A method for heavy oil high-temperature active water biological enzyme huff and puff oil production

Abstract

The present application relates to the technical field of oilfield enhanced oil recovery, and discloses a heavy oil high-temperature active water bio-enzyme huff and puff oil production method, which comprises the following steps: sequentially injecting a high-temperature active water slug, a transition active water slug, a bio-enzyme working solution and a post-positioning fluid into a target oil layer; the high-temperature active water slug and the transition active water slug both contain hydroxyl sulfobetaine and C8-C 10 alkyl glycoside; continuously injecting the transition active water slug to reduce the bottom hole temperature to below the 24h thermal inactivation threshold T 50,24 of the bio-enzyme working solution, and then injecting the bio-enzyme working solution, followed by shutting in, huffing and puffing and opening the well for production. The bio-enzyme working solution comprises immobilized composite enzyme particles, which are supported by aminated mesoporous silica, covalently immobilize lipase and esterase through glutaraldehyde, and are coated with genipin cross-linked carboxymethyl chitosan. The present application effectively protects enzyme activity through slug combination injection and precise temperature control, and significantly improves heavy oil recovery.

Description

Technical Field

[0001] This invention relates to the field of enhanced oil recovery technology, specifically a method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil. Background Technology

[0002] Heavy oil resources account for a large proportion of global oil reserves, and their high viscosity and high pour point characteristics result in low recovery rates with conventional extraction methods. Steam injection is a widely used thermal recovery method for heavy oil, which relies on injecting high-temperature steam into the well to heat the oil reservoir and reduce the viscosity of the crude oil. However, factors such as wellbore and formation heat loss, reservoir heterogeneity, and steam channeling limit the effective heating range of steam and the degree of improvement in unexploited areas.

[0003] To further improve extraction efficiency, active water huff and puff technology has been developed, which involves adding surfactants to the injected fluid to reduce oil-water interfacial tension and improve displacement mobility. In recent years, bioenzymes have shown application potential in heavy oil extraction due to their high efficiency and environmental friendliness. Bioenzymes can catalyze the hydrolysis or transesterification of specific chemical bonds in crude oil colloids, improving rock surface wettability and helping to reduce heavy oil viscosity. However, heavy oil reservoirs often have high formation temperatures and are accompanied by highly saline formation water. Conventional bioenzymes are prone to protein denaturation and inactivation under high temperature and high salinity, significantly limiting their actual effectiveness. While existing research explores high-temperature resistant bioenzymes and enzyme immobilization, the stability of enzyme systems and their effectiveness when used in combination with surfactants under complex reservoir conditions still need improvement. Furthermore, introducing immobilized bioenzymes into thermal huff and puff processes faces unique technological challenges: to achieve viscosity reduction in heavy oil, high-temperature fluids need to be injected into the reservoir to preheat it, but the high temperature environment exacerbates the thermal inactivation of bioenzymes; conversely, simply lowering the injected fluid temperature would negate the benefits of thermal viscosity reduction. The composition and salinity of water in different oil reservoirs vary greatly, which can significantly alter the thermal inactivation characteristics of immobilized enzymes. Using a pre-set uniform injection temperature window is difficult to adapt to the actual working conditions of different oil reservoirs, which can easily lead to the inactivation of biological enzymes during injection or well shut-in, resulting in waste of chemical agents and production enhancement effects that are not as expected.

