High-efficiency gas field biological foaming agent, preparation method and application thereof

Abstract

The present application relates to a kind of high-efficiency gas field biological foaming agent and its preparation method and application, belong to gas well bubble agent technical field.The foaming agent is composed of the following mass fraction components: rhamnolipid: 15~25%;Sophorose lipid: 10~20%;Lipophilic spherical nanosilica: 5~10%;Polyglutamic acid: 3~8%;E-polylysine: 2~7%;Deionized water or formation reuse water: 38~42%.Through the synergistic effect of multiple components, the foaming agent of the present application has excellent foaming property, foam stability and excellent liquid carrying capacity under high temperature (≤150℃), high salinity (≤20×10 4 mg / L) conditions.The preparation method is simple, suitable for gas field drainage gas production operation, and can effectively improve gas well productivity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas well foamers, and particularly relates to a high-efficiency gas field biological foamer as well as a preparation method and application thereof. BACKGROUND

[0002] In the middle and late stages of gas field development, wellbore fluid accumulation will hinder the flow of natural gas, resulting in a decrease in gas well productivity. As a core additive of drainage and production technology, the foamer needs to have high-temperature stability, high-salinity resistance, strong foaming property, long foam half-life and easy biodegradability.

[0003] At present, the gas field foamer has the following defects: chemical synthetic foamer (such as alkyl benzene sulfonate) is easy to decompose at high temperature, salt out in high-salinity environment, and has low biodegradability; single biological surfactant foamer (such as pure rhamnolipid) has insufficient foam toughness and short half-life under high-temperature and high-salinity conditions; traditional nano compound foamer is easy to agglomerate in high-salinity environment and has poor compatibility; and conventional preservatives are easy to fail at high temperature and have poor compatibility with biological surfactants. Therefore, there is an urgent need in the field to develop a gas field foamer with excellent comprehensive performance. SUMMARY

[0004] The application aims to provide a high-efficiency gas field biological foamer, which solves the problems of poor foam stability and low liquid carrying capacity of existing foams under high temperature and high salinity through multi-component synergistic design.

[0005] The above-mentioned purpose is achieved by the following technical solutions:

[0006] A high-efficiency gas field biological foamer is composed of the following components in mass fraction: rhamnolipid: 15-25%; sophorolipid: 10-20%; lipophilic spherical nano-silicon dioxide: 5-10%; polyglutamic acid: 3-8%; epsilon-polylysine: 2-7%; deionized water or formation recycled water: 38-42%.

[0007] Based on the foregoing, one kind of high-efficiency gas field biological foaming agent, wherein the rhamnolipid is prepared by fermentation of Pseudomonas aeruginosa (preserved in China General Microbiological Culture Collection Center, preservation number: CGMCC 1.1785), the mass ratio of mono-rhamnolipid to di-rhamnolipid is 1:2-3, and the purity is ≥95%; the sophorolipid is prepared by fermentation of Candida utilis (preserved in American Type Culture Collection, preservation number: ATCC 22023), the acid sophorolipid accounts for ≥80%, and the purity is ≥92%; the lipophilic spherical nano-silicon dioxide has a particle size of 50-100 nm, the surface is modified by silane coupling agent KH-570, and the contact angle is ≥105°; the polyglutamic acid is prepared by fermentation of Bacillus subtilis (preserved in American Type Culture Collection, preservation number: ATCC 6633), the molecular weight is 50-100 kDa, and the purity is ≥90%; and the ε-polylysine is prepared by fermentation of Streptomyces albus (preserved in China General Microbiological Culture Collection Center, preservation number: CGMCC 4.1), the molecular weight is 3-5 kDa, and the purity is ≥98%.

[0008] Based on the foregoing, one kind of high-efficiency gas field biological foaming agent, when the formation recycled water is used in the components, the formation recycled water needs to be filtered through a 0.22 μm microporous filter membrane.

