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Goncharuk Natalia

Goncharuk Natalia

Mainer - Geological Faculty

Technology and engineering of investigation of deposits of minerals

Master's work's theme: Development of a shell for liquidation sticking bore projectile with hydraulic management

Supervisor: Karakozov Artur Arkadyevich

Email: atalia_85@mail.ru

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CHARACTERISTIC OF MASTER'S THESIS

I. Introduction.
II. Development of a shell for liquidation sticking bore projectile with hydraulic management.

1. Design features of the percbssive mechanism.
2. Description of the propised mechanism design.
3. Application technology.
III. Conclusion.

The construction of a well is a labour-intensive engineering-technological process attended by various accidents which reduce labour productivity and increase drilling work prime cost. Every year 5–10% of working time is spent for the elimination of accident consequences. Usually the accidents are the reasons for writing-off of wells which have not fulfilled their geological task.

That is why the problem of creation of accident elimination mechanisms in exploration wells has been relevant during many years. All the devices being created have to correspond to the small sizes of modern wells and to join quickly and easily to the drill string while crossing the sticky zones. Taking into account the necessity of further technical re-equipment of geological exploration organizations and their equipping with high-performance equipment and facilities, the devices for prevention and elimination of sticking should also correspond to the world standards and norms.

The correlation of sticking data shows the occurrence of typical accidents caused by the same reasons and having the same severity. However, the higher level of selectivity of sticking elimination methods and technology, especially percussive mechanisms, allows the foreign specialists to reduce considerably the expenditure of time and resources for sticking elimination. In the domestic practice the percussive mechanisms for sticking elimination (PMSE) have been used for the last 25-30 years. But their use is limited, especially in geological exploration sphere in which the percussive mechanisms are not even included in the list of necessary emergency technical devices. At the same time the statistics shows that the use of PMSE during the drilling of oil and gas wells is very efficient especially by the 2d category sticking elimination by which the probability of stuck tool retrieving comprise 0.7. The use of jars with different operating principles is very efficient by the elimination of 3d category sticking. In this case the most effective result is obtained by emergency tool processing with impact impulses in combination with the violent reciprocation of the tool or installation of liquid baths. The use of jars in combination with other methods (e.g. installation of oil baths) for elimination of sticking caused by pressure differential (1st category) can also have positive results. Thus, the design features and versatility of the percussive mechanisms which are reliable by the elimination of a number of sticking types show the perspectives of the given class of machines. Besides, the work experience of organizations of the Ministry of Oil Industry in construction of PMSE can help in creation of the efficient mechanisms for the wells of minor diameter. In Donbass the wells are mainly drilled in the areas of coal mines where there are a great number of lost-circulation zones caused by mining work. As a result, the possibility of sticking occurrence caused by the lost return increases manifold. The use of jars in these conditions can turn things worse because the vibrating drill string can ruin the well walls not filled with liquid.

Application technology.
The mechanism can be used in two ways:
- after the accident;
- as a part of drilling string while redrilling the sticky zones.

The following processing sequence is to be followed while using this mechanism after the occurrence of sticking:

1. The drilling string is being detached from its stuck part and recovered to the surface.

2. The desired anvil block travel is being determined according to the liquid level in the well.

3. The detached reducing socket with finger grip is being connected to the piston-rod of mechanism.

4. The mechanism is being moved down fluently and without turns to the left to the location of the stuck drilling string and connected to its top face. While moving the mechanism down it is recommended to pack additionally the thread joints of pipes (with joint sealer, lubricant Ð-2, etc.) for the reliable pressurization of inner cavity of drilling string.

5. The drilling string is being lifted with the help of winch (it is recommended to use the maximum possible speed of winding a line on the drum). In this case the drilling liquid has the free access to the cavity situated under the mechanism plunger and the striker hits the anvil with hit being transmitted to the stuck drilling string.

6. In order to hit the anvil once again it is necessary to move the drilling string down. The liquid is being displaced from the cavity situated under the mechanism plunger to the well under tool gravity and the mechanism is being recovered.

7. After that the steps 5-6 are to be repeated until the accident is eliminated. It is also recommended to load the static load on the stuck drilling string after the series of 3-5 hits.

After the accident elimination the well is being flushed out for 20-30 minutes and the drilling string is being lifted to the surface.
If the drilling string is not released from sticking after 50-60 hits, the operation of mechanism must be stopped, the stuck drilling string must be detached and its loose part must be lifted to the surface.

8. After the mechanism is recovered from the well it is to be disassembled, examined with its worn-out parts to be replaced. The mechanism is being scraped out, oiled and reassembled.

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