RU2339786C1 - Method for profile shutter installation in well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil and gas industry, particularly to methods of insulation of troublesome zones at boring of wells and at repair of casing columns with shutters out of profile tubes. The method includes connecting of sections of profile tubes, lowering them into a well, straightening them under pressure and tight pressing them to walls of the well. Lowering of the shutter into the well and washing a bore of the well via interior channels of the shutter is performed with holders clamping initial shape of profiled hollows of tubes. Building-up pressure for straightening of tube hollows is carried out due to excess flow of liquid pumped which destructs the shutters.

EFFECT: upgrading quality and reliability of shutters and reducing power and financial costs.

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Description

The invention relates to the oil and gas industry, in particular to methods for isolating zones of complications when drilling wells and repairing casing strings from profile pipes.

There is a method of installing a profile overlap in the well (Oil Industry Journal, 1982, No. 4, pp. 26-28), which includes welding the joints of sections of profile pipes, lowering the overlap into the well, adjusting its pressure and expanding it until it is pressed firmly against the walls beforehand extended interval wells.

The disadvantage of this method is that it is necessary to carry out welding work on the wellhead, it is difficult to lower the cutter into horizontal and highly curved wells, as well as when lowering the profile cutter through areas that make it difficult for the cutter to pass with falls, puffs, etc., it is impossible to flush wells through the internal channel, since even small excess pressures straighten the profile part of the overlap. If it is necessary to lift the shutter, it is possible to straighten the profile part due to hydrostatic pressure of the fluid inside the shutter and drill pipes, and it is also necessary to have a valve assembly in the shutter layout to fill the inner cavity of the shutter with liquid, since it is possible to crush the profile associated with the loss of stability of the shutter when descending to great depths .

Closest to the technical nature of the claimed is a method of installing a profile shutoff in the well (RF patent No. 907220, ЕВВ 33/12, publ. Bulletin No. 7 of 23.02 82), including screwing sections of profile pipes, lowering into the well and correcting their pressure. At the same time, in order to simplify the installation process, the cylindrical ends of the overlapping sections are upset prior to screwing up to the diameter of the described circumference of the profile part. After straightening the overlap, the sections of the connection sections are increased to the diameter of the well.

The disadvantage of this method is that it is difficult to lower the cutter into horizontal highly curved and deep wells, and also when lowering the profile cutter through areas that impede the passage of the cutter with landslides, puffs, etc., it is impossible to flush the well through the internal channel, since at even small excess pressures, the profile part of the overlap is straightened. If it is necessary to lift the overlap, fluid overflow at the wellhead is possible, as well as the profile part is straightened out due to the hydrostatic pressure of the fluid inside the overlap and drill pipes, and it is necessary to have a valve assembly in the layout of the overlap to fill the internal cavity of the overlap with liquid, since the profile associated with loss of stability of the shutter during descent to great depths.

The technical objective of the method is to expand the use of the shutoff in horizontal, highly curved and deep wells, as well as in areas that impede the passage of the shutoff by landslides, puffs, etc., simplifying the installation process, improving the quality and reliability of installing the shutoff, reducing energy and financial costs .

The technical problem is solved by the method of installing the profile shutter in the well, including connecting sections of the profile pipes, lowering them into the well, pressure adjustment and tight pressing against the walls of the well

What is new is that the profile cutter is lowered into the well with the wellbore flushed through the internal channels of the cutter due to the fact that the initial shape of the profiled pipe cavities is fixed by clamps, and the pressure for straightening the profile pipe cavities is created due to the increased flow rate of the fluid pumped through the cutter with destruction of clamps.

Figure 1 shows a two-channel overlap with a longitudinal section, figure 2 is a transverse section of the overlap AA.

It is possible to use a multi-channel blocker with other clamps of the original shape of the profiled hollows of the pipes.

The method is carried out in the following sequence.

