Before reading the text, study the vocabulary. 2. Pay attention to the pronunciation of the following words:
| 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.
4. Give the adequate Russian variants for the following word combinations:
To drill by gouging and scraping; to contain compacts; to be composed of; abrasion resistance; the tungsten carbide's durability; to make long bit runs; to result in significant cost savings; to be reusable.
5. Agree or disagree with the following statements:
1. The original rotary drilling bit was a diamond bit.
2. A drag bit has no moving parts and drills by gouging and scraping.
3. New drag bits contain milled teeth composed of diamond crystals and tungsten carbide.
4. Polycrystalline diamond bits combine the diamond's hardness and abrasion resistance with the tungsten carbide's durability to make long bit runs.
5. Drag bits always require serious repair.
6. Answer the questions:
1. What compacts do modern drag bits contain?
2. What drag bit characteristics have resulted in significant cost savings?
3. What advantages do these bits offer?
You’ve got acquainted with the different bit types. To revise the information you’ve read earlier, do the given tasks:
7. Find in the texts the English equivalents for the following words and word combinations and learn them by heart:
Выбор долота, изнашиваться, свойства горной породы, шарошечное долото, карбидвольфрамовые вставки, фрезерованные зубья, образование сальника на долоте, скорость проходки, покрытие, штыревое долото, прочный, спускоподъемная операция, смещение осей шарошки, промывочный канал, направлять поток бурового раствора, шлам/металлические обломки, лопастное долото/долото режущего типа, прочность на истирание.
8. Match the words with their definitions and give their Russian equivalents:
| 1. compressive strength | a)the teeth or tungsten carbide inserts in the outermost row on the cones of a bit, so called because they cut the outside edge of the hole and determine the hole's gauge or size. |
| 2. gauge | b)the material in which the diamonds on a diamond bit are set. |
| 3. gauge cutters | c)the degree of resistance of a material to a force acting along one of its axes in a manner tending to collapse it; usually expressed in pounds of force per square inch (psi) of surface affected or in kilopascals. |
| 4. matrix | d)a cylindrical object, rounded or chisel-shaped on one end and usually made of tungsten carbide, that is inserted in the cones of a bit to form the cutting element of the bit. |
| 5. insert | e)the diameter of a bit or the hole drilled by the bit. |
9. Scan the texts and find the words which correspond to the given definitions:
a.Wearing away by friction.
b.The cutting or boring element used in drilling oil and gas wells. It consists of a cutting and a circulating element.
c.An extremely hard material, usually crushed tungsten carbide, that is applied to the outside surfaces of tool joints, drill collars, stabilizers, and other rotary drilling tools to minimize wear when they are in contact with the wall of the hole.
d.Metal debris lost in a hole. It may be a lost bit, pieces of a bit, milled pieces of pipe, wrenches, or any relatively small object that impedes drilling and must be fished out of the hole.
e.A hole inside a bit through which drilling fluid from the drill stem is directed.
10. Read the description of the bit and guess its type:
1. A drilling bit that has a steel body surfaced with a matrix and industrial diamonds. Cutting is performed by the rotation of the very hard diamonds over the rock surface.
2. A drilling bit with no moving parts but with cutting edges of hard alloys. First used when the rotary system of drilling was developed about 1900, it is still useful in drilling very soft formations.
3. A drilling bit made of two, three, or four cones, or cutters, that are mounted on extremely rugged bearings. The surface of each cone is made up of rows of steel teeth or rows of tungsten carbide inserts.
Complete the chart