A kind of oil well cement suitable for salt-gypsum layer cementing operation and preparation method thereof

A technology for oil well cement and salt gypsum layer, applied in the field of oil well cement, can solve the problems of admixtures interfering with normal action, ineffective resistance, shortening the service life of oil and gas wells, etc. Advantages and use effects, the effect of preventing formation salt corrosion

Active Publication Date: 2021-11-23
葛洲坝石门特种水泥有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 2. The dissolution of the salt-gypsum layer will expand the wellbore and cause irregular wellbore walls, which will affect drilling operations;
[0006] 4. The phenomenon of underground salt dissolution is continuous, and the cementation quality of the formation cannot effectively resist the external extrusion force caused by the creep of the salt-gypsum formation, resulting in the deformation of the thick-walled casing, and even the thick-walled casing being broken or broken. Collapse, shortening the life of oil and gas wells
[0007] In order to overcome the cementing risks brought by the above-mentioned conventional cement slurry, some people try to prepare cement slurry with the same salt content or directly take underground brine, because the salt has the effect of promoting coagulation and early strength, and the composition of underground brine is complex and contains trace elements. The addition of additives causes interference and cannot play its normal role. The fluidity of the cement slurry becomes poor, or even loses fluidity. The initial thickening is large, the thickening time is short, and flash coagulation is easy to occur, especially in summer or underground high-temperature cementing operations are more unfavorable.

Method used

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  • A kind of oil well cement suitable for salt-gypsum layer cementing operation and preparation method thereof

Examples

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Effect test

example 1

[0036] The amount of cement clinker is 95%, the amount of gypsum is 5%, the amount of retarder is 0.1 per ten thousand, the amount of dispersant is 0.1%, and the amount of atomized water is 0.20%. Use underground brine (salt content 18%), when the water-solid ratio is 0.44, the fluidity of the cement slurry is 200mm, and after standing for 15 minutes, the fluidity is 180mm. After the cement slurry is heated to 80°C, the fluidity is 180mm. The curing time is 133min, the strength is 4.0MPa at normal pressure 38°C for 8h, the strength is 17.2MPa at normal pressure at 60°C for 8h, and the free liquid is 5.0%.

example 2

[0038] The amount of cement clinker is 96%, the amount of gypsum is 4%, the amount of retarder is 0.2 per ten thousand, the amount of dispersant is 0.25%, and the amount of atomized water is 0.40%. Use underground brine (salt content 18%), when the water-solid ratio is 0.44, the fluidity of the cement slurry is 210mm, and after standing for 15 minutes, the fluidity is 200mm. After the cement slurry is heated to 80°C, the fluidity is 200mm. The curing time is 140min, the strength is 4.5MPa at normal pressure 38°C for 8h, the strength at normal pressure is 60°C for 8h is 19.1MPa, and the free liquid is 4.5%.

example 3

[0040] The amount of cement clinker is 97%, the amount of gypsum is 3%, the amount of retarder is 0.3 per ten thousand, the amount of dispersant is 0.35%, and the amount of atomized water is 0.70%. Use underground brine (salt content 18%), when the water-solid ratio is 0.44, the fluidity of the cement slurry is 220mm, and after standing for 15 minutes, the fluidity is 200mm. After the cement slurry is heated to 80°C, the fluidity is 200mm. The curing time is 140min, the strength is 4.7MPa at normal pressure 38°C for 8h, the strength is 21.7MPa at normal pressure at 60°C for 8h, and the free liquid is 3.4%.

[0041] From the above example and its results, it can be known that when applied to salt-gypsum layer cementing, the fluidity of the cement slurry is ≤220mm, and after a period of time, the fluidity is improved, and the thickening time at 52°C and 35.6MPa is in 130-140min, there will be no flash condensation, and it is also suitable for high-temperature salt-gypsum layers ...

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Abstract

The invention discloses an oil well cement suitable for cementing operations in salt-gypsum layers, which is mainly prepared from the following raw materials: cement clinker, gypsum, dispersant and water. The application overcomes the phenomenon that the fluidity of the conventional oil well cement deteriorates rapidly when encountering brine, the initial viscosity increases or even flashes, and its various properties meet the cementing requirements of the salt-gypsum layer.

Description

technical field [0001] The invention relates to an oil well cement suitable for cementing operations in salt-gypsum layers and a preparation method thereof, belonging to the technical field of oil well cement. Background technique [0002] There are salt mines and oil and gas fields in the Jianghan Plain and Lizhou Plain, which are also one of the important areas of energy development in my country. When working in complex sections such as deep well salt-gypsum layers and extremely thick salt-gypsum layers, fresh water is generally used to mix conventional cement slurry in the prior art. However, when the salt-gypsum layer is injected into the salt-gypsum layer, the salt in the contact area of ​​the salt-gypsum layer dissolves in the cement slurry to reach a saturated solution state, and a concentration gradient appears. This situation will destroy the balance of the underground salt-gypsum layer, and may cause undesired Risk control is embodied in the following aspects: ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B7/04C04B7/51C04B7/52C09K8/467
CPCC04B7/04C04B7/51C04B7/52C04B7/522C09K8/467
Inventor 覃爱平李昌清皮光忠李辉任家新伍云支程海平
Owner 葛洲坝石门特种水泥有限公司
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