A foaming agent for nitrogen foam fracturing and its preparation method and application

Abstract

The present invention belongs to the technical field of oil production, and in particular to a nitrogen foam fracturing foaming agent and its preparation method and application. The preparation method is as follows: 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, dimethylbenzene, catalyst are added to a high-pressure reactor, fully stirred, the pipeline and the reactor are purged with nitrogen for 5-10min, vacuumized, then stirred and warmed to 70-80°C, vacuumized, propylene oxide is added, warmed to 170-190°C, after reacting for 2-10h, the system is cooled to 70-80°C; the above-mentioned mixed solution is continued to be stirred, ethylene oxide is passed through, after the passing is complete, the temperature is raised to 180-200°C, the reaction is continued, and the system is cooled to room temperature; pH 8-9 is adjusted with hydrochloric acid, filtered, and vacuum distillation is performed to obtain a viscous solid, i.e., a foaming agent product. The foaming agent of the present invention has the advantages of large foaming volume and long half-life.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to a foaming agent for nitrogen foam fracturing and a preparation method and application thereof. Background Art

[0002] Hydraulic fracturing is to inject high-pressure fluid into the formation to propel rock cracks and form diversion channels, greatly improving the oil and gas seepage conditions. In the process of hydraulic fracturing, the application of foaming agents is becoming more and more critical, aiming to reduce the surface tension of the liquid, form a stable foam system, help carry proppants, control filtration and improve the efficiency of fracturing fluid return, which meets the urgent demand for efficient exploitation of complex oil and gas reservoirs.

[0003] Foam fracturing fluid usually uses nitrogen as the dispersed phase and a foaming agent-stabilized liquid phase as the continuous phase. It has emerged with advantages such as low density, low filtration loss, strong sand carrying capacity, and easy flowback. However, achieving ideal foam performance depends on the support of high-quality foaming agents.

[0004] There are many types of foaming agents used in fracturing at present, but in the complex environment of high temperature and high pressure in the formation, the half-life of the foam generated by some foaming agents is too short, and the rapid defoaming causes the proppant to settle and the cracks to close, and the flow conductivity cannot be maintained for a long time. The temperature of different oil and gas reservoirs ranges from room temperature to over 150℃, and the pressure reaches tens of MPa. The foaming agent is required to construct foam that can withstand severe temperature and pressure to ensure stability throughout the fracturing construction and subsequent production stages.

[0005] CN102796498A discloses a foam drilling fluid, comprising the following components, each component is calculated by mass percentage: 0.5% to 2.0% of a foaming agent, 0.2% to 0.5% of a foaming agent, 2% to 10% of a shale inhibitor, 0.2% to 1.0% of a shale stabilizer, and the remainder is water; and the pH value of the foam drilling fluid is 8 to 10. The foam drilling fluid of the invention has excellent foaming properties, strong shale inhibition ability and long-term shale inhibition performance, and can solve the problems of rock and water carrying after gas drilling encounters formation water, the problem of well wall instability, and the problem of adhesion and drill sticking and other complex downhole problems, thereby achieving safe and rapid drilling. However, the foaming volume of the foaming agent is small and the half-life time is short, and the prospects for promotion of its use in oil fields are poor.

[0006] CN102020981A discloses a heat-resistant, salt-resistant, low-tension foam oil-displacing agent and a preparation method thereof, which is prepared by continuously stirring alkanolamide, bipolar surfactant and water at 40-60°C until they are completely dissolved. The heat-resistant, salt-resistant, low-tension foam agent of the invention is suitable for tertiary oil recovery under conditions of a temperature of 50-120°C and a mineralization of 0-100000ppm. Compared with other commonly used foam agents in the prior art, the oil-water interfacial tension is reduced by 10 -2 mN / m down to 10 -3mN / m, compared with the commonly used surfactants in the prior art, the foam half-life at 50°C is increased from 15 minutes to more than 40 minutes, and the indoor model improves the recovery rate by more than 15%. However, the main agent of the foaming agent is alkanolamide and bipolar surfactant. Alkanolamide is easy to hydrolyze, has poor high temperature stability, is easy to fail in the formation, and its application is limited. Summary of the invention

[0007] The present invention aims at the above-mentioned deficiencies of the prior art and provides a nitrogen foam fracturing foaming agent and a preparation method and application thereof. The foaming agent of the present invention has the advantages of large foaming volume and long half-life.

