High-temperature high-salt oil reservoir in-situ emulsion system and application thereof

Abstract

The invention discloses a high-temperature high-salt oil reservoir in-situ emulsion system and an application thereof. The in-situ emulsion system comprises 0.1-0.3% of alkylphenol(alcohol) polyoxyethylene ether sulfonate, 0.05-0.1% of sodium dodecyl sulfate, 0.05-0.1% of nano silicon dioxide and the balance of water. The interfacial tension of the in-situ emulsion system and crude oil can reach 10 <-2>-10<-3> mN / m, and under a shearing condition, the crude oil and water can form an O / W emulsion, and viscosity of the emulsion is greater than viscosity of water, so that the mobility ratio can be effectively improved. When being applied to chemical flooding of a high-temperature high-salt oil reservoir, emulsion droplets can block large pores in a porous medium through a Jamin effect, heterogeneity of a reservoir stratum is improved, and a low-permeability layer is started, so that the recovery rate is greatly improved. Meanwhile, the anti-aging property of the system under a high-temperature high-salt condition is good, and the oil-displacing requirement of high-temperature high-salt oil reservoirs can be met.

Description

technical field [0001] The invention relates to an in-situ emulsification system for high-temperature and high-salt oil reservoirs and its application, and belongs to the technical fields of oilfield chemistry and oilfield exploitation. Background technique [0002] At present, most of the oil reservoirs in my country have entered the stage of high water cut, but the recovery rate is less than 40%. Therefore, there is a broad research space for enhanced oil recovery technology. However, chemical flooding has a high EOR and can meet most reservoir conditions, so it has broad research and application prospects. Chemical flooding mainly includes surfactant flooding, polymer flooding, alkaline water flooding and composite flooding. Affected by temperature, salinity and polymer properties, polymer flooding and polymer-based chemical flooding cannot be used in the development of type III reservoirs, and at the same time, due to scaling and scale damage to reservoirs during alkali...

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Problems solved by technology

Ning Jian et al. (Ning Jian et al. Compatibility of low-cost O / W emulsion with core pore throats and its oil displacement efficiency[J]. Oilfield Chemistry, 2018, 35(2): 142-146) studied the low-cost O / W emulsion Compatibility of W-type emulsion with core pore throat and its oil displacement efficiency. Experimental results show that when the matching coefficient of emulsion droplets and rock pore throat size is less than 1, the oil displacement efficiency is not high, but when the matching efficiency is greater than 1, the oil recovery can be improved. rate significantly, able to reach 17%

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