[0004] Therefore, developing a bio-enzyme-based heavy oil huff and puff method that takes into account both thermal viscosity reduction and the protection of bio-enzyme activity, and is adaptable to different formation water conditions, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil. By actively cooling the transition active water slug to below the thermal inactivation threshold of the bio-enzyme working fluid, and injecting immobilized composite enzyme particles with aminated mesoporous silica as a carrier and genipin-crosslinked carboxymethyl chitosan as a coating, the safe injection and long-term effect of bio-enzymes in high-temperature heavy oil reservoirs are achieved, significantly improving the recovery rate of heavy oil.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil, comprising the following steps: S1. Inject a high-temperature active water slug at a temperature of 95–125°C into the target oil layer. The high-temperature active water slug contains hydroxysulfobetaine and C8-C... 10 Alkyl glycosides; S2. After the high-temperature active water slug injection is completed, a transitional active water slug with a temperature of 50-75°C is injected into the target oil layer. The transitional active water slug contains hydroxysulfobetaine and C8-C 10 Alkyl glycosides, and the transition active aqueous septum contains hydroxysulfobetaine and C8-C 10 The total mass concentration of alkyl glycosides is lower than that of hydroxysulfobetaine and C8-C in the high-temperature active water slug. 10 Total mass concentration of alkyl glycosides; continuous injection of the transitional active water slug to reduce the bottomhole injection port temperature below the 24-hour thermal inactivation threshold T of the bio-enzyme working fluid. 50,24 ; S3, when the temperature at the bottom injection port is lower than T 50,24 When injecting oil into the target oil layer at a temperature lower than T... 50,24 The bio-enzyme working solution is then injected, followed by a post-displacement fluid, the temperature of which at the bottom-hole injection port is lower than T. 50,24 ; S4. After completing the injection of the post-displacement fluid, shut in the well and allow it to simmer, then start production. The bio-enzyme working solution contains immobilized composite enzyme particles, which include an aminated mesoporous silica carrier, lipase and esterase covalently immobilized on the aminated mesoporous silica carrier by glutaraldehyde, and a genipin crosslinked carboxymethyl chitosan layer coating the outer surface of the aminated mesoporous silica carrier. The T 50,24The process involves: using target formation water, or simulated formation water prepared based on the measured ion types, ion concentrations, and total mineralization of the target formation water, to prepare test samples with the same composition and mass concentration of each component as the bio-enzyme working solution used in step S3. These samples are then incubated at different temperatures for 24 hours each. The temperatures corresponding to a 50% residual enzyme activity for both lipase and esterase are determined, and the lower of the two temperatures is taken as T. 50,24 .

[0007] Furthermore, the lipase and esterase are covalently immobilized within the pores of the aminated mesoporous silica support using glutaraldehyde.

[0008] Furthermore, when the bio-enzyme working solution is injected in step S3, the temperature at the bottom of the well is higher than that at T. 50,24 The temperature is 3-5°C lower; the injection temperature of the bio-enzyme working solution is 45-65°C.

[0009] Furthermore, the bio-enzyme working solution also includes a composite surfactant, a protein protectant, a salt-tolerant agent, and a polyol; the composite surfactant includes hydroxysulfobetaine and C8-C... 10 Alkyl glycoside; the protein protectant includes trehalose and ectoine; the salt-tolerant agent is sodium citrate; the polyol is propylene glycol.

[0010] Further, in step S1, the high-temperature active water slug contains hydroxysulfonate betaine and C8-C... 10 The total mass concentration of alkyl glycosides is 0.20–0.80%; in step S2, the hydroxysulfonate betaine and C8-C in the transition active water slug are... 10 The total mass concentration of alkyl glycosides is 0.05–0.20%, and the transition active aqueous septum contains hydroxysulfobetaine and C8-C... 10 The total mass concentration of alkyl glycosides is lower than that of hydroxysulfobetaine and C8-C in the high-temperature active water slug. 10 Total mass concentration of alkyl glycosides.

[0011] Further, determine the T 50,24 At that time, the relationship between the residual enzyme activity of the lipase and esterase and the incubation temperature was established, and the temperature corresponding to 50% residual enzyme activity of the lipase and esterase was determined. When the temperature corresponding to 50% residual enzyme activity is between two adjacent test temperatures, the temperature is determined by linear interpolation based on the two adjacent test temperatures and their corresponding residual enzyme activity.

[0012] Furthermore, the bottom injection port temperature is obtained by actual measurement using a temperature detection device installed downhole; or, it is calculated using a wellbore heat transfer model based on the wellhead injection temperature, injection rate, well depth, wellbore structure, target oil layer temperature, and wellbore heat transfer parameters.

[0013] Furthermore, based on the effective pore volume Vp of the target treatment area, the injection volume of the high-temperature active water slug is 0.25Vp to 0.40Vp, the injection volume of the transition active water slug is 0.10Vp to 0.20Vp, the injection volume of the bio-enzyme working solution is 0.15Vp to 0.30Vp, and the injection volume of the post-displacement solution is 0.05Vp to 0.15Vp.

