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26. State whether the following sentences are True or False; correct the false ones.

  1. Ground-penetrating radar is widely used to reduce uncertainties across the full range of exploration and production operations.

  2. Gas chimneys are extremely useful for economically important areas.

  3. Reflection seismology is applied in deep groundwater surveying.

  4. The least accurate method of determining depths formation is reflection method.

  5. Surveys are used to execute oil-recovery strategies and monitor fluid movement in reservoirs.

  6. Geophysicists combine refraction and reflection methods to discriminate among sands and shales.

  7. GPR is widely used for mapping shallow subsurface.

27. 9 You will hear the report on seismic waves. Match the terms with their descriptions. One of them is extra.

1. Body waves

a waves that travel in a circular motion and cause damage by displacing material

2. Secondary waves

b waves propagating along the surface and deforming the material vertically

3. Primary wave shadow zone

c waves that travel through the interior of the earth

4. Secondary wave shadow zone

d waves that are deflected by the Earth’s core forming a special area

5. Love waves

e waves that travel only through solids thus they do not penetrate the Earth’s outer core forming a special zone

6. Rayleigh waves

f waves that move sideways at right angles to the direction of travel

g waves that do not penetrate the earth’s interior but follow the surface

28. Answer the following questions.

  1. What are the three main applications of reflection seismology?

  2. Which method is similar to reflection seismology?

  3. When is the GPR method applied?

  4. Which method is applied to determine the depths of formations in exploration of petroleum?

  5. What are three operations when 3D-seismic technology is applied?

  6. What are the capabilities of 3D-seismic technology?

  7. What is S-wave?

  8. What is P-wave?

  9. What does full-vector wave-field imaging help to “see”?

  10. When is the combination of P- and S-waves applied?

29. For the gaps 1 – 5, 6 - 10, choose one of the words on the right (1 -6) that best completes the gap in the text. You can use each word only once. For every 5 gaps, there is one extra word.

Ground Penetrating Radar

The depth range of GPR is limited by the electrical (1) ______ of the ground, and the transmitting frequency. As conductivity increases, the penetration depth (2) ______. This is because the electromagnetic energy is more quickly dissipated into heat energy, causing a loss in signal (3) __________ at depth. Higher frequencies do not (4) ________ as far as lower frequencies, but give better resolution. Optimal depth penetration is achieved in dry sandy soils or massive dry materials such as granite, (5) ____________, and concrete where the depth of penetration is up to 15 m. In moist and/or clay laden soils and soils with high electrical conductivity, penetration is sometimes only a few centimetres.

1. limestone

2. decreases

3. conductivity

4. penetrate

5. positions

  1. strength

GPR uses transmitting and receiving antennae. The transmitting antenna radiates short pulses of the (6) _________ (usually polarized) radio waves into the ground.

When the wave (7) _________ a buried object or a boundary with different dielectric constants, the receiving antenna records

(8) __________ in the reflected return signal. The principles involved are similar to (9) ____________ seismology, except that electromagnetic energy is used instead of acoustic energy, and reflections appear at boundaries with different dielectric constants instead of acoustic (10) __________ .

1. dimensional

2.impedances

3.high-frequency

4. encounters

5. variations

6. reflection

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