RU2498045C1 - Well repair method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes running-in of tubing string with packer to casing pipe, packer setting, determination of specific injectivity for each failure in casing pipe, isolation of failures. Two-position valve is installed over packer, tubing string is run-in up to bottom hole and wire trip of casing pipe is made. Packer is set over the lower failure, then initial specific injectivity of failure is determined. When specific injectivity is below 0.5 m³/(h·MPa) isolation of failure location is not performed. When specific injectivity is more than 0.5 m³/(h·MPa) pumping and flushing of locking compound is made to failure location, remainders of locking compound are washed, final specific injectivity is determined for this failure. The above operations are made against each failure location; thereafter packer is uplifted into head location of auxiliary small-sized extreme line casing. Two-position valve is actuated. Pipe casing is leak tested by swabbing. Auxiliary small-sized extreme line casing is run-in and cement mortar is pumped though till it reaches head of auxiliary extreme line casing.

EFFECT: improving efficiency, simplifying technology, reducing specific amount of metal per structure.

5 dwg

Description

The invention relates to the oil industry and may find application in the repair of wells.

A known method of restoring the tightness of production casing (patent RU No. 2416020, IPC E21B 29/10; E21B 33/13, publ. 04/10/2011 in bull. No. 10), including the injection into the insulation zone of a mineral binder - liquid glass and curing liquid followed by cementing with cement, at the same time, oil is first pumped into the well to displace water, then a liquid glass solution with sodium fluoride curing fluid is pumped in the following ratio, wt.%:

- liquid glass Na ₂ SiO ₃ 88-86 - sodium silicofluoride Na ₂ SiF ₆ 12-14.

The disadvantage of this method is the low success of restoring the tightness of the production casing with a chemical composition without fixing the isolation zone with an additional column.

Also known is a method of repairing a well (patent RU No. 2354804, IPC E21B 29/10; E21B 33/13, published on 05/10/2009 in bull. No. 13), including lowering a pipe string into the well, pumping and selling cement slurry, lifting pipe strings, technological exposure, drilling a cement bridge and determining the tightness of the well, while the bottom of the pipe string is lowered to a depth of 20-30 m below the interval of the detected casing string disturbances, create minimal fluid circulation through the pipe string and the annular space of the well, fluid exit annular spaces are directed into the groove system, counterpressure is established at the wellhead 3-4 MPa by covering the gate valve at the exit from the annulus, cement is injected with the outlet from the bottom of the pipe string to the fault interval, the column is raised and the pipe string bottom is set to 20-40 m above the violation interval, close the valve at the exit of the annular space of the well, push cement slurry into the violation interval, raise the pipe shoe to a height where they plan to install the head the cement bridge, and remove excess cement mortar by reverse circulation of the liquid, raise the pipe string to a safe distance or remove it completely, carry out technological exposure to harden the cement, determine the depth of the cement cup, compact the casing, drill the cement cup to an interval of 5-10 m below the violation interval, re-pressure the casing string, pressurize the casing to completely drill the cement cup, with non-hermetic the casing string to re-seal the violation.

The disadvantages of this method are the high complexity, duration and cost of repair without fixing the intervals of violation of the additional casing string with cementing.

Also known is a method of repairing damaged casing strings in a well with a large length of the defective interval of the string (patent RU No. 2273718, IPC E21B 29/10; E21B 33/13, published on 04.04.2006 in Bulletin No. 10). When implementing the method, the location of the defective interval is determined, below it, the outer longitudinally-corrugated patch is lowered and pressed, after which the inner longitudinally-corrugated patch is lowered and the lap is pressed out with the outer. Next, an additional flying column is lowered, the column is fixed by focusing its shoe on the upper ends of the double longitudinally corrugated patch and cemented.

The disadvantages of this method are the low reliability of the repair due to operations without analyzing the injectivity of the casing string violations and the absence of an additional casing string under the patch.

