الثلاثاء، 31 مايو 2016
الاثنين، 30 مايو 2016
الأحد، 29 مايو 2016
السبت، 21 مايو 2016
الجمعة، 20 مايو 2016
Probable asteroid (Apophis) impact
After its discovery in 2004, astronomers gave the asteroid Apophis a 2.4 percent chance of hitting the earth during its close flyby on April 13, 2029. If the 1,066-foot (325 meters) asteroid were to strike our planet, the blast could equal hundreds of megatons.
Fortunately, further analysis showed that Apophis will miss the Earth by 19,400 miles (31,300 kilometers) in 2029. Extrapolating further into the future, another approach in 2036 is an even bigger miss. Apophis has only a one in a million chance of hitting Earth on that pass.
Originally given a 1 in 37 chance to hit Earth, the near Earth object Apophis caused a bit of a panic in late 2004 with a high probability to hit Earth in 2029 or 2036. But what would happen if such a massive object collided with mother Earth? Don't even bother comparing it to a nuclear bomb because it's way beyond that.
Fortunately, further analysis showed that Apophis will miss the Earth by 19,400 miles (31,300 kilometers) in 2029. Extrapolating further into the future, another approach in 2036 is an even bigger miss. Apophis has only a one in a million chance of hitting Earth on that pass.
Originally given a 1 in 37 chance to hit Earth, the near Earth object Apophis caused a bit of a panic in late 2004 with a high probability to hit Earth in 2029 or 2036. But what would happen if such a massive object collided with mother Earth? Don't even bother comparing it to a nuclear bomb because it's way beyond that.
الخميس، 12 مايو 2016
Inside the Planet
Introduction
Seismologists, geologists who study seismic waves noticed in the early 20th century that P waves bended, or refracted, in their journey through Earth. Observations at stations far removed from the earthquake focus recorded waves that had traveled through the planet’s interior, as illustrated in part (1) of the figure.. Travel times of these waves indicated a refracted path, as shown in the figure, and wave speed is the distance divided by time (as determined by the amount of time elapsed since the start of the earthquake). Refraction was not too surprising because the increased pressure in Earth’s interior results in firmer structures and more resistance to oscillation, so the wave speed is greater and seismic waves refract. What surprised early seismologists was that beyond a certain point about 7,200 miles (11,600 km) from the focus, at an angular distance of 105 degrees S waves disappeared!
In 1906 the British seismologist Richard D. Oldham (1858–1936) proposed that the disappearance of the shear waves was due to the “shadow” of a liquid core. Since S waves are shear, they cannot propagate through liquid, so the existence of a liquid center inside the planet would explain why seismometers fail to record shear waves on the other side of the planet from the focus, as shown in part (2) of the fi gure below. P waves, being compression waves, refract at the boundary between rock and liquid, creating a smaller “shadow.” Th e rocky interior beneath the crust is called the mantle, and in 1914 the German seismologist Beno Gutenberg (1889–1960) used the seismic wave results to calculate that the mantlecore boundary is located at a depth of about 1,800 miles (2,900 km) below the surface. However, in 1936 the Danish seismologist Inge Lehmann (1888– 1993) analyzed seismic wave data and discovered an additional refractory step of P waves. Her analysis suggested the existence of another boundary, which she placed at a depth of about 3,200 miles (5,150 km). This boundary is between an outer core and an inner core.
The use of seismic waves to image Earth’s interior is similar to the use of ultrasound waves to image the body’s interior or sound waves in sonar to image the seafloor. Unlike ultrasound and sonar techniques, though, seismologists usually do not generate seismic waves these are natural occurrences beyond the control of researchers. Yet the waves reveal a lot of information about otherwise inaccessible places. Seismic waves are also plentiful; about 1 million or so earthquakes occur each year in the world, and although most of these are fortunately minor they are detectable with sensitive instruments.