[0008] One of the purposes of the present invention is to disclose a method for preparing a foaming agent for nitrogen foam fracturing, wherein the specific steps of the preparation method are as follows:

[0009] (1) Add 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, xylene and catalyst to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 5-10 minutes, evacuate, then stir and heat to 70-80°C, stop evacuating, add propylene oxide, heat to 170-190°C, react for 2-10 hours, and then cool the system to 70-80°C;

[0010] (2) Continue stirring the above mixed solution and introduce ethylene oxide. After the introduction is completed, heat it to 180-200°C, continue the reaction, and cool the system to room temperature;

[0011] (3) Adjust the pH to 8-9 with hydrochloric acid, filter, and distill under reduced pressure to obtain a viscous solid, i.e., the foaming agent product.

[0012] Preferably, based on 1 mole of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, the amounts of propylene oxide and ethylene oxide are 20-80 mole parts and 20-80 mole parts respectively.

[0013] More preferably, based on 1 mol part of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, the amounts of propylene oxide and ethylene oxide used are 40-60 mol parts and 40-60 mol parts respectively.

[0014] Preferably, the weight ratio of xylene to 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid in step (1) is 20-40:1.

[0015] Preferably, the catalyst in step (1) is one of sodium hydroxide, calcium hydroxide and potassium hydroxide.

[0016] Preferably, the weight ratio of the catalyst described in step (1) to 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid is 0.2-0.4:1.

[0017] Preferably, the reaction time in step (2) is 1-6 hours.

[0018] The reaction equation of the nitrogen foam fracturing foaming agent of the present invention is as follows:

[0019]

[0020] Another object of the present invention is to disclose a foaming agent for nitrogen foam fracturing, wherein the molecular structure of the foaming agent is as follows:

[0021] ;

[0022] Among them, m=5-20, n=5-20.

[0023] The third object of the present invention is to disclose the application of the above foaming agent in oil and gas reservoir fracturing.

[0024] The foaming agent for nitrogen foam fracturing of the present invention is a composite surfactant. The functional groups providing surface activity mainly include non-ionic lipophilic group multi-group polyoxypropylene ether, non-ionic hydrophilic group multi-group polyoxyethylene ether, and anionic hydrophilic group sulfonate. It is more active than conventional single-active group surfactants, can greatly reduce surface tension, increase foaming volume and capacity, and has higher stability. The molecule is a multi-linear molecule with strong flexibility and a large coverage area. When the foam liquid film becomes thinner, it can quickly attract other parts of the liquid film horizontally to supplement and enhance the stability of the foam.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] (1) The nitrogen foam fracturing foaming agent of the present invention has the characteristics of large foaming volume, reaching 800 ml or more at room temperature, and reaching 790 ml or more after rolling at 120 ° C / 16 h;

[0027] (2) The nitrogen foam fracturing foaming agent of the present invention has a long half-life, which is more than 780 seconds at room temperature and more than 720 seconds after rolling at 120°C / 16 h. DETAILED DESCRIPTION

[0028] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] The technical solution of the present invention is further described below in conjunction with specific embodiments:

[0030] Example 1

[0031] (1) Add 0.05 mol of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, 230 g of xylene, and 2.3 g of sodium hydroxide to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 5 min, evacuate, then stir and heat to 70°C, stop evacuating, add 1 mol of propylene oxide, heat to 170°C, react for 2 h, and then cool the system to 70°C;

[0032] (2) The above mixed solution was stirred continuously and 1 mol of ethylene oxide was introduced. After the introduction was completed, the temperature was raised to 180°C and the reaction was continued for 1 hour. The system was then cooled to room temperature.

[0033] (3) Adjust the pH to 8-9 with hydrochloric acid, filter, and distill under reduced pressure to obtain a viscous solid, i.e., the foaming agent product.

[0034] Example 2

[0035] (1) Add 0.05 mol of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, 250 g of xylene, and 2.8 g of sodium hydroxide to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 5 min, evacuate, then stir and heat to 70 °C, stop evacuating, add 1.5 mol of propylene oxide, heat to 175 °C, react for 2 h, and then cool the system to 70 °C;

[0036] (2) The above mixed solution was stirred continuously and 4 mol of ethylene oxide was introduced. After the introduction was completed, the temperature was raised to 200°C and the reaction was continued for 6 hours. The system was then cooled to room temperature.

