A petroleum reservoir or oil and gas reservoir is a subsurface pool of hydrocarbons contained in porous or fractured rock formations. Petroleum reservoirs are broadly classified as unconventional reservoirs. In case of conventional reservoirs, the occurring hydrocarbons, such as crude oil or natural gas, are trapped by overlying rock formations with lower permeability. While in unconventional reservoirs the rocks have high porosity and low permeability which keeps the hydrocarbons trapped in place, therefore not requiring a cap rock. Reservoirs are found using hydrocarbon exploration methods. A region with an abundance of oil wells extracting petroleum from below ground; because the oil reservoirs extend over a large area several hundred kilometres across, full exploitation entails multiple wells scattered across the area. In addition, there may be exploratory wells probing the edges, pipelines to transport the oil elsewhere, support facilities; because an oil field may be remote from civilization, establishing a field is an complicated exercise in logistics.
This goes beyond requirements for drilling. For instance, workers require housing to allow them to work onsite for years. In turn and equipment require electricity and water. In cold regions, pipelines may need to be heated. Excess natural gas may be burned off if there is no way to make use of it—which requires a furnace and pipes to carry it from the well to the furnace. Thus, the typical oil field resembles a small, self-contained town in the midst of a landscape dotted with drilling rigs or the pump jacks, which are known as "nodding donkeys" because of their bobbing arm. Several companies, such as Hill International, Esso, Weatherford International, Schlumberger Limited, Baker Hughes and Halliburton, have organizations that specialize in the large-scale construction of the infrastructure and providing specialized services required to operate a field profitably. More than 40,000 oil fields are scattered around the globe, on land and offshore; the largest are the Ghawar Field in Saudi Arabia and the Burgan Field in Kuwait, with more than 60 billion barrels estimated in each.
Most oil fields are much smaller. According to the US Department of Energy, as of 2003 the US alone had over 30,000 oil fields. In the modern age, the location of oil fields with proven oil reserves is a key underlying factor in many geopolitical conflicts; the term "oilfield" is used as a shorthand to refer to the entire petroleum industry. However, it is more accurate to divide the oil industry into three sectors: upstream and downstream. Natural gas originates by the same geological thermal cracking process that converts kerogen to petroleum; as a consequence and natural gas are found together. In common usage, deposits rich in oil are known as oil fields, deposits rich in natural gas are called natural gas fields. In general, organic sediments buried in depths of 1,000 m to 6,000 m generate oil, while sediments buried deeper and at higher temperatures generate natural gas; the deeper the source, the "drier" the gas. Because both oil and natural gas are lighter than water, they tend to rise from their sources until they either seep to the surface or are trapped by a non-permeable stratigraphic trap.
They can be extracted from the trap by drilling. The largest natural gas field is South Pars/Asalouyeh gas field, shared between Iran and Qatar; the second largest natural gas field is the Urengoy gas field, the third largest is the Yamburg gas field, both in Russia. Like oil, natural gas is found underwater in offshore gas fields such as the North Sea, Corrib Gas Field off Ireland, near Sable Island; the technology to extract and transport offshore natural gas is different from land-based fields. It uses a few large offshore drilling rigs, due to the cost and logistical difficulties in working over water. Rising gas prices in the early 21st century encouraged drillers to revisit fields that were not considered economically viable. For example, in 2008 McMoran Exploration passed a drilling depth of over 32,000 feet at the Blackbeard site in the Gulf of Mexico. Exxon Mobil's drill rig there had reached 30,000 feet by 2006 without finding gas, before it abandoned the site. Crude oil is found in all oil reservoirs formed in the Earth's crust from the remains of once-living things.
