Well killing fluids
Well killing fluids include foam, methanol, diesel, crude oil, emulsions and water with different additives.
Oil and oil emulsions can be successfully applied as killing fluids in formations with water-sensitive clays under specific geological conditions. However they are flammable and difficult to prepare. Methanol and diesel are also not common due to similar and other reasons.
If a fluid simultaneously having properties of a squeeze fluid and capable to dissolve paraffin's and asphaltenes is applied for well killing, then bottom hole treatment can be combined with work over operations. Taking into account that on average each well annually is worked over, application of such kill fluid will provide for annual cleaning of bottom hole, which in its turn, will allow maintaining hydrocarbon production rate.
Such process fluid is reverse emulsion containing required amount of hydrocarbon solvent capable to filter out without breaking emulsion. Efficiency of producing formation bottom hole treatment with reverse emulsion with dissolving properties is much higher than efficiency of formation treatment with pure hydrocarbon solvent. A specific of well killing technology in this case is mandatory pumping of kill fluid to the bottom of the well.
Text 2
Well workover
Well work over is associated with pulling out of the hole and running in the hole with equipment, tools, various instruments, and also injection of process fluids in the well. For this purpose the following work over methods are applied:
- with the help of down hole tubing assembled of individual pipes;
- with the help of coil tubing wound on a drum;
- using wire line technique or cable.
Well work over can be performed both with open and closed or sealed wellhead.
In the first case the well must be stopped by means of killing or displacement of down hole fluid with safe fluid in order to mitigate its aggressive impact on work over crew and the environment. As a rule, well killing makes the state of bottom hole area significantly worse and may result in its production rate decrease.
In the second case work over is performed without well killing, which does not result in its production rate decrease after performed work over, improves work over crew working conditions and mitigates potential pollution of the environment. However this requires application of complicated costly equipment capable to provide for hermetic running of tubing with collars. Moreover, opposite to work over with open wellhead, where running of equipment takes place by its own weight, it is necessary to use special devices on the wellhead, which provide for creation of axial load on tubing to push tubing string into the well at high pressures.
EXERCISE 9 Answer questions about the text.
1. How can oil and oil emulsions be applied as?
2. What properties must fluid possess to be used for well killing?
3. What is reserve emulsion?
4. What is well work over associated with?
5. What methods of well work over do you know?
6. Where can well work over be performed?
7. What are the drawbacks of well killing?
8. What are the advantages of well work over with the help of coil tubing wound on a drum?
EXERCISE 10 Connect the English equivalents to the Russian words combinations from the box.
1. Дизельное топливо
2. Уровень производства углеводородов
3. Глушение скважины жидкостями
4. Сжатие
5. Чувствительная к воде глина
6. Огнеопасный
7. Ежегодный
8. Капитальный ремонт скважины
9. Углеводородный растворитель
10. Скважина
11. Забой
12. Принудительный
13. Обработка
14. Закачка
15. Эмульсия
16. Эффективность
17. Геологические условия
| Well killing fluids, diesel, emulsions, bottom, pumping, hydrocarbon solvent, squeeze, water-sensitive clays,well work over, flammable, annual, hole, mandatory, efficiency, geological conditions, hydrocarbon production rate, treatment |
EXERCISE 11 Connect the terms with their definitions.
| 1. Well work over | a) operations to make holes in casing in the interval of a pay zone. |
| 2. Methods with the help of down hole tubing assembled of individual pipes | b) word over is performed without well killing, which does not result in its production rate decrease after performed work over. |
| 3. Methods with the help of coil tubing wound on a drum | c) major repairs of down hole equipment (casing repairs, cement squeeze job, re-perforation, fishing jobs). |
| 4. Perforating job | d) the well must be stopped by means of killing or displacement of down hole fluid with safe fluid. |
| 5. Logging tool | e) a metal instrument package containing both transmitting and receiving equipment that is run in a well to make a wire line well log. |
EXERCISE 12 Make up dialogues on the topics:
1. Methods of well work over;
2. Well killing fluids;
3. Fishing tools.
EXERCISE 13 Find a word in the text that has the same or similar meaning to the italicized word:
1. Crude petroleum
2. Silencing fluid
3. Invert emulsion
4. Flexible tube
5. Analog and other reasons
6. Overhaul
7. Special equipment
8. Lower hole
9. Bottom hole zone
10. Properties of compressed fluid
11. Forced pumping
12. Work over way
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