[0014] Furthermore, the temperature of the post-displacement fluid at the bottom of the well is 45-60℃; after the injection of the post-displacement fluid is completed, the well is shut down for 48-120 hours, and production is started after the shut-down period ends. The bottom-hole flowing pressure is gradually reduced within 24-72 hours from the start of the well opening, and the rate of decrease in bottom-hole flowing pressure is not greater than 2.0 MPa / d.

[0015] Further, in steps S1 and S2, the hydroxysulfonate betaine reacts with the C8-C... 10 The mass ratio of alkyl glycosides was 3:2.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention achieves active cooling by setting a transitional active water slug, and strictly adheres to the 24-hour thermal inactivation threshold T of the bio-enzyme working solution. 50,24 As a temperature control benchmark for enzyme injection, this threshold is taken as the lower of the half-inactivation temperatures of lipase and esterase, reducing the degree of thermal inactivation of the two enzymes during injection, improving enzyme activity retention, and ensuring the catalytic efficiency of the bioenzymes in the reservoir. The high-temperature active water slug and the transitional active water slug contain a compound of hydroxysulfobetaine and C8-C... 10 Alkyl glycosides, possessing temperature and salt resistance and the ability to reduce viscosity through compound formulation, work in conjunction with bio-enzyme working solutions in the huff-and-puff oil recovery process, further improving heavy oil recovery. The immobilized composite enzyme particles of this invention use aminated mesoporous silica as a carrier, with the two enzymes covalently immobilized within the carrier pores via glutaraldehyde. This microscopic pore confinement effect, combined with the strong interaction of covalent bonds, helps limit the decrease in enzyme activity under high-temperature conditions. Simultaneously, a genipin-crosslinked carboxymethyl chitosan layer is coated on the outer surface of the mesoporous carrier. This crosslinked layer helps reduce the possibility of immobilized enzyme diffusion and leakage from the pores and improves the stability of the immobilized two enzymes in high-mineralization media. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Unless otherwise stated, all reagents used are commercially available. The lipases and esterases used in the embodiments of this application are commercially available heat-resistant industrial enzyme preparations (the measured initial enzyme activity of lipase was 18500 U / g, and the measured initial enzyme activity of esterase was 22000 U / g). They are referred to as lipase and esterase below.

[0019] In this invention, residual enzyme activity is calculated using the following formula: Residual enzyme activity = Enzyme activity measured after incubation / Initial enzyme activity without incubation × 100%. Specifically, p-nitrophenyl palmitate is used as the substrate for lipase activity assay, and p-nitrophenyl acetate is used as the substrate for esterase activity assay. The lipase activity assay conditions are: phosphate buffer pH 7.4, substrate concentration 1.0 mmol / L, reaction at 45°C for 15 min, and absorbance measured at 410 nm. p-Nitrophenyl palmitate is prepared as a 10 mmol / L stock solution using isopropanol and diluted to 1.0 mmol / L with assay buffer before use. Esterase is assayed using the same method, but the substrate is replaced with p-nitrophenyl acetate. Under the above assay conditions, the amount of enzyme required to catalyze the generation of 1 μmol of p-nitrophenol per minute is defined as 1 U.

[0020] In the core injection simulation experiment, the measured core pore volume PV corresponds to the effective pore volume Vp of the target treatment area in the field, and each slug is simulated on a scale with the same volume ratio. The core inlet temperature is used to simulate the temperature at the bottom of the well in the field.

[0021] During on-site construction, the injection port temperature at the bottom of the well can be obtained by actual measurement using a temperature detection device installed downhole; or, it can be calculated using a wellbore heat transfer model based on the injection port temperature, injection rate, well depth, wellbore structure, target oil layer temperature, and wellbore heat transfer parameters.

[0022] After each segment of the core was injected, the relative effects under the saturation conditions were evaluated using a closed saturation method.

[0023] In the core experiments of this application, the slug temperature refers to the pipeline fluid temperature before the fluid enters the core holder; the core inlet temperature refers to the measured temperature at a temperature detection location near the core inlet. Because the preceding high-temperature slug preheats the core and inlet, during the injection of the transition active water slug, the measured core inlet temperature can be higher than the fluid temperature of the injected transition active water slug, and gradually decreases as the transition active water slug continues to be injected.