Evidence indicates that millions of years of heat and pressure changed the remains of microscopic plant and animal into oil and natural gas. Roy Nurmi, an interpretation adviser for Schlumberger oil field services company, described the process as follows: Plankton and algae and the life that's floating in the sea, as it dies, falls to the bottom, these organisms are going to be the source of our oil and gas; when they're buried with the accumulating sediment and reach an adequate temperature, something above 50 to 70 °C they start to cook. This transformation, this change, changes them into the liquid hydrocarbons that move and migrate, will become our oil and gas reservoir. In addition to the aquatic environment, a sea, but might be a river, coral reef or algal mat, the formation of an oil or gas reservoir requires a sedimentary basin that passes through four steps: Deep burial under sand and mud. Pressure cooking. Hydrocarbon migration from the sou
Miyako is a city located in Iwate Prefecture, Japan. As of 1 April 2017, the city had an estimated population of 54,573, a population density of 43.3 persons per km2. The total area of the city is 1,259.15 square kilometres. Miyako is located in central Iwate Prefecture, bordered by the Pacific Ocean to the east, with the main urban area fronting on Miyako Bay, it is connected to Morioka by an east-west train line and highway and the coastal highway goes through the town. The city has a small port but much of the shipping traffic is taken by larger cities along the coast. Parts of the coastal area of the city are within the borders of the Sanriku Fukkō National Park, part of the mountainous interior is within Hayachine Quasi-National Park. Over 80% of the city area is covered by mountains and forest; the easternmost point of Honshu island is at Cape Todo in Miyako. Iwate Prefecture Morioka Hanamaki Tōno Iwaizumi Yamada Ōtsuchi Miyako has a humid climate characterized by mild summers and cold winters.
The average annual temperature in Miyako is 10.9 °C. The average annual rainfall is 1282 mm with September as the wettest month and February as the driest month; the temperatures are highest on average in August, at around 22.9 °C, lowest in January, at around 0.2 °C. Per Japanese census data, the population of Miyako has declined over the past 40 years; the area of present-day Miyako was part of ancient Mutsu Province, has been settled since at least the Jōmon period. The area was inhabited by the Emishi people, came under the control of the Yamato dynasty during the early Heian period with the construction a fortified settlement on the coast. During the Muromachi period, the area came under the control of the Nambu clan, was the main seaport for Morioka Domain during the Edo period under the Tokugawa shogunate. During the Boshin War of the Meiji restoration, the Battle of Miyako Bay was one of the major naval engagements of the war. Under the Meiji period establishment of the modern municipalities system, the towns of Miyako and Kuwagasaki were established within Higashihei District.
The area was devastated by a 18.9 metres tsunami in 1896, which killed 1859 inhabitants. Higashihei District became part of Shimohei District on April 1, 1897. Miyako and Kuwagasaki merged on April 1, 1924. On March 3, 1933, much of the town was destroyed by the 1933 Sanriku earthquake, which killed 911 people and destroyed over 98% of the buildings in the town. Miyako attained city status on June 20, 1940. On June 6, 2005, Miyako absorbed the town of Tarō, village of Niisato, more than doubling the old city's size. On January 1, 2010, Miyaki absorbed the village of Kawai. On March 11, 2011, Miyako was devastated by a tsunami caused by the 2011 Tōhoku earthquake. Only about 30–60 boats survived from the town's 960 ship fishing fleet. A subsequent field study by the University of Tokyo's Earthquake Research Institute revealed that the waters had reached at least 37.9 metres above sea level equaling the 38.2 metres meter record of the 1896 Sanriku earthquake tsunami. The final reported death toll from the disaster was 420 confirmed dead, 92 missing, 4005 buildings destroyed.
Some of the most iconic footage of the tsunami broadcast worldwide, was shot in Miyako. It shows a dark black wave cresting and overflowing a floodwall and tossing cars, followed by a fishing ship capsizing as it hit the submerged floodwall and crushed as it was forced beneath a bridge. Miyako has a mayor-council form of government with a directly elected mayor and a unicameral city legislature of 28 members; the local economy of Miyako is based on commercial fishing and food processing. Miyako Junior College Miyako has 21 public elementary schools and 11 public junior high schools operated by the city government; the city has five public high schools operated by the Iwate Prefectural Board of Education and one private high school. Iwate Prefecture operates one special education school. East Japan Railway Company – Yamada Line Kuzakai - Matsukusa - Hiratsuto - Kawauchi - Hakoishi - Rikuchū-Kawai - Haratai - Moichi - Hikime - Kebaraichi - Sentoku - Miyako - Sokei - Tsugaruishi Sanriku Railway – Kita-Rias Line Miyako - Yamaguchi Danchi - Ichinowatari - Sabane - Tarō - Settai National Route 45 National Route 106 National Route 340 Port of Miyako Jōdogahama Sanriku Fukkō National Park Cape Todo Mount Hayachine, one of the 100 Famous Japanese Mountains Sakiyama Shell Mound, a Jōmon-period National Historic Site Yantai, Shandong province, China friendship city since April 1, 1966 Benguet, friendship city since August 7, 1992 Nobutoshi Hikage – judoka Toshio Fujiwara – kick-boxer Tokuichiro Tamazawa – politician Miyako was the filming location for Yorokobi mo kanashimi mo ikutoshitsuki starring Hideko Takamine in 1957.
