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Method for evaluating self-repairing performance of well cementation cement sheath

A cementing and self-repairing technology, which is applied in the preparation of test samples, material inspection products, etc., can solve the problems of inability to effectively evaluate the self-repairing performance of cement stones, slow development, etc. The method is simple and practical, the principle is reliable, Simple calculation method

Inactive Publication Date: 2014-02-05
SOUTHWEST PETROLEUM UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are no exact experiments, evaluation methods and standards for self-healing cement for well cementing. In particular, there is no definite method to compare the mechanical properties of cement stones before and after self-healing, and it is impossible to effectively evaluate whether cement stones have self-healing properties.
This is one of the reasons for the slow development of the technology

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Sample preparation: 100 parts of G grade oil well cement, 0.3 parts of dispersant, 2 parts of fluid loss reducer, 0.1 part of defoamer, 1 part of self-healing agent, 45.5 parts of water.

[0021] Mix the dry powder of each component in proportion, put the aqueous solution in the mixing container, rotate the agitator at a low speed (4000±200 rpm), and add the weighed dry powder mixture within 15 seconds, cover the agitator Cover, and continue to stir for 35 seconds at high speed (12000±500 rpm) to make a cementing self-repairing cement slurry system with good stability. Then pour the cement slurry into the pre-prepared anti-bending mold and splitting tensile mold, put it into a high-temperature and high-pressure curing kettle for curing, and simulate the working conditions of the underground, set the temperature at 110°C and the pressure at 20MPa. After curing for 48 hours, after the cement slurry forms cement stones, test its completely damaged flexural strength on a fl...

Embodiment 2

[0032] Sample preparation: 100 parts of G grade oil well cement, 0.3 parts of dispersant, 2 parts of fluid loss reducer, 0.1 part of defoamer, 3 parts of self-healing agent, 46.4 parts of water.

[0033] Mix the dry powder of each component in proportion, put the aqueous solution in the mixing container, rotate the agitator at a low speed (4000±200 rpm), and add the weighed dry powder mixture within 15 seconds, cover the agitator Cover, and continue to stir for 35 seconds at high speed (12000±500 rpm) to make a cementing self-repairing cement slurry system with good stability. Then pour the cement slurry into the pre-prepared anti-bending mold and splitting tensile mold, put it into a high-temperature and high-pressure curing kettle for curing, and simulate the working conditions of the underground, set the temperature at 110°C and the pressure at 20MPa. After curing for 48 hours, after the cement slurry forms cement stones, test its completely damaged flexural strength on a f...

Embodiment 3

[0044] Sample preparation: 100 parts of G grade oil well cement, 0.3 parts of dispersant, 2 parts of fluid loss reducer, 0.1 part of defoamer, 5 parts of self-healing agent, 47.3 parts of water.

[0045] Mix the dry powder of each component in proportion, put the aqueous solution in the mixing container, rotate the agitator at a low speed (4000±200 rpm), and add the weighed dry powder mixture within 15 seconds, cover the agitator Cover, and continue stirring at high speed (12000±500 rpm) for 35 seconds to make a cementing self-repairing cement slurry system with good stability. Then pour the cement slurry into the pre-prepared anti-bending mold and splitting tensile mold, put it into a high-temperature and high-pressure curing kettle for curing, and simulate the working conditions of the underground, set the temperature at 110°C and the pressure at 20MPa. After curing for 48 hours, after the cement slurry forms cement stones, test its completely damaged flexural strength on a ...

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Abstract

The invention discloses a method for evaluating self-repairing performance of a well cementation cement sheath. The method sequentially comprises the following steps: (1) preparing self-repairing cement paste for well cementation, pouring the self-repairing cement paste into a bending-resistant and splitting tensile mold, and maintaining for a certain time in a high-temperature high-pressure maintenance kettle, so that the cement paste is solidified into set cement; (2) testing the bending strength and tensile splitting strength of the set cement which is completely broken; (3) maintaining the tested broken set cement in a maintenance device for 24 hours, and measuring the bending strength and tensile splitting strength of the set cement again; (4) calculating a bending strength repair rate and a tensile splitting strength repair rate of the set cement; and (5) repeating the steps (2) to (4), and solving an average value of the repair rates, wherein the set cement is considered to have the self-repairing performance when the average bending strength repair rate is more than or equal to 50 percent and the average tensile splitting strength repair rate is more than or equal to 30 percent. The method has the advantages that the principle is reliable, a calculation method is simple, the repair rates of the set cement can be accurately tested, and the method is suitable for evaluating the self-repairing performance of various types of well cementation set cement.

Description

technical field [0001] The invention relates to a method for evaluating the self-repairing performance of a cement sheath in the field of well cementing technology in the oil and gas development process. Background technique [0002] In oil and gas exploration and development, the fundamental goal of cementing is to achieve long-term sealing integrity of the cement sheath. With the increase of time, various operations will exert certain stress on the cement, causing damage to the cement sheath, causing micro cracks and micro annulus to appear in the cement sheath. Moreover, these micro-cracks and micro-annulus are very small, and their specific positions cannot be accurately determined, so it is difficult to repair them. Even micro-cracks and micro-annulus can form channeling channels for formation fluid, causing the mechanical integrity and hydraulic sealing failure of the cement sheath, seriously affecting the productivity and production life of oil and gas wells. Self-h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N33/38G01N1/28
Inventor 李明郭小阳刘萌李早元程小伟刘健王平张春梅杨元意
Owner SOUTHWEST PETROLEUM UNIV
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