EXERCISE 6 Answer questions about the text.
1. What does significantly increase seismic exploration efficiency in the method of reflected waves?
2. What does the knowledge of speed propagation for both types of waves provide for?
3. What is the final task of seismic exploration?
4. What factors start to play the key role searching for oil and gas?
5. What allowsdetermining the absorption ratio?
6. What does «field» mean?
7. How to solve the problem of noises and irregular waves?
EXERCISE 7 Connect the terms with their definitions.
| 1. Arrival time | a) a method of seismic exploration in which an excited seismic wave directly returns to the source. |
| 2. Reflection method | b) interference during reception of seismic signal, can be coherent and incoherent. |
| 3. Seismic exploration | c) an instrument that detects and records seismic vibrations. |
| 4. Seismic noise | d) the use of seismic surveying and explosion seismology in prospecting for oil, gas or other mineral source. |
| 5. Seismograph | e) the time that it takes a particular wave phase of seismic energy to travel from the shot to a reflector and back to the detector that records it during seismic exploration. |
EXERCISE 8 Use the suitable nouns for adjectives and translate the word combinations.
| Nouns: 1. waves 2. task 3. operations 4. interferences 5. time 6. deposits 7. structure | Adjectives: a) seismic b) arrival c) reflected d) irregular e) final f) ore g) subsurface |
EXERCISE 9 Give the English equivalents to the following word combinations.
1. Скорость распространения
2. Заключительная задача
3. Время вступления (волны)
4. Динамические факторы
5. Средний коэффициент поглощения
6. Рудные месторождения
7. Сейсмические операции
8. Шумы
9. Помехи
10. Подземная структуры
11. Средние модели
12. Полезные сигналы
EXERCISE 10 Read and translate the text.
Types of waves
Exciting elastic waves close to the surface of the land or the sea and receiving waves that went into the ground and are coming back to the surface, in most cases on the basis of the observed waves allows reconstructing the object “image” i.e. develop its model. The most amazing is that such reconstruction is predominantly performed by means of identifying times of the waves travel from the source to the boundaries of the profile and back to the receiver, in other words, based on the rule linking this travel time with the distance from the source to the receiver, known in advance speed properties of the medium, and thickness of sediments under exploration.
Resolving the most complex objectives facing the modem exploration seismology became possible only due to the huge arsenal of theoretical knowledge and methodological techniques. Nowadays exploration seismology uses practically all phenomena related to exciting and propagation of elastic waves in complex mediums: reflection, refraction, diffraction, converting waves, dissipation, generation of head (refracted) waves, effects generated by propagation of waves in anisotropic mediums, phenomena in multi-component mediums.
Concerning the types of waves, P-waves are predominantly used currently, though some successful attempts are being taken to utilize both S-waves and converted waves.
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