By studying the nature and speed of seismic waves, geologists have learned much about the Earth’s interior. Earth consists of the following several layers:
- crust, composed of rocks having relatively low density, extending from the continental surface to an average depth of about 22 miles (35 km) and from the ocean floor an average of about four miles (6.4 km) down to a boundary known as the Mohorovicic discontinuity (Moho for short), named after the Croatian scientist Andrija Mohorovičić (1857–1936);
- mantle, extending from the crust to about 1,800 miles (2,900 km) below the surface, and divided into an upper and a lower section;
- outer core, which is liquid and extends from the mantle border to a depth of about 3,200 miles (5,150 km);
- inner core, which is solid, with a radius of about 750 miles (1,220 km).
The mantle gets its name from Wiechert, who thought of it as a coat that covered the core (mantle derives from the German word, mantel, for “shell” or “coat”). About 67 percent of Earth’s mass is contained in this large region. The mantle is mostly solid, although as discussed below there is some degree of fluidity in spots; it consists of minerals such as olivine and another silicate called perovskite (MgSiO3). Silicon and aluminium are less abundant in the mantle compared to the crust, but magnesium is much more plentiful.
Wiechert assumed from the studies of Earth’s density that the core must be dense. A greater density for the core also makes sense because the large portion of the heavier elements would have sunk to the interior as the hot, molten planet formed long ago. Iron and nickel possess relatively high densities and are commonly found in certain meteorites, indicating their abundance throughout the solar system. These metals are likely constituents of the core. The absence of shear wave propagation indicates the outer core is liquid, but studies of other seismic waves indicates a density slightly less than that expected if the outer core contained only melted iron and nickel. Instead, the outer core is about 90 percent iron and nickel, and most of this is iron about 85 percent of the outer core is made of this element. The remaining 10 percent consists of lighter elements such as sulphur and oxygen.
The inner core forms a boundary with the outer core, reflecting some of the waves and transmitting the rest. Shear waves cannot pass through the outer core, but as compression waves cross the boundary between the inner and outer core, some of these disturbances create shear waves. The shear waves travel through the inner core and get converted back into compression waves as they proceed from the inner to the outer core. Seismologists can detect the paths of these waves, and the propagation of shear waves in the inner core implies it cannot be liquid. Density studies suggest the inner core is mostly solid iron, mixed with a small percentage of nickel.
Researchers continue to study seismic waves and similar data to learn more of the details on the structure and composition inside Earth. In 2005 John W. Hernlund and Paul J. Tackley of the University of California, Los Angeles, and Christine Thomas of the University of Liverpool in the Britain found data suggesting the presence of a thin layer around the mantle-core boundary. This layer, previously unknown and not yet widely studied, might help scientists to understand and identify further properties of the mantle. The researchers published their report “A Doubling of the Post-Perovskite Phase Boundary and Structure of the Earth’s Lowermost Mantle” in a 2005 issue of Nature.
Although researchers can study the finer structure of Earth’s hidden interior with sensitive seismometers, a large amount of information could also be gained by burrowing inside and taking a look. There are limitations on how far down people can drill, even with the hardest bits (the tip of the drill), but researchers are sharpening their drill bits in the effort to reach greater depths.
الأحد، 1 مايو 2016
Petroleum system
Petroleum System
Petroleum system starts with the deposition to storage from where the production is obtained.
Petroleum system journey starts with the deposition of organic matter.
