Application of modified nano graphene oxide as as a chemical for improving the oil recovery of low-permeability reservoir

Abstract

The invention discloses application of modified nano graphene oxide as a chemical for improving the oil recovery of a low-permeability reservoir. The modified nano graphene oxide is prepared by oxidizing and stripping microcrystalline graphite to obtain microcrystalline graphene oxide and modifying the microcrystalline graphene oxide with a modifier. The modified nano graphene oxide and water aremixed to form fluid to be injected into a low-permeability reservoir stratum, and the oil recovery can be effectively increased. The modified nano graphene oxide material is of a flexible lamellar structure, the size of the material is smaller than 300 nm, the material adapts to the pore throat size of the low-permeability reservoir, damage such as blockage to the stratum is avoided, and the modified material is small in stratum adsorption loss and excellent in temperature resistance and salt resistance and can help to solve the problems in the existing low-permeability reservoir development process.

Description

technical field [0001] The application relates to the application of modified nano-graphene oxide as a chemical agent for enhancing oil recovery in low-permeability oil reservoirs, and belongs to the field of chemical materials. Background technique [0002] Oil plays an irreplaceable role in the national economy. With the rapid growth of my country's national economy, the demand for oil is constantly increasing rapidly. According to the data in the "Blue Book of China's Oil and Gas Industry Development Analysis and Prospect Report (2018-2019)", my country's crude oil production in 2018 was 189 million tons, and crude oil imports were 462 million tons, and the dependence on foreign countries rose to nearly 70%. However, after primary oil recovery and secondary oil recovery, there are still abundant oil reserves underground, but the difficulty of extraction is gradually increasing, especially in low-permeability reservoirs with a permeability lower than 50mD, where huge oil r...

AI Technical Summary

Problems solved by technology

The affected area of ​​water flooding in low permeability reservoirs is small, water channeling and flooding are easy, the oil displacement efficiency is low, the recovery rate of water flooding is only about 20%, and most of the crude oil remains in the reservoir and cannot be recovered

When the surfactant flooding technology is applied in the field, there are problems such as high formation adsorption loss, intolerance to divalent salts, and difficult treatment of the oil-water emulsification of the produced fluid.

However, due to the small throat and complex pore structure of low-permeability reservoirs, the application of polymer flooding in low-permeability reservoirs has the problems of formation plugging, high temperature and high salt resistance, and it cannot effectively improve oil recovery.

However, microbial flooding technology has problems such as short effective time, activator channeling, and unsatisfactory oil displacement efficiency.

Binary and three-element compound flooding technologies not only have the above-mentioned problems, but also because a large amount of chemicals are not easy to biodegrade after being injected into the formation, which will cause groundwater resource pollution and damage to the ecological environment of the reservoir.

However, when nano-silica materials are applied to low-permeability reservoirs, there are still limitations such as large formation adsorption, resistance to high temperature and high salt, etc.

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