Summary of research and developments
Сontent
The chink as a technical construction should provide variety of technical and economic requirements directed on achievement оf planned parameters of its operation, first of all by maintenance of durability of a trunk of a chink both in the course of drilling, and in operation. Such problem can be solved by properly secured unstable intervals of a trunk and isolation of productive and water-bearing layers by casings. Thus the durability of work of a chink depends on quality of casings’cementation. To ensure the quality of cementation it is supposed tightness of casings and reliable dissociation of absorbing layers is also supposed. To fulfill these conditions there must be good contact between casing string and the borehole with cement stone, which can be done only at increased requirements of the borehole to the cementation: osmosis removal from caverns, gutter elimination and maintaining the stability of the borehole walls in preparation for the casing.
The principal is also the problem of technical supply of the annulus hole cementing process. To date, there were designed dozens of devices (packer) to provide the casing cementing.
The multiplicity and diversity of their design is caused mainly by search of the rational decisions directed on increase of reliability and profitability of works, connected with the filling of a given interval borehole with cement or other binder solution.
In recent years, a great work was done to create and implement systems to perform the cementing collar of both vertical and horizontal wells. Among modern packers, which are used for the preparation of the barrel to the cementation, as well as for direct filling it with cement mortar sufficiently well known and proven in production are devices in which the executive unit is deformable elastic element inserted into the body, and tightly interlocking with the walls of the barrel wells.
There is proposed a device for cleaning of stagnant zones, which works on the principle of reducing the cross flow of washing liquid on the enlarged diameter sections of the trunk. In this case, it’s possible to increase the velocity of the fluid in contact with the walls of her hole. Fulfillment of the condition is ensured by increasing volume of the elastic force of the cylinder pressure of the fluid, forming a working chamber 5. (Figure 1)
Fig. 2 shows a diagram of the packer to divide rocks of productive horizons, and perform lip-cementing the overlying horizon. The device consists of a body comprising the top adapter 1, the upper 4-cylinder, clutch 7, the lower cylinder 10 and the lower adapter 11.
Inside the case there are set hollow tubes 2 and 5 with the sealing cuffs. Both the sleeve in a starting position fixed relative to the upper and lower cylinders due to pins 3 and 6.
On the outer surface of the lower cylinder there is set a rubber bulb 8. Connection with the bulb housing is ensured by clamping its upper end for screwing the lower cylinder 10 in the sleeve 7. The lower end of the bulb is clamped at unscrewed nuts 9 on the cylinder 10. Initially, the cementing port "a" closed to the lower pipe 5, while the holes "b" of the lower pipe combined with the rug flask with holes "c" made in the lower cylinder 10.
Work on cementing the casings consists in the following. The device on the casing down to the depth of the roof of uncoupling bed. At a given point in the process of cementing a casing dropping the ball 12, which sits on the seat of the lower nozzle 5 and closes the central channel of the packer. When you turn on the pump fluid into the chamber bulb 8, which is increasing in volume, covers the annulus. With further increasing the pressure pin 6 is cut off, and the lower tube 5 together with the ball is moved down into a lower level of the cylinder. In this tightly overlapped holes "c" open and cementing the hole "a".
There is produced in the injection well (in the area above the packer) the calculated amount of cement. Following the grout put down the tube, which displaces the grout in the annulus. When pushed to the upper outlet tube 2, the cut off pins 3. Tube and top tube are moved down into the lower tube 5, closing the hole cementing. After setting and hardening of cement drilled cementing plug, ball and cement glass. Further exploited productive layer by issuing to the surface of the mineral.
Pic. 1 Devices for cementation improvement of quality obsadnykh columns
The device works as follows:
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