[0024] Preparation Example 1 Preparation of immobilized complex enzyme particles.

[0025] 100 g of mesoporous silica (original average particle size 200 nm, SEM statistical value) was added to 2000 mL of anhydrous ethanol and ultrasonically dispersed for 20 min. Then, 50 mL of 3-aminopropyltriethoxysilane was added, and the mixture was refluxed at 78 °C for 6 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, and the resulting solid was washed three times with anhydrous ethanol and twice with deionized water. The solid was then vacuum dried at 60 °C for 12 h to obtain the aminated mesoporous silica support.

[0026] The pore structure of the aminated mesoporous silica support was determined using a nitrogen adsorption-desorption method. Specific surface area was calculated using the BET method, and pore size distribution was calculated using the BJH method. The pore size corresponding to the peak value of the pore size distribution curve was taken as the most probable pore size. The sample was degassed under vacuum at 120℃ for 6 hours before testing.

[0027] The most probable pore size of the obtained aminated mesoporous silica support is 12.5 nm, and the BET specific surface area is 415 m². 2 / g.

[0028] Take 100g of the above-mentioned aminated mesoporous silica support and disperse it in 2000mL of phosphate buffer solution with pH 7.4. Add glutaraldehyde to make the final mass concentration of glutaraldehyde in the system 0.40%, and stir and activate at 20℃ for 1h. After activation, centrifuge and wash three times with phosphate buffer solution with pH 7.4 to remove free glutaraldehyde, to obtain the glutaraldehyde-activated support.

[0029] 18g of lipase and 6g of esterase were added to 2400mL of phosphate buffer (pH 7.4), mixed thoroughly, and then the glutaraldehyde activation carrier was added. The mixture was stirred at low speed at 10℃ for 8 hours. After the reaction was completed, 0.2mol / L glycine solution was added to block the remaining active aldehyde groups. The mixture was then centrifuged and thoroughly washed with phosphate buffer to obtain the immobilized dual-enzyme intermediate.

[0030] The pore structure before and after immobilization of the two enzymes was determined using a nitrogen adsorption-desorption method. The BET specific surface area of ​​the carrier after immobilization of the two enzymes was 286 m². 2 / g, total pore volume is 0.42cm³ 3 / g, with a most probable pore size of 9.8nm; the protein loading was 165mg / g of the carrier, and the difference in protein content in the supernatant before and after immobilization was determined by the BCA method.

[0031] The BET specific surface area and pore size of the immobilized dual enzymes carrier decreased compared to the aminated mesoporous silica carrier. Combined with the protein loading test results, this confirms that lipase and esterase entered the mesoporous structure and were immobilized.

[0032] The above-mentioned immobilized dual-enzyme intermediate was dispersed in 2200 mL of an aqueous system with pH 6.3, 6.0 g of carboxymethyl chitosan was added, followed by 0.12 g of genipin. The mixture was stirred and cross-linked at 25 °C for 3 h. After cross-linking, the mixture was centrifuged, washed three times with deionized water, and freeze-dried to obtain immobilized composite enzyme particles.

[0033] The D50 of the obtained immobilized complex enzyme particles was 186 nm and the D90 was 328 nm, which were determined by a laser particle size analyzer (wet dispersion).

[0034] Simulated formation water composition The simulated formation water used in this application embodiment was prepared based on the actual analysis results of the formation water in the target oil reservoir, and its main ionic composition is: Na + 3850mg / L, K + 210 mg / L, Ca 2+ 580 mg / L, Mg 2+ 165mg / L, Cl - 6820mg / L, HCO3 - 420 mg / L, SO4 2- It has a concentration of 85 mg / L, a total mineralization of 12130 mg / L, and a pH of 7.2 at 25℃.

[0035] Preparation Example 2 Preparation of working solutions for biological enzymes.