Media related to Miyako, Iwate at Wikimedia Commons Official Website
Effective stress is a force that keeps a collection of particles rigid. This applies to sand, soil, or gravel. If you pinch a stack of coins between your fingers, the stack stays together. If you loosen the pressure between your fingers, the coin stack falls apart. A pile of sand keeps from spreading out like a liquid because the weight of the sand keeps the grains stuck together in their current arrangement out of static friction; this weight and pressure is the effective stress. Effective stress is easy to disrupt by the application of additional forces, it is an important factor in the study of slope stability and soil liquefaction from earthquakes. Karl von Terzaghi first proposed the relationship for effective stress in 1925. For him, the term "effective" meant the calculated stress, effective in moving soil, or causing displacements, it represents the average stress carried by the soil skeleton. Effective stress acting on a soil is calculated from two parameters, total stress and pore water pressure according to: σ ′ = σ − u Typically, for simple examples σ = H s o i l γ s o i l u = H w γ w Much like the concept of stress itself, the formula is a construct, for the easier visualization of forces acting on a soil mass simple analysis models for slope stability, involving a slip plane.
With these models, it is important to know the total weight of the soil above, the pore water pressure within the slip plane, assuming it is acting as a confined layer. However, the formula becomes confusing when considering the true behaviour of the soil particles under different measurable conditions, since none of the parameters are independent actors on the particles. Consider a grouping of round quartz sand grains, piled loosely, in a classic "cannonball" arrangement; as can be seen, there is a contact stress where the spheres touch. Pile on more spheres and the contact stresses increase, to the point of causing frictional instability, failure; the independent parameter affecting the contacts is the force of the spheres above. This can be calculated by using the overall average density of the spheres and the height of spheres above. If we have these spheres in a beaker and add some water, they will begin to float a little depending on their density. With natural soil materials, the effect can be significant, as anyone who has lifted a large rock out of a lake can attest.
The contact stress on the spheres decreases as the beaker is filled to the top of the spheres, but nothing changes if more water is added. Although the water pressure between the spheres is increasing, the effective stress remains the same, because the concept of "total stress" includes the weight of all the water above; this is where the equation can become confusing, the effective stress can be calculated using the buoyant density of the spheres, the height of the soil above. The concept of effective stress becomes interesting when dealing with non-hydrostatic pore water pressure. Under the conditions of a pore pressure gradient, the ground water flows, according to the permeability equation. Using our spheres as a model, this is the same as injecting water between the spheres. If water is being injected, the seepage force acts to separate the spheres and reduces the effective stress. Thus, the soil mass becomes weaker. If water is being withdrawn, the spheres are forced together and the effective stress increases.
Two extremes of this effect are quicksand, where the groundwater gradient and seepage force act against gravity. As well, effective stress plays an important role in slope stability, other geotechnical engineering and engineering geology problems, such as groundwater-related subsidence
Derbyshire is a county in the East Midlands of England. A substantial portion of the Peak District National Park lies within Derbyshire, containing the southern extremity of the Pennine range of hills which extend into the north of the county; the county contains part of the National Forest, borders on Greater Manchester to the northwest, West Yorkshire to the north, South Yorkshire to the northeast, Nottinghamshire to the east, Leicestershire to the southeast, Staffordshire to the west and southwest and Cheshire to the west. Kinder Scout, at 636 metres, is the highest point in the county, whilst Trent Meadows, where the River Trent leaves Derbyshire, is its lowest point at 27 metres.:1 The River Derwent is the county's longest river at 66 miles, runs north to south through the county. In 2003 the Ordnance Survey placed Church Flatts Farm at Coton in the Elms as the furthest point from the sea in Great Britain; the city of Derby is a unitary authority area, but remains part of the ceremonial county of Derbyshire.
