RU2162511C1 - Device for separation of drill string-casing annulus of well equipped with cemented liner - Google Patents

Abstract

FIELD: oil and gas producing industry; applicable in sealing of drill string-casing annulus. SUBSTANCE: device includes a hollow with seat and plugging plunger with plug. Part of its external surface is made conical for body seat. Plugging plunger has fastening threads on its end and is located inside body. Body and plugging plunger have centering ribs on their one end. EFFECT: protection of casing string wall from effect of high pressure and aggressive media, and in treatment of bottom-hole formation zone with deep differential pressure. 3 dwg

Description

 The invention relates to the oil industry and will find application in sealing the annulus of a well in order to protect the casing from high pressure and aggressive environments.

 A device for separating the space of a well is known, comprising a barrel, a sealing element with upper and lower stops, a conical sleeve with splines and springs, a hollow shut-off device in which a diaphragm device with a low-pressure cavity and a cavity filled with liquid is closed, which is closed from below by a piston connected to the barrel, a cutter connected to a conical sleeve and closed by a plunger-sleeve [1].

 The known device is complex in design and, since the central channel is closed by a piston, it is of limited use, it prevents the descent of instruments and tools.

 The closest analogue of the invention is a device for uncoupling the annular space of a well equipped with a cemented liner, including a hollow body with a landing seat and a plug plug with a plug and a part of its outer surface made conical under the landing seat of the body [2].

 This device is also complex in design, it requires to bring the sealing elements into working condition the estimated volume of the elastic polymer composition.

 The technical result of the invention is the elimination of these disadvantages.

 The required technical result is achieved in that a device for uncoupling the annular space of a well equipped with a cemented liner, comprising a hollow body with a seat saddle and a plug plunger with a plug and a part of its outer surface made conical under the seat saddle of the housing, according to the invention, the plug plunger threads at the ends and placed inside the housing, while the housing and the plug plug are made at one end with centering ribs.

 In FIG. 1 shows a General view of the proposed device, in partial longitudinal section; in FIG. 2 is a view A of FIG. 1, where the centering ribs of the housing and the plug plug are visible and the gaps between them; in FIG. 3 - the process of processing productive formations by the pulse-implosive method - creating a deep depression on the treated formation.

 A device for uncoupling the annular space of the well contains a hollow body 1 (see Fig. 1) with a landing seat 2, a connecting thread 3 and centering ribs 4 made at its upper end. The housing is equipped with a plug plunger 5, placed in it, with connecting threads 6 and 7 at the ends and a conical surface 8 made under the saddle 2 of the housing 1, centering ribs 9.

 The sealing elements 10 of the plunger with the help of the rings 11 and the abutment 12 are pressed against the annular ledge of the plunger 5. When creating a deep depression on the workpiece to the lower threaded thread 7 of the plunger screw the plug 13 (see Fig. 3), thus forming a "plunger plug" .

 The operation of the device is as follows.

 The housing 1 before lowering into the well is freed from the plug plug 5 and screwed to the upper end of the shank 14 (see Fig. 3) and cemented with it. The installation of a shank by cementing is associated with the need to seal production casing, shutting off the upper and intermediate water-filled formations, and restoring low-production and inactive wells by cutting the second shafts. Currently, the annual volume of such work only in JSC TATNEFT is 120-150 wells and has a tendency to intensive increase.

 After OZZ (waiting for cement to harden) tubing (tubing) on which the shank 14 is lowered, disconnected by an autotap (not shown) and raised to the surface. Next, the reservoir is opened by one of the known methods.

If necessary, depending on the type of work in the well, the plunger 5 is equipped with a plug 13, after which it is lowered into the well on the tubing string 15, having equipped the latter with a non-return valve 16 and a relief valve 17, and the wellhead is sealed with stuffing box seal 18. When the plunger reaches body 1 with its conical surface 8, it sits on the saddle 2 of the body, thereby separating the inner tube space 19 of the liner from the annular space 20 of the well. The latter is ready for various technological operations in which the well walls are already protected from high pressure, so the device allows you to:
- to carry out the treatment of the bottom-hole zone (BHP) of the productive strata of producing and injection wells by the impulsive-depression method by creating multiple effects on the formation;
- to carry out SCR and waterproofing works using various chemical reagents under pressure without using recoverable packers in the traditional way;
- protect the production casing of injection wells from high injection pressures;
- install a gas anchor - a probe above the device body, while the plunger will play the role of the lower sealing cuffs. Reliable tightness of the plunger body ensures a trouble-free period of operation of submersible pumps during the operation of wells.

 Processing PZP of productive formations by the impulsive-depression method using the proposed device is as follows.

 The plunger plug with the plug 13 on the tubing string 15 is lowered, providing them with check and knockdown valves 16 and 17, respectively, before the plunger fits with its conical surface 8 on the seat 2 of the housing 1, cemented together with the shank 14 in advance. In this case, the check valve 16 serves to reduce the level of the well fluid and participate in creating the necessary depression on the formation. After landing of the plunger 5 on the saddle 2 of the casing, the tool is unloaded to push the plunger out of the casing by borehole overpressure. Then, the liquid level in the well is reduced to the required value with the help of a compressor (swabbing), after which the mouth is depressurized and the plunger 5 is released from the housing 1 by tension, raising by about 1 m.A sharp increase in the load on the hook indicates the plunger leaves the housing. At the same time, a vacuum is created under the plunger - a deep depression, leading to intensive cleaning of the bottomhole formation zone.

 This process is then repeated 3-4 times. In this case, the created depression in the well by manipulating the plunger is agreed with the customer (NGDU). Based on this, the number and depth of installation of check valves are determined 16. Moreover, as practice shows, the depression on the formation should not be more than 15.0 MPa for a production string with a diameter of 168 mm, 20 MPa - for a production string with a diameter of 146 mm. In addition, if the impermeable layer of the developed or treated formation and located above or below it is not covered by perforation of an aquifer or irrigated formation, the pressure drop per 1 m of the height of the cement ring should be no more than 20 kgf / cm. At the end of the work to create a deep depression on the formation, the collapsing valve 17 is destroyed, which prevents the outflow of the borehole fluid when lifting the tool, and the tubing string 15 with the plunger is raised to the surface. After washing the bottom of the well by creating a fluid circulation, the well is put into operation.

 The technical and economic advantage of the invention is as follows.

 Its use eliminates the use of expensive disconnecting devices, simplifies the implementation of various technological operations (SCR, cementing, insulation work, etc.), while expanding the scope of its application, for example, the creation of a pulse-depression effect.

Sources of information
1. RU 2057896 C1, 04/10/1996.

 2. SU 983255 A, 12.23.1982.

Claims (1)

 A device for uncoupling the annular space of a well equipped with a cemented liner, comprising a hollow body with a seating saddle and a plug plunger with a plug and a part of its outer surface made conical under the housing seating saddle, characterized in that the plug plunger has connecting threads at the ends and is placed inside the housing, while the housing and the plug plug are made at one end with centering ribs.

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