[0009] Based on the foregoing, a preparation method of one kind of high-efficiency gas field biological foaming agent, comprising the following steps:

[0010] Step 1: deionized water or formation recycled water filtered through a 0.22 μm microporous filter membrane is added into a reaction kettle with stirring and temperature control functions, rhamnolipid and sophorolipid are sequentially added under stirring at a speed of 30-40 ℃ and 150-200 rpm, and stirring is performed for 35-45 min to form a uniform transparent mixed solution;

[0011] Step 2: lipophilic spherical nano-silicon dioxide is added into the mixed solution obtained in step 1, and stirring is performed at a speed of 300-400 rpm and ultrasonic dispersion is performed at a power of 300-500 W for 20-25 min to ensure uniform dispersion of the nano-particles;

[0012] Step 3: the temperature is kept at 30-40 ℃, the stirring speed is kept at 200-250 rpm, polyglutamic acid is first added and stirred for 25-30 min until completely dissolved, then ε-polylysine is added and stirred for 20-25 min to form a uniform and stable solution;

[0013] Step 4: the obtained solution is filtered through a 0.45 μm microporous filter membrane, the pH value is detected to be 6.5-7.5, and the finished product foaming agent is obtained.

[0014] Based on the foregoing, one kind of high-efficiency gas field biological foaming agent, which is suitable for well bottom temperature ≤150 ℃ and formation water salinity ≤20×104 Gas production operations in a mg / L gas field involving drainage. Beneficial effects

[0015] Compared with the prior art, the present invention has the following significant advantages:

[0016] 1. Utilizing the synergistic effect of multiple components such as biosurfactants and lipophilic nano-silica, it exhibits excellent foaming performance and liquid carrying capacity at 150℃ and 20×10⁻⁶. 4 Under the conditions of mg / L mineralization, the foaming volume is ≥500 mL, the foam half-life is ≥20 min, and the foam liquid carrying capacity is ≥85.6%. Furthermore, since the main components are bio-fermentation products, the product exhibits good biodegradability.

[0017] 2. The preparation process is simple, requiring no high-temperature and high-pressure equipment, resulting in low production costs, high finished product concentration, and small dosage.

[0018] 3. It has strong compatibility and can be used in combination with commonly used corrosion inhibitors and scale inhibitors in gas fields to improve gas well productivity.

[0019] Instructions for the Preservation of Biological Materials

[0020] The microbial strains used in this invention were purchased from Shanghai Preservation Microorganisms Co., Ltd. and the Institute of Microbiology, Chinese Academy of Sciences, respectively. The information on the microbial strains is as follows: *Pseudomonas aeruginosa* (… Pseudomonas aeruginosa The genera *Candida utilis*, deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC 1.1785 and deposit date of April 1, 1994, was collected. Candida utilis Bacillus subtilis (), deposited at the American Center for Type Culture Collection (ATCC), accession number ATCC 22023, deposited on January 1, 1983; Bacillus subtilis ), deposited at the American Center for Type Culture Collection (ATCC), accession number ATCC 6633, deposited on May 15, 2019; Streptomyces albopictus ( Streptomyces albulus The specimen, numbered CGMCC 4.1, is deposited at the China General Microbiological Culture Collection Center (CGMCC) on July 28, 1956. The public can obtain it from the aforementioned collection institution prior to the application date based on the deposit information provided in this specification. Detailed Implementation

[0021] The present invention is further illustrated by the following examples, but these examples do not constitute a limitation on the scope of protection of the present invention.

[0022] Preparation Example 1: Preparation of rhamnolipids by fermentation of Pseudomonas aeruginosa

[0023] 1. Strain activation and seed broth preparation: Pseudomonas aeruginosa glycerol tube preserved at -80°C was streaked on LB solid medium (Luria-Bertani solid medium) with the composition of tryptone 10 g / L, yeast extract 5 g / L, sodium chloride 10 g / L, agar 15 g / L, pH 7.0. The culture was incubated at 30°C for 24 hours. Single colony was picked and inoculated into a 250 mL flask containing 50 mL LB seed medium (Luria-Bertani liquid medium) with the same composition as above without agar, and incubated at 30°C, 200 rpm for 12 hours to obtain the first-stage seed broth;

[0024] 2. Fermentation culture: the first-stage seed broth was transferred into fermentation medium at an inoculation amount of 5% (v / v). The fermentation medium had the composition of glycerol 40 g / L, sodium nitrate 6 g / L, potassium phosphate dibasic 4 g / L, potassium phosphate monobasic 4 g / L, magnesium sulfate heptahydrate 0.4 g / L, ferrous sulfate heptahydrate 0.03 g / L, pH 6.8. The fermentation was carried out in a fermenter at 30°C, 1.0 vvm of aeration amount, 400 rpm of stirring speed for 96 hours;

