One of the main reasons for the effectiveness of the exploratory drilling, is the existence of accidents, the elimination of which takes about 7 - 8% of the time of drilling.
The most common and complex kind of accident is sticking the drill pipe or casing - an accident in the well, which is characterized by partial or complete cessation of movement of the drill, in which situated in the well column can not freely raise.
The elimination of such accidents is spent on average 30 to 80% of non-productive time and cost. With increasing depth of drilling wells of technical complexity and severity of sticking, as well as the process of their elimination is continuously increasing.
Clamps of the drill are a very large group of accidents, which have the highest number of types.
1. Sticking of the drill by cuttings.
This type of accident - the most numerous in the group of stickings. Most-sticking occurs when you stop the circulation of drilling fluid, when the sludge is deposited in the annular gap between the core-set and the borehole wall (with a straight pattern of fluid circulation) or between the inner surface of the core barrel and core (in the reverse pattern of circulation). If there is a lot of sludge, it can also accumulate over an adapter or a slurry pipe wedging projectile not only on the lateral surface, but also from above.
Often, these clamps arise during drilling at intervals of partial, complete and catastrophic absorption of drilling fluid.
2. Sticking of the drill by cores.
This accident occurs when lifting the drill, during which the core barrels from the individual pieces can fall out of core, located in the walls of wells and trenches at various intervals. In the subsequent descent of the crown wedging between the borehole wall and cores, causing sticking projectile.
3. Sticking of the drill by mud cake.
This kind of stuck is going through the drill sticking to the filter cake under pressure drop of liquid or adhesive.
Factors contributing to the emergence of such an accident are: the presence of porous and permeable rocks, the difference between the hydrostatic and formation pressure; small gap between the drill and core barrel and the borehole wall, a thick, crumbly and sticky clay coating.
4. Sticking of the drill as a result of the collapse of the borehole walls.
A significant number of stickings caused due to the collapse of the borehole during drilling of unstable, weakly connected, fractured rocks, tectonic and karst zones.
If the borehole wall falls at a considerable interval, then the circulation is terminated and does not restored. Loosing rock accumulates in the trunk, forming a tube hanging over the slaughter. The main reason for these complications in the sediments should be regarded as physical and chemical effects of drilling fluid on the breed.
Collapses are also observed with a sharp decrease in the level of liquid in the well after the rise of the projectile on the surface.
In the rocks falls are possible only when the mechanical action of drillstring. Sticking a projectile from the collapse of the walls can occur at uglubke, tripping, jamming core elaboration and extension of the trunk, emergency response, removing the casing.
To select the technology and emergency response are distinguished:
Upper sticking when set weasel is clamped by rock just above the adapter or slurry pipe.
Lateral sticking when the rock falls into the annular gap between the pipe and the borehole wall and prevents rotation and extraction of the projectile on the surface.
Complete freeze when set weasel is released and on the lateral surface and the top (the tool does not rotate or move).
5. Seize of the rock cutting tool.
Under burns is meant sticking the drill caused by sintering of the matrix diamond crown with rock or sludge. The reason for this is the complete lack of or insufficient supply of drilling fluid on the face, resulting in a crown and breed (sludge) are heated by friction to high temperatures and sintered or welded together.
6. Clamps of the drill with metal fragments and unobstructed things.
There are two types of accidents:
a) Sticking of the drill by bars and pieces of metal located in the well. They occur during or after drilling and milling of core barrels and bits - due to incomplete removal of debris left behind, hitting the latter in the caverns and fissures.
b) Wedging of tool objects fallen from the surface (nuts, clamping dies, wrenches and others).
When combining the above-described sticking raise complex (combined) clamps.
The purpose of the work - to explore the duty cycle and on the basis of the results to develop a design incorporated into the drill hydraulic shock device in order to eliminate stickings.
Research tasks:
1. Choose the concept of a hydraulic device for the elimination of sticking of the drill, which provides obtaining of high-energy shock.
2. Mathematically describe the motion of the piston-striker unit during the operating cycle. Develop a methodology for calculating the hydraulic device.
3. Develop design hydraulic device in order to remove stuck drill string SBTM-50.
4. Describe the valve site.
Develop and implement of effective methods and technical means of preventing and eliminating sticking is one of the important technical problems of drilling wells.
Hydraulic Device (Img. 1) made under the scheme hammers with the opposite active move smartly. It consists of a body 2, in the upper part is connected to the adapter 1 in the drill pipe. Installed in the housing with bypass valve 3 (-pass) channels 5, spring-loaded by spring 4, and the firing pin 10 with the side channels 9 and 12, spring-loaded by spring 11.
The valve 3 and 10 there is a brisk axial channel 6 for the passage of fluid. In the shank of the striker is starting valve 13 with spring 15. Start-up valve is fixed by shear pins 16.
At the bottom house 2 is attached to the adapter 19 on the core barrel. The adapter 19 has a terminal channel 18 for output working (drilling) fluid in the annulus.
The device operates as follows:
If you have stuck in the hole to trigger the starting valve 13 unit increases supply of washing fluid. Starting valve 13 closes bore and the firing pin 10 compressing spring 11 begins to move down, with sleeve 14 starter valve cuts off the pin 15 and sits on the stress liner 17 of the striker 10. Side channels 12 striker open, the system pressure drops and the firing pin 10 by spring 11 returns to its original position.
On the surface the ball 8 throws, which covers the axial channel 6 of striker 10. Above the valve 3 the pressure increases and the valve 3 together with striker 10 begins to move downward, compressing the spring 4 and 11. In contact with by-pass valve channels 5 into the cavity of low pressure, pressure drops over the valve and through the spring 4 the valve 3 is returned to its original position. The firing pin 10 to the inertia continues its downward spiral to a complete stop. After which the firing pin spring 11 comes back up and at the end of the stroke strikes the anvil 7. Above the valve 3 the pressure increases and the cycle repeats.
The advantage of this device is that the device is included in the drill, as well as start-up valve is used instead of the reverse. This saves time for the start, because it need not to unscrew the drill pipe 2 times (for dropping the ball in the valve and to release the tube, overlapping the central channel of the impactor). The use of the ball instead of tubes with a device for dropping the ball without unscrewing the pipe string allows immediately respond to the freeze and run hydraulic hammer.
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