPEC is trying to drive the US oil shale companies out of business The discovery of the Eagle Ford and Bakken fields have meant that the US could become the world’s largest producer of oil. This obviously threatens OPECs monopoly and they might be driving the oil price down so that production in the US becomes uneconomical. However, this means that OPEC too is losing money, which while not a problem from Kuwait, Qatar and Saudi Arabia in the short term, could cripple countries such as Nigeria whose economy depends on oil revenue. 2) OPEC and the US are working together to punish Russia Saudi Arabia and the US are on good terms and recently Russia has acted in a way that has riled both of them. Russia has reopened a cold war base on an island off the coast of the US as well as “reclaiming” parts of Europe that have been recognised as independent countries by the west. Furthermore, Russia’s move to support Syria during the ongoing disturbances did nothing to improve its relations with Saudi Arabia. Russia’s income depends almost solely on the sale of its vast oil and gas reserves and by driving the price down, the US and Saudi Arabia are hurting Russia far more than any of the European imposed sanctions. 3) Saudi Arabia is reminding OPEC’s members to play by the rules As previously stated each country is given a quota or a certain amount of barrels of oil to produce that must not be exceeded. Earlier in 2014 several of the countries such as Nigeria and Iran surpassed their quotas to capitalise on the high oil price. Furthermore many of the countries have conflicting views on how the cartel should be operating. It has been proposed that Saudi Arabia is now attempting to punish these countries for their disobedience by driving the price down, crippling their economies and causing them to reign back on production. Regardless of the cause, if exporting countries don’t curb their production while demand is low the price will continue to fall. So enjoy the low petrol prices while you can as the oil price could rise as again as quickly as it fell! - Watson  References: http://www.ft.com/cms/s/0/dcdab458-86c4-11e4-8a51-00144feabdc0.html http://www.ft.com/cms/s/0/bcf89006-5096-11e4-b73e-00144feab7de.html Further Reading:http://www.ft.com/cms/s/0/86916314-8776-11e4-bc7c-00144feabdc0.html http://www.ft.com/cms/s/2/3f5e4914-8490-11e4-ba4f-00144feabdc0.html http://www.ft.com/cms/s/0/a2bf0be8-929a-11e4-9e68-00144feabdc0.html http://www.ft.com/cms/s/0/9ab77884-57cd-11e4-8493-00144feab7de.html

Mount Kenya is the 2nd highest peak in Africa and the highest in Kenya. Like most mountains near the tropics, it has seen huge retreats of its glaciers over the past century as greenhouse gases in the atmosphere have increased - over 90% of the glacier area on Mount Kenya has vanished in the last 80 years. British photographer Simon Norfolk decided a new way to document these changes, too subtle to see on any single day, would be to outline the former edges of the glaciers. To illustrate the relationship between the shrinking glaciers and fossil fuels, he lit the former edges of the glaciers using petroleum.  Also a particularly fun scene of him defrosting his camera gear. 

From Phytoplankton to Jet Fuel As you may know, petroleum forms from dead plants and animals which were buried millions of years ago under water. What most of us don’t know is exactly how and why this process works. Petroleum formation is actually a lot like cooking. You start with the ingredients, turn up the heat and set the timer. The basic required elements are: organic matter (ingredients), a source rock (oven) and time.  Firstly an oil- or gas-prone source rock must be formed; this is our oven. Under normal marine conditions, where the organisms which die are scavenged, very little organic matter remains to be buried on the sea floor and therefore little to turn into petroleum. So where do the ingredients come from? There are two main ways to disrupt this cycle: (1) periods of high biological activity at the surface such as an algal bloom, and (2) the development of anoxic (oxygen poor) conditions at depth which greatly reduce the number of scavengers. Once the organic matter is actually buried, we’ve got our ingredients. As the organic matter is buried under more and more layers of sediment, the temperature and pressure increase. The pressure increase is due to the weight of the overlying sediment whilst the temperature naturally increases with depth below the surface of the Earth; this is known as the geothermal gradient. After the first kilometer or so, the organic matter changes into kerogen.  Kerogen is the most abundant organic component on Earth and can be used to describe the collection of complex organic compounds depended on the original source organism.   These increases in temperature and pressure continue, ‘cooking’ the kerogen. At a depth of around 3-4km/100°C, the chemical bonds in the kerogen begin to break in a process known as catagenesis. Here the kerogen is within the ‘oil window’; the conditions where kerogen is converted to oil. With further depth the temperature will increase moving the kerogen into the ‘gas window’, where it is instead converted to methane a.k.a. natural gas. Whether the kerogen will produce oil or gas is dependent on several factors principally kerogen type and depth of burial.  It’s just like cooking; you get out what you put in, it’s all about how you cook it, and all good things come to those who wait. -LO Photo courtesy of Ian West, University of Southampton

