Ultra-low interfacial tension self-assembly carbon dioxide foam oil-displacing agent suitable for low-permeability reservoir as well as preparation method and application of oil-displacing agent

Abstract

The invention provides an ultralow interfacial tension self-assembly carbon dioxide foam oil displacement agent suitable for a low-permeability reservoir. The oil displacement agent is prepared from the following components in percentage by weight: 0.2-0.3% of {bis [N-methyl-N-(3-dodecyloxy-2-hydroxyl) propyl-N-(2-hydroxy-3-sodium sulfonate) propyl] ammonium chloride} ethane, 0.2-0.3% of cocamidopropyl betaine, 0.2-0.3% of sodium dodecyl benzene sulfonate and the balance of water. The cleaning agent is prepared from the following components in percentage by weight: 0.1 to 0.35 percent of dodecyl dimethyl amine oxide, 0.02 to 0.07 percent of sodium salicylate, 0.04 to 0.14 percent of chelating agent, 5 to 7 percent of inorganic salt and the balance of water. The invention also provides a preparation method and application of the self-assembled carbon dioxide foam oil-displacing agent with ultralow interfacial tension. The self-assembled carbon dioxide foam oil-displacing agent is good in salt resistance and acid resistance and high in foaming liquid viscosity, enables oil-water interfacial tension to reach 10 <-3 > mN / m order of magnitude and below, generates fine and rich foam, is good in stability, is good in injectability in a low-permeability reservoir, and can improve the oil-water mobility ratio, remarkably increase the sweep efficiency, reduce the oil-water interfacial tension and remarkably improve the oil washing efficiency; the foaming agent does not generate a salting-out phenomenon, and does not generate chemical reaction with calcium and magnesium ions to generate precipitates.

Description

technical field [0001] The invention belongs to the field of chemical oil displacement, and in particular relates to an ultra-low interfacial tension self-assembled carbon dioxide foam oil displacement agent suitable for low permeability reservoirs, a preparation method and application thereof. Background technique [0002] In recent years, the country has proposed a national strategy of carbon peaking and carbon neutralization. Geological storage and utilization of carbon dioxide is an effective way to directly achieve carbon peaking and carbon neutralization. The use of carbon dioxide foam flooding can not only effectively achieve carbon dioxide sequestration , but also use the properties of carbon dioxide to further enhance oil recovery. Carbon dioxide flooding is chosen for low-permeability reservoirs because compared with high-permeability reservoirs, the migration ability of carbon dioxide in low-permeability reservoirs is weakened, gas channeling time is greatly delay...

AI Technical Summary

Problems solved by technology

[0006] At present, although some foam oil displacement agents have been developed on the market, there are still some problems, such as poor foamability, low viscosity, and reduced The interfacial tension is not enough, the foam comprehensive index is not high, the foam is not stable enough, etc.

For example, the invention patent ZL201710864250.3 "a self-assembled ultra-fine foam oil displacement agent and its preparation method and application" has insufficient interfacial tension reduction under high salinity conditions, low viscosity of foaming liquid, insufficient foam strength, and relatively high cost. The practical problem of insufficient sweep volume for low-permeability reservoirs with good reservoir permeability but strong heterogeneity

In addition, although some foaming systems can reduce interfacial tension and have high strength, the concentration of surfactant used is too high, resulting in too high cost, and it cannot be applied in the field at all.

Such as the invention patent CN110776893A "a kind of ultra-low interfacial tension strong foam oil displacement agent", the minimum concentration of the surfactant used reaches 30%, while the oil displacement efficiency is between 16-21%, the oil displacement efficiency is not high, so Difficult to apply on a large scale in the oil field

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