Method for reducing viscosity of heavy oil in heavy oil reservoir and application

Abstract

The invention belongs to the field of oil exploitation, and particularly discloses a method for reducing viscosity of heavy oil in a heavy oil reservoir and application. The method comprises the step of injecting a dimethyl ether aqueous solution into the heavy oil reservoir. According to the method, the aqueous solution of the dimethyl ether is injected into the heavy oil reservoir, and the dimethyl ether can be separated out from water and transferred into the heavy oil by utilizing the property that the dimethyl ether is preferentially dissolved in crude oil, so that the viscosity of the heavy oil is remarkably reduced, the fluidity of the heavy oil is improved, and the exploitation effect is improved. Dimethyl ether is in contact with the thickened oil in the underground pore seepage process, is separated out from an aqueous solution and is preferentially dissolved into the thickened oil, so that the thickened oil is expanded and viscosity is reduced, the fluidity of the thickened oil is improved, and the recovery effect of the thickened oil is improved.

Description

technical field [0001] The invention belongs to the field of petroleum exploitation, and more specifically relates to a method and application for reducing the viscosity of heavy oil in a heavy oil reservoir. Background technique [0002] Petroleum is related to the energy security of the country and has an important impact on national defense construction, economic development and people's daily life. At present, most of my country's oil fields have entered the middle and late stages of oil development, and the exploitation of thin oil can no longer meet the consumption demand for oil. However, my country is rich in heavy oil resources, and its reserves exceed 20% of the total recoverable oil resources. The exploitation of heavy oil accounts for only 10% of the total crude oil exploitation, so the exploitation of heavy oil is of great significance to the stable and increasing production of oil. [0003] Heavy oil has high content of colloid and asphaltene, and is characteri...

AI Technical Summary

Problems solved by technology

Mixing thin oil into heavy oil is also an effective method of reducing viscosity, but the production of thin oil in many heavy oil fields is not sufficient. If the thin oil is not mixed enough, it will easily lead to shutdown of heavy oil wells and affect production

In addition, downhole injection of natural gas and carbon dioxide can also reduce the viscosity of heavy oil and improve fluidity, but because of the low solubility of such gases in crude oil, the effect of reducing the viscosity of heavy oil is poor, and gas channeling is easy to occur in the formation

Chinese patent application CN108071390A introduces a method for reducing the viscosity of heavy oil by mixing natural gas and propane gas. Combining the respective advantages of natural gas and propane gas, it solves the problem of low dissolving capacity of natural gas and poor effect of reducing the viscosity of heavy oil. However, the patent design The mixed gas formula requires that the mixed gas be kept in a gaseous state under the temperature and pressure of the reservoir, which makes it difficult to avoid gas channeling of the mixed gas, which affects the viscosity reduction and production effect of heavy oil

This application directly injects pure dimethyl ether liquid, and the part of dimethyl ether that is in contact with the water in the formation does not touch the crude oil, which must be an invalid injection, resulting in waste of dimethyl ether and increased costs

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