[0025] 3. Product extraction: after the fermentation, the fermentation broth was centrifuged at 4°C, 10,000 rpm for 15 minutes to remove the bacteria. The supernatant was collected, and the pH was adjusted to 2.0 with 6 M hydrochloric acid, and then the mixture was placed at 4°C overnight to precipitate rhamnolipids. The precipitate was collected by centrifugation again, and extracted with an equal volume of ethyl acetate for three times. The organic phase was combined, and the solvent was removed by rotary evaporation to obtain rhamnolipids.

[0026] Preparation Example 2 Fermentation of Candida utilis for preparing sophorolipids

[0027] 1. Strain activation and seed broth preparation: Candida utilis slant strain was inoculated into YPD seed medium (Yeast Extract Peptone Dextrose Medium) with the composition of glucose 20 g / L, peptone 20 g / L, yeast extract 10 g / L, pH 6.0. The culture was incubated at 28°C, 220 rpm for 18 hours to obtain the seed broth;

[0028] 2. Fermentation culture: the seed liquid was inoculated into fermentation medium at an inoculation amount of 8% (v / v). The fermentation medium consisted of glucose 80 g / L, yeast extract 3 g / L, urea 1 g / L, magnesium sulfate heptahydrate 0.3 g / L, potassium dihydrogen phosphate 2 g / L, pH 5.5. The fermentation was carried out in a fermenter at 28℃, aeration amount 1.2 vvm, stirring speed 500 rpm for 120 hours. The glucose concentration was controlled at 10-20 g / L by using the flow feeding method during the fermentation process;

[0029] 3. Product extraction: the fermentation broth was centrifuged to remove the bacterial cells. The supernatant was extracted with an equal volume of ethyl acetate four times, and the organic phases were combined. After drying with anhydrous sodium sulfate, filtration, and rotary evaporation concentration, the sophorolipid was obtained.

[0030] Preparation Example 3 Fermentation of Bacillus subtilis to prepare polyglutamic acid

[0031] 1. Activation of bacterial strain and preparation of seed liquid: Bacillus subtilis was inoculated into LB solid medium (composition same as Preparation Example 1) and cultured at 37℃ for 16 hours. A single colony was picked and inoculated into seed medium. The seed medium consisted of glucose 10 g / L, peptone 10 g / L, beef extract 5 g / L, sodium chloride 5 g / L, pH 7.2. The seed culture was carried out at 37℃ with 200 rpm shaking for 10 hours;

[0032] 2. Fermentation culture: the seed liquid was inoculated into fermentation medium at an inoculation amount of 4% (v / v). The fermentation medium consisted of glucose 60 g / L, L-glutamic acid sodium 40 g / L, ammonium citrate 8 g / L, magnesium sulfate heptahydrate 0.5 g / L, potassium dihydrogen phosphate 5 g / L, pH 7.0. The fermentation was carried out in a fermenter at 37℃, aeration amount 1.5 vvm, stirring speed 600 rpm for 48 hours;

[0033] 3. Product extraction: the fermentation broth was centrifuged at 10000 rpm for 15 minutes to remove the bacterial cells. 3 times the volume of anhydrous ethanol was added to the supernatant while stirring, and a large amount of white flocculent precipitate was observed. After standing for 2 hours, the precipitate was collected by centrifugation. The precipitate was dissolved with an appropriate amount of deionized water and loaded into a dialysis bag with a molecular weight cutoff of 8000-14000 Da, and dialyzed against flowing water for 48 hours to remove small molecular impurities. Finally, the liquid in the dialysis bag was freeze-dried to obtain the γ-polyglutamic acid product.

