CABLE TOOL DRILLING. - In drilling a well with a cable tool, it is impractical to either drive the tool down with the hammer or to blow debris from the hole. So the cutting is suspended on a rope and raised and dropped repeatedly to drill the hole. Enough water is used in the hole to mix with the cuttings to produce a fluid mud. When this mixture is sufficiently thick, the drilling tool is withdrawn and a bailer is run into the hole. The bailer resembles a slender, bottom-filling water bucket used on bored farm-wells. Sludge is sucked into bailer on bottom and dumped at the surface. This process is repeated until the desired depth is reached or until a soft formation or water sand is encountered.
One of the big disadvantages of the cable tool method is the difficulty of penetrating soft formations. Wall of the hole is unsupported and tends to cave in or slough. To overcome this trouble, it is necessary to run casing through such sections to establish a wall to permit drilling to continue. If several soft formations are encountered, a string of casing will be required at each point to protect the hole. Consequently, the cable tool hole starts with a large diameter to have room for nesting the required strings of pipe needed to reach the projected depth.
A derrick is necessary for lifting tools and pipe in and out of the hole. As the maximum length of any single join! of pipe will exceed 40ft. slightly, the derrick does not have to be as high as average rotary derrick.
Three hoisting reels distinguish the cable tool machine. The bull wheel handles the drilling tools going in and out of the hole. The calf wheel is used for hoisting and running of casing. The sand reel carries the small line on which the bailer and, later, the swab is run.
An up and down motion is imparted to the drilling tools by the walking beam or by a spudding arm. The walking beam, used on the standard rig, operates like a pump jack or see-saw in lifting and dropping the drilling string attached to the end over the hole. The spudding arm operates by pushing a grooved sheave against the fixed line of the drilling string for raising in the hole and then dropping by suddenly releasing the line.
The bit is screwed into a heavy stem to impart additional weight for cutting. Immediately above this, in the drilling string, are the jars, which permit flexibility in the string and aid in giving a free striking motion. The jars are similar to two huge chain links. This arrangement permits blows to be struck upward so that a stuck bit may be retrieved. The jars may be weighed from above by a sinker, which is a long, cylindrical joint of solid metal. The complete string of drilling tools is surmounted by a rope socket to which is attached the drilling line,
Importance of Cable Tool Method. While the importance of the cable tool drilling method has declined, there are still many shallow holes drilled by this procedure. Chief advantages of the technique are:
(1)Ability to penetrate very hard formations at relatively low cost;
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(2)Full recovery of all cutting from ail formations so that no oil possibilities are missed; and,
(3)Safeguarding the formations from damage (particularly low pressure sections) that might result from columns of fluid as used in rotary drilling,
This third advantage has made the cable tool method desirable for the completion of wells. Consequently, many portable cable tool units are engaged in well completion work
Chief reasons why the rotary method has gradually replaced the cable tool operations are: (1) Greater speed of penetration (particularly in the softer formations);
(2)Expense of multiple strings of casing required in cable too! practice;
(3)The extreme difficulty of controlling high bottom hole pressures with cable tools.
ROTARY DRILLING METHOD. - The rotary method derives its name from the fact that a boring, twisting, or rotary motion isemployed in cutting the hole. Because of an ingenious arrangement for circulating fluid, it is not necessary to withdraw the bit to remove cuttings from the hole. The cutting bit is earned on the end of hollow pipe through which fluid is forced downward and out of the openings in the bit. After release, at the bottom of the hole, the fluid is forced upward by pressure and carries with it debt is from the bottom of the hole. Minute rock fragments, called cuttings, are removed from the fluid before the fluid makes the cycle again.
You have no doubt had the experience of forcing the nozzle of a garden hose into the earth and boring a hole by allowing the water jet to wash the dirt out. If you had cut a serrated edge on the nozzle of your hose and could have rotated it asit was forced down you would have had a rotary drilling machine. The refinements in size and design constitute the modem rotary drilling rig. There must be some way of lifting the heavy pipe, drill collars, and bits used in making the hole, For this purpose, as with cable tool, a derrick is employed. Derricks are generally of two types: Standard derricks built on the job arid dismantled for removal to the next location, and sue jack-knife or portable derricks. The jack-knife derrick con be moved and erected on the job by regular drilling crew members. The derrick is hauled to the location in sections by trucks, ft is bolted together on the ground, in a horizontal position, and the whole derrick is then raised to a vertical standing position by rig hoisting equipment.
