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A typical shale is composed of about 58% clay minerals, 28% quartz, 6% feldspar, 5% carbonate minerals, and 2% iron oxides. Most of the quartz is detrital (part of the original sediments that formed the shale) rather than authigenic (crystallized within the shale after deposition).
What is the chemical composition of shale?
The data derived from these analyses indicate that the average mineralogical composition of shale is: 30.8 percent quartz, 4.5 percent feldspar, 3.6 percent carbonate, <0.5 percent iron oxides, 60.9 percent clay minerals, 1 percent organic material, and 2 per- cent other materials.
What are the main minerals in shale?
Shale is a sedimentary rock composed of very fine clay particles. Clay forms from the decomposition of the mineral feldspar. Other minerals present in shale are quartz, mica, pyrite, and organic matter.
What are the advantages of shale oil?
Shale oil production makes the United States more energy independent. Storing barrels of shale oil helps prices remain more stable. Shale oil extraction (fracking) benefits from innovative drilling techniques. Fracking causes ecological damage to the environment.
Where are oil shale found?
The largest deposit of oil shale in the world is found in the Green River basin of Colorado, Utah, and Wyoming. It contains the equivalent of about 1.5 trillion barrels of shale oil.
Is shale a strong rock?
Shale is a hardened, compacted clay or silty clay that commonly breaks along bedding planes some of which are no thicker than paper. The best exposures are found beneath ledges of harder more resistant rocks such as limestone and sandstones. Most shales are soft enough to be cut with a knife and can be very brittle.
Is oil found in shale?
Oil-bearing shales are underground rock formations that contain trapped petroleum. The petroleum trapped within the rocks is known as “tight oil” and is difficult to extract. Companies extracting tight oil often use hydraulic fracturing (fracking), while companies extracting shale oil most often use heat.
Is shale good to build on?
Rock. Solid rock, such as crystalline bedrock, bears the most weight of any type of soil, making it one building option. However, some types of sedimentary rock, such as shale, are not always a safe option on which to build. In time, sedimentary rock can break apart, causing the ground to shift beneath your structure.
What is the properties of shale?
Shale is a fine-grained rock made of compressed mud and clay. The defining characteristic of the shales is its fragility. In other words, shale is easily divided into thin layers. Black and gray shales are common, but the rock can appear in any color.
Where is black shale found?
Most black shales are found in marine sediments (Potter et al., 1980), but they can also form prominent deposits in lacustrine successions (Bohacs et al., 2000). Their black color is due to two constituents: (1) the contained organic matter, and (2) finely disseminated pyrite.
When was black shale formed?
The black shales deposited in the early Aptian around 120 million years ago, and at the Cenomanian-Turonian boundary around 94 million years ago,2,5,12–14) have a global distribution and an extraordinarily high organic carbon content.
How is black shale formed?
A black color in sedimentary rocks almost always indicates the presence of organic materials. Just one or two percent organic materials can impart a dark gray or black color to the rock. In addition, this black color almost always implies that the shale formed from sediment deposited in an oxygen-deficient environment.
How long will US shale oil last?
It’s closing in on the 2 million barrels a day produced by Texas. In 20 years, its number of wells could increase from the current 8,000 to at least 40,000. Part of the reason for expansion is that each well runs dry after about two years.
Is shale formed chemically?
Oil shales consist of solid organic matter entrained in an inorganic mineral matrix. Chemically, the mineral content consists primarily of silicon, calcium, aluminum, magnesium, iron, sodium, and potassium found in silicate, carbonate, oxide, and sulfide minerals.
What is shale and its uses?
Shale has many commercial uses. It is a source material in the ceramics industry to make brick, tile, and pottery. Shale used to make pottery and building materials requires little processing besides crushing and mixing with water. Crushing shale and heating it with limestone makes cement for the construction industry.
What does Black shale indicate?
Black shale results from the presence of greater than one percent carbonaceous material and indicates a reducing environment. Pale blue to blue-green shales typically are rich in carbonate minerals. Clays are the major constituent of shales and other mudrocks.
What kind of rock is shale?
Shale rocks are those that are made of clay-sized particles and are have a laminated appearance. They are a type of sedimentary rock. Shale is the abundant rock found on Earth. They are usually found in areas where gentle waters have deposited sediments that become compacted together.
How do you identify black shale?
Black shales are dark-colored, usually thinly laminated mudstones containing appreciable organic matter (>0.5 wt% C), authigenic iron sulfides and, silt- and clay-sized detrital particles that in most cases have been accumulated under anoxic bottom water and/or bottom sediment conditions in marine or continental
Which country has the largest shale oil resources?
Russia has the biggest shale oil reserves in the world.
Is shale oil better than crude oil?
Shale oil is a substitute for conventional crude oil; however, extracting shale oil is more costly than the production of conventional crude oil both financially and in terms of its environmental impact. Deposits of oil shale occur around the world, including major deposits in the United States.
Where is shale most commonly found?
Shales are often found with layers of sandstone or limestone. They typically form in environments where muds, silts, and other sediments were deposited by gentle transporting currents and became compacted, as, for example, the deep-ocean floor, basins of shallow seas, river floodplains, and playas.