The closest in technical essence is a method of repairing a well (patent RU No. 2354803, IPC E21B 29/10; E21B 33/13, published May 10, 2009, Bulletin No. 13), including installing a patch, lowering an additional casing string to the intermediate depth and cementing, while first pumping tubing (tubing) with a packer is lowered into the casing, the packer is planted over the casing violation and the specific injection rate of the casing violation is determined, the violation is closed with a patch with specific injection rate of more than 2 m ³ / (h · MPa), for repair and disorders having a specific pick-up of less than 2 m ³ / (h · MPa) is lowered further casing of smaller diameter, having on the end fitting with the teeth inclined inwardly by an amount more than the wall thickness of the patch, by an additional casing string during its lowering to the full depth pumped cement the mortar is raised along the annulus to a depth of 10-50 m below the level of the cement ring in the annulus of the well, or when lowering the additional casing to an intermediate depth, the cement mortar is pumped p with raising it to the "head" of an additional casing string.

The disadvantages of this method are:

- firstly, before lowering the tubing string with the packer, it is necessary to perform an additional round-trip operation of the template in the well to make sure the subsequent passage of the packer;

- secondly, before installing an additional casing string into the well, it is necessary to conduct tests on the tightness of the insulated casing string above the “head” of the proposed lowering of the additional small-diameter string, for this it is necessary to remove the tubing string with a packer and re-equip the layout for research, for example, for lowering swab into the tubing string, which leads to a delay in the process of well repair;

- thirdly, the violation intervals with specific injectivity of more than 2 m ³ / (h · MPa) are covered with a patch, and then an additional small-diameter column with cementing is installed over the patch, which significantly narrows the borehole cross section and reduces the technological capabilities of the well, for example, research on annulus during the operation of the well. In addition, additional resistance is created when cement is pushed through a narrow annular space between the plaster and the additional casing string, which can lead to under-rise of cement behind the additional casing string and, as a result, the quality of the repair is reduced, as well as the metal consumption of the well structure;

- fourthly, each violation of the casing string with a specific injectivity of less than 2 m ² / h · MPa) is repaired separately by pumping cement into the interval of violation with the installation of a cement bridge in the well, followed by its drilling with a bit after waiting for the solution to harden (OZZ), while to isolate only one violation, it is necessary to carry out several tripping operations of the equipment into the well, which leads to an increase in both the duration and cost of well repair.

The technical objectives of the invention are to increase the efficiency of well repair by reducing the metal consumption of the well structure, increasing the well life until the next casing repair and maintaining the technological capabilities of the well, as well as simplifying the methodology.

The technical problem is solved by the method of repairing the well, including the descent of the tubing string — tubing with a packer into the casing, packing the packer, determining the specific injectivity of each casing violation, isolating the violations, lowering an additional small diameter casing to an intermediate depth and pumping cement with raising it to the "head" of the additional casing string.

New is that at the wellhead before lowering into the casing string of tubing with a packer, a template is placed below the packer and a two-position valve is installed above the packer, then the tubing string is lowered to the bottom of the well and the casing is patterned, after which from the bottom up, isolation intervals of the casing string violation are made, for this, the packer is first planted over the lower violation, the initial specific injectivity of the violation is determined, with specific injectivity below 0.5 m ³ / (h · MPa) isolation of the violation interval is not performed, with specific injection rates above 0.5 m ³ / (h · MPa), when the packer is planted, they are pumped into the tubing string and forced into the interval of violation of the blocking composition, then unpack the packer and wash the excess blocking composition from the well, determine the final specific injectivity of this violation with the packer landing in the same casing interval, perform the above operations opposite each violation interval, and then raise the packer to the interval of finding the “head” additional collarless casing string of small diameter and plant it, actuate the on-off valve, which cuts off the space below the packer and communicates the inner space of the tubing above the valve with the annulus of the borehole, examine the casing for tightness by swabbing along the tubing string in the interval from the mouth to the landing interval packer, after lowering the level in the well to a depth of 800 m, the fluid level in the well is monitored after 1 h, 3 h and 5 h, then an additional sleeveless casing string of small diameter to an intermediate depth and pump the cement slurry up to the "head" of the clutchless additional casing string of small diameter.

