The area being surveyed, a low probability, the time taken for the waves to travel, the rocks are arranged in strata, onshore search, advanced technology, the reflecting rock, fossil record, oil and gas in quantities worth developing, to work out the thickness, to give a picture of deep rock structures, show promise teams, to calculate the distance traveled.
EXERCISE 14 Give the English equivalents to the following words.
; ; ; ; ; ; ; ; ; ; - ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; , .
EXERCISE 15 Answer the questions below, using the information from the text "How to Find Oil".
1. What equipment is used in searching onshore oil and gas?
2. What methods are used to search for oil and gas?
3. How do specialists work?
4. How can you explain the term "seismic survey"?
5. What do surveys show?
6. What kind of activity is drilling? Can you prove it?
7. What kind of drilling equipment can you enumerate?
8. What for is a carefully constituted mud?
EXERCISE 16 Read and translate the text, using the words after the text.
Fluid Flow
Fluids move from regions of high pressure to regions of low pressure. When the well is drilled into a hydrocarbon reservoir and open at the surface, the area in the vicinity of the well bore becomes an area of low pressure. If the reservoir has sufficient permeability, oil and gas flow from all directions into the well bore. When fluids are flowing into the well the pressure at the well bottom is called the bottom hole flowing pressure. The pressure at surface, when the well is flowing, is called the wellhead or flowing tubing pressure. The pressure at the surface when the well is shut-in and fluids are not flowing through the tubing is called the shut-in or static tubing pressure.
The pressure within a column of fluid increases with depth and is greater at the bottom of the column than at the top. This principle can be demonstrated by the change you feel on your ears when you dive to the bottom of a swimming pool. The pressure is directly related to the depth and the density of the fluid, and is called hydrostatic pressure.
For a given height of a column of fluid, the hydrostatic pressure of liquids is much greater than the hydrostatic pressure of gas. For example, the change of pressure with depth (called the hydrostatic gradient) is about 1.0 Kpa/m in gas. In oil the gradient varies from 8.0 to 9.0 Kpa/m.
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In order for fluids to flow up the well bore, the reservoir pressure must be greater than the total of the hydrostatic and atmospheric pressure. The flow rate of oil or gas into the well bore depends on the permeability of the reservoir rock, the area of flow into the well bore and the viscosity of the fluid.
Oil and gas energy drives
Oil and gas reservoirs and fields have also been classified according to the type of natural energy and forces available to produce the oil and gas. At the time oil was forming and accumulating in reservoirs, pressure and energy in the gas and salt water associated with the oil was also being stored which would later be available to assist in producing the oil and gas from the underground reservoir to the surface. Oil cannot move and lift itself from reservoirs through wells to the surface. It is largely the energy in the gas or the salt water (or both) occurring under high pressures with the oil that furnishes the force to drive or displace the oil through and from the pores of the reservoir into the wells.
The words to be memorized:
1. Drill
2. Flow
3. Flowrate ,
4. Hydrostatic gradient
5. Shut-in a well
6. Tubing - (HKT)
7. Well, hole
8. Wellbore
9. Wellbottom
10. Bottom hole flowing pressure
11. Bottom hole-
12. Wellhead
13. Buttom
14. Depositions
15. Development ()
16. Gas cap
17. Permeability factor
18. Pores
19. Reservoir
20. Residual
21. Impermeablecaprock
