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.

EXERCISE 11 Answer questions about the text.

1. Is it possible to reconstruct the object «image»? How?

2. What phenomena allow solving complex tasks facing the modem exploration seismology?

EXERCISE 12 Are the following statements true or false? Correct the false ones with the right information and discuss your answers with a partner. Use the texts 1, 2 if necessary.

1. Elastic waves are excited in seismic operations, which provides for searching for oil and gas depositions.

2. Concerning the types of waves, S-waves are predominantly used currently.

3. 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”.

4. Resolving the most complex objectives facing the modem exploration seismology is impossible nowadays.

5. In the method of reflected waves seismic exploration efficiency significantly decreases when S-waves and P-waves are used jointly.

6. Joint usage of S-waves and P-waves and determination of the medium absorption properties allow seismic exploration putting more and more complicated tasks.

7. Seismic operations, as is known, are performed both in the lab and in the "field”.

8. Sources of such irregular interferences or noises, as a rule are strong, but being located far from to seismic receivers, they can disguise arrival of even very intensive useful waves.

EXERCISE 13 Insert the omitted word from the text

1. Exciting __________ close to the surface of the land or the sea and receiving waves that went into the ground and are coming back to the__________, in most cases on the basis of the observed waves allows reconstructing the object “image”.

2. The most amazing is that such__________ 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

3. Resolving the most complex objectives facing the modem __________ seismologybecame possible

4. Concerning the types of waves, P-waves are predominantly used currently, though some successful attempts are being taken to utilize both__________ and converted waves.

Reconstruction, surface, S-waves, exploration, elastic waves

EXERCISE 14 Give the Russian equivalents to the following word combinations.

1. Elastic waves

2. Identifying times

3. Travel time

4. Theoretical knowledge

5. Methodological techniques

6. Reflection

7. Converting waves

8. Diffraction

9. Dissipation

10. Anisotropic mediums

11. Multi-component mediums

EXERCISE 15 Match the terms with their definitions.

1. Travel time

1. time required for seismic wave to travel from source to detector.

2. seismic method in which reaction to excitation of consequent areas is received along profile line.

3. a sedimentary rock rich in organic matter, which can or has been transformed under geological conditions such as heat and time into gas and oil.

2. Seismology

1. the indication on a seismic record of the instant the shot or charge was detonated.

2. the location of a seismic exploration shot, a well with a charge.

3. a science that studies earthquakes including their origin, propagation, energy manifestations and possible techniques of prediction.

3. Wave arrival

1. an area that a seismic wave comes through with low velocity.

2. a process of a seismic wave coming back to the source of its excitation.

3. seismic equipment including cables, seismographs and accessories needed for seismic.

4. Signal

1. energy that contains information.

2. the record made by a seismograph.

3. an instrument that increases the amplitude of a signal such as voltage, current or power.

5. Source rock

1. the location of a seismic exploration shot, a well with a charge.

2. interference during reception of seismic signal, can be coherent and incoherent.

3. a sedimentary rock rich in organic matter, which can or has been transformed under geological conditions such as heat and time into gas and oil.

CHAPTER IV

EQUIPMENT USED FOR DRILLING OPERATIONS

Part 1

EXERCISE 1 Read and translate the text "Drilling", using the words after the text.

Drilling

The well is created by drilling a hole 5 to 30 inches (13-76 cm) in diameter into the earth with an oil rig which rotates a drill bit. After the hole is drilled, a steel pipe (casing) slightly smaller than the hole is placed in the hole, and secured with cement. The casing provides structural integrity to the newly drilled wellbore in addition to isolating potentially dangerous high pressure zones from each other and from the surface. This process is all facilitated by a drilling rig which contains all necessary equipment to circulate the drilling fluid, hoist and turn the pipe, control downhole pressures, remove cuttings from the drilling fluid, and generate onsite power for these operations.

The words to be memorized:

cement – цементный раствор

circulate fluid – прокачиваемый буровой раствор по системе

cuttings – буровой шлам

downhole pressure – давление в скважине

drilling – бурение

drill bit – буровое долото

drilling fluid – буровая жидкость

drilling rig – буровая установка

drilling site – буровая площадка

integrity - целостность

hole – отверстие, выработка малого сечения, скважина

hoist – подъем

oil rig – нефтяная вышка

to secure – закреплять

steel pipe (casing) – обсадная колонна

EXERCISE 2 Read and translate the text "Drilling mud", using the words after the text.