[0034] Preparation Example 4 Fermentation of Streptomyces albus to prepare ε-polylysine

[0035] 1. Strain activation and seed broth preparation: Spread the spore suspension of Streptomyces albus on Gauze's Medium No. 1 and incubate at 30°C for 7 days until the spores are fully grown. Scrape the spores into a flask containing glass beads and sterile water, and shake to prepare a spore suspension. Inoculate the seed medium at a 1% (v / v) inoculum. The seed medium consists of: glucose 20 g / L, yeast extract 5 g / L, ammonium sulfate 5 g / L, potassium dihydrogen phosphate 1 g / L, magnesium sulfate heptahydrate 0.5 g / L, pH 6.8. Incubate at 30°C with 220 rpm shaking for 24 hours;

[0036] 2. Fermentation: Inoculate the fermentation medium with the seed broth at a 10% (v / v) inoculum. The fermentation medium consists of: glucose 50 g / L, yeast extract 10 g / L, ammonium sulfate 15 g / L, magnesium sulfate heptahydrate 0.8 g / L, potassium dihydrogen phosphate 1.5 g / L, trace element solution 1 mL / L, pH 6.5. Ferment in a fermenter at 30°C with aeration of 1.0 vvm and stirring speed of 400 rpm for 72 hours. Control the pH at 6.5±0.2 by feeding ammonia during the fermentation;

[0037] 3. Product extraction: Centrifuge the fermentation broth to collect the supernatant. Add a certain amount of ammonium sulfate to the supernatant to reach 60% saturation, and stir in an ice bath for 2 hours to allow ε-polylysine to precipitate. Centrifuge to collect the precipitate and dissolve it with a small amount of deionized water. Place the dissolved solution in a dialysis bag with a molecular weight cutoff of 3500 Da and dialyze against deionized water for 24 hours. Finally, adsorb the dialyzed solution on an anion exchange resin, elute with 0.5 M NaCl solution, collect the elution peak containing ε-polylysine, desalt and concentrate, and freeze-dry to obtain the ε-polylysine product.

[0038] Preparation Example 5 Silane coupling agent KH-570 modified nano-silica

[0039] 1. Pretreatment: Weigh 10.0 grams of nano-silica with an average particle size of 70 nm, place it in a vacuum drying oven, and dry it at 105°C for 3 hours to completely remove the surface physically adsorbed water;

[0040] 2. Dispersion: Transfer the dried nano-silica to a 500 mL three-neck flask containing 200 mL of anhydrous ethanol, and disperse it in an ultrasonic cell disruptor with a power of 300 W for 30 minutes to form a uniform suspension;

[0041] 3. Hydrolysis solution preparation: In another beaker, 60 mL of anhydrous ethanol and 60 mL of deionized water were mixed, and the pH value was adjusted to 4.5 with 1.0 mol / L acetic acid solution. Then 3.0 g of silane coupling agent KH-570 was added under stirring, and the hydrolysis was carried out at 60°C in a water bath for 30 min to obtain a clear KH-570 hydrolysis solution;

[0042] 4. Modification reaction: The three-necked flask in step (2) was placed on a heat collecting constant temperature magnetic stirrer, and a condensation reflux device was installed. Under continuous stirring at a speed of 500 rpm, the hydrolysis solution obtained in step (3) was slowly added to the suspension using a constant pressure dropping funnel within 30 min. After completion, the temperature was raised to 80°C, and the reaction was carried out at constant temperature and reflux for 5 hours;

[0043] 5. Post-treatment: The reaction system was naturally cooled to room temperature, and suction filtration was performed using a Buchner funnel. The obtained solid filter cake was washed with anhydrous ethanol 3 times, each time 50 mL, and then washed with deionized water 3 times. Finally, the product was placed in a vacuum drying oven at 80°C for drying for 6 hours, and after taking out, it was slightly ground in a mortar to obtain the modified nano-silica product.

[0044] Examples and Comparative Examples

[0045] In the following examples and comparative examples, the rhamnolipid, sophorolipid, polyglutamic acid and ε-polylysine used were respectively prepared by Preparation Example 1, Preparation Example 2, Preparation Example 3 and Preparation Example 4 to ensure the consistency and comparability of the raw material sources. The oleophilic spherical nano-silica was prepared by Preparation Example 5.