The non-metropolitan county contains 30 towns with between 100,000 inhabitants. There is a large amount of sparsely populated agricultural upland: 75% of the population live in 25% of the area; the area, now Derbyshire was first visited briefly, by humans 200,000 years ago during the Aveley interglacial as evidenced by a Middle Paleolithic Acheulean hand axe found near Hopton. Further occupation came with the Upper Paleolithic and Neolithic periods of the Stone Age when Mesolithic hunter gatherers roamed the hilly tundra. Evidence of these nomadic tribes has been found in limestone caves located on the Nottinghamshire border. Deposits left in the caves date the occupancy at around 12,000 to 7,000 BCE. Burial mounds of Neolithic settlers are situated throughout the county; these chambered tombs were designed for collective burial and are located in the central Derbyshire region. There are tombs at Minninglow and Five Wells that date back to between 2000 and 2500 BCE. Three miles west of Youlgreave lies the Neolithic henge monument of Arbor Low, dated to 2500 BCE.
It is not until the Bronze Age that real signs of agriculture and settlement are found in the county. In the moors of the Peak District signs of clearance, arable fields and hut circles were discovered after archaeological investigation; however this area and another settlement at Swarkestone are all. During the Roman invasion the invaders were attracted to Derbyshire because of the lead ore in the limestone hills of the area, they settled throughout the county with forts built near Glossop. They settled around Buxton, famed for its warm springs, set up a fort near modern-day Derby in an area now known as Little Chester. Several kings of Mercia are buried in the Repton area. Following the Norman Conquest, much of the county was subject to the forest laws. To the northwest was the Forest of High Peak under the custodianship of William Peverel and his descendants; the rest of the county was bestowed upon a part of it becoming Duffield Frith. In time the whole area was given to the Duchy of Lancaster.
Meanwhile, the Forest of East Derbyshire covered the whole county to the east of the River Derwent from the reign of Henry II to that of Edward I. Most of Derbyshire consists of rolling hills and uplands, with the southern Pennines extending from the north of Derby throughout the Peak District and into the north of the county, reaching a high point at Kinder Scout; the south and east of the county are lower around the valley of the River Trent, the Coal Measures, the areas of clay and sandstones between the Peak District and the south west of the county. The main rivers in the county are the River Derwent and the River Dove which both join the River Trent in the south; the River Derwent rises in the moorland of Bleaklow and flows throughout the Peak District and county for the majority of its course, while the River Dove rises in Axe Edge Moor and forms a boundary between Derbyshire and Staffordshire for most of its length. The varied landscapes within Derbyshire have been formed as a consequence of the underlying geology, but by the way the land has been managed and shaped by human activity.
The county contains 11 discrete landscape types, known as National Character Areas, which have been described in detail by Natural England and further refined and described by Derbyshire County Council and the Peak District National Park. The 11 National Character Areas found within Derbyshire are: Dark Peak White Peak South West Peak Derbyshire Peak Fringe & Lower Derwent Nottinghamshire, Derbyshire & Yorkshire Coalfield Southern Magnesian Limestone Needwood & South Derbyshire Claylands Trent Valley Washlands Melbourne Parklands Leicestershire & South Derbyshire Coalfield Mease/Sence Lowlands From a geological perspective, Derbyshire's solid geology can be split into two different halves; the oldest rocks occur in the northern, more upland half of the county, are of Carboniferous age, comprising limestones, gritstones and shales. In its north-east corner to the east of Bolsover there are Magnesian Limestone rocks of Permian age. In contrast, the southern and more lowland half of Derbyshire contains much softer rocks mudstones and sandstones of Permo-Triassic age, which create gentler, more rolling landscapes with few rock outcrops.