[0036] The simulated formation water described above was used as the continuous phase. Based on the total mass of the bio-enzyme working solution, the mass percentages of each component were: immobilized composite enzyme particles 0.20%; hydroxysulfobetaine 0.15%; C8-C 10 Alkyl glycoside 0.10%; trehalose 0.15%; ectoine 0.03%; sodium citrate 0.05%; propylene glycol 0.80%; balance is simulated formation water.

[0037] First, trehalose, ectoine, and sodium citrate were added to simulated formation water and stirred until dissolved; then propylene glycol, hydroxysulfobetaine, and C8-C were added. 10 Add alkyl glycosides and continue stirring for 20 minutes; finally, add immobilized complex enzyme particles and stir at low speed for 20 minutes at a temperature not exceeding 30°C. Adjust the pH of the system to 7.0 to obtain the working solution of the biological enzyme.

[0038] The above formula is a specific implementation formula. The dosage of each component can be adjusted according to the target reservoir temperature, salinity, crude oil viscosity, and the results of core injection and enzyme activity stability tests.

[0039] Measurement Example 1 T 50,24 Determination: Test samples with the same composition and mass concentration of each component as the working solution of the biological enzyme described in Example 2 were used. Equal amounts of test samples were taken and incubated at different temperatures for 24 hours, with at least three parallel samples at each temperature. After incubation, the test samples were cooled to the same enzyme activity determination temperature, and the residual enzyme activities of lipase and esterase were measured. The relationship between the residual enzyme activities of the two enzymes and the 24-hour incubation temperature was established. The temperatures corresponding to a 50% residual enzyme activity for lipase and esterase were determined. When the temperature corresponding to a 50% residual enzyme activity falls between two adjacent test temperatures, linear interpolation was used to calculate: T 50 =T1+[(R1-50) / (R1-R2)]×(T2-T1). Where T1 and T2 are two adjacent test temperatures above and below 50% residual enzyme activity; R1 is the residual enzyme activity corresponding to temperature T1; and R2 is the residual enzyme activity corresponding to temperature T2.

[0040] The residual enzyme activity of the two enzymes at different 24-hour incubation temperatures is shown in Table 1.

[0041] Table 1: Residual enzyme activity of dual enzymes under different 24h incubation temperatures

[0042] Table 1 shows that the temperature corresponding to 50% residual enzyme activity of lipase is between 75℃ and 80℃. Linear interpolation yields a 24-hour half-inactivation temperature of 78.0℃ for lipase. Similarly, the temperature corresponding to 50% residual enzyme activity of esterase is between 70℃ and 75℃. Linear interpolation yields a 24-hour half-inactivation temperature of esterase of 72.6℃. The lower of these two temperatures is taken as the 24-hour thermal inactivation threshold T for the bio-enzyme working solution. 50,24 Therefore, in this measurement example: T 50,24 =72.6℃.

[0043] Core swallowing simulation experiment In the following embodiments, the confining pressure of the core holder was set to 3.5 MPa, the back pressure was set to 2.0 MPa, and the injection rate of each slug was 0.3 mL / min. Core experiments were used to evaluate the relative effects of different process parameters. The temperature history during the field well shut-in process needs to be determined based on the thermal properties of the target reservoir and the wellbore-formation heat transfer conditions.

[0044] In Examples 1-3, Comparative Examples 2 and 3, the method for determining the immobilized enzyme activity retention rate was as follows: After well shut-in, reverse displacement was performed at 0.3 mL / min until the produced fluid no longer showed significant oil production. The produced fluid was centrifuged at 8000 rpm for 10 min, and the precipitated immobilized composite enzyme particles were collected. After washing twice with pH 7.4 phosphate buffer, the particles were redispersed in the assay buffer. The enzyme activity per unit mass of lipase and esterase in the recovered particles was determined according to the aforementioned enzyme activity determination method. The enzyme activity retention rate was calculated using the following formula: Enzyme activity retention rate = (Enzyme activity per unit mass of recovered particles / Initial enzyme activity per unit mass of particles before injection) × 100%. The huff-and-puff recovery rate was calculated using the following formula: Huff-and-puff recovery rate = (Cumulative oil produced during huff-and-puff process / Initial oil content in the core) × 100%. The cumulative oil produced was determined by weighing and measured after oil-water separation. Examples 1-3, Comparative Examples 2 and 3 were determined using this method; Comparative Example 1 used a free enzyme, and its enzyme activity was determined according to the free enzyme assay method.

