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Method for enhancing oil recovery of low permeability sandstone reservoir

A sandstone reservoir, low-permeability technology, applied in the fields of fluid production, earth-moving drilling, wellbore/well components, etc., can solve the problems of low average permeability of the formation, loss of oil displacement, and reduced viscosity, and achieve improved crude oil recovery. Yield, good water dispersibility, good elasticity and flexibility

Active Publication Date: 2014-01-29
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, because the average permeability of the ultra-low permeability sandstone reservoir is very low (less than 1 millidarcy), and the pore throat size of the formation is at the level of hundreds of nanometers, linear oil displacement polymer injection is very difficult, the injection pressure is high, and energy consumption is high. At the same time, when the linear polymer penetrates into the deep formation, it is easily sheared by the narrow pore throat of the formation, so that its viscosity decreases, the degradation is serious, and the oil displacement effect is lost
In addition, some profile control and water shutoff materials used in medium and high permeability reservoirs, such as inorganic sediments, bulky particles, cross-linked polymer gels, etc., due to their large volume, cannot be used in ultra-low permeability reservoirs The application will cause injection difficulties, and it can only improve the water absorption profile in the near-wellbore area, and cannot go deep into the formation, and the effect of increasing oil and reducing water is very limited
So far, there is no effective tertiary oil recovery technology for the exploitation of ultra-low permeability sandstone reservoirs. The water cut of most oil wells in the reservoir rises, the injected water forms an invalid circulation, and the production efficiency gradually decreases

Method used

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  • Method for enhancing oil recovery of low permeability sandstone reservoir

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Effect test

Embodiment 1

[0018] The method for improving the oil recovery rate in the late stage of fracturing water injection in ultra-low permeability sandstone reservoirs, the steps are as follows:

[0019] The average permeability of the ultra-low permeability sandstone reservoir formation is 0.6 mD, the daily water injection volume of the water injection well is 30 tons, and the soft microgel deep control and displacement agent is selected. The initial average particle size is 106nm. The equipment is connected as attached figure 1 As shown, the flexible microgel deep water control agent is placed in the storage tank 1, and the pump speed of the metering pump 2 is controlled to make the injected water control agent concentration 1000ppm. After continuous injection for 12 months, stop, and then continue to inject water separately , corresponding to 8% cumulative increase in oil wells, and a duration of 2.5 years for stable and increased production.

Embodiment 2

[0021] The method for improving the oil recovery rate in the late stage of fracturing water injection in ultra-low permeability sandstone reservoirs, the steps are as follows:

[0022] The average permeability of the ultra-low permeability sandstone reservoir formation is 0.9 mD, and the daily water injection volume of the water injection well is 40 tons. The soft microgel deep control and displacement agent is selected, and the initial average particle size is 200nm. The equipment is connected as attached figure 1 As shown, the flexible microgel deep water-regulating agent is placed in the storage tank 1, and the pumping speed of the metering pump 2 is controlled so that the concentration of the injected water-controlling agent is 5000ppm. After continuous injection for 6 months, stop, and then continue to inject water separately , corresponding to a 5% cumulative increase in oil wells, and a duration of 1.5 years for stable and increased production.

Embodiment 3

[0024] The method for improving the oil recovery rate in the late stage of fracturing water injection in ultra-low permeability sandstone reservoirs, the steps are as follows:

[0025] The average permeability of the ultra-low permeability sandstone reservoir formation is 0.2 mD, the daily water injection volume of the water injection well is 20 tons, and the soft microgel deep control and displacement agent is selected, the initial average particle size is 20nm, and the equipment is connected as attached figure 1 As shown, the flexible microgel deep water-regulating agent is placed in the storage tank 1, and the pumping speed of the metering pump 2 is controlled so that the concentration of the injected water-controlling agent is 100ppm. After continuous injection for 36 months, stop, and then continue to inject water separately , corresponding to a cumulative oil increase of 10% for oil wells, and a period of 5 years for stable and increased production.

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Abstract

The invention relates to a method for enhancing oil recovery of a low permeability sandstone reservoir. A flexible microgel in-depth profile modifying agent is injected into an oil extraction well water distribution water pipeline of an ultralow permeability sandstone reservoir in the middle and later stage of fracture water injection, and the injection concentration of the flexible microgel in-depth profile modifying agent ranges from 100ppm to 10000ppm. According to the method, corresponding affected oil well stable production and increasing production duration of the water injection well is one to five years, after the flexible microgel in-depth profile modifying agent is injected into the water injection well of the ultralow permeability sandstone reservoir, oil increasing of an oil well can correspondingly reach 5% to 20% on the calculation basis generally, and the obvious effect of improving crude oil extraction rate is achieved.

Description

technical field [0001] The invention belongs to the technical field of tertiary oil recovery of ultra-low permeability sandstone oil reservoirs, and in particular relates to a method for improving the recovery rate of crude oil in the late stage of fracturing water injection in ultra-low permeability sandstone oil reservoirs. Background technique [0002] At present, among the low permeability reservoirs, petroleum scientists and technicians call the reservoirs with less than 1 millidarcy as ultra-low permeability. Among my country's proven oil reserves, the reservoirs with a permeability of about 1 millidarcy account for more than 70%, and most of them are sandstone reservoirs, which are the main resources for the future development of my country's petroleum industry. Ultra-low permeability sandstone reservoirs are commonly known as "whetstones", with extremely low permeability, small formation porosity, poor connectivity, average formation pressure coefficient of reservoir...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B43/22E21B43/20E21B33/13
Inventor 黎晓茸张涛李忠兴慕立俊李宪文郭方元谭俊领贾玉琴刘笑春杨棠英
Owner PETROCHINA CO LTD
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