阅读说明：本技术 一种新型耐盐耐温两性离子粘弹性表面活性剂以及储层改造工作液的制备方法 (Novel salt-tolerant temperature-tolerant zwitterionic viscoelastic surfactant and preparation method of reservoir transformation working solution ) 是由 毛金成 寸猛 张文龙 杨小江 林冲 于 2019-11-21 设计创作，主要内容包括：本发明提出了一种新型耐盐耐温两性离子粘弹性表面活性剂的制备方法和以其为稠化剂的高矿化度水基清洁压裂液配方,同时利用酸液可以配置成具有酸浓度、盐浓度黏度响应的转向酸体系。高矿化度水基清洁压裂液,其包括上述耐盐型单子两性离子粘弹性表面活性剂2-5wt％,无机盐类占3-20wt％,余量为水,即用矿化度在30000-180000mg/L的海洋水或地层产出水配制的清洁压裂液。该类型粘弹性表面活性剂可以采用海洋水或地层产出水直接配制,且配制的压裂液耐温、耐剪切良好,在140℃、170s<Sup>-1</Sup>的剪切条件下,2小时后黏度维持在40mPa·s以上。同时利用其与酸液按照比例配置的转向酸在140℃下仍具有较高的粘度。(The invention provides a preparation method of a novel salt-resistant temperature-resistant zwitterion viscoelastic surfactant and a high-salinity water-based clean fracturing fluid formula using the surfactant as a thickening agent, and a diverting acid system with acid concentration and salt concentration viscosity response can be prepared by using acid liquor. The high-salinity water-based clean fracturing fluid comprises 2-5 wt% of the salt-resistant type single zwitterion viscoelastic surfactant, 3-20 wt% of inorganic salt and the balance of water, namely clean fracturing fluid prepared from ocean water or stratum produced water with the salinity of 30000-180000mg/LAnd (4) liquid. The viscoelastic surfactant can be directly prepared from ocean water or stratum produced water, and the prepared fracturing fluid has good temperature resistance and shearing resistance, and the temperature is 140 ℃ and the shearing resistance is 170s ‑1 Under the shear condition of (3), the viscosity is maintained at 40 mPas or more after 2 hours. Meanwhile, the diverting acid prepared by the diverting agent and the acid liquor in proportion still has higher viscosity at 140 ℃.)

1. A novel salt-resistant temperature-resistant zwitter-ion viscoelastic surface activity has the following structural formula:

wherein R is a saturated hydrocarbon chain or an unsaturated hydrocarbon chain having 17 to 21 carbon atoms.

2. The synthesis method of the novel salt-tolerant temperature-tolerant zwitterionic viscoelastic surface activity as claimed in claim 1, characterized by comprising the following steps in sequence:

(1) dissolving erucamidopropyl dimethylamine and p-chlorobenzoic acid in a molar ratio of 1:1 in a mixed solution of sodium hydroxide aqueous solution and ethanol, heating to 80 ℃, reacting for 24 hours, removing the solvent through rotary evaporation, and recrystallizing for 2-3 times to prepare the salt-resistant and temperature-resistant type monomer zwitterionic viscoelastic surfactant;

(2) dissolving the crude product with ethyl acetate at 40-50 deg.C, and recrystallizing the ethyl acetate solution at 0-5 deg.C to remove unreacted erucamidopropyldimethylamine to obtain crystalline product; the crystallized product was treated by rotary evaporation to remove ethyl acetate to give pure salt tolerant mono zwitterionic viscoelastic surfactant.

3. The high salinity water-based clean fracturing fluid with the single viscoelastic surfactant as the thickening agent as claimed in claim 1, is characterized in that the high salinity water-based clean fracturing fluid comprises 2-5 wt% of the salt-resistant single zwitterionic viscoelastic surfactant, 3-20 wt% of inorganic salts and the balance of water, namely clean fracturing fluid prepared from ocean water or stratum produced water with the salinity of 30000-180000 mg/L.

4. The monomodal viscoelastic surfactant of claim 1 formulated with a concentration of hydrochloric acid into a diverting acid system having an acid concentration, salt concentration viscosity response; characterized by a temperature of 140 ℃ for 170s^-1Shearing for about 2 hours, shown in the specificationThe apparent viscosity was maintained at about 40 mPas.