[0037] (3) Adjust the pH to 8-9 with hydrochloric acid, filter, and distill under reduced pressure to obtain a viscous solid, i.e., the foaming agent product.

[0038] Example 3

[0039] (1) Add 0.05 mol of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, 268 g of xylene, and 3.9 g of sodium hydroxide to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 10 min, evacuate, then stir and heat to 80 °C, stop evacuating, add 2 mol of propylene oxide, heat to 175 °C, react for 4 h, and then cool the system to 75 °C;

[0040] (2) The above mixed solution was stirred continuously and 1.5 mol of ethylene oxide was introduced. After the introduction was completed, the temperature was raised to 180°C and the reaction was continued for 2 hours. The system was then cooled to room temperature.

[0041] (3) Adjust the pH to 8-9 with hydrochloric acid, filter, and distill under reduced pressure to obtain a viscous solid, i.e., the foaming agent product.

[0042] Example 4

[0043] (1) Add 0.05 mol of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, 314 g of xylene, and 4 g of sodium hydroxide to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 10 min, evacuate, then stir and heat to 80°C, stop evacuating, add 2.5 mol of propylene oxide, heat to 180°C, react for 4 h, and then cool the system to 76°C;

[0044] (2) The above mixed solution was stirred continuously and 1.8 mol of ethylene oxide was introduced. After the introduction was completed, the temperature was raised to 180°C and the reaction was continued for 3 hours. The system was then cooled to room temperature.

[0045] (3) Adjust the pH to 8-9 with hydrochloric acid, filter, and distill under reduced pressure to obtain a viscous solid, i.e., the foaming agent product.

[0046] Example 5

[0047] (1) Add 0.05 mol of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, 384 g of xylene, and 4.3 g of calcium hydroxide to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 8 min, evacuate, then stir and heat to 75°C, stop evacuating, add 3 mol of propylene oxide, heat to 185°C, react for 6 h, and then cool the system to 78°C;

[0048] (2) The above mixed solution was stirred continuously and 2.2 mol of ethylene oxide was introduced. After the introduction was completed, the temperature was raised to 190°C and the reaction was continued for 4 hours. The system was then cooled to room temperature.

[0049] (3) Adjust the pH to 8-9 with hydrochloric acid, filter, and distill under reduced pressure to obtain a viscous solid, i.e., the foaming agent product.

[0050] Example 6

[0051] (1) Add 0.05 mol of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, 460 g of xylene, and 4.5 g of calcium hydroxide to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 8 min, evacuate, then stir and heat to 77 °C, stop evacuating, add 3.2 mol of propylene oxide, heat to 190 °C, react for 8 h, and then cool the system to 80 °C;

[0052] (2) The above mixed solution was stirred continuously and 2.5 mol of ethylene oxide was introduced. After the introduction was completed, the temperature was raised to 185°C and the reaction was continued for 5 hours. The system was then cooled to room temperature.

[0053] (3) Adjust the pH to 8-9 with hydrochloric acid, filter, and distill under reduced pressure to obtain a viscous solid, i.e., the foaming agent product.

[0054] Example 7

[0055] (1) Add 0.05 mol of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, 430 g of xylene, and 4.6 g of potassium hydroxide to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 10 min, evacuate, then stir and heat to 70°C, stop evacuating, add 3.7 mol of propylene oxide, heat to 190°C, react for 8 h, and then cool the system to 80°C;

[0056] (2) The above mixed solution was stirred continuously and 3 mol of ethylene oxide was introduced. After the introduction was completed, the temperature was raised to 195°C and the reaction was continued for 5 hours. The system was then cooled to room temperature.

[0057] (3) Adjust the pH to 8-9 with hydrochloric acid, filter, and distill under reduced pressure to obtain a viscous solid, i.e., the foaming agent product.

