RU2354802C1 - Method for well repair - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to oil industry and may find application in repair of well that opened two and more payout beds. Provides for increased efficiency of repair of cemented casing string space of well between neighbouring payout beds. Packer is installed in well, hardening grouting mortar is pumped in casing string space, remains of grouting mortar are washed out, then it is hardened, pressure is reduced and packer is withdrawn. Packer installation is carried out between upper and lower payout beds. Prior to pumping of insulating material under-packer space is filled with insulating material, and packer is installed. To pump insulating material in casing string space, pressure is increased in under-packer space, pressure is reduced in well in above-packer space without pressure drop in under-packer space. Prior to packer withdrawal pressures are equalised in above-packer and under-packer space. After packer withdrawal well is washed from remains of insulating material, and technological exposure is realised for setting and hardening of insulating material.

EFFECT: increased efficiency of repair of cemented casing string space of well between neighbouring payout beds.

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Description

The invention relates to the oil industry and may find application in the repair of a well that has uncovered two or more productive formations.

A known method of cementing casing strings, which includes lowering the casing string into a well filled with flushing fluid, pumping cement slurry from the wellhead into the casing string and pushing it with cementing aggregates into the annulus with a rise to the wellhead or to the estimated height. In addition, before pumping the grouting mortar, the annular (annular) space at the mouth is sealed, a vacuum gauge is installed, a valve and connected to the reception with the pump unit through the piping line. In the process of pumping cement slurry into the casing and forcing it into the annular space, the displaced fluid from the annular space is pumped out by the pump unit with an open valve into the measuring unit, at the beginning with a capacity equal to the forcing capacity, and by the end of the forcing, the flow rate is reduced to the minimum without changing the pumping capacity. After forcing the grouting mortar to the mouth or the estimated height, pumping is stopped, and the valve on the mouth is closed for the period of cement hardening (Publication number 93033445, published. 1996.07.10).

The known method does not allow to create a high-quality insulating bridge in the annular space between two productive layers.

Closest to the proposed invention in technical essence is a method of repairing the annulus of the well, including determining the depth of the defect or hole in the casing, installing a recoverable packer, injecting the hardening grout into the annulus, washing out the remnants of the grout, waiting for it to solidify under pressure, dumping pressure and packer extraction. The grouting solution is injected into the defect zone or holes after installing the packer below the defect or holes, leaving a part of the grouting solution with the packer, then the pressure is released and the packer is immediately lifted and the defect or hole in the column is closed, and the grouting residue is washed out over the packer by creating over it circulation of the squeezing fluid, and the pressure in the casing is relieved while maintaining pressure in the packer (RF Patent No. 1832822, published. 2000.09.20 - prototype).

The method allows you to repair the annular space of the well in the absence of a cement ring there. In the presence of a defective cement ring or its residues, the cement slurry does not penetrate into the annular space and does not create a reliable bridge between productive formations in the near-wellbore space.

The proposed invention solves the problem of repairing the cemented annulus of the well between adjacent productive formations.

The problem is solved in that in a method of repairing a well, including installing a packer, injecting a hardening grouting mortar into the annulus, washing out the remnants of the grouting mortar, waiting for it to solidify, depressurizing and removing the packer, according to the invention, the packer is installed between the lower and upper reservoirs, before by injection of the insulating material, the under-packer space is filled with insulating material and the packer is set up to pump the insulating material into the annular space They increase the pressure in the under-packer space, reduce the pressure in the well in the over-packer space without reducing the pressure in the under-packer space, before removing the packer, equalize the pressures in the over-packer and under-packer space, after removing the packer, wash the well from the remnants of the insulating material and carry out technological exposure to set and harden the insulating material.

The features of the invention are:

1. installation of the packer;

2. injection of hardening grouting mortar into the annulus;

3. washing out the remains of cement slurry;

4. waiting for its solidification;

5. pressure relief;

6. removing the packer;

7. installation of the packer between the lower and upper reservoirs;

8. before the injection of insulating material, filling the sub-packer space with insulating material and setting the packer;

9. pressure increase in the under-packer space;

10. reducing the pressure in the well in the above-packer space without reducing the pressure in the under-packer space;

11. pressure equalization in the above-packer and under-packer space;

12. removal of the packer;

13. flushing the well from residues of insulating material;

14. holding technological exposure for setting and hardening of the insulating material.