[0045] Example 1

[0046] A huff-and-puff simulation experiment was conducted using natural heavy oil cores. After washing and drying, the cores were vacuum-saturated to simulate formation water, and the target heavy oil was used for oil-driven water displacement to bring the cores to a bound water state.

[0047] S1. A high-temperature activated water slug was prepared using simulated formation water. The concentration of hydroxysulfobetaine was 0.27%, and the C8-C... 10 The alkyl glycoside concentration was 0.18%, and the total concentration of both was 0.45%. The high-temperature active water slug was heated to 110°C, and 0.30 PV was injected into the core.

[0048] S2. A transitional active water slug was prepared using simulated formation water. The concentration of hydroxysulfobetaine was 0.072%, and the C8-C... 10 The alkyl glycoside concentration was 0.048%, and the total concentration of both was 0.12%. The temperature of the transition active water slug was controlled at 65°C, and continuous injection was performed while monitoring the core inlet temperature. When the cumulative injection volume reached 0.15 PV, the core inlet temperature decreased to the level obtained in Test Example 1. 50,24 Lower the temperature by 4°C, then stop the injection of transition active water slug and proceed to the next step.

[0049] S3. The bio-enzyme working solution described in Example 2 is prepared. The injection temperature of the bio-enzyme working solution is 58°C, which is lower than the T... 50,24 The injection volume was 0.20 PV. After the bio-enzyme working solution was injected, simulated formation water was used as the post-displacement fluid. The temperature of the post-displacement fluid at the core inlet was controlled at 52℃, which was lower than the T... 50,24 The injection volume is 0.10 PV.

[0050] S4. After the replacement fluid is injected, the core holder is sealed and left to stand for 72 hours at 52°C. After the sealing and standing period, reverse extraction is carried out.

[0051] Example 2

[0052] A huff-and-puff simulation experiment was conducted using natural heavy oil cores. The core pretreatment method was the same as in Example 1.

[0053] S1. A high-temperature activated water slug was prepared using simulated formation water. The concentration of hydroxysulfobetaine was 0.45%, and the C8-C... 10 The alkyl glycoside concentration was 0.30%, and the total concentration of both was 0.75%. The high-temperature active water slug was heated to 122°C, and 0.38 PV was injected into the core.

[0054] S2. A transitional active water slug was prepared using simulated formation water. The concentration of hydroxysulfobetaine was 0.108%, and the C8-C... 10 The alkyl glycoside concentration was 0.072%, and the total concentration of both was 0.18%. The temperature of the transition active water slug was controlled at 68°C, and continuous injection was performed while monitoring the core inlet temperature. When the cumulative injection volume reached 0.19 PV, the core inlet temperature decreased to the level obtained in Test Example 1. 50,24 Lower the temperature by 3°C, then stop the injection of transition active water slug and proceed to the next step.

[0055] S3. The working solution of the bio-enzyme described in Example 2 is prepared. The injection temperature of the bio-enzyme working solution is 64°C, which is lower than the T value. 50,24 The injection volume was 0.28 PV. After the bio-enzyme working solution was injected, simulated formation water was used as the post-displacement fluid. The temperature of the post-displacement fluid at the core inlet was controlled at 58℃, which was lower than the T... 50,24 The injection volume was 0.14 PV.

[0056] S4. After the replacement fluid is injected, the core holder is sealed and simmered at 58°C for 96 hours; after the sealing and simmering is completed, reverse extraction is carried out.

[0057] Example 3

[0058] A huff-and-puff simulation experiment was conducted using natural heavy oil cores. The core pretreatment method was the same as in Example 1.

[0059] S1. A high-temperature activated water slug was prepared using simulated formation water. The concentration of hydroxysulfobetaine was 0.15%, and the C8-C... 10 The alkyl glycoside concentration was 0.10%, and the total concentration of both was 0.25%. The high-temperature active water slug was heated to 98°C, and 0.26 PV was injected into the core.

