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A wetting reversal agent for improving the depressurization and injection enhancement effect of low-permeability reservoir water injection wells and its preparation method

A low-permeability reservoir and wettability reversal technology, applied in the field of wettability reversal agent and its preparation, can solve the problems of reduced crude oil production, low water injection efficiency in low-permeability oilfields, and reduced final output rate of oilfields, etc., to improve The effect of reducing pressure and increasing injection, improving ultimate oil recovery, and improving mutual solubility stability

Active Publication Date: 2020-07-14
PETROCHINA CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In order to solve the problems of low water injection efficiency in water injection development and low permeability oilfields, resulting in reduced crude oil production and lower oilfield final output rate, the purpose of the present invention is to provide a wetting reversal agent for oil-water well depressurization and injection enhancement and its preparation The method uses the charge adsorption of the surfactant to change the pore-throat surface of the reservoir from the oil-wetting phase to the hydrophilic-wetting phase, which improves the water flooding efficiency; The oil phase attached to scale plugs improves the effectiveness of measures such as acidification and scale removal, and achieves the effect of reducing pressure and increasing injection in oil and water wells

Method used

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  • A wetting reversal agent for improving the depressurization and injection enhancement effect of low-permeability reservoir water injection wells and its preparation method
  • A wetting reversal agent for improving the depressurization and injection enhancement effect of low-permeability reservoir water injection wells and its preparation method
  • A wetting reversal agent for improving the depressurization and injection enhancement effect of low-permeability reservoir water injection wells and its preparation method

Examples

Experimental program
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Effect test

Embodiment 1

[0050] Example 1: Measures for pressure reduction and injection enhancement in water injection wells

[0051] In a low-permeability oilfield, the average porosity of oil layers is 10.6%, and the average permeability is 0.85×10 -3 μm 2 , the reservoir has oil wettability and small pore throat, and the injected water (SO 4 2- Content 2800mg / L) and reservoir water (Ba 2+ / Sr 2+ content of 3300mg / L) is incompatible, and Ba(Sr)SO 4 Scaling and clogging mainly lead to an increase in water injection pressure, a decrease in water injection volume or even no water injection, which affects the normal water injection development of the oil field.

[0052] Water injection well Yuan*-51, composite perforation + high-energy gas fracturing injection in May 2012, water injection pressure was 15.5Mpa and water injection volume was 15m in June 2012 3 / d, to meet the water injection allocation requirements, the water injection pressure of the well continued to increase after injection, unt...

Embodiment 2

[0054] Example 2: Measures for pressure reduction and injection enhancement in water injection wells

[0055] In a low-permeability oilfield, the average porosity of oil layers is 9.36%, and the average permeability is 0.64×10 -3 μm 2 , the reservoir has oil wettability and small pore throat, and the injected water (SO 4 2- Content 2550mg / L) and reservoir water (Ba 2+ \Sr 2+ content of 3400mg / L) is incompatible, and Ba(Sr)SO 4 Scaling and clogging mainly lead to an increase in water injection pressure, a decrease in water injection volume or even no water injection, which affects the normal water injection development of the oil field.

[0056] Water injection well Yuan*-48, composite perforation + high-energy gas fracturing injection in December 2010, water injection pressure 15.1Mpa, water injection volume 15m in January 2011 3 / d, to meet the water injection allocation requirements, the water injection pressure of the well continued to increase after injection, until ...

Embodiment 3

[0059] Example 3: Measures for removing scale and plugging in oil wells

[0060] Well Xinyuan*-7 was completed on November 2, 2001, and put into production after deflagration and fracturing of oil layers. In December 2001, the production fluid was 9.59m 3 / d, the oil production is 3.62t / d, and the water content is 55.1%. During the production process, due to the corrosion of the casing in the upper water layer of the oil well, the casing is broken and leaked, and the water produced in the upper formation is poured back into the oil layer, resulting in a decrease in the oil production of the oil well. In July 2006, the production fluid was 17.05m 3 / d, the oil production is 2.55t / d, and the water content is 82.2%. After isolation by the oil production packer, in April 2012, the fluid production was 2.08m 3 / d, water 0.43t / d, water content 75.0%.

[0061] In June 2012, the technological measure of "cleaning and descaling" was applied, that is, the wetting reversal agent pre...

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Abstract

The invention relates to a reverse wetting agent for improving low permeability reservoir water injection well decompression and augmented injection effects and a preparation method thereof. The preparation method comprises the steps of firstly mixing water, alcohol alkoxylate and a dispersing agent uniformly in a reaction kettle, then stirring until the alcohol alkoxylate and the dispersing agent are dissolved, adding sodium alkyl benzene sulfonate and fatty alcohol-polyoxyethylene ether sodium sulfate, continuously stirring for 4 to 5 hours, adding a dissolution accelerant, and uniformly stirring to obtain the reverse wetting agent. According to the reverse wetting agent, by utilizing interaction of a charge-absorbed lipophilic group-containing surface active agent and an oil-water two-phase dispersing agent, an oil phase absorbed by the surface of an oil deposit pore throat is stripped; through a charge-absorbed hydrophilic group-containing surface active agent, the surface of the oil deposit pore throat is changed from an lipophilic wetting phase to a hydrophilic wetting phase. The reverse wetting agent has the advantages of low oil-water interfacial tension, thorough reverse wetting, high oil washing efficiency and the like; the agent is used as a pretreatment plug for water injection well decompression and augmented injection, so that the effectiveness of oil reservoir acidification, dirt removal and other plug removal measures is remarkably improved.

Description

technical field [0001] The invention relates to a wetting reversal agent for increasing pressure reduction and increasing injection of water injection wells in low-permeability reservoirs and a preparation method thereof, belonging to the field of enhanced oil recovery of low-permeability reservoirs. Background technique [0002] Low-permeability sandstone reservoirs are generally buried deep, more than 2,000 meters deep. Under the geological depositional environment of hundreds of millions of years, the pore throat surface of the reservoir presents a partial oil-wet phase or oil-wet phase. In the process of water flooding, due to The injected water is in non-wetting contact with the surface of the pore throat, so it is difficult to form a uniform displacement of oil and water, resulting in coning of water injection. Laboratory experiments show that the displacement efficiency of crude oil in the pore throat is less than 30%, and 70% of the crude oil remains in the pore Thro...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K8/584C09K8/528
CPCC09K8/528C09K8/584
Inventor 何治武周志平刘宁周佩董俊唐泽玮姜毅何淼刘爱华
Owner PETROCHINA CO LTD
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