Anionic Surfactant Crosslinked Acid

Abstract

The invention relates to an anionic surfactant crosslinked acid, which consists of 1.5 to 2 parts of dodecylbenzene sulfonic acid, 1 to 2 parts of lauryl sodium sulfate, 8 to 10 parts of solid sodium chloride, 3 to 4 parts of isooctane, 1 to 2 parts of gel breaker, and 80 to 85 parts of 1 to 12 percent hydrochloric acid or organic acid, wherein the organic acid consists of 1 percent of hydrochloric acid, 3 percent formic acid and 6 percent acetic acid; and the gel breaker is prepared by the following steps: metering 50mL of cyclohexanol, weighing 20g of anhydrous calcium oxide, stirring until the anhydrous calcium oxide is completely dissolved, adding 10g of magnesium oxide, uniformly mixing, airing indoors for 2 to 3 days, crushing, and sieving by using a 100-mesh sieve. When the crosslinked acid is continuously sheared for 90 minutes at a rate of 170s<-1>, the viscosity is kept at about 50mPa.s, and sand can be carried; and the gel breaker breaks gel radically, and has the viscosity of less than 5.0mPa.s.

Description

Technical field: [0001] The invention relates to an anionic surfactant cross-linking acid suitable for cross-linking acid sanding fracturing of oil wells in ultra-low permeability oil and gas layers, and deep acidizing injection of oil and water wells. Background technique: [0002] At present, ultra-low permeability oil and gas reservoirs have poor physical properties, low permeability, fine pore throat, low surface porosity, low single well production, but generally high content of acid-soluble minerals. Cross-linked acid-carrying sand has good production stimulation potential. While forming propped fractures in the reservoir, the acid in the system can dissolve the acid-soluble minerals in the reservoir to further improve the permeability of the reservoir matrix and further increase the single well production. The performance of the current cross-linking acid is not perfect: some systems can realize cross-linking and carrying sand under the condition of higher concentrati...

AI Technical Summary

Problems solved by technology

[0002] At present, ultra-low permeability oil and gas reservoirs have poor physical properties, low permeability, fine pore throats, low surface porosity, low single well production, but generally high content of acid-soluble minerals

Cross-linked acid-carrying sand has good production stimulation potential. While forming propped fractures in the reservoir, the acid in the system can dissolve the acid-soluble minerals in the reservoir to further improve the permeability of the reservoir matrix and further increase the single well production. The performance of the current cross-linking acid is not perfect: some systems can realize cross-linking and carrying sand under the condition of higher concentration of acid (acid concentration greater than 10%), but the main agent is made of high molecular polymer, and the cross-linking agent is made of metal Cross-linking agent, it is difficult for the system to break the gel, and it is difficult to flow back in the ultra-low permeability reservoir with fine pores and microthroats, and the damage is great; Thickening in acidic environment, or only in low-concentration acid environment (hydrochloric acid concentration less than 3%) to achieve thickening and sand-carrying ability, poor sand-carrying ability

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