The derrick proper sets on a base called the substructure. This is a table-like structure used to provide working room below the floor and the rotary table. It permits easy access to the well head and blow-out preventers as they are placed below the rig working area. Upon completion, the Christmas tree can be installed easily and the derrick moved without interfering with the well. The flow line for the mud returning from the bore-hole can be located in a better position with reference to the mud tanks. In the top of the derrick is the crown block containing several sheaves. These are sheaves or pulleys similar to those used in driving the fan or generator on your automobile.
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Unit 5
I Learn the words:
1.groove - желоб
2. medium - средний
3.line - канат
4.to spool - наматывать
5.drum - барабан
6.draw - works - лебедка
7.to lower - опускать, понижать
8.sheave - шкив
9.thread - резьба
10.traveling block - талевый блок
11.crown block - кронблок
12.edge - край, ребро
13.brake - тормоз
14.flange - фланец
15.to cool - охлаждать
16.cathead - катушка
17.tongs - ключи, клещи
18.to tighten - затягивать
19.to loosen - ослаблять
20.power — энергия, мощность, сила
21.prime mover - привод
22.gasoline - бензин
23.engine - двигатель, мотор
24.boiler - котел, бойлер
25.fuel - топливо
26.flexibility - гибкость
27.slush pump - грязевой насос
28. standpipe -стояк
29 kelly - рабочая труба
30 hose - шланг
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The grooves are made to fit the large sizes of wire rope used in hoisting. Normal size for medium depth drilling is line that is 1 1/8 in. in diameter. Line size increases to 11/4 in. in diameter at about 9000 ft. of depth.
Wire line is spooled on the drum of the draw-works, which does the work of hoisting and lowering tools in the hole. After the line passes over the first sheave in the crown block it is threaded through one sheave of the traveling block and so on back and forth until the line is "strung up". Six or eight lines, meaning the use of three or four sheaves on each block, are most commonly used.
The drum of the draw-works can be operated at several different speeds. The outer edges are equipped with brake drums and flanges. These brakes are often cooled by water jackets and are aided by other devices built into the draw-works.
Other integral parts of the draw-works are the catheads. These spool-like reels are used for hoisting or moving small loads with the manila rope for pulling the tongs (huge wrenches) that tighten or loosen the threaded joints of drill pipe.
The power that drives machinery of the rotary or cable tool rig may be selected from several sources. Most rigs today are "mechanical", meaning that their prime movers are gas, gasoline, or diesel engines. Steam rigs, with their batteries of boilers, held a very prominent place in the past and are still greatly admired for the smoothness of their operation. Steam has been largely displaced because of the heavy expense of moving, inadequate water supplies, high fuel cost, and fire hazard. Great attention is paid to securing the most horsepower for the least weight. This has limited the popularity of electric powered rigs that rival steam in their smooth flexibility of operation.
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Since the prime movers also drive slush pumps, the entire amount of power is not usually moving through the draw-works. Slush pumps or mud pumps require considerable power to keep them pulsing. The pumps are the heart of the circulatory system. Through the suction hose is drawn the mud from earthen slush pits or steel mud tanks. Under pressure, this mud is delivered through the discharge of the pump to the standpipe.
Mud leaves the standpipe at the gooseneck to enter the rotary hose. This hose is necessary for making a flexible connection so the drill pipe may move up and down, within a range of 30 to 40 ft., without interfering with the circulation of mud.
Mud flows from the rotary hose through the swivel to the drilling string. Swivel is constructed so that the upper portion, attached to the hose, remains stationary while the lower part, fastened to the kelly, rotates freely. This arrangement permits the entire drilling string to be rotated while fluid is coursing through it to the bit.