5. The process for preparing a mono-viscoelastic surfactant as a thickener according to claim 2, wherein the long-chain tertiary amine is erucamidopropyldimethyl tertiary amine or oleamidopropyldimethyl tertiary amine.

6. The highly mineralized water-based clean fracturing fluid of claim 3, wherein the mineralization of the highly mineralized water is 30000-180000 mg/L; more preferably, the weight ratio of the counter ion salts is 30000mg/L, 50000mg/L or 150000 mg/L; further, in a preferred embodiment of the present invention, the inorganic salt is a mixture of potassium chloride, magnesium chloride, calcium chloride and sodium bicarbonate.

7. The highly mineralized, water-based clean and clean fracturing fluid according to claim 3, wherein hydrocarbons such as crude oil, kerosene, etc. may be completely broken.

Technical Field

The invention relates to the technical field of oilfield reservoir production increase modification, comprises hydraulic fracturing and acidification, and particularly relates to a preparation method of a salt-tolerant temperature-resistant zwitterionic viscoelastic surfactant and preparation of a high-salinity water-based clean fracturing fluid and a clean diverting acid solution. The salt-tolerant temperature-resistant zwitter-ion viscoelastic surfactant disclosed by the invention has a benzene ring structure and has anions and cations, so that the salt-tolerant temperature-resistant zwitter-ion viscoelastic surfactant has good salt-tolerant and temperature-tolerant capabilities, is superior to the viscoelastic surfactants of the same type in surface activity and has a lower critical micelle concentration. The viscoelastic surfactant has the advantages that the viscoelastic surfactant can be used for directly preparing clean fracturing fluid by utilizing high-salinity formation water or seawater, and can be used for preparing a diverting acid system with acid concentration and salt concentration viscosity response by utilizing high-concentration hydrochloric acid.

Background

With the development of special oil and gas reservoirs in China from shallow oil and gas reservoirs to deep oil and gas reservoirs gradually, the progress of the oil exploitation technology cannot meet the requirement of continuously increasing reservoir temperature. These all seriously affect the development of sustainable oil and gas exploitation in China. The research at home and abroad finds that the oil-gas reservoir of the special oil-gas reservoir can be effectively transformed through hydraulic fracturing, and the oil-gas yield increase and the water well injection increase are realized. With the rapid development of oil and gas exploration, water-based fracturing fluid is more and more concerned by petroleum workers, and clean fracturing fluid prepared by viscoelastic surfactant proposed in recent 20 years has good effects of carrying sand, making cracks and reducing reservoir damage in hydraulic fracturing. Meanwhile, the acidification technology is an effective means for removing the blockage and increasing the yield and is widely applied, and the acidification technology is switched to an acid-acid system, so that the acidification technology has good effects on improving the acid storage efficiency of the oil production well and the water injection well, and achieving the uniform acidification of the oil production well and the uniform blockage removal of the water injection well.

At present, most thickening agents are polymers which are difficult to degrade and have great damage to the stratum. The conventional acid liquor system is adopted, so that the problems of poor temperature resistance and salt tolerance, uneven acid liquor distribution and poor acidification and blockage removal effects exist. The diversion acidification device can be used as diversion acid, can automatically become viscous under the high-temperature condition, effectively plugs a high seepage layer, promotes the acid inlet amount of a low seepage layer, and greatly promotes the diversion acidification effect by optimizing construction parameters.

Viscoelastic Surfactant (VES) fracturing fluid can be classified into three types according to the type of hydrophilic group: i.e., cationic, anionic, zwitterionic, etc., surfactant thickened clean fracturing fluids. Compared with a water-based fracturing fluid system taking a traditional polymer or guar gum as a main thickening agent, the VES fracturing fluid has the following advantages:

a) the field preparation work is simple, and no cross-linking agent is needed during preparation;

b) low friction resistance, good viscoelasticity and good sand carrying performance;

c) the surfactant has small molecular weight and is easy to flow back, and can automatically break gel when contacting with hydrocarbon fluid in a stratum without a gel breaker;

d) no filter cake is formed, and meanwhile, the filter cake is easy to decompose and has little damage to the stratum.

