MIGRATION STRATEGIES

on Wednesday, July 28, 2010

decision require migration of seismic data in practice related to

  1. appropriate migration strategies
  2. migration algorithm compatible with strategy
  3. appropriate parameter
  4. migration velocities
Migration strategies include:-

  1. 2- D versus 3 -D migration
  2. post-stack versus pres-tack migration
  3. time versus depth migration

TYPE OF MIGRATION

1. KICHHOFF MIGRATION

advantage :-
  • can handle all dip up 90 degree
  • offer full wave
disadvantage:-
  • can be cumbersome handly lateral v variation
  • it is computational expensive
2. FINITE DIFFERENT MIGRATION

advantage :-
  • can handle all type v variations
disadvantage:-
  • dip id limited
  • it is relatively computational expensive because data transfer operation in the recursion algorithm.
3. F-K MIGRATION

advantage:-
  • can handle all dip up 90 degree
  • it computational inexpensive
disadvantage:-
  • cannot accommodate multivalue v point in section
  • distortion occur when t-v fn vary rapidly
  • has great difficulty honoring lateral in v charge

MIGRATION ALGORITHMS

3 MAIN CATEGORIES:-

  1. BASED ON INTEGRAL SOLUTION TO SOLAR WAVE EXAMPLE KICHOFF MIGRATION
  2. BASED ON FINITE DIFFERENT SOLUTION
  3. BASED ON F-WAVENUMBER IMPLEMENTATION
F-K MIGRATION BASED ON CONTANT-V ASSUMPTION INVOLVE A COORDINATE TRANSFORMATION FROM f to v WAVE NUMBER AXIS H WAVENUMBER KEPT UNCHANGED.

GLOBAL WARMING

CO2 is a greenhouse gas that strongly absorbs infrared radiation and plays a major role in warming the lower atmosphere. CO2 has been increasing steadily in the atmosphere due to the burning of fossil fuel. However, deforestation is also adding to this increase as tropical rain forests are cut down and replaced with plants less efficient in removing CO2 from the atmosphere. Trace gases sush as methane ,nitrous oxide and chlorofluorocarbons, all of which readily absorb infrared radiation. The increase in these gases is about equal to CO2 in its ability to enhance the atmospheric greenhouse effect. Increasing concentration of greenhouse gases will result in a mean global warming of surface air between 1.4 and 5.8 C above the average surface air temperature of 1990. The most abundant greenhouse gasses will produce a positive feedback on the climate system by enhancing the atmospheric greenhouse effect and accelerating the temperature rise.

HALOS


A ring of light encircling and extending outward from the sun or moon is called a halo.The most common type of halo is the 22 halo- a ring of light 22 from the sun or moon. A halo froms when tiny suspended column-type ice crystals become randomly oriented as air molecules constantly bump against them. The refraction of light rays through these crystals forms a halo. A halo usually seen as a bright, white ring ,but there are refraction effects that can cause it to have color.

clouds

clouds are aesthetically appealing and add excitement to the atmosphere. Without them,there would be no rain or snow, thunder,lightning,rainbow or halos.

CLASSIFICATION OF CLOUDS
1. HIGH CLOUDS
-cirrus
-cirrostratus
-cirrocumulus

2. middle clouds
- altostratus
-altocumulus

3. low clouds
- stratus
-stratocumulus
-nimbostratus

4. clouds with vertical development
- cumulus
-cumulonimbus


CLOUD IDENTIFICATION

1. CIRRUS

cirrus which are thin,wispy, clouds blown by high winds into long streamers called mares' tail. They can look like a white, feathery patch with a faint wisp of atail at one end. Cirrus clouds usually move across the sky from west to east, indicating the prevailing winds at their elevation.
2. CIRROCUMULUS

Clouds seen less frequently than cirrus, appear as small. rounded. white puffs that may occur individually or in long rows.

3.CIRROSTRATUS

which are so thin that the sun and moon can be clearly seen through them. A wide spread high cloud composed of ice crystals, that is normally white and usually covers a large portion of the sky.
4. ALTOCUMULUS

altocumulus are middle cloud that appear as gray, puffy masses,sometimes rolled out in parallel waves or bands. it Composed of water droplets and ice crystals at elevation usually between 2000m and 7000m above the surface.


