Read and translate the text. To make a hole fast and at alow cost, a bit that is suited for the formations it will be drilling in must be used

To make a hole fast and at alow cost, a bit that is suited for the formations it will be drilling in must be used. Selecting the right bit can be tricky. In fact, bit programs may differ from well to well in the same field. Knowledge of basic bit construction and formation properties can make bit selection a little easier.

The variety of available bits complicates bit selection. Bit records, dull bit evaluations, and a working knowledge of the way bits function in different formations can all help in the selection of the best bit for the drilling situation. The ideal bit is one that will do the job for the least money, when all the costs have been taken into account. Unfortunately, a bit has not yet been invented that can drill efficiently in every formation and not wear out. If there were such a bit, rotary drilling could be an entirely automatedprocess, and the only decision to be made wouldbe whento stop drilling.

To clarify any confusion that can result from the different ways that bit manufacturers iden­tify their products, the IADC has devised a standard classification system for bits. Using this system, bits from each manufac­turer are entered on a form that indicates the characteristics of each bit and the formations that the bit may be used in. The IADC Drilling Manual contains classification forms for all of the major bit manufacturers. Obsolete bits are also included to facilitate the comparison of information from old bit records.

Drilling performance records, particularly bit records, are of prime importance for the selec­tion of bits and proper operating procedures. These forms give a record of the perti­nent facts of the well location, rig capability, mud type, and, most important, vital statistics of each bit run in the course of drilling the hole. Bit type, jet nozzle sizes, footage drilled, dull condition, and hours run are all included in the record, facilitating cost calculations.

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

To complicate bit selection; to clarify confusion; to devise a standard classification system; the IADC Drilling Manual; to facilitate cost calculations; rig capability; dull condition; to gives a complete account of the drilling progress.

5. Find in the texts the English equivalents for the following words and word combinations and learn them by heart:

Бурить скважину; свойства горной породы; осложнять выбор долота; оценка износа бурового долота; принимать во внимание; изнашиваться; прояснить ситуацию/устранить путаницу; устаревшее долото; расположение скважины; производительность буровой установки; тип бурового раствора; характеристики долота.

6. Complete the following sentences:

1. To make a hole fast and at alow cost ...

2. Bit programs may differ ...

3. Bit records, dull bit evaluations, and a working knowledge of the way bits function in different formations ...

4. To clarify any confusion ...

5. Bit records are of prime importance ...

7. Answer the questions:

1. What bit must be used to make a hole fast and at alow cost?

2. What can help in the selection of the best bit for the drilling situation?

3. What for has a standard classification system for bits been devised?

4. What does this system indicate?

5. What information do drilling performance records and bit records contain?

Summarize the information which must be taken into account in bit selection.

Bit Design

Roller cone bits

Roller cone, or rock, bits are bits made up of cones mounted on rugged bear­ings. Usually there are three cones, so they are also called tricone bits. Each cone houses several rows of steel teeth or tungsten carbide inserts that do the cutting. The quantity, place­ment, and composition of the teeth or inserts and the angle at which the cones meet the for­mation all affect the efficiency with which a cer­tain formation can be drilled.

Steel-tooth roller cone bits

Before reading the text, study the vocabulary

2. Use the dictionary and write down the transcription of the following words:

- rugged bear­ings

- tricone bits

- tungsten carbide

- gypsum

- dolomite

- quartzite

- granite

- abrasiveness

Practise their pronunciation!