Meanwhile, the preparation of the fracturing fluid needs to consume a large amount of fresh water resources, so that how to reduce the utilization of fresh water or directly prepare the high-performance fracturing fluid by utilizing high-salinity stratum water is of great concern at home and abroad. Prior viscoelastic surfactants include: (1) the single-chain viscoelastic elastic surfactant has the problems of poor temperature resistance and large dosage; (2) a monomeric surfactant; this type. The surfactant has strong temperature resistance, but the surfactant is strong in surface activity and is easy to agglomerate under the action of counter ions, so that the single surfactant with higher mineralization degree is easy to separate, and the solution system loses viscosity, so that the functions of carrying sand, forming seams and the like cannot be realized.

Therefore, by combining the problems of shortage of fresh water resources, poor temperature resistance of the conventional surfactant and the like, the salt-tolerant temperature-resistant viscoelastic surfactant is developed, and has important significance for realizing direct preparation of clean fracturing fluid from high-salinity formation water and expanding the practicability of VES clean fracturing fluid on high-temperature formations.

Disclosure of Invention

The invention aims to provide a salt-tolerant and temperature-tolerant zwitterionic viscoelastic surfactant, a preparation method thereof and a high-salinity water-based clean fracturing fluid, so as to solve the problems of poor mineralization tolerance and poor temperature tolerance of the conventional viscoelastic surfactant in the application of the clean fracturing fluid.

The technical scheme for solving the technical problems is as follows:

a novel salt-resistant temperature-resistant zwitter-ion viscoelastic surface activity has the following structural formula:

wherein R is C₂₁Hydrophobic carbon chain or C of erucic acid₁₇The hydrophobic carbon chain of oleic acid.

Wherein the hydrophobic carbon chain structural formula of the erucic acid is as follows:

the hydrophobic carbon chain structural formula of oleic acid is:

the hydrophobic chain containing unsaturated double bonds in the two structures ensures that the water solubility of the synthesized structure is better. Finally, a benzene ring structure is added, and the surfactant has anions and cations, so that the surface activity of the surfactant is superior to that of the viscoelastic surfactant of the same type.

The molecular formula of the salt-resistant and temperature-resistant type single-seed zwitterion viscoelastic surfactant is R₂C₁₃H₅₉N₄O₃Na₁. The number of carbon atoms of R may be 17 or 21.

The salt-resistant and temperature-resistant type single-seed zwitter-ion viscoelastic surfactant has special smell, is in a light yellow paste shape, and has the density of 0.95-0.98g/cm³Within the range of (a). The salt-tolerant and temperature-tolerant type single-seed zwitterion viscoelastic surfactant has strong surface activity and good salt tolerance and temperature tolerance, and can be used as a salt-tolerant thickening agent, a self-diverting acid diverting agent, a salt-tolerant emulsifier and a foaming agent or used in a micelle-enhanced ultrafiltration wastewater treatment process.

The preparation method of the salt-resistant and temperature-resistant single-seed zwitterion viscoelastic surfactant comprises the steps of dissolving erucamidopropyl dimethylamine and p-chlorobenzoic acid in a molar ratio of 1:1 in a mixed solution of sodium hydroxide aqueous solution and ethanol, heating to 80 ℃, reacting for 24 hours, removing the solvent through rotary evaporation, and recrystallizing for 2-3 times to finally prepare the salt-resistant and temperature-resistant single-seed zwitterion viscoelastic surfactant.

Compared with the conventional salt-tolerant temperature difference-resistant single-seed surfactant, the cationic groups and the anionic groups on the surface of the zwitterion can weaken the influence of counter ions on the area of the hydrophilic head group of the surfactant, so that the phase separation phenomenon caused by excessive agglomeration is prevented.

