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A method for plugging abandoned wells

A technology for well cleaning and tubing, which is applied in earthwork drilling, sealing/isolation, wellbore/well components, etc. It can solve problems such as hidden dangers left by safe operation of gas storage, natural gas leakage, etc., so as to improve the plugging effect, The effect of ensuring safe operation and avoiding leakage

Active Publication Date: 2021-11-02
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] After the cement plug has blocked the abandoned well for a period of time, it is easy to create a gap between the well wall of the abandoned well under the action of formation pressure, resulting in natural gas leakage, leaving hidden dangers for the subsequent safe operation of the gas storage

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] This embodiment provides a method for plugging an abandoned well, the plugging method comprising: lowering the oil pipe into the abandoned well 8m above the cement plug.

[0042] Flush the well with fresh water circulation for 2 weeks.

[0043] The water of 980 parts by weight, the bentonite of 40 parts by weight, the sodium carbonate of 2 parts by weight, the barite powder of 1000 parts by weight were mixed, and stirred for 25min, after the bentonite, sodium carbonate and barite powder were mixed with water, they hydrated and swelled, A mixed slurry is formed.

[0044] Add 10 parts by weight of diluent to the mixed slurry and stir for 10 minutes to form a protective plug slurry.

[0045] The protective plug slurry is filled above the cement plug of the abandoned well through the tubing, and the protective plug slurry is left to settle to obtain a protective plug to complete the plugging of the abandoned well.

[0046]The abandoned well plugging method provided in Exa...

Embodiment 2

[0048] This embodiment provides a plugging method for an abandoned well, the plugging method comprising: running an oil pipe into a place 10 m above the cement plug of the abandoned well.

[0049] Flush the well with fresh water circulation for 2 weeks.

[0050] The water of 1000 parts by weight, the bentonite of 50 parts by weight, the sodium carbonate of 2.5 parts by weight, the barite powder of 1025 parts by weight were mixed, and stirred for 30min, after the bentonite, sodium carbonate and barite powder were mixed with water, they hydrated and swelled, A mixed slurry is formed.

[0051] Add 15 parts by weight of diluent to the mixed slurry and stir for 12 minutes to form a protective plug slurry.

[0052] The protective plug slurry is filled above the cement plug of the abandoned well through the tubing, and the protective plug slurry is left to settle to obtain a protective plug to complete the plugging of the abandoned well.

[0053] The abandoned well plugging method ...

Embodiment 3

[0055] This embodiment provides a plugging method for an abandoned well, the plugging method comprising: lowering an oil pipe into a place 12m above the cement plug of the abandoned well.

[0056] Flush the well with fresh water circulation for 2 weeks.

[0057] The water of 1020 parts by weight, the bentonite of 60 parts by weight, the sodium carbonate of 3 parts by weight, the barite powder of 1050 parts by weight were mixed, and stirred for 35min, after the bentonite, sodium carbonate and barite powder were mixed with water, they hydrated and swelled, A mixed slurry is formed.

[0058] Add 20 parts by weight of diluent to the mixed slurry and stir for 15 minutes to form a protective plug slurry.

[0059] The protective plug slurry is filled above the cement plug of the abandoned well through the tubing, and the protective plug slurry is left to settle to obtain a protective plug to complete the plugging of the abandoned well.

[0060] The abandoned well plugging method pr...

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PUM

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Abstract

The invention discloses a plugging method for an abandoned well, which belongs to the field of well workover. The plugging method includes: running the oil pipe into the abandoned well to a predetermined depth. Injecting a preset amount of protective plug slurry over the cement plug of the abandoned well through the tubing, and allowing the protective plug slurry to settle to obtain a protective plug to complete the plugging of the abandoned well. The protective plug slurry is prepared by the following method: 980-1020 parts by weight of water, 40-60 parts by weight of bentonite, 2-3 parts by weight of sodium carbonate, and 1000-1050 parts by weight of barite powder are mixed and stirred In the first preset time, the bentonite, sodium carbonate, and barite powder are mixed with water to hydrate and expand to form a mixed slurry. Add 10-20 parts by weight of diluent to the mixed slurry and stir for a second preset time to form a protective plug slurry. The abandoned well plugging method provided by the invention can prevent natural gas leakage in the abandoned well even if there is a gap between the cement plug and the well wall of the abandoned well, and improves the plugging effect of the abandoned well.

Description

technical field [0001] The invention relates to the technical field of well workover, in particular to an abandoned well plugging method. Background technique [0002] The gas storage is an artificial oil and gas reservoir formed by reinjecting the natural gas transported by the long-distance pipeline into the underground space. In order to avoid natural gas leakage from unusable abandoned wells in the gas storage, which will affect the safe operation of the gas storage, Permanently seal abandoned wells. [0003] The related technology utilizes cement plugs to block the unusable abandoned wells in the gas storage. Specifically, a preset amount of cement slurry is injected into the abandoned well to be plugged, and after the cement slurry is solidified in the waste gas well, a cement plug can be formed to realize the plugging of the abandoned well. [0004] The inventors have found that the related art has at least the following problems: [0005] After the cement plug blo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B33/134E21F17/16
CPCE21B33/134E21F17/16
Inventor 张亚明范红喜王海军高振涛张裔王培森杨晶柳灵艳李昊辰李磊
Owner PETROCHINA CO LTD