[0046] Example 1

[0047] Raw material composition: rhamnolipid 20%, sophorolipid 15%, oleophilic spherical nano-silica 8%, polyglutamic acid 6%, ε-polylysine 1%, deionized water 40%

[0048] Preparation method:

[0049] Step 1: Deionized water was added to a reaction kettle with stirring and temperature control function, and rhamnolipid and sophorolipid were added in sequence under stirring at 35°C and a stirring speed of 180 rpm for 40 min;

[0050] Step 2: The oleophilic spherical nano-silica was added to the mixture obtained in step 1, and treated under stirring at a speed of 400 rpm and ultrasonic dispersion at 400 W for 22 min;

[0051] Step 3: The temperature was maintained at 35°C, and the stirring speed was 220 rpm. First, polyglutamic acid was added and stirred for 28 min until completely dissolved, and then ε-polylysine was added and stirred for 22 min to form a uniform and stable solution;

[0052] Step 4: The resulting solution was filtered through a 0.45 μm microporous filter membrane, and the pH value was detected as 7.0, to obtain the finished product, foaming agent A.

[0053] Example 2

[0054] Raw materials: rhamnolipid 22%, sophorolipid 17%, lipophilic spherical nanosilica 9%, polyglutamic acid 7%, ε-polylysine 5%, and formation water 40%

[0055] Preparation method:

[0056] Step 1: Formation water was added to a reaction kettle with stirring and temperature control functions. Under stirring at 40°C and a rotation speed of 200 rpm, rhamnolipid and sophorolipid were sequentially added, and stirring was performed for 45 min;

[0057] Step 2: Lipophilic spherical nanosilica was added to the mixture obtained in step 1, and stirring was performed at a rotation speed of 350 rpm and ultrasonic dispersion at 500 W for 25 min;

[0058] Step 3: The temperature was maintained at 40°C, and the stirring speed was 250 rpm. Polyglutamic acid was first added and stirred for 30 min until complete dissolution, and then ε-polylysine was added and stirred for 25 min, to form a uniform and stable solution;

[0059] Step 4: The resulting solution was filtered through a 0.45 μm microporous filter membrane, and the pH value was detected as 7.2, to obtain the finished product, foaming agent B.

[0060] Comparative Example 1 (complex system lacking sophorolipid)

[0061] Raw materials: rhamnolipid 39%, lipophilic spherical nanosilica 9%, polyglutamic acid 7%, ε-polylysine 5%, and deionized water 40%

[0062] The preparation method was the same as in Example 1, to obtain foaming agent C.

[0063] Comparative Example 2 (without nanoparticles)

[0064] Raw materials: rhamnolipid 26%, sophorolipid 21%, polyglutamic acid 6%, ε-polylysine 1%, and deionized water 46%

[0065] The preparation method was the same as in Example 1, to obtain foaming agent D.

[0066] Comparative Example 3 (conventional preservative)

[0067] Raw materials: rhamnolipid 20%, sophorolipid 15%, lipophilic spherical nanosilica 8%, polyglutamic acid 6%, isothiazolinone 1% (conventional gas field preservative), and deionized water 50%

[0068] The preparation method is the same as that in Example 1 to obtain foaming agent E.

[0069] The technical effects of the present application are further verified by comparing the example with the comparative sample, and the performance test is carried out according to the People's Republic of China Petroleum and Natural Gas Industry Standard "SY / T 7494-2020 Experimental Evaluation Method for Foaming Agent for Oil and Gas Fields", and the foaming volume of the foaming agent, the foam liquid drainage half-life, and the foam liquid carrying rate are determined.

[0070] Table 1 Performance test results of test samples A and B and control samples C, D and E at a conventional temperature and salinity

[0071] Sample Foaming volume mL Foam drainage half-life min Foam liquid carry-over % Foaming agent A 530 25 93.8 Foaming agent B 514 22 91.6 Foaming agent C 400 16 75.2 Foaming agent D 360 13 62.2 Foaming agent E 470 18 87.3

[0072] Table 2 Performance test results of test samples A and B and control samples C, D and E at 150℃, 20×10 4 mg / L salinity

[0073] Sample Foaming volume mL Foam drainage half-life min Foam liquid carry-over % Foaming agent A 525 23 90.7 Foaming agent B 500 20 85.6 Foaming agent C 340 14 56.8 Foaming agent D 280 12 43.1 Foaming agent E 440 15 81.2

[0074] From the above test results, it can be seen that the foaming agents of Examples 1 and 2 of the present application are significantly superior to the comparative examples in foaming performance and high temperature and high salinity stability, proving the technical advantages of the synergistic design of multiple raw materials.