Figure 1-5 schematically and sequentially shows the proposed method of repairing a well.

The proposed method is as follows.

At the wellhead, before the descent into the casing 1 of the tubing string 2 with packer 3, a template 4 is placed below the packer 3, and a two-position valve 5 is installed above the packer 3.

For example, if the well is equipped with a casing 1 with a standard size of 146 × 7 mm, then the mechanical packer of the axial installation PRO-YamO-122 mm manufactured by NPF Packer (Oktyabrsky, Republic of Bashkortostan, Russian Federation) is used as packer 3; as template 4, a template 30 m long and an external diameter of the template 124 mm is used.

As a two-position valve, for example, a disconnector from a device for treating formations in a well is used (patent RU No. 2234589, IPC E21B 33/12, published in Bulletin No. 23 of 08/20/2004, or patent RU No. 2282017, IPC E21B 33 / 12, published in Bulletin No. 23 of 08/20/2006).

Lower the string of tubing 2 (see figure 1) to the bottom (in figure 1, 2, 3, 4, 5 not shown) and make the casing string 1 (see figure 1).

Next, from the bottom up, the intervals of violation 6, 6 ', 6''... 6 ^{n of} casing 1 are isolated. For this, the packer 3 is first planted over the lower violation 6 (see figure 2), while the intervals of perforation of the formation are considered as violation 6 casing string 1, since they require isolation with a blocking composition during the subsequent installation of an additional small-diameter string and raising the cement behind it.

The initial specific injectivity of the violation 6 is determined, if the initial specific injectivity is below 0.5 m ³ / (h · MPa), then the violation interval is not isolated, i.e. violation 6 is not blocked and the packer 3 is lifted and planted in the violation interval 6 '.

If the initial specific injectivity is higher than 0.5 m ³ / (h · MPa), then when packer 3 is planted, the tubing 2 is injected into the string 2 and squeezed in the interval of violation 6 of the blocking composition, for example, water-swelling polymer (GNP). The acrylamide polymer AK-639 water-absorbing according to TU 2216-016-553733-66-2007 is used as GNP.

Packer 3 is unpacked and washed with the process fluid along the tubing string 2 (not shown in FIGS. 1, 2, 3, and 4, 5) of excess blocking composition from the well. As a process fluid, for example, fresh water with a density of 1000 kg / m ^{3 is used} .

Packer 3 is again planted (see FIG. 2) in the same interval of casing 1 and the final specific injectivity is checked; at a specific injectivity below 0.5 m ³ / (h · MPa), the violation interval is not isolated.

The above operations are performed opposite each violation interval 6 ', 6''... 6 ⁿ (see FIG. 3), moving the packer landing interval each time higher. For example, the violation intervals 6, 6 '', 6 ⁿ (see Fig. 1) have an initial specific throttle response higher than 0.5 m ³ / (h · MPa), then they are blocked, and if the violation intervals 6 'and 6'''have an initial specific injectivity below 0.5 m ³ / (h · MPa), they are not isolated with a blocking composition, i.e. left open.

The specific throttle response equal to 0.5 m ³ / (h · MPa) was determined empirically and ensures the rise of cement in the annular space between the casing 1 and the additional clutchless casing of small diameter 7 (see Fig. 5) to its “head” "Without leaving cement in one or more violations 6, 6 ', 6''... 6 ⁿ (see figure 4).

After that, the packer 3 is lifted and planted in the interval of finding the “head” of the small-diameter casing string 7 supposed to be launched for the descent of the clutchless additional casing (see FIG. 5), the on-off valve 4 is activated (see FIG. 4), which cuts off the space 8 below packer 3 and communicates the interior of tubing 9 above valve 4 with annulus 10 of the well.

The casing 1 is examined in the interval from the wellhead to the packer 3 landing interval for swab tightness by monitoring the fluid level in the well with a resistivity meter, after lowering the fluid level in the well to a depth of 800 m, the fluid level in the well is monitored after 1 h, 3 h and 5 h ( figure 1, 2, 3,4, 5 is not shown).

