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

To fail below a preestablished rate; cost-effective choice of bit; the size and arrangement of diamonds; the pattern of the watercourses; to govern the flow of drilling fluid; commonly used configurations; the radial flow configuration; to be routed from the center of the bit to its outer diameter; to permit high mud velocity; medium-sized diamonds; to guard against shearing; a hole free of junk; to recover bit's cost; to remain cool; to burn into the matrix.

5. Agree or disagree with the following statements:

1. A diamond bit may be the best alternative when a roller cone bit's progress fails below a preestablished rate.

2. Under certain conditions diamond bits can be the most cost-effective choice of bit.

3. The diamond bit is basically spherical in shape.

4. The size and arrangement of the watercourses determine the bit's suitability for drilling a particular formation.

5. The watercourses govern the flow of crude oil across the bit.

6. The watercourses for soft-formation diamond bits may be in three configurations.

7. In medium-strength formations large-sized diamonds are set in a radial pattern on a cone that is shallower and more rounded than the soft-formation bit cone.

8. A rounded, shallow cone prevents the damage to the center of the bit that can occur on a deeper cone when extreme weight is applied.

9. When diamond bits are used, a hole free of junk must be maintained to avoid breaking the diamonds.

6. Answer the questions:

1. In what cases are diamond bits considered to be the best alternative?

2. What bit’s characteristics determine its suitability for drilling a particular formation?

3. What design do diamond bits for soft formations have?

4. What are two commonly used configurations of the watercourses?

5. How can the cross-pad watercourse direct the flow of the drilling fluid?

6. What does the radial flow configuration permit?

7. What diamond sizes are used in medium-strength and hard formations?

8. Why are the diamonds on hard-formation bits set in dense patterns?

9. What working conditions are required to avoid bit breakage and recover the half of bit's cost?

Drag bits

1. Before reading the text, study the vocabulary

drag bit	Лопастное долото, долото режущего типа
fishtail bit	Долото типа «рыбий хвост», долото лопастного типа
polycrystalline diamond	Поликристаллический алмаз
resistance	Сопротивление
durability	Износоустойчивость, долговечность

2. Pay attention to the pronunciation of the following words:

• polycrystalline diamond

• abra­sion resistance

• tungsten carbide's durability

3. Read and translate the text

The original rotary drilling bit was a drag bit. A drag bit has no moving parts and drills by gouging and scraping. The fishtail bit, so named for its design, is no longer used, but new drag bits have come into use recently that are providing alternatives to the widely used roller cone and diamond bits.

These new drag bits contain compacts that are composed of diamond crystals and tungsten car­bide. These polycrystalline diamond, or PCD, bits combine the diamond's hardness and abra­sion resistance with the tungsten carbide's durability to make long bit runs. Fast rates of penetration, increased time in the hole, and a reduced number of trips have resulted in signifi­cant cost savings when compared with conven­tional bit types in certain drilling situations.

Drag bits offer other advantages. The weights imposed are relatively light, and the shearing action of the inserts requires less energy (weight on bit and rotary speed) to drill than most con­ventional bits do. With no moving parts, drag bits have proven to be reusable, often requiring only slight repair. The newer drag bits are evidence of positive trends in bit design toward the goal of achieving faster drilling rates at lower costs.