A kind of acid fracturing fluid and its preparation method and application

Abstract

The invention provides an acidic fracturing fluid and its preparation method and application. The raw material composition of the acidic fracturing fluid includes: 0.05wt%-0.3wt% thickener, 0.05wt%-0.3wt% crosslinking agent, pH regulator and water; the thickener is carboxymethylhydroxypropyl Guar gum or modified carboxymethyl hydroxypropyl guar gum; The raw material composition of crosslinking agent comprises 100 parts by weight of water, 5-25 parts by weight of zirconium oxychloride, 0.1-1 parts by weight of sodium chloride, 0.01-0.1 parts by weight Ammonium chloride, 15-40 parts by weight of ethylene glycol, 10-20 parts by weight of lactic acid. The present invention also provides a preparation method for the above-mentioned acidic fracturing fluid. The acidic fracturing fluid is used for fracturing operations in tight oil reservoirs, can realize a low amount of thickening agent in a strongly acidic environment, and has little damage to the reservoir.

Description

technical field

[0001] The invention relates to a fracturing fluid, in particular to an acid carboxymethyl hydroxypropyl guaridine fracturing fluid and its application, and belongs to the technical field of fracturing and exploitation of tight oil and gas reservoirs. Background technique

[0002] Oil and gas reservoirs have ultra-low permeability, which will cause the expansion and migration of reservoir clay minerals during the water-based fracturing process, causing serious damage to the formation, and seriously affecting the production stimulation effect of fracturing stimulation.

[0003] At present, most fracturing fluids are alkaline, and the reaction between clay minerals and alkali will increase the negative charge of the clay, causing an increase in the repulsion between particles, causing a large number of particles to block pore throats, resulting in a decrease in permeability. The acidic environment can effectively inhibit the expansion and migration of clay mine...

Examples

Embodiment 1

[0030] Preparation of crosslinking agent:

[0031] Warm up 100 parts by weight of deionized water to 50°C, add 10 parts by weight of zirconium oxychloride, 0.25 parts by weight of sodium chloride, and 0.025 parts by weight of ammonium chloride, stir at a speed of 20-40 rpm, and wait for the oxychloride to After the zirconium is completely dissolved, add 30 parts by weight of ethylene glycol and stir at a speed of 20-40 rpm. After fully dissolving, continue to add 15 parts by weight of lactic acid, and then drop in 20% concentration of sodium hydroxide lye to adjust the pH When the value reaches 6, react at constant temperature for 8 hours to obtain a colorless and transparent organic zirconium crosslinking agent.

Embodiment 2

[0039] Gelling properties at different pH values

[0040] The organozirconium cross-linking agent of Example 1 is used for performance evaluation of water-based fracturing fluid. The test conditions are: water-based liquid preparation, thickening agent is carboxymethyl hydroxypropyl guar gum, cross-linking agent dosage 0.3%, pH They are 0.5, 1, 2, 3 respectively, and the temperature is 60°C. The results are shown in Table 2.

[0041] Table 2

[0042]

[0043]

[0044] It can be seen from Table 2 that the use of carboxymethyl hydroxypropyl guar gum allows the acidic fracturing fluid to gel at a concentration of 0.1% and a pH of 1 to form a fracturing fluid system that meets the application requirements.

Embodiment 3

[0046] The preparation method of modified carboxymethyl hydroxypropyl guar gum:

[0047] 10 parts by weight of carboxymethyl hydroxypropyl guar gum are dissolved in 100 parts by weight of deionized water, stirred and dissolved to obtain carboxymethyl hydroxypropyl guar gum solution;

[0048] 0.25 parts by weight of N-isopropylacrylamide and 0.25 parts by weight of acrylic acid were dissolved in 20 parts by weight of deionized water and placed in a dropping funnel for use to obtain a monomer solution.

[0049]Add 0.01 part by weight of initiator (ammonium persulfate + sodium sulfite) to carboxymethyl hydroxypropyl guar gum solution, stir to dissolve, heat up to 50°C, then add monomer solution dropwise, react for 5 hours, add ethanol to precipitate the product.

[0050] Suction filter the product, wash with ethanol solvent, and dry to obtain modified carboxymethyl hydroxypropyl guar gum.

[0051] Characterization of Modified Carboxymethyl Hydroxypropyl Guar Gum

[0052] The mo...

technical field

[0001] The invention relates to a fracturing fluid, in particular to an acid carboxymethyl hydroxypropyl guaridine fracturing fluid and its application, and belongs to the technical field of fracturing and exploitation of tight oil and gas reservoirs. Background technique

[0002] Oil and gas reservoirs have ultra-low permeability, which will cause the expansion and migration of reservoir clay minerals during the water-based fracturing process, causing serious damage to the formation, and seriously affecting the production stimulation effect of fracturing stimulation.

[0003] At present, most fracturing fluids are alkaline, and the reaction between clay minerals and alkali will increase the negative charge of the clay, causing an increase in the repulsion between particles, causing a large number of particles to block pore throats, resulting in a decrease in permeability. The acidic environment can effectively inhibit the expansion and migration of clay mine...

Examples

Embodiment 1

[0030] Preparation of crosslinking agent:

[0031] Warm up 100 parts by weight of deionized water to 50°C, add 10 parts by weight of zirconium oxychloride, 0.25 parts by weight of sodium chloride, and 0.025 parts by weight of ammonium chloride, stir at a speed of 20-40 rpm, and wait for the oxychloride to After the zirconium is completely dissolved, add 30 parts by weight of ethylene glycol and stir at a speed of 20-40 rpm. After fully dissolving, continue to add 15 parts by weight of lactic acid, and then drop in 20% concentration of sodium hydroxide lye to adjust the pH When the value reaches 6, react at constant temperature for 8 hours to obtain a colorless and transparent organic zirconium crosslinking agent.

Embodiment 2

[0039] Gelling properties at different pH values

[0040] The organozirconium cross-linking agent of Example 1 is used for performance evaluation of water-based fracturing fluid. The test conditions are: water-based liquid preparation, thickening agent is carboxymethyl hydroxypropyl guar gum, cross-linking agent dosage 0.3%, pH They are 0.5, 1, 2, 3 respectively, and the temperature is 60°C. The results are shown in Table 2.

[0041] Table 2

[0042]

[0043]

[0044] It can be seen from Table 2 that the use of carboxymethyl hydroxypropyl guar gum allows the acidic fracturing fluid to gel at a concentration of 0.1% and a pH of 1 to form a fracturing fluid system that meets the application requirements.

Embodiment 3

[0046] The preparation method of modified carboxymethyl hydroxypropyl guar gum:

[0047] 10 parts by weight of carboxymethyl hydroxypropyl guar gum are dissolved in 100 parts by weight of deionized water, stirred and dissolved to obtain carboxymethyl hydroxypropyl guar gum solution;

[0048] 0.25 parts by weight of N-isopropylacrylamide and 0.25 parts by weight of acrylic acid were dissolved in 20 parts by weight of deionized water and placed in a dropping funnel for use to obtain a monomer solution.

[0049]Add 0.01 part by weight of initiator (ammonium persulfate + sodium sulfite) to carboxymethyl hydroxypropyl guar gum solution, stir to dissolve, heat up to 50°C, then add monomer solution dropwise, react for 5 hours, add ethanol to precipitate the product.

[0050] Suction filter the product, wash with ethanol solvent, and dry to obtain modified carboxymethyl hydroxypropyl guar gum.

[0051] Characterization of Modified Carboxymethyl Hydroxypropyl Guar Gum

[0052] The mo...

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