CN106268496B - A kind of Shuangzi amphoteric viscoelastic surfactant and preparation method thereof and using it as the clean fracturing fluid of thickening agent - Google Patents

Abstract

The present invention proposes a gemini amphoteric viscoelastic surfactant and its preparation method and a clean fracturing fluid using it as a thickening agent. The clean fracturing fluid prepared by the method is simple in materials, low in cost, and has an obvious microscopic network structure , good viscoelasticity, excellent sand suspension, and thorough gel breaking. Its biggest advantage is good temperature resistance. The shear viscosity of the best product below 160°C is not less than 130mPa·s, which is far greater than the site construction requirements of clean fracturing fluid. 25mPa·s.

Description

A kind of Gemini amphoteric viscoelastic surfactant and preparation method thereof and use it as thickening agent agent clean fracturing fluid

technical field

The invention relates to the technical field of oil and gas field development, in particular to a gemini amphoteric viscoelastic surfactant, a preparation method thereof and a clean fracturing fluid using it as a thickening agent.

Background technique

In today's world, the era of relying on the natural energy of the formation to make oil bubbling out of the ground has come to an end. Most large-scale high-permeability oil and gas fields in the world have entered the late stage of exploitation, but the demand for oil in countries around the world continues to rise. The teams of oil exploration and development at home and abroad have begun to Entering low-permeability, ultra-low-permeability and unconventional marginal oil and gas reservoirs, reservoir fracturing has become the key to improving oil recovery. Oilfield production has continuously increased requirements for reservoir production and fracturing efficiency. Reservoir stimulation (including stimulation technology and working fluid) has exposed various drawbacks, especially with the development of unconventional shale gas and tight oil, conventional reservoir stimulation can no longer meet the current requirements of fracturing stimulation, and working fluid As the "soul" of reservoir modification, its quality determines the success or failure of modification measures. The research and development of high-performance working fluid has become an urgent problem to be solved in the reservoir modification of unconventional oil and gas reservoirs.

In 1997, Schlumberger successfully applied viscoelastic surfactant fracturing fluid in reservoir fracturing stimulation, setting off a research upsurge in clean fracturing fluid, and providing the possibility for efficient stimulation of low-grade oil and gas reservoirs in the world. The biggest difference between this kind of fracturing fluid and conventional polymer fracturing fluid is that it is a structural fluid, which is a typical elastic fluid under shear conditions, and has good sand-carrying ability at low viscosity, breaking natural or artificial Polymer fracturing fluid relies on the conventional mode of fluid viscosity suspending proppant, which is conducive to the formation of long fractures at low viscosity, and the gel breaking fluid has no residue and has the effect of cleaning the fracture wall, which can effectively improve the fracture conductivity, thereby It has received extensive attention in the oilfield field.

However, due to the instability of surfactants under high temperature and high salt conditions, as well as their dosage and cost, the application of clean fracturing fluids in reservoir stimulation has been severely limited. The prominent problems existing in the current clean fracturing fluids are: (1) high cost of use, such as the viscoelastic surfactants used in the clean fracturing fluids reported in the literature are all traditional single-tail surfactants, and their critical micelle concentration is relatively high , the amount used in practical application is too large and the cost is high; (2) According to literature reports, the applicable formation temperature is generally lower than 120°C, and the existing clean fracturing fluid technology cannot be applied to formations with higher temperatures; (3) In strong electrolytes Poor stability, especially lower resistance to divalent metal ions, prone to saponification or salting-out in water with high salinity, making clean fracturing fluid unusable.

Contents of the invention

The present invention proposes a gemini amphoteric viscoelastic surfactant and its preparation method and a clean fracturing fluid using it as a thickening agent, which can solve the problems of poor temperature resistance, high cost and complicated preparation process existing in the existing clean fracturing fluid system The problem.

A kind of technical scheme of the present invention is achieved like this: a kind of Gemini amphoteric viscoelastic surfactant, it has following general structural formula:

Wherein R is an unsaturated hydrocarbon chain with 18-21 carbon atoms.