[0075] Application scenarios

[0076] The gas field foaming agent of the present application is suitable for various gas fields requiring water drainage for gas production, especially for high temperature and high salinity deep wells and gas fields with high environmental protection requirements, and the specific application modes are as follows:

[0077] 1. On-site dilution and injection: the finished foaming agent is diluted with formation water at a mass ratio of 1:80~1:150, injected into the wellbore through the gas well casing or tubing, and the injection amount is adjusted according to the gas well liquid accumulation amount (conventional 30~150L / well), which can be continuously injected or intermittently injected (every 30~45 days);

[0078] 2. Suitable gas reservoir types: suitable for sandstone gas reservoirs and carbonate gas reservoirs with a bottom hole temperature of ≤150℃ and a formation water salinity of ≤20×10 4 mg / L, especially for remote onshore gas fields and offshore gas fields;

[0079] 3. Synergistic operation scheme: compounded with the commonly used corrosion inhibitor and scale inhibitor for gas fields at a ratio of 15:1:1, and injected through the same injection system, which can solve the problems of water drainage, corrosion prevention and scale prevention at the same time;

[0080] 4. Performance monitoring and adjustment: when used on site, the wellhead foam state is regularly detected, such as foaming volume, half-life, and liquid carrying rate.

Claims

1. A high efficiency gas field bio-foaming agent, characterized in that, consists of the following components by mass fraction Composition: rhamnolipid: 15~25%; sophorolipid: 10~20%; lipophilic spherical nanosilica: 5~10%; polyglutamic acid: 3~8%; epsilon-polylysine: 2~7%; deionized water or produced water: 38~42%; the rhamnolipid is prepared by fermentation of Pseudomonas aeruginosa, the mass ratio of mono-rhamnolipid to di-rhamnolipid is 1:2~3, and the purity is ≥95%; the sophorolipid is prepared by fermentation of Candida utilis, the proportion of acidic sophorolipid is ≥80%, and the purity is ≥92%; the lipophilic spherical nanosilica has a particle size of 50~100 nm, the surface is modified by silane coupling agent KH-570, and the contact angle is ≥105°; the polyglutamic acid is prepared by fermentation of Bacillus subtilis, has a molecular weight of 50~100 kDa, and the purity is ≥90%; and the epsilon-polylysine is prepared by fermentation of Streptomyces albus, has a molecular weight of 3~5 kDa, and the purity is ≥98%.

2. The high-efficiency gas field biological foaming agent according to claim 1, characterized in that, When the produced water is used in the components, the produced water needs to be filtered through a 0.22 μm microporous filter membrane.

3. The method according to any one of claims 1-2, characterized in that, The method comprises the following steps: Step 1: deionized water or produced water filtered through a 0.22 μm microporous filter membrane is added into a reaction kettle with stirring and temperature control functions, rhamnolipid and sophorolipid are sequentially added under stirring at a speed of 30~40 ℃ and 150~200 rpm, and stirring is performed for 35~45 min to form a uniform transparent mixture; Step 2: lipophilic spherical nanosilica is added into the mixture obtained in step 1, and stirring is performed at a speed of 300~400 rpm and ultrasonic dispersion is performed at a power of 300~500 W for 20~25 min to ensure uniform dispersion of the nanoparticles; Step 3: the temperature is kept at 30~40 ℃, the stirring speed is 200~250 rpm, polyglutamic acid is first added and stirred for 25~30 min until completely dissolved, then epsilon-polylysine is added and stirred for 20~25 min to form a uniform and stable solution; Step 4: the obtained solution is filtered through a 0.45 μm microporous filter membrane, the pH value is detected to be 6.5~7.5, and the finished product foaming agent is obtained.

4. The use of a high-efficiency gas field biological foaming agent according to any one of claims 1-2, characterized in that: It is suitable for the drainage gas recovery operation of gas field with bottom hole temperature ≤ 150 ℃ and formation water salinity ≤ 20 × 10 4 mg / L.