Composition for reducing minimum miscible pressure of carbon dioxide and crude oil and preparation method thereof

Abstract

The application discloses a composition for reducing the minimum miscible pressure of carbon dioxide and crude oil and a preparation method thereof, belonging to the field of carbon dioxide flooding, wherein, in parts by weight, the composition is prepared from the following raw materials: supercritical carbon dioxide 10-30 parts, 10-25 parts of nonionic surfactant, 10-25 parts of anionic surfactant, 5-15 parts of initiator, 5-15 parts of reaction auxiliary agent, 40-60 parts of co-solvent and fluorine-containing cymbal 10-30 parts of hydrocarbons; the nonionic surfactant is polyoxyethylene alkanolamide, wherein R is C 10 -C 16 The alkyl group, n is any integer among 22-35. The composition uses fluorine-containing cymene and synthetic anion-nonionic surfactant, which can significantly reduce the minimum miscible pressure of carbon dioxide and crude oil, reduce the viscosity of crude oil, improve the wax crystal structure in high waxy crude oil, and reduce wax crystal molecules The generation of the three-dimensional structure also has good high temperature resistance, is not easy to decompose, and improves the recovery rate of high waxy crude oil; the preparation method is simple, efficient and low in cost.

Description

technical field [0001] The application relates to a composition for reducing the minimum miscible pressure of carbon dioxide and crude oil and a preparation method thereof, belonging to the technical field of carbon dioxide flooding. Background technique [0002] The carbon dioxide miscible flooding method is under high temperature reservoir conditions, the carbon dioxide component can extract the light hydrocarbon molecules in the crude oil into the gas phase, at this time, a gas phase rich in hydrocarbons and a liquid liquid in which carbon dioxide is dissolved in the crude oil are formed. phase, the fluidity of the original gas phase will be deteriorated, and the fluidity of the liquid phase crude oil will be improved, thus forming miscible flooding. The effect of miscible flooding is greater than that of near-miscible flooding and immiscible flooding, but the formation pressure in actual reservoirs is often lower than the minimum miscible pressure of carbon dioxide and c...

AI Technical Summary

Problems solved by technology

[0004] In the prior art, most of the techniques for reducing the minimum miscible pressure of carbon dioxide and crude oil are aimed at ordinary oil reservoirs, and high-waxy crude oil accounts for a considerable proportion of existing crude oil reserves, but the overlapping of wax crystal molecules to form a complex three-dimensional structure is extremely difficult. Affect the fluidity of crude oil and increase the difficulty of mining

[0005] Chinese patent CN107178345B - a composition in reducing CO 2 The application of the minimum miscible pressure with crude oil is to inject ethanol, isopropanol, hexanol and carbon dioxide into the formation. This method is not suitable for high temperature and high waxy oil reservoirs. Low carbon alcohols become flammable and explosive gases at high temperatures, which is safe poor performance, and it is difficult to drive crude oil in high waxy reservoirs

[0006] Chinese patent CN111909679B-a method for preparing a composition based on gas-soluble surfactants to reduce the minimum miscible pressure of carbon dioxide and crude oil discloses the use of ethanol solutions of gas-soluble surfactants mixed with liquid carbon dioxide, and the gas-soluble surfactants are fatty alcohols Oxyethylene polyoxypropylene ether or nonylphenol polyoxyethylene ether, although this method has a good pressure reduction effect, it is still not suitable for high temperature and high waxy reservoirs

[0007] In the prior art, compositions that reduce the minimum miscible pressure of carbon dioxide and crude oil have poor high temperature resistance and viscosity reduction effects, and their application range is limited