Another technical scheme of the present invention is achieved in that a kind of preparation method of gemini amphoteric viscoelastic surfactant comprises the following steps:

(1) Add 10 mmol of 2,2 bis(bromomethyl)-1,3-propanediol into a round bottom flask, use THF as solvent, add 20 mmol of fatty acid amidopropyl dimethylamine, reflux at 60°C for 12 hours, Wherein n(2,2 bis(bromomethyl)-1,3-propanediol):n(fatty acid amidopropyl dimethylamine)=1:2, after reaction finishes, underpressure distillation obtains intermediate A;

(2) Dissolve the intermediate A obtained in the first step with tetrahydrofuran, add 20-22mmol of sodium hydride, stir at room temperature for 15min, then dissolve 20mmol of 1,3-propane sultone in 50mL of tetrahydrofuran, and slowly add it dropwise to In the reaction solution of intermediate A and sodium hydride, reflux at 60°C for 12 hours, wherein n(intermediate A):n(sodium hydride):n(1,3-propane sultone)=1:2～2.2:2 After the reaction, react with hydrochloric acid and excess sodium hydride, filter and distill under reduced pressure to obtain a yellow viscous gel-like gemini amphoteric viscoelastic surfactant.

As a preferred technical solution, the molar amount of sodium hydride added during the reaction should be 2 to 2.2 times that of intermediate A.

As a preferred technical solution, the fatty acid is stearic acid, oleic acid, arachidic acid or erucic acid.

Another technical solution of the present invention is achieved in the following way: a clean fracturing fluid using a Gemini amphoteric viscoelastic surfactant as a thickening agent, comprising: 1.8 to 4.3% viscoelastic surfactant, 0.8% viscoelastic surfactant according to mass fraction ~1.1% of counter ion salt or inorganic salt, the balance of water.

As a preferred technical scheme, the counterion or inorganic salt includes potassium chloride, ammonium chloride, sodium salicylate, sodium benzoate, potassium hydrogen benzoate, carboxybenzenesulfonate and sodium sulfosalicylate wherein one or a mixture of several.

As a preferred technical solution, the preparation of the clean fracturing fluid only needs to add a viscoelastic surfactant with a mass fraction of 1.4 to 4.3% into an aqueous solution in which a counterion salt is dissolved with a mass fraction of 0.8 to 1.1%, and stir until completely dissolved.

The invention provides a method for preparing gemini amphoteric salt viscoelastic surfactant by using fatty acid, and a method for preparing clean fracturing fluid by using the viscoelastic surfactant. The prepared clean fracturing fluid can maintain excellent The viscoelasticity can be used for stimulation of fracturing fluid in medium and low permeability reservoirs.

Adopt above-mentioned technical scheme, the beneficial effect of the present invention is:

(1) The preparation method of the thickening agent is simple, the product yield is high, generally reaching more than 98%, and the impurity is few, and the influence on product performance is relatively small.

(2) The dosage is small and the cost is low. The critical micelle concentration of the viscoelastic surfactant prepared by the above method is 2 to 3×10 ^-4 mol/L, which is 1 to 2 lower than that of the conventional single tail viscoelastic surfactant. order of magnitude.

(3) Good temperature resistance. The temperature resistance of existing clean fracturing fluids is generally lower than 120°C. Only a very small number of clean fracturing fluids can reach 135°C by adding additives, which makes the composition of the system more complicated and the cost increases. The best clean fracturing fluid provided by the invention is sheared for 1 hour under the conditions of 159°C and 170s ^-1 , the viscosity remains above 130mPa·s, and it has excellent viscoelasticity.

(4) The preparation of clean fracturing fluid is simple, only need to add the required quality of thickener to a certain concentration of counter ion brine solution, and stir until dissolved.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the rheological curve of the clean fracturing fluid prepared with 4.3% thickener + 1.1% KCl in Example 1

Figure 2 is the rheological curve of the clean fracturing fluid prepared with 1.8% thickener+0.8% KCl in Example 1

Fig. 3 is the rheological curve of the clean fracturing fluid prepared with 4.3% thickener+1.1% KCl in Example 2

Figure 4 is the rheological curve of the clean fracturing fluid prepared with 1.8% thickener+0.8% KCl in Example 2

Figure 5 is the rheological curve of the clean fracturing fluid prepared with 4.3% thickener + 1.1% KCl in Example 3

Figure 6 is the rheological curve of the clean fracturing fluid prepared with 1.8% thickener+0.8% KCl in Example 3

Figure 7 is the rheological curve of the clean fracturing fluid prepared with 4.3% thickener+1.1% KCl in Example 4

Figure 8 is the rheological curve of the clean fracturing fluid prepared with 1.8% thickener+0.8% KCl in Example 4

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

A kind of Gemini amphoteric viscoelastic surfactant, it has following general structural formula:

Wherein R is an unsaturated hydrocarbon chain with 18-21 carbon atoms.