Deposition of organic matter
The deposition of organic matter starts when organism starts to die and deposits deep down the ocean floor and the above deposition of clay (finer grains). The clay particles are about 1/256 mm size and is called shale. Organic matter deposited on the ocean floor cannot be oxidized due to the depth factor so they can produce hydrocarbon. Hydrocarbon generation needs the cooking of organic matter at high temperature and pressure and it is obtained when it goes into overburden of deposition by clay particles and greater depths.Source rock
In the petroleum system the source rock are the shale (clay that goes under high pressure and temperature which cooks the organic matter). Sometimes limestone can also be the source rock with 1% of organic matter contains. So theses rocks undergo cooking where the temperature and pressure determines what type of fuel will be generated. Despite of temperature and pressure another factor in producing hydrocarbon is the time span required to generate fuel. The time is a critical factor as if the organic matter is cooked for less time it will not generate hydrocarbon and when it is greater than the oil produce will be converted into gas.Reservoir rock
Reservoir as indicated by the name reserves of hydrocarbon. the hydrocarbon cannot be obtained from the source rock because of the higher pores but are lesser to none interconnection. For the extraction the pores should be interconnected so that it can travel when are extracted. But if there is no reservoir and obtaining fuel from source rock it must be fractured for permeability generation. Reservoir rock are mostly sandstone which have higher porosity and permeability but in some cases limestone also serves as reservoir rock. Limestone all by self is not a good reservoir due to fine particles present which give less permeability but as limestone is calcium carbonate so it can be dissolved in water which are the Karst topography. Only then can limestone have permeability required for hydrocarbon to be obtained.Migration
Primary migration
Migration itself is cleared so the primary migration occurs when hydrocarbon moves from source rock to the reservoir rocks. Primary migration occurs when the source rock is fractured due to tectonic forces (plate movements) or by the overburden squeezing the source rock. As HC (hydrocarbon) have low density they moves upward.Secondary migration
Secondary migration is the HC movement within the reservoir rocks. The HC will moves upward in the reservoir rocks.Seal rock
Trap or seal rocks are those that are present above reservoir rocks as HC movement will always be upward. Seal rock are those that have low to none permeability so that HC cannot escape but are trapped within the reservoir rocks. Shale can be seal rock also as they have porosity but do not have permeability factor so HC will be trapped. Types of traps include stratigraphic and structural.Stratigraphic traps example is shale as a seal rock and structural traps are fold or faults.
Time period
The last thing in the petroleum system is time as have said it above already, time is required for HC generation which is always critical. No more time and no less time while cooking of the organic matter or it will not produce the fuel.
Online geology degree and courses
Online geology degree and courses
Online geology degree and courses are offered at multiple forums. Geology is study of the rocks, minerals, and the forces that shape the earth, like water, wind and earthquakes. Learn about the levels of geology degrees online you can pursue partly or fully online, common courses and career options in the field. Schools offering Environmental Science degrees can also be found in these popular choices.
A geology degree is widely valued by employers when looking for employment as a geoscientist, hydrogeologist, or an environmental attorney. Geology majors also go on to work as a sedimentologist, a geophysicist, and many other important careers that help our environment. The schools we list on our site are accredited degree programs in geology and related fields at the associate and bachelor’s degree levels.
Definition of Geology
Geology is a science that studies the Earth and the materials that it’s made of. It looks at the rocks that the Earth is composed of, the structure of the earth’s materials, and the processes acting upon those materials that cause the Earth to evolve. Through the study of geology we can understand the history of the Earth. Geologists decipher evidence for plate tectonics, the evolutionary history of life, and the past climates the Earth has been through. Geology also includes the study of organisms that have inhabited the planet, and how they’ve changed over time.
Currently we use geology for mineral and hydrocarbon exploration, evaluating water resources, predicting natural hazards, finding remedies for environmental problems, providing insights into past climate change, and geotechnical engineering. Through geology degrees people can study geology, become a geologist, and use their knowledge to improve our Earth.
A Geology Education - An Overview
If you’re interested in studying online geology degree, there are a few different degree options open to you in both undergrad and graduate education. The following are a few options:
- Bachelor of Arts in Geology: The BA in geology degree is intended for students who plan to pursue teacher certification, natural resource management, scientific or technical writing, and other fields that combine a strong liberal arts background with science training. BA classes may include earth materials, minerals, igneous and metamorphic rocks, oceanography, principles of astronomy, deformation of the Earth, sedimentary processes, earth surface processes, and field methods.
- Bachelor of Science in Geology: The BS in geology degree differs from the BA in that it has a strong mathematical component. It’s typically designed for students planning to pursue graduate study in geology, or work as a professional geologist. Courses may include: History of the Earth, Earth materials, deformation of the Earth, sedimentary processes, Earth surface processes, field methods, chemistry, physics, physics in electricity and magnetism, and calculus classes.
- Master of Science in Geology: This is a graduate degree in geology. Master programs are advanced geology degrees with a focus on geology classes. They typically come in both thesis and non-thesis options. Those who want to get a master’s in geology degree must have an undergraduate degree in geology or a closely related science field. Sometimes they’ll let applicants without a bachelor’s degree in geology to take pre-requisite classes before beginning a master’s program. Pre-requisite classes include: physical geology, mineralogy, paleobiology, petrography, geologic field methods, stratigraphy, igneous/metamorphic petrogenesis, structural geology, sedimentary petrogenesis, and introduction to geophysics.