[0058] Example 8

[0059] (1) Add 0.05 mol of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, 460 g of xylene, and 4.6 g of potassium hydroxide to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 5 min, evacuate, then stir and heat to 70°C, stop evacuating, add 4 mol of propylene oxide, heat to 190°C, react for 10 h, and then cool the system to 80°C;

[0060] (2) The mixture was stirred continuously and 3.5 mol of ethylene oxide was introduced. After the introduction was completed, the temperature was raised to 195°C and the reaction was continued for 6 hours. The system was then cooled to room temperature.

[0061] (3) Adjust the pH to 8-9 with hydrochloric acid, filter, and distill under reduced pressure to obtain a viscous solid, i.e., the foaming agent product.

[0062] Example 9 Foaming agent performance test

[0063] The nitrogen foam fracturing foaming agent (Examples 1-8) of the present invention was configured to a concentration of 0.2 wt %, and the room temperature foaming volume, room temperature foam half-life, foaming volume after rolling at 120 ° C / 16 h, and foam half-life after rolling at 120 ° C / 16 h were tested with reference to the method of Q / SH1020 1873-2015 "General Technical Conditions for Foaming Agents for Drilling Fluids". The test results are shown in Table 1.

[0064] At the same time, a comparative experiment was conducted using the anti-oil foaming agent for fracturing produced by Shaanxi Senrui Petroleum Technology Development Co., Ltd.

[0065] Table 1 Foaming performance test results

[0066]

[0067] From Table 1 we can see that:

[0068] (1) The foaming agent for nitrogen foam fracturing of the present invention has the characteristic of large foaming volume. When the concentration is 0.2wt% and the foaming volume is at room temperature, it reaches 800ml or more, and the maximum is 910ml (Example 6), while the foaming volume of the comparative example is 455ml; after rolling at 120℃ / 16h, the foaming volume reaches 790ml or more, and the maximum is 885ml (Example 6), while the foaming volume of the comparative example is 430ml, which is significantly lower than that of the present invention.

[0069] (2) The nitrogen foam fracturing foaming agent of the present invention has the characteristic of a long half-life. When the concentration is 0.2wt% and the half-life is at room temperature, it reaches more than 780s, and the highest is 802s (Example 5), while the half-life of the comparative example is 450s. After rolling at 120℃ / 16h, it reaches 720s and more, and the highest is 735s (Example 5), while the half-life of the comparative example is 412s, which is significantly lower than that of the present invention.

[0070] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0071] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0072] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a foaming agent for nitrogen foam fracturing, characterized in that: The specific steps of the preparation method are as follows: (1) Add 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, xylene and catalyst to a high-pressure reactor, stir thoroughly, purge the pipeline and reactor with nitrogen for 5-10 minutes, evacuate, then stir and heat to 70-80°C, stop evacuating, add propylene oxide, heat to 170-190°C, react for 2-10 hours, and then cool the system to 70-80°C; (2) Continue stirring the above mixed solution and introduce ethylene oxide. After the introduction is completed, heat it to 180-200°C, continue the reaction, and cool the system to room temperature; (3) Adjusting the pH to 8-9 with hydrochloric acid, filtering, and distilling under reduced pressure to obtain a viscous solid, i.e., the foaming agent product; Based on 1 mole of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, the amounts of propylene oxide and ethylene oxide used are 20-80 mole parts and 20-80 mole parts respectively.

2. The method for preparing a nitrogen foam fracturing foaming agent according to claim 1, characterized in that: Based on 1 mole of 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid, the amounts of propylene oxide and ethylene oxide used are 40-60 mole parts and 40-60 mole parts respectively.

3. The method for preparing a nitrogen foam fracturing foaming agent according to claim 1, characterized in that: The weight ratio of xylene to 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid in step (1) is 20-40:

1.

4. The method for preparing a foaming agent for nitrogen foam fracturing according to claim 1, characterized in that: The catalyst described in step (1) is one of sodium hydroxide, calcium hydroxide and potassium hydroxide.

5. The method for preparing a foaming agent for nitrogen foam fracturing according to claim 1, characterized in that: The weight ratio of the catalyst described in step (1) to 2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid is 0.2-0.4:

1.

6. The method for preparing a foaming agent for nitrogen foam fracturing according to claim 1, characterized in that: The reaction time in step (2) is 1-6 hours.

7. Use of the foaming agent prepared by the preparation method according to any one of claims 1 to 6 in oil and gas reservoir fracturing.

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