The reaction process of the method is as follows:

(1) surfactant synthesis

Further, in the preferred embodiment of the invention, erucamidopropyldimethylamine and p-chlorobenzoic acid are dissolved in a molar ratio of 1:1 in a mixed solution of sodium hydroxide aqueous solution and ethanol, the mixture is heated to 80 ℃ for 24 hours, the solvent is removed by rotary evaporation, and recrystallization is carried out for 2-3 times, thus finally obtaining the salt-resistant and temperature-resistant type monomer zwitterionic viscoelastic surfactant. Obtaining the pure salt-resistant and temperature-resistant type single-ion zwitter-ion viscoelastic surfactant.

Further, in a preferred embodiment of the present invention, the preparation method further comprises a purification step: dissolving the crude product with ethyl acetate at 40-50 deg.C, and recrystallizing the ethyl acetate solution at 0-5 deg.C to remove unreacted erucamidopropyldimethylamine to obtain crystalline product; the crystallized product was treated by rotary evaporation to remove ethyl acetate to give pure salt tolerant mono zwitterionic viscoelastic surfactant.

The high-salinity water-based clean fracturing fluid comprises 2-5 wt% of the salt-tolerant and temperature-resistant type single zwitterion viscoelastic surfactant, 3-20 wt% of inorganic salt and the balance of water, namely the clean fracturing fluid prepared from ocean water or stratum produced water with the salinity of 70000-230000 mg/L.

Preferably, the salt-tolerant temperature-tolerant type mono-zwitterionic viscoelastic surfactant is present in a weight ratio of 2 wt.%, 3 wt.% or 5 wt.%.

Preferably, the degree of mineralization of the highly mineralized water is 30000-180000 mg/L. More preferably, the weight ratio of the counterion salt is 30000mg/L, 50000mg/L or 150000 mg/L. Further, in a preferred embodiment of the present invention, the inorganic salt is a mixture of potassium chloride, magnesium chloride, calcium chloride and sodium bicarbonate.

Compared with the prior art, the invention has the following beneficial effects:

1) the compounds adopted by the invention are all fine chemicals produced industrially, the raw materials are easy to obtain, and the production cost is low.

2) The invention has a benzene ring structure and an anion-cation structure, so that the salt-resistant and temperature-resistant composite surfactant has good salt-resistant and temperature-resistant capabilities, has surface activity superior to that of the same type of viscoelastic surfactant, and has lower critical micelle concentration.

3) The preparation method of the single-seed zwitterion viscoelastic surfactant is simple, easy to decompose and small in damage to the stratum; meanwhile, the yield of the product is greatly improved and generally reaches more than 93 percent.

4) The invention still effectively reduces the oil-water interfacial tension under the conditions of 130-140 ℃, the mineralization degree of 30000-180000mg/L and the calcium-magnesium content of 1500-3000 mg/L.

5) According to the invention, a diverting acid system with acid concentration and salt concentration viscosity response can be prepared by using high-concentration hydrochloric acid, so that the hypertonic layer is effectively blocked, the acid inlet amount of the hypotonic layer is increased, and the yield increasing effect is improved.

6) The invention can directly prepare clean fracturing fluid by utilizing high-salinity stratum water or seawater, thereby effectively reducing the utilization of fresh water resources.

7) The surfactant has a critical micelle concentration of 2-6 x 10^-5mol/L is far lower than that of the traditional single-chain viscoelastic surfactant and single-cation surfactant.

Drawings

Table 1 shows mineral compositions of seawater in north sea, black sea, and gulf of guinea, china;

FIG. 1 is a rheological diagram of a seawater-based clean fracturing fluid containing 5 w% erucic acid hydrophobic chain viscoelastic surfactant formulated with seawater from North China sea;

figure 2 rheology diagram of seawater based clean fracturing fluid containing 5 w% erucic acid hydrophobic chain viscoelastic surfactant formulated with black sea water;

figure 3 rheology diagram of seawater water based clean fracturing fluid containing 5 w% erucic acid hydrophobic chain viscoelastic surfactant formulated in a guaiac bay seawater;

FIG. 4 shows the use of a single zwitterionic viscoelastic surfactant of the invention with 25% CaCl₂15% HCl residual acid was simulated and the pH was adjusted to 4 with a small amount of HCl. At 140 ℃ for 170s^-1A lower rheology chart;

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.