Embodiment one:

10mmol of 2,2 bis(bromomethyl)-1,3-propanediol was added to a round bottom flask, with tetrahydrofuran as a solvent, 20mmol of erucamide propyl dimethylamine was added, and refluxed at 60°C for 12 hours, wherein n (2,2 bis(bromomethyl)-1,3-propanediol):n(erucamide propyl dimethylamine)=1:2, intermediate A was obtained by distillation under reduced pressure after the reaction was completed. Dissolve the intermediate A obtained in the first step in tetrahydrofuran, add 20-22 mmol of sodium hydride, stir at room temperature for 15 minutes, then dissolve 20 mmol of 1,3 propane sultone in 50 mL of tetrahydrofuran, and slowly add it dropwise to intermediate A In the solution reacted with sodium hydride, reflux at 60°C for 12 hours, wherein n(intermediate A):n(sodium hydride):n(1,3 propane sultone)=1:2～2.2:2, after the reaction Use hydrochloric acid to react with excess sodium hydride, filter and distill under reduced pressure to obtain a yellow viscous gel-like gemini amphoteric viscoelastic surfactant. The critical micelle concentration of the obtained surfactant was 3.63×10 ^-4 mol/L, and the clean fracturing fluids prepared with 4.3% thickener + 1.1% KCl and 1.8% thickener + 0.8% KCl were respectively heated at 159°C, The rheological properties at 170s ^-1 and 119°C, 170s ^-1 are shown in Figures 1 and 2. The static suspended sand has no obvious settlement for 2 hours, and the viscosity of the broken gel is 0 after breaking the gel with 30% kerosene.

Embodiment two:

Add 10mmol of 2,2 bis(bromomethyl)-1,3-propanediol into a round bottom flask, use tetrahydrofuran as solvent, add 20mmol of arachidamide propyl dimethylamine, reflux at 60°C for 12 hours, where n (2,2 bis(bromomethyl)-1,3-propanediol):n(arachidic acid amidopropyl dimethylamine)=1:2, intermediate A was obtained by distillation under reduced pressure after the reaction was completed. Dissolve the intermediate A obtained in the first step in tetrahydrofuran, add 20-22 mmol of sodium hydride, stir at room temperature for 15 minutes, then dissolve 20 mmol of 1,3 propane sultone in 50 mL of tetrahydrofuran, and slowly add it dropwise to intermediate A In the solution reacted with sodium hydride, reflux at 60°C for 12 hours, wherein n(intermediate A):n(sodium hydride):n(1,3 propane sultone)=1:2～2.2:2, after the reaction Use hydrochloric acid to react with excess sodium hydride, filter and distill under reduced pressure to obtain a yellow viscous gel-like gemini amphoteric viscoelastic surfactant. The critical micelle concentration of the obtained surfactant is 3.63×10 ^-4 mol/L, the clean fracturing prepared by 4.3% thickener+1.1% sodium salicylate and 1.8% thickener+0.8% sodium salicylate The rheological properties of the liquid at 159°C, 170s ^-1 and 119°C, 170s ^-1 are shown in Figure 3 and Figure 4, the static suspended sand has no obvious settlement for 2 hours, and the gel breaking fluid after breaking the gel with 30% kerosene The viscosity is 0.

Embodiment three:

10mmol of 2,2 bis(bromomethyl)-1,3-propanediol was added to a round bottom flask, with tetrahydrofuran as a solvent, 20mmol of oleic acid amidopropyl dimethylamine was added, and refluxed at 60°C for 12 hours, wherein n (2,2 bis(bromomethyl)-1,3-propanediol):n(oleic acid amidopropyl dimethylamine)=1:2, and intermediate A was obtained by distillation under reduced pressure after the reaction was completed. Dissolve the intermediate A obtained in the first step in tetrahydrofuran, add 20-22 mmol of sodium hydride, stir at room temperature for 15 minutes, then dissolve 20 mmol of 1,3 propane sultone in 50 mL of tetrahydrofuran, and slowly add it dropwise to intermediate A In the solution reacted with sodium hydride, reflux at 60°C for 12 hours, wherein n(intermediate A):n(sodium hydride):n(1,3 propane sultone)=1:2～2.2:2, after the reaction Use hydrochloric acid to react with excess sodium hydride, filter and distill under reduced pressure to obtain a yellow viscous gel-like gemini amphoteric viscoelastic surfactant. The critical micelle concentration of the obtained surfactant was 3.63×10 ^-4 mol/L, and the clean fracturing fluids prepared with 4.3% thickener + 0.8% KCl and 1.8% thickener + 1.1% sodium salicylate were prepared in The rheological properties at 159°C, 170s ^-1 and 119°C, 170s ^-1 are shown in Figure 5 and Figure 6. There is no obvious settlement of the static suspended sand for 2 hours, and the viscosity of the broken gel is 0 after breaking the gel with 30% kerosene.