- Doctorate in Geology: A PhD is the highest level of degree a person can get in geology. These programs are designed to develop creative scholarship and to prepare the student for a professional career in the geological sciences. Typically a person chooses a specialization or focus such as geochemistry, geology, geophysics, planetary geology, minerals, or more. Students can be admitted into PhD programs with either a bachelor’s or master’s degree in geology. Depending on the previous degree earned, a PhD may take one to two years of study.
In all geology degree levels, the goal is for students to master basic concepts and vocabulary in geology. Through these programs you’ll learn the following materials:
- Plate tectonics
- Origin and classification of rocks and minerals
- Geological time scale and how this relates to major events in the history of Earth and its life
- Geophysical properties of the Earth and crustal deformation
- Processes that shape the surface of the Earth
- Environmental hazards and issues
You’ll also be expected to:
- Develop skills in observing and recording geologic features and processes
- Develop competency in the interpretation of earth science data, including both qualitative and quantitative analyses
- Achieve competence in: locating and interpreting scientific literature,
- Giving oral presentations,
- Using computers at a level consistent with current professional practice
- Be able to express earth science concepts in writing
What Geology online Degrees Are Available?
You can pursue a Bachelor of Arts, Bachelor of Science, Master of Science in geology and Ph.D. in geology. People who earn a B.S. in Geology usually pursue advanced degrees. However, in a Master of Science program in geology, your classmates may have a B.S. in Geology or an undergraduate degree in a related field like engineering or physics. The online geology degree or online geoscience degree can be obtain in B.S.
While some schools offer some geology courses online, entire undergraduate degree programs online are extremely rare. Many science lab courses can't be completed online, and fieldwork requires in-person attendance. However, it is possible to earn a Bachelor of Arts, Bachelor of Science, or Master of Science in Geology entirely online with taking online geology courses.
Online Degrees Bachelor's and Master's degrees available online
Online Computer, software, completing assignments by due date, degree
Requirements completion within 8 years
Common Courses Soils, hydrology, plate tectonics, chemistry, physics
Career Options Geochemist, mineralogist, government geologist, geology teacher
How Do I Complete My Degree Online?
In an online degree geology program, classes start and end at the same calendar time as the on-campus courses. You do not have to be logged in to the class at a specific time, and instead may view the lectures at your convenience. However, during the course, you may be given assignments that have specific due dates. All of your assignments must be completed by the last day of class.
You may have up to eight years to complete your degree. Students attending part-time take 3-4 years to complete their geology master's degree online. If you choose to attend full-time, you may be able to complete your geology online degree faster. You will need access to specific software, usually available for purchase through the school.
What Topics Will I Study?
In a bachelor's online degree in geology program, you learn how certain rocks and minerals are formed and how to classify them. You study the forces that shape Earth's surface, such as weather and plate tectonics, the movement of the Earth's crust. You may also take classes about soil, hydrology or palaeontology. You can also expect to take classes in math, computers, chemistry and physics.
You will likely have to complete a field course, in which you may spend an entire semester or a summer in the field, practising your skills on a real-world geology project. Some schools offer field courses on-campus, while others offer them only at off-campus sites.
Master's degree students concentrate coursework and thesis projects on a particular area of interest, like earthquake prediction or environmental geology. Ph.D. students take their interest to the next level by completing a dissertation that contributes original research to their chosen area of geology.
What Kinds of Careers Will Be Open to Me?
While you will be qualified for entry-level employment with only a geology bachelor's degree, many graduates choose to pursue either an advanced geology degree or a professional degree for a career that joins the two interests. For example, you could pursue your law degree and work in environmental law.
Geology graduates can find employment as an oceanographer, geochemist or mineralogist, doing direct science research. You could work for the U.S. Geological Survey, or advise state and local agencies on infrastructure planning and policy. Some graduates with advanced degrees also pursue teaching careers.