How Deep do we Drill for Oil? Deeper every year as the easy shallow oil is depleted and drilling technology evolves. In 1949, the average depth for an oil well was 1108 m (3,635 ft), or about the half the height of the highest of the Appalachians above sea level. By 2008, the average well was about 1830 m (~6000 ft), now getting a high as some of the highest peaks of the Appalachians (~6000 ft). Oil platforms of today, in the deep oceans, exploit reservoirs at several km depth -- 2.850 km below the waves for the Perdido platform in the Gulf of Mexico. The Deepwater Horizon, before blowing out and spewing its petroleum throughout the Gulf, was capable of drilling in water as deep as ~2500 m, and reach oil at a depth of ~9,100 km. That is, to keep this to a scale we can somewhat comprehend, these wells are capable of reaching depths below sea level about equivalent to the height of Mt Everest above sea level, deeper in fact than the Marianas Trench. What limits the drilling depths? Technology can be advanced, but technology costs money. So, the price of crude is a major limiting factor. But as well, petroleum itself reaches a depth limit: at high pressures and temperatures, oil breaks down, probably converting to gas. The point of this conversion is variable around the planet, depending on such things as the thickness of the crust and its regional heat flow.  Recognized as the world’s deepest well is the Soviet Era Kola Borehole of Siberia that went down 12 km into the earth’s crust to literally go where no man has gone before (see our post here: http://tmblr.co/Zyv2Js1FTDFmX). This hole was not for oil, but for scientific exploration: it went into rocks of the Archean, found microfossils, didn’t find a change in rock type from granite to basalt that had been the accepted consensus model before this hole, and shut down when it came to a place where rocks become ductile enough that they really could be drilled anymore.  Annie R Read also: http://science.howstuffworks.com/environmental/energy/underground-oil-deposits.htm http://www.theglobeandmail.com/report-on-business/industry-news/energy-and-resources/offshore-oil-rigs-drilling-deeper-than-ever/article4481035/ http://rt.com/business/exxon-sakhalin-well-record-727/ http://www.atlasobscura.com/places/kola-superdeep-borehole Image Source: Downloaded from http://xkcd.com/

Oil Series Part 3- Locating and Extracting At this stage you have a complete petroleum system. Over thousands of years the trap accumulates more and more petroleum becoming what is known as “charged”. This is what petroleum geologists want! Other geological processes such as plate tectonics and sea level rise/fall going on throughout this period means that the systems can be found on land or at sea today.  The first thing geologists look for is what’s known as sedimentary basins (sites of large sediment accumulation and burial) where vast reservoir rocks are found. The petroleum systems in these more modern times are located by a whole arsenal of quite complex tools such as geological mapping, satellite imagery, wire logging, core sampling, gravity, magnetic and seismic surveys (see links for more on this). Once data has been collected through these tools it is fed through powerful computers and their software modeling programs, which are able to transform the numerical and 2D data into a 3D model of the area below the surface. Calculations such STOIIP (see links) can be made to determine the size of each system and whether it is cost effective to continue. Also depending on how remote the area and/or how deep the water is can dramatically affect the future profit. Should the oil company deem it sufficiently profitable they normally bid on government owned blocks to acquire drilling rights to that area. Infrastructure such as pipelines, roads drilling platforms and workers accommodation must be designed and built around the area before full scale drilling can begin.  By this point other companies would be onto the find and be moving into the areas nearby. If the company can set up a pipeline first they can charge others for use and regain some of the initial costs. Once everything has been set up and a workforce established drilling begins, bringing the endeavor into the stage known as production. Part 4 will focus on declining extraction rates, peak oil and other petroleum-based alternatives. -Matt J This is part 3 of a mini series on oil, if you haven’t already please read part 1 and 2 of the story. Part 2 is here and links to part 1: http://www.facebook.com/photo.php?fbid=426164590777924&set=a.352867368107647.80532.352857924775258&type=1&theater More on techniques used to locate the oil: http://science.howstuffworks.com/environmental/energy/oil-drilling2.htm STOIIP calculation: http://en.wikipedia.org/wiki/Oil_in_place Photo courtesy of http://gazprom-sh.nl/sakhalin-2/

We're going through the Earth Story's sequence of posts on oil geology. Here you can see an example of how oil is formed and trapped in the ground when black shales (kerogen) are deposited, buried, and heated to generate free hydrocarbons, and how those hydrocarbons migrate as the rocks are folded and faulted.

This is part 2 of a mini series on oil, if you haven’t already please read part 1 of the story which can be found by either scrolling down or clicking here: http://www.facebook.com/photo.php?fbid=425744824153234&set=a.352867368107647.80532.352857924775258&type=1&theater Part 2- Migration and Trapping Hydrocarbons once formed begin to be expelled from the mature source rock, they are also less dense than water (why you see hydrocarbons at the surface after an oil spill) so tend to migrate upwards through small fractures and spaces in the rock. For a successful petroleum system to occur the hydrocarbons must migrate upwards from the source rock into a permeable and porous rock also known as a reservoir rock. A good example of a reservoir rock is porous sandstone. Unlike what many people imagine the oil is only very rarely found pure in underground caves but is instead found between the individual grains in what is known as pore space within the porous rock. The petroleum must also be trapped above the reservoir rock; this is very important without trapping the hydrocarbons migrate all the way to the surface of the ocean and disperse.  A hydrocarbon trap is a naturally occurring impermeable cap rock feature that prevents the escape allowing concentration to build up. There are a number of different ways this can occur in nature (See links for more); one of the most common is a 4-way dip closure fold trap. A 4-way dip closure is a 3D structure (sometimes shown in 2D as an anticline fold) that best resembles an upside down bowl. The hydrocarbons cannot pass through this impermeable cap rock layer and cannot escape round the sides as the layer is curved downwards in all directions so they become trapped, this can occur on massive scales spanning many 10s of kilometers.  Part 3 will look at locating the trapped hydrocarbons. -Matt J Photo courtesy of http://www.universalfuels.co.uk/ More on traps and reservoir rocks: http://www.mpgpetroleum.com/fundamentals.html