Then, an additional sleeveless casing of small diameter 7 (see FIG. 5) is lowered to an intermediate depth, i.e. in the interval of the casing 1 between the lower violation 6 and the uppermost violation 6 ⁿ and pumped cement 11 to raise it to the "head" 12 of the clutch additional casing of small diameter 7.

An example of practical application. At well No. 2530 of NGDU Bavlyneft (see FIGS. 1-5). Violations of the tightness of the casing string with a diameter of 146 × 7 mm in the intervals: 1792-1796 m perforation intervals of the casing are considered as a violation 6, since if they are not blocked, the perforation intervals will absorb the cement mortar when lifting it behind an additional coupling without a small diameter , and also given violations in the intervals: 1720 m - 6 ', 1645 m - 6``, 1534 - 6' ''. The “head” of the additional small-diameter string is in the range of 1468 m. The well was repaired in the following sequence:

1. At the wellhead, the following arrangement was assembled on the tubing string (bottom to top): a 30-meter-long template with an outer diameter of 124 mm, a PRO-YAM02-122 packer, a two-position valve of any known design, for example, an isolator described in RU patent No. 2234589, “Device for processing a formation in a well” MPK Е21В 33/12, publ. in bull. No.23 of 08/20/2004

2. On the tubing string with a diameter of 73 mm, the assembled assembly was lowered into the casing of the well and the casing was patterned up to the bottom of the well.

3. The layout was raised so that the PRO-YaM02-122 packer was 5-10 m higher than the perforation intervals 1792-1796 m, i.e. above violation 6 (see figure 1) of the casing string.

4. The packer was planted in the interval 1782-1787 m. The initial specific injectivity of the formation perforation intervals was determined; for this, 6 m ^{3 of} process fluid was pumped at a pressure of not more than 9 MPa, which turned out to be 1.2 m ³ / (h · MPa).

5. The intervals of formation perforation were blocked by injection of a blocking composition, for example, water swelling polymer (GNP) according to the calculation agreed with the customer’s repair service, for example, in a volume of 2 m ³ .

6. Unpacked the packer, washed the remaining GNP by pumping the technological fluid through the tubing string in one and a half volume of the well (in the volume of 39 m ³ ) with a flow rate of Q = 8-10 l / s direct washing.

7. Once again, the packer was installed and the final specific injectivity was determined to evaluate the effectiveness of measures to reduce the absorption capacity of the perforation interval by briefly pumping the process fluid at a minimum flow rate for test pressure.

8. The final specific injection rate was 0.8 (m ³ / h · MPa), therefore, the blocking of violation 6 was repeated by GNP injection, as described above. After re-injection of the blocking composition, the final specific injectivity of the violation interval 6 was 0.3 m ³ / (h · MPa). Tore off the packer.

9. Raised the tubing string so that the packer is above the 6 'violation, i.e. in the range of 1710-1715 m.

10. The packer was planted, the initial injection rate was determined for pumping the process fluid through the tubing string at a pressure of not more than 9 MPa, while the initial specific injection rate was 0.4 m ³ / (h · MPa).

11. Since the initial specific injectivity was 0.4 m ³ / (h · MPa), and this is less than 0.5 m ³ / (h · MPa), no violation 6 'was blocked.

12. Tore off the packer, raised the tubing string so that the packer was above the 6 ”violation, i.e. in the range of 1635-1640 m.

13. The packer was planted, the initial injection rate of the violation by pumping the process fluid along the tubing string at a pressure of not more than 9 MPa was determined, while the initial specific injection rate was 0.5 m ³ / (h · MPa).

14. Since the initial specific injectivity of 0.5 m ³ / (h · MPa), and this ensures the rise of cement in the annular space between the casing 1 and the additional clutchless casing of small diameter 7 (see figure 5) to its "head 'Without leaving the cement slurry, then a 6''violation was not blocked.

15. Tore off the packer, raised the tubing string so that the packer was above the 6 '' violation, i.e. in the interval 1529-1524 m.

16. Planted the packer. The initial specific injectivity of the violation of the 6 '''process fluid was determined at a pressure of not more than 9 MPa, which turned out to be equal to 1.9 m ³ / (h · MPa).