Across both regions can be found drift deposits of Quaternary age – terrace and river gravel deposits and boulder clays. Landslip features are found on unstable layers of sandstones and shales, with Mam Tor and Alport Castles being the most well-known. Cemented screes and tufa deposits occur rarely in the limestone dales and
Soil is a mixture of organic matter, gases and organisms that together support life. Earth's body of soil, called the pedosphere, has four important functions: as a medium for plant growth as a means of water storage and purification as a modifier of Earth's atmosphere as a habitat for organismsAll of these functions, in their turn, modify the soil; the pedosphere interfaces with the lithosphere, the hydrosphere, the atmosphere, the biosphere. The term pedolith, used to refer to the soil, translates to ground stone in the sense "fundamental stone". Soil consists of a solid phase of minerals and organic matter, as well as a porous phase that holds gases and water. Accordingly, soil scientists can envisage soils as a three-state system of solids and gases. Soil is a product of several factors: the influence of climate, relief and the soil's parent materials interacting over time, it continually undergoes development by way of numerous physical and biological processes, which include weathering with associated erosion.
Given its complexity and strong internal connectedness, soil ecologists regard soil as an ecosystem. Most soils have a dry bulk density between 1.1 and 1.6 g/cm3, while the soil particle density is much higher, in the range of 2.6 to 2.7 g/cm3. Little of the soil of planet Earth is older than the Pleistocene and none is older than the Cenozoic, although fossilized soils are preserved from as far back as the Archean. Soil science has two basic branches of study: pedology. Edaphology studies the influence of soils on living things. Pedology focuses on the formation and classification of soils in their natural environment. In engineering terms, soil is included in the broader concept of regolith, which includes other loose material that lies above the bedrock, as can be found on the Moon and on other celestial objects as well. Soil is commonly referred to as earth or dirt. Soil is a major component of the Earth's ecosystem; the world's ecosystems are impacted in far-reaching ways by the processes carried out in the soil, from ozone depletion and global warming to rainforest destruction and water pollution.
With respect to Earth's carbon cycle, soil is an important carbon reservoir, it is one of the most reactive to human disturbance and climate change. As the planet warms, it has been predicted that soils will add carbon dioxide to the atmosphere due to increased biological activity at higher temperatures, a positive feedback; this prediction has, been questioned on consideration of more recent knowledge on soil carbon turnover. Soil acts as an engineering medium, a habitat for soil organisms, a recycling system for nutrients and organic wastes, a regulator of water quality, a modifier of atmospheric composition, a medium for plant growth, making it a critically important provider of ecosystem services. Since soil has a tremendous range of available niches and habitats, it contains most of the Earth's genetic diversity. A gram of soil can contain billions of organisms, belonging to thousands of species microbial and in the main still unexplored. Soil has a mean prokaryotic density of 108 organisms per gram, whereas the ocean has no more than 107 procaryotic organisms per milliliter of seawater.
Organic carbon held in soil is returned to the atmosphere through the process of respiration carried out by heterotrophic organisms, but a substantial part is retained in the soil in the form of soil organic matter. Since plant roots need oxygen, ventilation is an important characteristic of soil; this ventilation can be accomplished via networks of interconnected soil pores, which absorb and hold rainwater making it available for uptake by plants. Since plants require a nearly continuous supply of water, but most regions receive sporadic rainfall, the water-holding capacity of soils is vital for plant survival. Soils can remove impurities, kill disease agents, degrade contaminants, this latter property being called natural attenuation. Soils maintain a net absorption of oxygen and methane and undergo a net release of carbon dioxide and nitrous oxide. Soils offer plants physical support, water, temperature moderation and protection from toxins. Soils provide available nutrients to plants and animals by converting dead organic matter into various nutrient forms.
A typical soil is about 50% solids, 50% voids of which half is occupied by water and half by gas. The percent soil mineral and organic content can be treated as a constant, while the percent soil water and gas content is considered variable whereby a rise in one is balanced by a reduction in the other; the pore space allows for the infiltration and movement of air and water, both of which are critical for life existing in soil. Compaction, a common problem with soils, reduces this space, preventing air and water from reaching plant roots and soil organisms. Given sufficient time, an undifferentiated soil will evolve a soil profile which consists of two or more layers, referred to as soil horizons, that differ in one or more properties such as in their texture, density, consistency, temperature and reactivity; the horizons differ in thickness and gene
A caldera is a large cauldron-like hollow that forms following the evacuation of a magma chamber/reservoir. When large volumes of magma are erupted over a short time, structural support for the crust above the magma chamber is lost; the ground surface collapses downward into the emptied magma chamber, leaving a massive depression at the surface. Although sometimes described as a crater, the feature is a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Only seven known caldera-forming collapses have occurred since the start of the 20th century, most at Bárðarbunga volcano in Iceland; the word comes from Spanish caldera, Latin caldaria, meaning "cooking pot". In some texts the English term cauldron is used; the term caldera was introduced into the geological vocabulary by the German geologist Leopold von Buch when he published his memoirs of his 1815 visit to the Canary Islands, where he first saw the Las Cañadas caldera on Tenerife, with Montaña Teide dominating the landscape, the Caldera de Taburiente on La Palma.
