Where is shale

Most fossils are found in sedimentary rock. The fossils formed when sediments covered dead plants and animals. As the sediments changed to rock, either the remains or the outlines of the plants and animals were preserved. Some limestone is made entirely of fossil shells.

Shales that are subject to heat and pressure alter into a hard, fissile, metamorphic rock known as slate , which is often used in building construction.

Resources "shale". Chambers Dictionary of Science and Technology. Chambers Harrap Publishers Ltd. Rocks: Materials of the Lithosphere - Summary. Retrieved on Jenson Vanities James Martin Vanities. Design Services What's New? Oil and natural gas can migrate out of the shale, moving upwards where they are trapped within the pores of some other rock—such as sandstone.

These deposits are known as conventional reservoirs since the fluid flows easily through the pores of the rock. Although drilling to extract oil and natural gas is possible, a large amount is still trapped inside the pore spaces of the shale. This oil and gas is difficult to remove, and it takes unconventional methods to access this oil and gas. Pore spaces in shale are extremely tiny, and because of this gas cannot easily move out of the shale.

However, some gas can be released through hydraulic fracturing , a method where water and chemicals are pumped down a well under pressure to fracture the shale. In addition, horizontal drilling was found to help with the release of natural gas trapped in shale.

Like most rocks, the color of shale is often determined by the presence of specific materials in minor amounts. Just a few percent of organic materials or iron can significantly alter the color of a rock. Shale gas plays: Since the late s, dozens of previously unproductive black organic shales have been successfully developed into valuable gas fields. See the article: " What is Shale Gas? 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. Any oxygen that entered the environment quickly reacted with the decaying organic debris. If a large amount of oxygen was present, the organic debris would all have decayed. An oxygen-poor environment also provides the proper conditions for the formation of sulfide minerals such as pyrite , another important mineral found in most black shales.

The presence of organic debris in black shales makes them the candidates for oil and gas generation. If the organic material is preserved and properly heated after burial, oil and natural gas might be produced. The Barnett Shale, Marcellus Shale , Haynesville Shale , Fayetteville Shale , and other gas-producing rocks are all dark gray or black shales that yield natural gas. Gray shales sometimes contain a small amount of organic matter.

However, gray shales can also be rocks that contain calcareous materials or simply clay minerals that result in a gray color. Utica and Marcellus Shale: Two black organic shales in the Appalachian Basin are thought to contain enough natural gas to supply the United States for several years. These are the Marcellus Shale and Utica Shale. Shales that are deposited in oxygen-rich environments often contain tiny particles of iron oxide or iron hydroxide minerals such as hematite , goethite, or limonite.

Just a few percent of these minerals distributed through the rock can produce the red, brown, or yellow colors exhibited by many types of shale.

The presence of hematite can produce a red shale. The presence of limonite or goethite can produce a yellow or brown shale. Green shales are occasionally found.

This should not be surprising because some of the clay minerals and micas that make up much of the volume of these rocks are typically a greenish color. Natural gas shale well: In less than ten years, shale has skyrocketed to prominence in the energy sector.

New drilling and well development methods such as hydraulic fracturing and horizontal drilling can tap the oil and natural gas trapped within the tight matrix of organic shales. Hydraulic properties are characteristics of a rock such as permeability and porosity that reflect its ability to hold and transmit fluids such as water, oil, or natural gas. Shale has a very small particle size, so the interstitial spaces are very small. In fact they are so small that oil, natural gas, and water have difficulty moving through the rock.

Shale can therefore serve as a cap rock for oil and natural gas traps, and it also is an aquiclude that blocks or limits the flow of groundwater. Although the interstitial spaces in a shale are very small, they can take up a significant volume of the rock. This allows the shale to hold significant amounts of water, gas, or oil but not be able to effectively transmit them because of the low permeability.

The oil and gas industry overcomes these limitations of shale by using horizontal drilling and hydraulic fracturing to create artificial porosity and permeability within the rock.

