Method for inhibiting escape of hydrogen sulfide in acidification process of water injection well
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A water injection well and hydrogen sulfide technology, applied in chemical instruments and methods, separation methods, earthwork drilling and mining, etc., can solve problems such as large damage, hydrogen sulfide escape, and human hazards
Active Publication Date: 2020-05-12
PETROCHINA CO LTD
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[0002] At present, during drilling, water injection, oil production and downhole operations such as acidizing and acid fracturing, hydrogen sulfide gas may escape. The main reason is that the water injected into the formation contains sulfate. Bacteria in the formation will escape hydrogen sulfide; in addition, during the acidizing process, hydrogen sulfide gas may also escape as the acid fluid reacts with ferrous sulfide in the wellbore
However, hydrogen sulfide is highly toxic and extremely harmful to humans. Hydrogen sulfide dissolves in water to form a weak acid, causing hydrogen embrittlement of pipelines and pipe columns, which is extremely harmful.
[0003] At present, there are mainly physical absorption and chemical reaction for hydrogen sulfide absorption at home and abroad. In the early days, liquid desulfurization agents ethanolamine (MEA) and diethanolamine (DEA) were widely used, and were mainly used in natural gas desulfurization. In the middle of the 20th century, foreign countries began to study bacteria Desulfurization and biological desulfurization technologies have been developed rapidly, but the high cost has become the main constraint factor, and the removal is mainly carried out on the main production line; currently the market mainly uses azine solutions for hydrogen sulfide absorption, but there is a problem of high cost. And it is not used in the process of water injection and acidification in the well
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Embodiment 1
[0020] A method for suppressing the escape of hydrogen sulfide in the acidizing process of water injection wells, comprising the following steps:
[0021] The first step is to seal the well and wash the well, and carry out closed cycle flushing on the water injection well until the water quality in the well drops to 15 mg / L or less, and the mechanical impurities drop to 15 mg / L or less; the water quality drops to 15 mg / L or 15 mg / L. Below L, mechanical impurities are reduced to 15 mg / L or below 15 mg / L;
[0022] In the second step, liquid seal, the first desulfurizer is injected into the annular space between the oil pipe and the casing from the casing valve. Form a liquid column to act as a liquid seal;
[0023] The first desulfurizing agent is a triazine solution.
[0024] Inject a triazine solution of 10%-15% of the volume of the acid liquid into the annular space as the first desulfurizing agent, form a liquid column in the annular space to realize liquid sealing, absorb...
Embodiment 2
[0033] On the basis of Example 1, in the third step and the fifth step, when the acid solution is injected, the acid solution adopts a slow chelating acid with a volume concentration of 50%.
[0034] The slow chelating acid is specifically composed of 25% hydrochloric acid by volume fraction, 20% hydrofluoric acid by volume fraction, 5% phosphoric acid by volume fraction, 5% acidified corrosion inhibitor aldehyde, ketone and amine condensate by volume fraction, The volume fraction is 3% of the dispersant alkylphenol polyoxyethylene ether, and the rest is composed of water.
[0035] The second desulfurizing agent is composed of paraformaldehyde with a volume fraction of 30%-50%, penetrant JFC with a volume fraction of 8%-10%, potassium iodate with a volume fraction of 3%-5%, and the rest is water. The paraformaldehyde in the second desulfurizer is a colorless needle crystal with an effective content of 99.5% and a molecular weight of 90.08. In water medium, paraformaldehyde ca...
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Abstract
The invention discloses a method for inhibiting escape of hydrogen sulfide in the acidification process of a water injection well. The method comprises the following steps: 1, carrying out closed wellwashing: carrying out closed circulating well washing on the water injection well; 2, carrying out liquid sealing: injecting a first desulfurizing agent into an annulus between an oil pipe and a sleeve from a sleeve valve, and forming a liquid column in the annulus so as to play a role of liquid sealing; 3, starting to acidify, stopping acid injection when the volume of an acid liquor injected into a shaft is half of the shaft volume, and then injecting isolation section plug water into the shaft; injecting a second desulfurizing agent into the shaft, and injecting the isolation slug water again after the second desulfurizing agent is completely injected; injecting the remaining acid liquor into the shaft to complete acidizing construction; and finally, closing the well for 4-6 h after acidification construction is completed, and then entering a normal water injection process. A certain amount of the first desulfurizing agent is injected into the oil jacket annulus to form liquid seal, and the isolation section water is injected in the shaft to separate the second desulfurizing agent from the acid liquor, so that the overflowed hydrogen sulfide gas is absorbed in the water injection and acidification process.
Description
technical field [0001] The invention belongs to the technical field of petroleum industry, and in particular relates to a method for suppressing the escape of hydrogen sulfide during the acidification process of water injection wells. Background technique [0002] At present, during drilling, water injection, oil production and downhole operations such as acidizing and acid fracturing, hydrogen sulfide gas may escape. The main reason is that the water injected into the formation contains sulfate. Bacteria in the formation will escape hydrogen sulfide; in addition, during the acidizing process, hydrogen sulfide gas may also escape as the acid fluid reacts with ferrous sulfide in the wellbore. However, hydrogen sulfide is highly toxic and extremely harmful to humans. Hydrogen sulfide dissolves in water to form a weak acid, causing hydrogen embrittlement of pipelines and pipe columns, which is extremely harmful. [0003] At present, there are mainly physical absorption and che...
Claims
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