Nanometer emulsion discharge aiding agent for irregular gas reservoir fracturing and preparation method thereof

Abstract

The invention relates to the technical field of oil gas field mining, in particular to a nanometer emulsion discharge aiding agent for irregular gas reservoir fracturing and a preparation method thereof. The nanometer emulsion discharge aiding agent is prepared from the following ingredients in parts by mass: 10 to 30 percent of nonpolar oil phases, 10 to 15 percent of main surfactants, 10 to 15 percent of cosurfactants and the balance of inorganic salt water solution; the nonpolar oil phases are alkane with the carbon chain length being 7 to 10; the alkane is cycloalkane and alkane; the mainsurfactants are quaternary ammonium salt gemini surfactants and tween; the cosurfactants are one or several kinds of materials from ethanol, propanol, isopropanol, normal butanol or n-amyl alcohol; the inorganic salt is soluble metal halide. The discharge aiding agent can reduce the surface tension of the solution to 20.1 mN / m; the rock surface wetting performance is changed, so that the contact angle between water and rock surface exceeds 90 degrees; the capillary force effect can be obviously weakened; the flowback effect of the irregular gas reservoir fracturing liquid is greatly improved.

Description

technical field [0001] The invention relates to the technical field of oil and gas field exploitation, in particular to a nanoemulsion drainage aid for unconventional gas reservoir fracturing and a preparation method thereof. Background technique [0002] Unconventional gas reservoirs generally have geological characteristics of low porosity and low permeability, which makes the intrusion of fracturing fluid during reservoir fracturing very easy to cause reservoir water lock damage. For example, coalbed methane, shale gas, and tight gas reservoir rocks have small pores and throats, and natural micro-fractures are slightly or not developed. When the fracturing fluid is pressed into the reservoir, the water-based fluid will quickly invade the well. The fracture network around the borehole and the fracture network formed are affected by the capillary force, making it difficult to flow back the fracturing fluid, resulting in liquid phase retention, resulting in a decrease in res...

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Problems solved by technology

However, nanoemulsions are kinetically stable systems, and there are unstable phenomena such as Oswald ripening, demulsification, and delamination after long-term storage. For example, the literature "Oil-in-water nanoemulsions for pesticide formulations" shows that under the conditions of different agent-oil ratios The nanoemulsions of nanoemulsions grow with time, and the particle size becomes larger and larger; the literature "Impact of Oil Type on Nanoemulsion Formation and Ostwald Ripening Stability" shows that the nanoemulsions formed with short-chain alkanes as the oil phase have poor stability and Ostwald ripening Obvious phenomenon, easy to demulsify and stratify

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