Some of the clay minerals that occur in shale have the ability to absorb or adsorb large amounts of water, natural gas, ions, or other substances. This property of shale can enable it to selectively and tenaciously hold or freely release fluids or ions. Expansive soils map: The United States Geological Survey has prepared a generalized expansive soils map for the lower 48 states. Shales and the soils derived from them are some of the most troublesome materials to build upon.

They are subject to changes in volume and competence that generally make them unreliable construction substrates. Oil shale is a sedimentary rock. As it reaches its oil window, oil shale releases a liquid known as shale oil. Oil shale is the rock from which shale oil is extract ed. Shale oil is similar to petroleum, and can be refined into many different substances, including diesel fuel, gasoline , and liquid petroleum gas LPG.

Companies can also refine shale oil to produce other commercial products, such as ammonia and sulfur. The spent rock can be used in cement. Oil-bearing shale s are underground rock formations that contain trapped petroleum. Companies extracting tight oil often use hydraulic fracturing fracking , while companies extracting shale oil most often use heat.

The Bakken formation , for example, is made of oil-bearing shale. It is a series of layered shale rocks with a petroleum reservoir trapped between the layers. The Bakken formation stretches from the province of Saskatchewan, Canada, through the U.

Improved drilling technologies have allowed companies to extract oil from the Bakken formation, creating an economic boom in the region. Oil shales are often classified by their depositional history and mineral content. The depositional history of an oil shale includes the organisms and sediments that were deposited, as well as how those deposits interacted with pressure and heat.

The van Krevelen Diagram is a method of classifying oil shales based on their depositional history. The diagram divides oil shales according to where they were deposited: in lakes lacustrine , in the ocean marine , or on land terrestrial.

Oil shales from lacustrine environments formed mostly from algae living in freshwater, saltwater, or brackish water. Lamosite and torbanite are types of oil shales associated with lacustrine environments. Lamosite deposits make up some of the largest oil shale formations in the world. Oil shales from marine environments formed mostly from deposits of algae and plankton. Kukersite, tasmanite, and marinite are types of marine shales. Tasmanite is named after the region in which it was discovered, the island of Tasmania, Australia.

Marinite, the most abundant of all oil shales, is found in environments that once held wide, shallow seas. Although marinite is abundant, it is often a thin layer and not economically practical to extract. The largest marinite deposits in the world are in the United States, stretching from the states of Indiana and Ohio through Kentucky and Tennessee.

Oil shales from terrestrial environments formed in shallow bog s and swamp s with low amounts of oxygen. The deposits were mostly the waxy or corky stems of hardy plants. Cannel coal was used primarily as fuel for streetlights and other illumination in the 19th century. Oil shales are classified in three main types based on their mineral content: carbonate-rich shale, siliceous shale, and cannel shale.

Carbonate-rich shale deposits have high amounts of carbonate minerals. Carbonate minerals are made of various forms of the carbonate ion a unique compound of carbon and oxygen. Calcite, for instance, is a carbonate mineral common in carbonate-rich shales. Calcite is a primary component of many marine organisms. Calcite helps form the shells and hard exteriors of oysters, sea stars, and sand dollars.

Plankton, red algae, and sponges are also important sources of calcite. Siliceous shale is rich in the mineral silica, or silicon dioxide. Siliceous shale formed from organisms such as algae, sponges, and microoganisms called radiolarians.

Algae have a cell wall made of silica, while sponges and radiolarians have skeletons or spicule s made of silica. Siliceous oil shale is sometimes not as hard as carbonate-rich shale, and can more easily be mined.

Cannel shale has terrestrial origins, and is often classified as coal. It is made up from the remains of resin, spores, and corky materials from woody plants. It can contain the minerals inertinite and vitrinite.

Cannel shale is rich in hydrogen, and burns easily. People have been using oil shale for thousands of years. Ancient Mesopotamia ns used shale oil to pave roads and caulk ships.

Ancient Mongolians dipped the tips of their arrows in shale oil during battles, sending flaming arrows at their enemies. In the Middle East, sticky shale oil was even a component of decorative mosaic s. The modern shale industry began in the 19th century.