On drill pipes (not shown), an assembly consisting of a seating head 1 (FIG. 1) is lowered, which is connected by a left-hand thread 2 to the upper section 3 of the shutoff, and the other end of the landing head 1 is connected to a drill string (not shown). On the line 4 (figure 2) of the mating of the inner surfaces of the troughs of the profile of the sections of the overlap 3, 6 (figure 1), a latch 5 (figure 2) is made (spot welding in an amount necessary and sufficient to ensure the initial cross-sectional shape of the profile overlap) which, when creating excessive pressure during the descent with direct flushing of the well, ensures the preservation of the original shape of the profiled hollows of the pipes. The lower section 6 (Fig. 1) of the overlap is provided with a shoe 7 having an opening 8 of calibrated size. By creating a pump with excess pressure in the sections of the overlap 3, 6, not exceeding the design pressure for the destruction of the clamps, the shutter is lowered into the complication zone. Then the pressure is raised in the inner cavity of the overlapper due to the increased flow rate of the fluid pumped through the isolator with the destruction of contact spot welding 5 (Fig. 2), fixing the initial shape of the depressions of the overlap sections. With a further increase in pressure in the sections of the overlap 3, 6 (Fig. 1), its walls straighten out, tightly pressing against the walls of the well. After straightening the shutter, rotating the drill string (not shown), disconnect the shutter from the landing head 1 using the left thread 2 and perform further work on expanding the cylindrical sections of the shutter, on the final rolling of the shutter walls, on raising or destroying the shoe 7.

An example of specific preliminary calculations for the installation of a two-channel profile shutoff 3, 6 in a well with a diameter of 215.9 with a wall thickness of 9 mm is provided.

The calculations are based on the following data:

- the shutter is released at a flushing pressure of at least 30 atm;

- fluid flow during operation with one pump 15 l / s;

- the pressure required to tightly press the walls of the shutoff to the walls of the well is 150 atm;

- fluid flow when working with two pumps 30 l / s;

- the pressure at which the straightening of the initially profiled cavity of the pipe begins for a well with a diameter of 215.9 mm is 12 atm.

Using well-known methods for calculating pressure losses on bit nozzles (Bulatov A.I., Proselkov Yu.M., Ryabchenko V.I. “Well flushing technology”, p. 242), we determine the required diameter of the hole in the overlap shoe, which will provide a pressure drop 150 atm when the solution is supplied with two pumps of 30 l / s for tightly pressing the walls of the shutoff to the walls of the well, which is 16 mm. Next, we determine the magnitude of the pressure drop in the hole of the shoe 7 when working with one pump with a solution flow of 15 l / s. The pressure drop was 45 atm, which provides the necessary pressure drop when flushing 30 atm. Based on the foregoing, we assume that the pressure at which the destruction of spot resistance welding 5 along the length of the contact of the depressions is equal to 80 atm and ensures the release of the overlap with washing with one pump at 45 atm, while the margin of safety of the welded joint is 35 atm, which will ensure the destruction of the spot resistance welding 5, since by connecting a second pump, the pressure rises to 150 atm, which is necessary to press the walls of the shutoff to the walls of the well. The diameter of the spot spot welding spot 5 and their number are determined experimentally.

The pressure required at the wellhead is determined by the correction for the pressure loss in the elements of the wellhead piping, from the depth of installation of the overlap and from the hydrogeological conditions of the particular well.

Expanding the use of the overlap in horizontal highly curved and deep wells, as well as in areas that impede the passage of the overlap with landslides, puffs, etc., simplifying the installation process, improving the quality and reliability of installing the overlap, reducing energy and financial costs are carried out by what:

- during the shutter descent, the sections are filled with fluid through the hole in the shoe and, if necessary, the shutter is lifted, the fluid flows freely from it, which eliminates the overflow of fluid at the wellhead;

- there is no need to manufacture and use in the layout of the shutter valve to fill the inner channel of the shutter;

- the shutter is lowered into the well by flushing the wellbore through the internal channels of the shutoff, which eliminates the interference with the passage of the shutoff into the overlapped zone;

- during the descent, straightening of the profile and expansion of the cylindrical sections and subsequent rolling of the overlap to the walls of the well, scale, rust and other extraneous mechanical impurities from the inner walls are removed into the bottom of the well, without interfering with the process of further installation of the overlap;

- the increase in pressure at the wellhead during direct flushing in the process of straightening profile sections is a signal of the successful conduct of the installation process of the shutoff.

Claims (1)

A method of installing a profile shutter in the well, including connecting sections of the profile pipes, lowering them into the well, adjusting the pressure and tightly pressing against the walls of the well, characterized in that the profile shutter is lowered into the well with washing the wellbore through the internal channels of the overlap due to the fact that the initial shape of the profiled hollows of the pipes is fixed by clamps, and the creation of pressure to straighten the hollows of the pipes is done due to the increased flow rate pumped through the ceiling fluid receiver with destruction of fixatives.

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