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Method for improving CO2 miscible flooding recovery efficiency

A miscible flooding and CO2 technology, applied in chemical instruments and methods, production fluids, earth drilling and production, etc., can solve the problems of small miscible flooding area, unsatisfactory effect, and difficulty in water injection in ultra-low permeability reservoirs

Active Publication Date: 2020-04-24
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Experiments show that CO 2 The recovery rate of miscible flooding can reach more than 90%, but the actual oil recovery rate is very low, usually not more than 20%, which is mainly caused by CO 2 The swept area of ​​miscible flooding is small, and it is caused by gas channeling, whether it is CO 2 Miscible or CO 2 For flooding, the method of gas and water delivery or foam channeling prevention is usually adopted to increase the swept area and thus improve the recovery factor. However, it is difficult to inject water into ultra-low permeability reservoirs, and it is not suitable for gas and water alternate injection. Conventional foam sealing channeling improves CO 2 Flooding technology is a passive anti-channeling technology, although it can improve CO 2 flooding recovery, but the effect is still unsatisfactory

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Embodiment 1 A kind of improving CO 2 Miscible Flooding Recovery Method

[0032] Formation permeability of A oilfield is 0.5×10 -3 μm 2 , the original pressure of the formation is 45MPa, the formation temperature is 80°C, and the experimental test of formation oil and CO 2 The miscible pressure is 28MPa, the formation water sensitivity is serious, and it is difficult to inject water. The production well has a daily liquid production of 2 tons, a daily oil production of 1.8 tons, and a water cut of 10%. It is designed for CO 2 Miscible flooding, daily injection of CO into the injection well 2 30 tons / day, add CO 2 Amount of 1% CO 2 Miscible profile control agent TH-1, injected continuously until CO 2 Miscible flooding ends, design injects CO 2 50,000 tons, inject 500 tons of miscible profile control agent TH-1.

[0033] The composition of TH-1 is 20% sodium 2-ethylhexyl succinate sulfonate, 15% fatty alcohol polyoxyethylene ether sodium sulfate, 10% Span-80, 30% e...

Embodiment 2

[0034] Embodiment 2 A kind of improving CO 2 Miscible Flooding Recovery Method

[0035] Formation permeability of B oilfield 1.0×10 -3 μm 2 , the original pressure of the formation is 40MPa, the formation temperature is 75°C, and the experimental test of formation oil and CO 2 Miscible pressure 26MPa, injection well daily water 10m 3 , the injection pressure is 28MPa, the production well has a daily liquid production of 3 tons, a daily oil production of 2.85 tons, and a water cut of 5%. It is designed for CO 2 Miscible flooding, daily injection of CO into the injection well 2 40 tons / day, add CO 2 Amount of 0.5% CO 2 Miscible profile control agent TH-2, injecting miscible agent TH-2 intermittently, adding miscible agent and simply injecting CO 2 Time 1:1, alternating every 30 days, designed to inject CO 2 80,000 tons, inject 200 tons of miscible profile control agent TH-2.

[0036] The composition of TH-2 is 15% sodium 2-ethylhexyl succinate sulfonate, 10% fatty alco...

Embodiment 3

[0037] Embodiment 3 A kind of improving CO 2 Miscible Flooding Recovery Method

[0038] Formation permeability of Bing Oilfield is 0.2×10 -3 μm 2 , the original pressure of the formation is 42MPa, the formation temperature is 85°C, and the experimental test of formation oil and CO 2 The miscible pressure is 32MPa, it is difficult to inject water, the production well has a daily liquid production of 1 ton, a daily oil production of 0.8 tons, and a water cut of 20%. It is designed for CO 2 Miscible flooding, daily injection of CO into the injection well 2 20 tons / day, add CO 2 Amount of 1% CO 2 Miscible profile control agent TH-3, injected continuously until CO 2 Miscible flooding ends, design injects CO 2 30,000 tons, inject 300 tons of miscible profile control agent TH-3.

[0039] The composition of TH-3 is sodium 2-ethylhexyl succinate sulfonate 20%, cocamidopropyl betaine 10%, butyl acetate 10%, ethyl acetate 10%, Span-80 10%, Ethanol 40%. Indoor test CO 2 The vi...

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PUM

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Abstract

The invention provides a method for improving CO2 miscible flooding recovery efficiency. The method comprises the following steps that a chemical agent capable of improving the macroscopic apparent viscosity of a supercritical CO2 miscible flooding system is added in the CO2 miscible flooding process, the chemical agent is partially or completely dissolved in supercritical CO2, the viscosity of supercritical CO2 can be improved, the chemical agent can be dissolved in formation water, and an aqueous solution and supercritical CO2 can form a stable dispersion. According to the method, the macroscopic apparent viscosity of the supercritical CO2 system is improved, so that the swept area of supercritical CO2 is further increased, and the CO2 miscible-phase displacement recovery ratio of the low-permeability reservoir is improved.

Description

technical field [0001] The invention belongs to CO 2 In the field of oil flooding technology, it relates to a method of improving CO 2 The recovery method of miscible flooding. Background technique [0002] Low-permeability reservoirs are very rich in resources, but the conventional method of water injection to enhance oil recovery is not suitable for low-permeability and ultra-low-permeability reservoirs, CO 2 It is an effective method to enhance the recovery of low permeability reservoirs, especially CO 2 Miscible flooding can greatly increase the recovery of low-permeability reservoirs. [0003] Experiments show that CO 2 The recovery rate of miscible flooding can reach more than 90%, but the actual oil recovery rate is very low, usually not more than 20%, which is mainly caused by CO 2 The swept area of ​​miscible flooding is small, and it is caused by gas channeling, whether it is CO 2 Miscible or CO 2 For flooding, the method of gas and water delivery or foam ch...

Claims

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Application Information

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IPC IPC(8): E21B43/22C09K8/594
CPCE21B43/164C09K8/594Y02P20/54
Inventor 杨勇王其伟张世明吕广忠张传宝李雪松郭平张营华李友全盛强
Owner CHINA PETROLEUM & CHEM CORP
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