A kind of non-alkali binary compound flooding system and its preparation method

Abstract

The invention relates to an alkali-free binary compound oil displacement system and preparation method thereof. The system comprises, be weight, 20-40 parts of alkylbenzene sulfonate, 5-20 parts of surface active agents, 0.5-5 parts of polymeric modifier, 0.5-5 parts of viscosity depressants, 0.5-5 parts of addictive agents and 25-75 parts of water. According to the alkali-free binary compound oildisplacement system, each component cooperates with one another to obtain an ideal synergistic effect; the system is alkali-free, and the problems of viscoelasticity reduction of polymers caused by alkali, and stratum structure destruction and stuck pump clean out operation caused by alkali scale formed by the alkali are solved; the system is not only conform with requirements of environmental protection, but also reduces the production cost.

Description

technical field [0001] The invention relates to enhanced oil recovery by three oil recovery methods, in particular to an alkali-free binary compound oil displacement system suitable for crude oil recovery and a preparation method thereof. Background technique [0002] After the primary and secondary extraction of underground crude oil, more than 40% of the crude oil remains in the formation. If the formation conditions are not ideal, even 80% of the crude oil remains in the formation after the primary and secondary extraction. At present, my country's major oil fields have entered a period of high water cut, and underground crude oil is in a discontinuous state of dispersion. The oil displacement technology mainly uses the synergistic effect of alkali, polymer and surfactant to achieve the effect of increasing oil and reducing water, and improving oil recovery. [0003] Alkali / surfactant / polymer ASP flooding system can greatly improve oil recovery, but there are some problem...

AI Technical Summary

Problems solved by technology

[0003] Alkali / surfactant / polymer ASP flooding system can greatly improve oil recovery, but there are some problems in the process of large-scale industrial application: 1. The use of alkali will cause the precipitation of multivalent ions 1. Rock mineral dissolution, thus destroying the structure of the oil layer and oil well, seriously damaging the formation, and cleaning the pump barrel every 10-15 days, which increases the cost of oil production; 2. The existence of alkali will not only increase the amount of polymer used, but also reduce The viscoelasticity of polymers, especially the elasticity of polymers; 3. The use of alkali will also cause the produced fluid to be a W / O emulsion with high viscosity, which not only affects the productivity of oil wells, but also increases the difficulty of demulsification

At present, the commonly used non-alkali binary flooding oil recovery surfactants are mainly based on petroleum sulfonate as a compound system with other surfactants. However, the commonly used petroleum sulfonate surfactants have the following problems: 1. Poor adaptability: Field tests have proved that even if used in the same oil field, the surfactant components used in different blocks are different, and the surfactant formula needs to be adjusted at any time to adapt the surfactant components to the crude oil components, which makes the product not easy Large-scale and commercialized, and petroleum sulfonate has poor salt resistance, which is not suitable for high salinity reservoir conditions; especially for heavy oil conditions

2. Poor solubility: The product has poor solubility and needs a large amount of low-carbon alcohol / ether co-solvent to disperse and dissolve, which leads to low flash point of the product, complex supporting ground engineering, and large investment and operation range; 3. Poor stability: since most of the raw materials used are petrochemicals The by-products of the product make the raw material components complex and fluctuate greatly, resulting in poor performance stability of the final surfactant product; 4. Poor compatibility: some cannot be used in a single agent, require synergists, or are selective to compatible polymers and alkalis , the compatibility range is narrow, and the synergistic effect is not ideal; 5. Low cost performance: to achieve a wide range of ultra-low interfacial tension, a high amount of use is required, and poor adaptability and poor adsorption resistance lead to low cost performance

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