Read and translate the text. Variations in the drilling rate can indicate bit wear, formation changes, or whether weight on bit, rotary speed

Variations in the drilling rate can indicate bit wear, formation changes, or whether weight on bit, rotary speed, and hydraulics are being properly handled. A sharp bit, used in the right formation and properly run, will drill faster than a worn bit that is being run improperly or in the wrong kind of rocks. With this in mind, a driller will periodically measure how much time is required to drill a certain distance. Whatever the distance - 1 foot, 10 feet, or the length of the kelly - this measurement is converted into feet per hour, the usual basis for comparing bit per­formance. Many rigs are equipped with drilling rate recorders, which allow quick comparison of rates of penetration. If automatic devices are not available, the driller can determine the drill­ing rate by marking the kelly, maintaining a constant weight on bit, and simply measuring the time it takes to drill a foot. Comparing measurements provides a sufficient rough estimate of bit performance.

A commonly used method of measuring rate of penetration to determine optimum weight on bit and rotary speed is the drill-off technique. This test makes use of the fact that the drill stem is an elastic medium like a spring, the length of which varies with its tension. Main­taining circulation and rotary speed at constant rates, a given amount of weight is imposed, or slacked off on the bit. The bit is then allowed to drill off some of the applied weight. Since more drill string weight is suspended from the crown block, there is actu­ally less weight on bit. Weight is usually slacked off in increments of 2,000-5,000 lb, and the time required to drill off each weight increment is measured. Since the weight on bit will change with each drill-off test unless additional weight is slacked off, drill-off tests can help determine the best weight to use.

Drill-off tests can be used to determine the effectiveness of different variables that affect the rate of penetra­tion. By maintaining constant weight on bit and hydraulic effort, drill-off tests can be useful for finding optimum rotary speed. Likewise, the effect of increased hydraulic horsepower at the bit can be measured by varying that factor while holding bit weight and rotary speed constant. Drill-off tests may be repeated several times to take formation changes into account.

5. Give the adequate Russian variants for the following word combinations:

To be equipped with drilling rate recorders; to determine the drill­ing rate by marking the kelly; to provide a sufficient rough estimate of bit performance; the drill-off technique; an elastic medium like a spring; to vary with tension; to drill off some of the applied weight; to be suspended from the crown block; to be slacked off in increments of 2,000-5,000 lb; likewise;

to take formation changes into account.

6. Find the English equivalents for the following words and word combinations:

Правильно использовать; определять скорость проходки; быть оборудованным записывающей аппаратурой для измерения скорости проходки; длина ведущей бурильной трубы; исследование режима бурения в скважине; бурильная колонна; ослаблять нагрузку на долото; поддерживать постоянную нагрузку на долото; принимать во внимание изменения горной породы.

7. Find the words which correspond to the given definitions:

- An assembly of sheaves, mounted on beams at the top of the derrick, over which the drilling line is reeved.

- A method of determining optimum weight on bit and overall bit performance by tying down the brake and measuring the time required to drill off certain weight intervals as the drill stem decompresses.

- All members in the assembly used for rotary drilling from the swivel to the bit, including the kelly, drill pipe and tool joints, drill collars, stabilizers, and various specialty items.

- The heavy steel member, three-, four-, six-, or eight-sided, suspended from the swivel through the rotary table and connected to the topmost joint of drill pipe to turn the drill stem as the rotary table turns. It has a bored passageway that permits fluid to be cir­culated into the drill stem and up the annulus, or vice versa.

- An automatic machine designed to work without needing someone to operate it for each part of the process.

8. Agree or disagree with the following statements:

1. A sharp bit, used in the right formation and properly run, will drill faster than a worn bit improperly run or used in the wrong kind of rocks.

2. Many rigs are equipped with drilling rate recorders, which allow quick comparison of penetration rates.

3. Comparing measurements provides an accurate estimate of bit performance.

4. Drill-off technique makes use of the fact that the drill stem is an elastic medium like a spring, the length of which varies with its tension.

5. By maintaining constant weight on bit and hydraulic effort, drill-off tests can be useful for finding optimum rotary speed.

9. Answer the questions:

1. What can variations in the drilling rate indicate?

2. What is the usual basis for comparing bit performance?

3. How can a driller determine the drilling rate without the help oа automatic devices?

4. What is a commonly used method of measuring rate of penetration to determine optimum weight on bit and rotary speed?

5. How does it work?

6. What can drill-off tests be used for?

7. Why are drill-off tests repeated several times?

Explain why it is crucially important to observe variations in the drilling rate and how the rate of penetration can be measured to determine optimum weight on bit and rotary speed.

Unit 5