Gas cycling

Natural gas reservoirs often contain appreciable quantities of liquid hydrocarbons held in the gaseous state. Since these liquids are liquefied petroleum gases such as propane and butane, they are important sources of both fuel and chemical feedstocks. If the pressure in such a reservoir is allowed to decline during gas production, these liquids will condense in the reservoir and become nonrecoverable. To prevent this decline in pressure, a quantity of the produced gas from which the liquids have been removed is put back into the reservoir. This process, called gas cycling, is continued until the optimum quantity of liquids has been removed. The reservoir pressure is then allowed to decline during the production of the nearly dry gas. In effect, this process defers the use of the reinjected natural gas until after the liquids have been produced.

Overall, the production of oil and gas has become an exacting engineering job. Although new oil fields are being discovered, the huge consumption of petroleum requires that fields already in production be used more efficiently.

COMPREHENSION TASK

I. Translate the following words and word combinations

oil and gas reservoirs, pressure, to force, to remain, commercial quantities, oil fields, crude oil, substantially, gas cap, secondary recovery, to restrict, high flow potential, gas injection, gravity segregation, to obtain, jellying agents.

II. Translate into English

резервуары нефти и газа, поверхность, искусственный, заставлять жидкость течь, большая часть сырой нефти, существенно увеличивать, собираться, эффективное использование, возгорание нефти, нагретая нефть

III. Complete the sentences

1. Both oil and gas reservoirs start with ….

2. In nearly all crude oil fields less then one third of the oil originally present can

be produced using ….

3. An injected fluid replaces the produced oil and thus maintains ….

4. Another secondary recovery method is ….

5. Several recent methods for secondary recovery involve the application of heat to the reservoir to make ….

6. The heat thus generated makes the oil ….

IV. Make up the word combinations

1. artificial a) fluid

2. injected b) segregation

3. gas c) project

4. secondary d) agents

5. gravity e) flooding

6. water f) lift

7. gellying g) recovery

8. successful h) cap