Straight hole drilling

Frequently it is necessary to drill a straighter hole than was originally planned when the job was started with a certain string of drill collars. Also, it may happen that it is desired to put more weight on the bit without increasing the deviation. The best single proven way to do either of these things with the same string of drill collars is to add stabilizers. For deviation control a single stabilizer is sufficient if it is properly located in the drill string. The proper location is the first bend in the drill string above the bit. Since the bending point depends on the hole size, drill size and weight on the bit, it may occur at different points. To some extent the placement is also dependable on the formation characteristics.

It has been considered good practice in some cases to space additional stabilizers about one stand apart through a portion or all of the rest of the drill collar string. The additional stabilizers do not help to keep the hole straight. They do help in preventing wall sticking and other problems associated with hole conditions.

With the use of stabilizers, it is important to remember that stabilizers are usually the weakest point in the drill string and, therefore, subject not only to wear but failure. Some of the more modern stabilizers have been designed so that the wings do not create a serious hazard in the hole. For example, some of these are made of drillable material and some may be removed with washover pipe.

By reducing the weight on the bit, the bending characteristics of the drill string are changed and the hole will tend to be straighter. One of the oldest techniques for straightening a hole was to reduce the weight on the bit and speed up the rotary table. In recent years it has been found that this is not always the best procedure because reducing the bit weight sacrifices considerable penetration rate.

The straightening of a hole by reducing bit weight should be done very gradually so that the hole will tend to return to vertical without sharp bends and will therefore be much more safer for future drilling.

The words to be memorized:

1. Bending point – точка перегиба

2. Penetration rate – скорость проникновения

3. Space – помещать, размещать

4. Washover pipe – промывочная труба

5. Stabilizer – стабилизатор

6. Sticking – прихват

7. Collar – муфта трубы

8. Drilling equipment – буровое оборудование

9. Rotary table – роторный стол

10. Bottom-holeassembly(ВНА) – компоновка инструмента для бурения

11. Logging – каротаж

12. Blowout preventer (ВОР) – противовыбросовый превентор

13. Pay zone – продуктивная зона

14. Wild well –неуправляемая скважина;

15. Kill line –линия глушения;

16. Flare pit –факельный амбар;

17. Dummytrip – «холостой» подъем-спуск

EXERCISE 8 Answer questions about the text.

1. What is the best way to put more weight on a bit without increasing deviation?

2. What does the placement of a stabilizer depend upon?

3. What are the purposes of a stabilizer?

4. Describe stabilizer’s disadvantages.

5. What was one of the oldest techniques to straighten the hole and what is the disadvantage of this method?

6. What is the proper method to straighten a hole?

EXERCISE 9 Give the English equivalents to the following word combinations.

1. Drilling

2. Formation

3. Stabilizer

4. String

5. The drill collar

6. Sticking, failure

7. The wings, weight

8. To tend

9. The rotary table

10. To sacrifice

11. The straightening

12. Gradually

13. Sharp bend.

EXERCISE 10 Make up sentences out of two parts from the table:

For deviation control a single stabilizer …	… wall sticking and other problems associated with hole conditions.
To some extent the placement …	… was to reduce the weight on the bit and speed up the rotary table.
The additional stabilizers do help in preventing …	… is also dependable on the formation characteristics.
Some of the more modern stabilizers …	… by reducing bit weight should be done very gradually.
One of the oldest techniques for straightening a hole …	… is sufficient if it is properly located in the drill string.
The straightening of a hole …	… have been designed so that the wings do not create a serious hazard in the hole.

EXERCISE 11 Open brackets and use active or passive form of the verb.

1. Horizontal drilling (to be) __________ a type of drilling in which directional well gradually becomes horizontal.

2. Drilling incidents (to include) __________ oil and gas blowouts, breakage and leaving in a well of drill pipe and casing, drilling bits, down hole engines, pipe string sticking, twist-off.

3. Annular preventer (to design) __________ in such a way that it can close annulus around drill pipe, drill collars or completely close an open well.

4. Well blowout can (to define) __________ as uncontrolled flow of formation fluid under pressure, which may damage drilling equipment and injure maintenance personnel.

5. Production surveys (to perform) __________ to determine production rate of an oil or gas well.

EXERCISE 12 Translate into English in written form.

1. Чтобы контролировать отклонения достаточно одного стабилизатора, если он правильно расположен в бурильной колонне.

2. Дополнительные стабилизаторы не помогают сохранить скважину прямой.

3. С использованием стабилизаторов, важно помнить, что стабилизаторы, как правило, самое слабое место в бурильной колонне.

4. Один из старейших методов для выпрямления скважины было снижение нагрузки на долото и ускорение роторного стола.

5. Скважина будет стремиться вернуться в вертикальное положение без резких перегибов

EXERCISE 13 Read and translate the texts.