Water soluble temporary plugging agent for acidification of water injection well in low permeability oilfield, and preparation method and application thereof

A temporary plugging agent, water-soluble technology, applied in the field of acidizing water injection wells, can solve problems such as low permeability, large particle size, and inability to effectively produce well sections, and achieve high temporary plugging rate, high water solubility, and improved effectiveness Effect

Active Publication Date: 2013-07-31
PETROCHINA CO LTD
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  • Claims
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AI Technical Summary

Problems solved by technology

[0002] During the actual acidizing operation of water injection wells in the oil field, due to the existence of interlayer and intralayer heterogeneity, the acid liquid preferentially enters the hyperpermeable layer with the least resistance. If the water injection condition is low, the well section with low permeability or severe damage cannot be effectively produced, which may further aggravate the interlayer conflict of the water injection well.
However, the existing water-soluble temporary plugging agent has a large particle size (for example, the finished water-soluble fracturing and acidizing temporary plugging agent disclosed in CN1597873A has a particle size of 3-6mm in diameter), and it is difficult to enter the reservoir for temporary plugging when applied to low-permeability oil fields. The purpose of the hyperpermeable layer, especially the inability to solve the problem of intra-layer heterogeneity of the reservoir

Method used

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  • Water soluble temporary plugging agent for acidification of water injection well in low permeability oilfield, and preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Preparation: Take 20g of sodium benzoate, 1g of methanol, and 0.2g of ATMP, add water to make up to 100g, and slowly stir until each component is completely dissolved while adding water, that is, 100g of a water-soluble temporary plugging agent sample with a solid content of about 20%.

[0022] Add 10ml of 10% hydrochloric acid solution to this solution, and a large number of white particles can be seen to be precipitated. The particle size is less than 40 μm, and the main body is concentrated between 5 μm and 30 μm. Compared with the precipitated particles in the same concentration of sodium benzoate aqueous solution when it encounters acid, it is found that the developed water-soluble temporary plugging agent can effectively solve the problem of the mutual aggregation of the precipitated particles in the sodium benzoate aqueous solution when encountering acid, the particle size is large and widely distributed, and it cannot effectively enter the low-permeability reservo...

Embodiment 2

[0024] Preparation: Prepare six samples containing 20% ​​sodium benzoate, 1% methanol, and ATMP contents of 0, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%. The particle size of the precipitated solid particles after encountering acid was tested respectively, and the results are shown in Table 1. Experiments have shown that when the content of the particle size control agent is above 0.2%, it can effectively prevent the agglomeration of the precipitated solid particles. When the content of the particle size control agent continues to increase, the particle size of the precipitated solid particles continues to decrease, but the difference is not significant. The dosage of particle size control agent is preferably between 0.2% and 0.5%.

[0025] Table 1 The size of the precipitated particles of water-soluble temporary plugging agent and sodium benzoate aqueous solution

[0026] HCl concentration%

Embodiment 3

[0028] Preparation: Take 20g of sodium benzoate, 1g of methanol, and 0.3g of ATMP, add water to 100g, and slowly stir until each component is completely dissolved while adding water, that is, 100g of a water-soluble temporary plugging agent sample with a solid content of 20%.

[0029] Add 10ml of 10% hydrochloric acid solution to this solution, and a large number of white particles can be seen to precipitate out. Slowly add distilled water into the solution while monitoring the pH value. During the addition process, as the pH value increases, the white particles in the solution gradually dissolve. When the pH=7, the white particles in the solution dissolve completely, and the solution is transparent, indicating that the The temporary plugging agent can be completely dissolved with the injection of injection water after the acidification measures, and will not cause damage to the reservoir.

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Abstract

The invention provides a water soluble temporary plugging agent for acidification of a water injection well in a low permeability oilfield, and a preparation method and an application thereof. The water soluble temporary plugging agent is prepared by mixing an inorganic salt, a dispersing agent and a particle size control agent uniformly, wherein based on a total weight of the water soluble temporary plugging agent, the content of the inorganic salt is 1%-20% (depending on application requirements); the content of the dispersing agent is 1%; the content of the particle size control agent is 0.2%-0.5%; the inorganic salt is selected one or more from sodium salicylate, sodium p-benzene sulfonate and sodium benzoate; the dispersing agent is selected one or more from methanol, ethanol, propanol and n-butanol; and the particle size control agent is selected one or more from isoamyl alcohol, n-hexane, EDTMPS and ATMP. The temporary plugging agent can effectively enter a reservoir stratum of the low permeability oilfield and be mainly applied in acidification works of the water injection well.

Description

technical field [0001] The invention relates to a water-soluble temporary plugging agent and its preparation method and application. The temporary plugging agent can effectively enter low-permeability oilfield reservoirs and is mainly used in acidizing water injection wells. Background technique [0002] During the actual acidizing operation of water injection wells in the oil field, due to the existence of interlayer and intralayer heterogeneity, the acid liquid preferentially enters the hyperpermeable layer with the least resistance. Due to the poor water injection conditions, the well sections with low permeability or serious damage cannot be effectively produced, which may further aggravate the interlayer contradiction of water injection wells. However, the existing water-soluble temporary plugging agent has a large particle size (for example, the finished water-soluble fracturing and acidizing temporary plugging agent disclosed in CN1597873A has a particle size of 3-6mm...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/506
Inventor 成一袁飞张健强刘伟刘应根王斌吴丽蓉
Owner PETROCHINA CO LTD
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