17. The intervals of formation perforation were blocked by injection of a blocking composition, for example, water swelling polymer (GNP) according to the calculation agreed with the customer’s repair service.

18. Unpacked the packer, washed the remaining GNP by pumping the technological fluid through the tubing string in one and a half volume of the well (in the volume of 37 m ³ ) with a flow rate of Q = 8-10 l / s with direct washing.

19. Once again, the packer was installed and the final specific injectivity was determined to evaluate the effectiveness of measures to reduce the absorption capacity of the perforation interval by briefly pumping the process fluid at a minimum flow rate for test pressure.

20. The final specific throttle response was 0.4 (m ³ / h · MPa). Tore off the packer.

21. Raised and planted the packer in the range of 1469-1470, i.e. in the interval of finding the “head” of the additional coupling sleeve of small diameter supposed to be launched.

22. Inside the tubing, a ball was dropped to block the lower channel of the on-off valve.

23. The pressure in the tubing string was increased to 8.0 MPa before the pipe and annular space communication, i.e. opening the upper radial holes of the valve and closing the lower channel of the valve.

24. The casing was examined by swabbing in the interval from the mouth to the interval of packer landing (from 0 to 1470 m) for tightness by lowering the level to a depth of 800 m by swabbing. The fluid level in the well was monitored by a resistivimeter 1 hour, 3 hours, 5 hours after the decrease. The fluid level in the well has changed, which indicates the tightness of the casing from the mouth to the interval of the packer. Tore the packer, raised the tubing string with the layout according to claim 1.

25. An additional sleeveless casing string was lowered to an intermediate depth, that is, so as to completely cover the interval between the lowest (1796 m) and the highest (1534 m) violations, for example, they lowered 114 mm an additional sleeveless column with a diameter of 114 mm, 330 m long in the interval 1800-1470 m and cemented it.

The proposed method of well repair can improve the efficiency of well repair, reduce the number of tripping operations in the process of repairing a well, and therefore, simplify the technology of the method and reduce the metal consumption of the structure after repair of the well by eliminating the installation of the patch against the violation of the casing string.

The proposed method allows to increase the life of the well until the next repair of the casing string by raising the cement slurry to the "head" of the additional casing string of small diameter, and the minimum narrowing of the borehole cross section due to the use of a sleeveless additional casing string allows to increase the technological capabilities of the well.

Claims (1)

A method of repairing a well, including lowering a tubing string — tubing with a packer into the casing, landing the packer, determining the specific injectivity of each casing violation, isolating the violations, lowering the additional small-diameter casing to an intermediate depth and pumping cement to raise it to “Heads” of an additional casing string, characterized in that a template is placed below the packer at the wellhead prior to lowering into the casing string of the tubing with a packer, and above the on-off valve is installed by the packer, then the tubing string is lowered to the bottom of the well and the casing is patterned, then the intervals of casing violation are made from bottom to top, for this, the packer is first planted over the lower violation, the initial specific acceleration of the violation is determined, with the specific pick-up of less than 0.5 m ³ / (h · MPa) violation interval insulation does not produce, when planted packer when the specific pickup than 0.5 m ³ / (h · MPa) to produce injection the tubing string and squeezing into the interval of blocking composition violation, then unpack the packer and rinse the excess blocking composition from the well, determine the final specific injectivity of this violation with the packer landing in the same casing interval, perform the above operations opposite each violation interval, and then raise the packer to the interval of finding the "head" of an additional collarless casing string of small diameter and plant it, actuate the on-off valve, which cuts off the spaces about below the packer and informs the internal space of the tubing above the valve with the annulus of the well, the casing string is examined for tightness by swabbing along the tubing string in the interval from the mouth to the interval of the packer landing, after lowering the level in the well to a depth of 800 m, the fluid level in the well is traced through 1 h, 3 h and 5 h, then lower the additional sleeveless casing string of small diameter to an intermediate depth and pump the cement slurry up to the “head” of the sleeveless additional casing garden columns of small diameter.

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