The kelly or kelly joint or grief stem is the top section of the drilling string. It is made square, hexagonal, or fluted in cross section so that it can be easily gripped by the drive bushings which act as wedges to transfer motion from, the spinning rotary table. Round pipe would be hard to hold for rotating without the use of teeth that would cut into and damage the metal.
The kelly is normally longer than any single joint of pipe. It is always the top joint in drilling. As it passes through the center of the rotary table it is held from the sides by drive bushings so that it has to revolve with the table. In this manner a rotating motion is imparted through the string of drill pipe to the bit on the bottom of the hole.
The drive bushings fit loosely so the kelly may be raised or lowered through the table whether the rotary table is in motion or not. This permits the driller to allow the drill stem and bit to progress downward (by releasing the brake slightly) as the rock is cut away at the bottom of the hole. It also allows any desired amount of weight to be applied through the bit.
When drilling progresses to the point where the kelly is "all the way down" (meaning the kelly has moved down through the table as far as it can go), a new joint of pipe is added. Drilling is stopped temporarily while the whole section of pipe in the hole is lifted sufficiently for the kelly to be completely out of the rotary table. This is called "picking up".
At this time, the first joint of pipe below the kelly protrudes several feet above the table. Lifting is halted and slips are put into the table around the pipe in the place of the drive bushings which are withdrawn with the kelly.
The slips are simply wedges with toothed faces to grip the pipe so it cannot fall
into the hole. When the driller is sure the slips are set, he permits his helpers to unscrew the kelly from the pipe. This is done with the tongs.
The new joint of pipe to be added to the string for drilling deeper may now be handled in one of two ways. Conventional method is to lower the released
kelly with the swivel attached into a shallow hole. This is the rathole. It has a protective casing of pipe large enough to sheath the kelly. The rathole is dug and the rathole pipe inserted when the rig is initially set up. With the kelly out of the way, a new joint of pipe is picked up and screwed on to the top of the drilling string. The whole string is then lowered with elevators to the top of the rotary table. Slips are again inserted to hold the pipe while the elevators are detached. The hook is then moved to the bail of the swivel and the kelly is withdrawn from the rathole.
After the kelly is re-attached to the drilling string, work goes on as before until another joint is needed.
These maneuvers, in variation, are repeated many times during the drilling of a well. Each time a bit becomes dull and needs replacement, the entire string of pipe has to be pulled from the hole and re-run. To save time, the pipe is generally pulled in doubles (two joints at a time) or trebles (three joints at a time) and stacked upright in the derrick in rows called stands. Going in or out of the hole with the drill pipe is called a trip. A complete "in and out" job is referred to as a round trip.
The bottom joints of the drill string are frequently made with very thick walls for increased weight These are drill collars and they serve a similar purpose to the plumb bob on a string. By placing additional weight in the bottom portion of the drill string it is kept in tension, and greater efficiency is achieved. The added weight also permits the driller greater range in the amount of weight that he may carry on the bit. Other advantages are In keeping straight hole and in reducing wear on tool joints (the connections between joints of drill pipe). Immediately below the drill collars, the bit is attached
Unit 6
I Learn the words:
1.slips - клинья, плашки
2.wedge - клин
3.toothed - зазубренный, зубчатый
4.to grip - зажимать, захватывать
5.recovery - извлечение, добыча
6.temporary - временный
7.to displace - вытеснять
8.water drive - водонапорный режим (вытеснение нефти нагнетаемой водой)
9.primary - главный, первичный
10.gas cap drive - режим газовой шапки
11.expansion - расширение
12.to dissolve - растворять
13.solution - раствор
14.to expel - вытеснять, исключать
15.maintenance - поддержание
16.desirable - желаемый
17.beneficial - благоприятный
18.to retain - удерживать, сохранять
19.injection - нагнетание
20.loss - потеря
22.secondary - вторичный
23.common - обычный, общий, распространенный
24.ordinary - значительный
25.artificial - искусственный
26.to employ - применять, использовать
27.water flooding - заводнение
28.favorable - благоприятный
29.to flush - вымывать, промывать
30. to push - толкать
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