5. ALTOSTRATUS

It gray or blue-gray cloud that often covers the entire sky over an area that extends over many hundreds of square kilometers.The gray color, height and dimmes of the sun are good clues to identifying an altostratus

6. NIMBOSTRATUS
It is dark gray,"WET" -looking cloud ever associated with more or less continuously falling rain or snow.The base of nimbostratus cloud is normally impossible to identify clearly and is easily confused with the altostatus.

7. SRATOCUMULUS

It appear in rows. in patches, or as rounded masses with blue sky visible between the individual clouds elements. A low, lumpy- looking wide spread cloud with dark and light shading.

8. STRATUS

The low, unifrom,grayish -looking cloud typically has a base below 2000m . Drizzle may fall from its base. It is distinguished from altostratus in that the sun is not usually visible through stratus.

9. CUMULUS

Small ,puffy clouds with relatively flat bases and limited vertical growth

10. CUMULONIMBUS

If a cumulus congestus continues to grow vertically it develops in a giant cumulonimbus- a thunderstorm cloud. Lightning, thunder and even tornadoes are associated with cumulonimbus.

ACID RAIN

on Tuesday, July 27, 2010

SOURCE OF ACID RAIN

  1. man -made air pollution
  • industries
  • smoking
  • transportation
  • utilities
  • open burning
  • burning fuel
2. natural air pollution

  • forest fire
  • volcanic eruptions
  • methane emission cattle
EFFECT

  1. damage building and physical structures
  2. plant and animal unhealthy
  3. human health effect - brain damage, kidney problems,other health risk
  4. aquatic flora and fauna unhealthy
AVOIDING RESPONSE

  1. stop smoking
  2. walk,carpool use public transport
  3. support care environment group
  4. stop burning waste
  5. conserve water and electricity

EFFECT OF OZONE

EFFECT OF OZONE

OZONE

  • most important air pollutant affecting human health
  • molecule built of 3 of atom O
  • when contact with surface release extra force in form chemical energy
  • this energy cause damage to sensitive tissue in lower and upper airways.
OZONE FORMATION

  • product of solar energy and photochemical reaction of pollutants.Concentration highest when sunlight most instense.
  • reaches peak levels during the middle of the day in the summer month.
  • types air pollution pattern is diurnal and seasonal variation
OZONE AIR QUALITY STANDART

  • ozone level more than 0.08 ppm averaged over 8 h is considered unhealthful
  • the effect of ozone on people
- irritation of nose and throat
- increased mucus production and tendency to cough
- eye irritation and headaches
- chest pain and difficulty take a deep breath without coughing

AIR POLLUTION

AIR POLLUTION

Secondary pollutants are form in atmosphere throungh chemical and photochemical reaction from primary pollutants

example
  1. asid sulfuric-
cause respiratory problems
effect- asid sulfuric exist in particle/droplets in the air if released to atmosphere
- it dissolves when mix with water. It has moderate acute(short term)toxicity aquatic life. Asid sulfuric very corrosive and badly burn plants, bird or land animal exposed to it. It has moderate chronic (long-term) toxicity to aquatic life. Chronic effect not determined on plants,bird or land animals.Small quantity sulfuric asid will neutralized by natural alkalinity in aquatic system.Concentration of asid sulfuric high because emission by industrial.
- asid sulfuric can dissolve in clouds,fog.rain.dew or snow. the result is it dilute acid solutions.

2. nitrogen dioxide -give air the brownish coloration
  • nitrogen oxides produce during combustion process.
  • 80% the nitrogen oxides telease immediately in form nitric oxide (NO)
  • Oxidation during the day causes NO2 to form nitric acid and nitrate particle.
  • in the dark- NO2 + ozone = very reactive radical
  • - free radical + organic compound(in air) = nitrogen organic compound

GLOBAL CLIMATE

GLOBAL CLIMATE

  • factor regulate global climate
  • how climated classified
  • examine different type of climate
climate control factor produce the climate
  1. intensity of sunshine and its variation of latitude
  2. distribution of land and water
  3. ocean currents
  4. prevailing wind
  5. positions of high and low pressure areas
  6. mountain barries
  7. altitude
 
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