SUMMARY OF THE INVENTION

When a well opens two or more productive strata, inevitably flows from the lower stratum with high pressure to the upper stratum with lower pressure over the cemented annular space occur. Violation of the integrity of the cement stone in the annulus and adhesion to the casing occurs during well operation, during perforation, acid treatments, etc. Re-cementing by conventional methods is not possible due to the very small streamlines and the impossibility of cement slurry entering the cemented annular space. The proposed invention solves the problem of repairing the cemented annulus of the well between adjacent productive formations. The problem is solved as follows.

In the well, the lower and upper reservoir are opened by perforation. A tubing string with a packer at the end is lowered into the well. The packer is placed between the reservoirs closer to the roof of the lower reservoir. Grouting mortar is pumped into the under-packer zone. Emphasize the face and installation of the packer. Increase pressure in the under-packer zone. Raise the tubing string from the packer. In this case, the landing hole in the packer is automatically closed and the pressure in the sub-packer zone is maintained. They reduce the pressure in the well in the overpacker space without reducing the pressure in the underpacker space. To do this, through the tubing, the end of which is located above the packer, pump gas or start a swab with the selection of fluid in the tank at the wellhead. The fluid level in the well decreases, so the pressure too. The combined effect of pressure on the plugging material from the subpacker zone and the decrease in pressure in the overpacker zone facilitates the entry of the plugging material through the perforations of the lower reservoir into the annulus between the reservoirs and its exit through the perforations of the upper reservoir into the well. The annular space appears to be plugged. Fill nadpakerny space with liquid. Insert the tubing string into the packer, reduce the pressure in the sub-packer area through the tubing string. Tear down the packer. The well is washed from the remnants of the insulating material and technological exposure is carried out for setting and hardening the insulating material in the near-wellbore space.

As a result, it is possible to create reliable isolation of the annulus of the well and to eliminate overflows along the well from the lower reservoir with high reservoir pressure to the upper reservoir with low reservoir pressure.

Concrete example

An oil producing well is opened that has uncovered two reservoirs with a distance between the reservoirs of 12 m. The reservoir pressure in the lower reservoir is 3 MPa greater than in the upper reservoir. After perforation of both productive strata and selection of oil, it was noticed that oil comes only from the lower stratum through the perforations of both strata. There was a need to repair the annulus of the well. To do this, a tubing string with a packer at the end is lowered into the well. As a packer use a packer type PGRK. The packer is placed between the reservoirs closer to the roof of the lower reservoir. A cement grout is pumped into the under-packer zone. Emphasize the face and installation of the packer. Increase the pressure in the sub-packer zone by creating a pressure at the wellhead of 10 MPa. Raise the tubing string from the packer. In this case, the landing hole in the packer is automatically closed and the pressure in the sub-packer zone is maintained. They reduce the pressure in the well in the overpacker space without reducing the pressure in the underpacker space. To do this, a swab is launched through the tubing string with fluid withdrawal in a tank at the wellhead. The liquid level in the well is reduced to 600 m from the wellhead, respectively, the pressure too. The combined effect of pressure on the plugging material from the subpacker zone and the decrease in pressure in the overpacker zone facilitates the entry of the plugging material through the perforations of the lower productive formation into the annulus of the well between the productive formations and its exit through the perforations of the upper productive formation into the well. The annular space appears to be plugged. Fill nadpakerny space with water. Insert the tubing string into the packer, reduce the pressure in the sub-packer area through the tubing string. Tear down the packer. The well is washed from the remnants of the insulating material and the process is held for 48 hours to set and harden the insulating material in the near-wellbore space. Master the well.

As a result of studies, it was found that after repair both productive formations have an oil flow rate in accordance with their productivity, which indicates the creation of reliable isolation of the annulus of the well and the exclusion of overflows along the well from the lower productive formation with high reservoir pressure to the upper production reservoir with low reservoir pressure .

Claims (1)

A method of repairing a well, including installing a packer, injecting a hardening cement slurry into the annulus, washing out the remnants of the cement slurry, waiting for it to solidify, depressurizing and removing the packer, characterized in that the packer is installed between the lower and upper productive layers, before the insulating material is injected filling the sub-packer space with insulating material and setting the packer, to pump the insulating material into the annular space increase the pressure in odpakernom space, reduce the pressure downhole in nadpakernom space without reducing the pressure in the packer space, before removing the packer nadpakernom equalize pressure in the space and the packer, the packer is washed after removal from the borehole insulating material balances and conduct exposure process for setting and hardening of the insulating material.