A collapse is triggered by the emptying of the magma chamber beneath the volcano, sometimes as the result of a large explosive volcanic eruption, but during effusive eruptions on the flanks of a volcano or in a connected fissure system. If enough magma is ejected, the emptied chamber is unable to support the weight of the volcanic edifice above it. A circular fracture, the "ring fault", develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are known as ring dikes. Secondary volcanic vents may form above the ring fracture; as the magma chamber empties, the center of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions; the total area that collapses may be thousands of square kilometers. Some calderas are known to host rich ore deposits. One of the world's best-preserved mineralized calderas is the Sturgeon Lake Caldera in northwestern Ontario, which formed during the Neoarchean era about 2,700 million years ago.
If the magma is rich in silica, the caldera is filled in with ignimbrite, tuff and other igneous rocks. Silica-rich magma has a high viscosity, therefore does not flow like basalt; as a result, gases tend to become trapped at high pressure within the magma. When the magma approaches the surface of the Earth, the rapid off-loading of overlying material causes the trapped gases to decompress thus triggering explosive destruction of the magma and spreading volcanic ash over wide areas. Further lava flows may be erupted. If volcanic activity continues, the center of the caldera may be uplifted in the form of a resurgent dome such as is seen at Cerro Galán, Lake Toba, etc. by subsequent intrusion of magma. A silicic or rhyolitic caldera may erupt hundreds or thousands of cubic kilometers of material in a single event. Small caldera-forming eruptions, such as Krakatoa in 1883 or Mount Pinatubo in 1991, may result in significant local destruction and a noticeable drop in temperature around the world.
Large calderas may have greater effects. When Yellowstone Caldera last erupted some 650,000 years ago, it released about 1,000 km3 of material, covering a substantial part of North America in up to two metres of debris. By comparison, when Mount St. Helens erupted in 1980, it released ~1.2 km3 of ejecta. The ecological effects of the eruption of a large caldera can be seen in the record of the Lake Toba eruption in Indonesia. About 74,000 years ago, this Indonesian volcano released about 2,800 cubic kilometres dense-rock equivalent of ejecta; this was the largest known eruption during the ongoing Quaternary period and the largest known explosive eruption during the last 25 million years. In the late 1990s, anthropologist Stanley Ambrose proposed that a volcanic winter induced by this eruption reduced the human population to about 2,000–20,000 individuals, resulting in a population bottleneck. More Lynn Jorde and Henry Harpending proposed that the human species was reduced to 5,000-10,000 people.
There is no direct evidence, that either theory is correct, there is no evidence for any other animal decline or extinction in environmentally sensitive species. There is evidence. Eruptions forming larger calderas are known La Garita Caldera in the San Juan Mountains of Colorado, where the 5,000 cubic kilometres Fish Canyon Tuff was blasted out in eruptions about 27.8 million years ago. At some points in geological time, rhyolitic calderas have appeared in distinct clusters; the remnants of such clusters may be found in places such as the San Juan Mountains of Colorado or the Saint Francois Mountain Range of Missouri. Some volcanoes, such as the large shield volcanoes Kīlauea and Mauna Loa on the island of Hawaii, form calderas in a different fashion; the magma feeding these volcanoes is basalt, silica poor. As a result, the magma is much less viscous than the magma of a rhyolitic volcano, the magma chamber is drained by large lava flows rather than by explosive events; the resulting calderas are known as subsidence calderas and can form more than explosive calderas.
For instance, the caldera atop Fernandina Island collapsed