Embodiment four:

Add 10 mmol of 2,2 bis(bromomethyl)-1,3-propanediol into a round bottom flask, use THF as solvent, add 20 mmol of stearamidopropyl dimethylamine, reflux at 60°C for 12 hours, wherein n(2,2bis(bromomethyl)-1,3-propanediol):n(stearic acid amidopropyl dimethylamine)=1:2, and intermediate A was obtained by distillation under reduced pressure after the reaction. Dissolve the intermediate A obtained in the first step in tetrahydrofuran, add 20-22 mmol of sodium hydride, stir at room temperature for 15 minutes, then dissolve 20 mmol of 1,3 propane sultone in 50 mL of tetrahydrofuran, and slowly add it dropwise to intermediate A In the solution reacted with sodium hydride, reflux at 60°C for 12 hours, wherein n(intermediate A):n(sodium hydride):n(1,3 propane sultone)=1:2～2.2:2, after the reaction Use hydrochloric acid to react with excess sodium hydride, filter and distill under reduced pressure to obtain a yellow viscous gel-like gemini amphoteric viscoelastic surfactant. The critical micelle concentration of the obtained surfactant was 3.63×10 ^-4 mol/L, and the clean fracturing fluids prepared with 4.0% thickener+1.0% sodium salicylate and 2.2% thickener+0.8% KCl were respectively The rheological properties at 159°C, 170s ^-1 and 119°C, 170s ^-1 are shown in Figure 7 and Figure 8. There is no obvious settlement of the static suspended sand for 2 hours, and the viscosity of the gel breaking solution after breaking the gel with 30% kerosene is 0 .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (5)

1. a gemini amphoteric viscoelastic surfactant, is characterized in that, it has following general structural formula: Wherein R is an unsaturated hydrocarbon chain with 18-21 carbon atoms. 2. a preparation method of gemini amphoteric viscoelastic surfactant, is characterized in that, comprises the following steps: (1) Add 10mmol of 2,2 bis(bromomethyl)-1,3-propanediol into a round bottom flask, use tetrahydrofuran as solvent, add 20mmol of fatty acid amidopropyl dimethylamine, reflux at 60°C for 12 hours, Wherein n (2,2 bis(bromomethyl)-1,3-propanediol):n (fatty acid amidopropyl dimethylamine)=1:2, underpressure distillation obtains intermediate A after reaction finishes, and described fatty acid amide Propyl dimethylamine is any one of erucamide propyl dimethylamine, arachidamide propyl dimethylamine, oleic acid amidopropyl dimethylamine or stearic acid amidopropyl dimethylamine; (2) Dissolve the intermediate A obtained in the first step with tetrahydrofuran, add 20~22mmol of sodium hydride, stir at room temperature for 15min, then dissolve 20mmol of 1,3-propane sultone in 50mL of tetrahydrofuran, and slowly drop it into In the reaction solution of intermediate A and sodium hydride, reflux at 60°C for 12 hours, where n (intermediate A):n (sodium hydride):n (1,3-propane sultone)=1:2~2.2:2 After the reaction, react with hydrochloric acid and excess sodium hydride, filter and distill under reduced pressure to obtain a yellow viscous gel-like gemini amphoteric viscoelastic surfactant. 3. the preparation method of a kind of gemini amphoteric viscoelastic surfactant as claimed in claim 2, is characterized in that, the molar addition of sodium hydride is 2～2.2 times of intermediate A in the reaction process. 4. A clean fracturing fluid using the gemini amphoteric viscoelastic surfactant as claimed in claim 1 as a thickener, characterized in that, according to the mass fraction, it comprises: 1.8 to 4.3% of the viscoelastic surfactant, 0.8 to 1.1% % of counter ion salt or inorganic salt, and the balance of water. 5. clean fracturing fluid as claimed in claim 4, is characterized in that, described counterion salt or inorganic salt comprise potassium chloride, ammonium chloride, sodium salicylate, sodium benzoate, potassium hydrogen benzoate, carboxybenzene One or more of sulfonate and sodium sulfosalicylate.