[0060] S2. A transitional active water slug was prepared using simulated formation water. The concentration of hydroxysulfobetaine was 0.048%, and the C8-C... 10 The alkyl glycoside concentration was 0.032%, and the total concentration of both was 0.08%. The temperature of the transition active water slug was controlled at 52°C, and continuous injection was performed while monitoring the core inlet temperature. When the cumulative injection volume reached 0.11 PV, the core inlet temperature decreased to the level obtained in Test Example 1. 50,24 Lower the temperature by 5°C, then stop the injection of transition active water slug and proceed to the next step.

[0061] S3. The working solution of the bio-enzyme described in Example 2 is prepared. The injection temperature of the bio-enzyme working solution is 46°C, which is lower than the T value. 50,24 The injection volume was 0.16 PV. After the bio-enzyme working solution was injected, simulated formation water was used as the post-displacement fluid. The temperature of the post-displacement fluid at the core inlet was controlled at 46℃, which was lower than the T... 50,24 The injection volume was 0.06 PV.

[0062] S4. After the replacement fluid is injected, the core holder is sealed and left to stand for 50 hours at 46°C. After the sealing and standing period, reverse extraction is carried out.

[0063] Comparative Example 1 The main difference between this comparative example and Example 1 is that: instead of immobilized complex enzyme particles, free lipase and free esterase are used; wherein, the amount of free lipase added makes its initial total enzyme activity the same as that of the lipase in Example 1, and the amount of free esterase added makes its initial total enzyme activity the same as that of the esterase in Example 1.

[0064] In addition to the differences mentioned above, the free enzyme working solution contains hydroxysulfobetaine and C8-C 10 The mass concentrations of alkyl glycosides, trehalose, ectoine, sodium citrate, and propylene glycol, as well as the injection temperature and volume of the free enzyme working solution, the composition, temperature, injection volume, and sealed aging conditions of the high-temperature active water slug, the transitional active water slug, and the post-displacement solution, were all the same as in Example 1.

[0065] In this comparative example, the method for determining the total enzyme activity recovery rate of free enzymes is as follows: After the simmering period, reverse extraction was performed under the same conditions as in Example 1, and the extracted liquid was collected. After centrifugation to remove solid impurities and separate the oil phase, the aqueous phase was taken and the activities of lipase and esterase were determined according to the aforementioned enzyme activity determination method. The total enzyme activity of the corresponding enzyme in the extracted liquid was calculated based on the volume of the extracted aqueous phase. Using the initial total enzyme activity of the corresponding free enzyme before injection as a benchmark, the total enzyme activity recovery rate was calculated using the following formula: Total enzyme activity recovery rate = (Total enzyme activity of free enzyme in extracted liquid / Initial total enzyme activity of free enzyme before injection) × 100%.

[0066] Comparative Example 2 The main difference between this comparative example and Example 1 is that: after the immobilized enzyme particles are covalently immobilized with lipase and esterase, they are not coated with a genipin-crosslinked carboxymethyl chitosan layer, and uncoated immobilized dual enzyme particles are obtained directly.

[0067] The amount of uncoated immobilized dual enzyme particles added was adjusted so that the initial total enzyme activity of lipase and esterase was the same as that of the corresponding enzymes in Example 1.

[0068] Apart from the differences mentioned above, the other components of the bio-enzyme working solution and the swallowing and spitting process conditions are the same as in Example 1.

[0069] Comparative Example 3 The main difference between this comparative example and Example 1 is that: it does not use T... 50,24 As a control benchmark for the timing of the initial injection of the bio-enzyme working solution, the temperature of the transition active water slug was adjusted to 74.3℃, and 0.15PV was injected at a rate of 0.3mL / min. At the end of the injection, the core inlet temperature was measured to be 78.6℃, which is higher than T. 50,24 The temperature was raised to 6.0°C (72.6°C), and then immediately the same temperature (58°C) and volume (0.20 PV) of the bio-enzyme working solution as in Example 1 were injected.

[0070] Except for the differences mentioned above, the composition, mass concentration, injection volume, and other swallowing and spitting conditions of the high-temperature active water slug, the transitional active water slug, the bio-enzyme working solution, and the post-displacement solution are the same as in Example 1.

[0071] Comparative Example 4 The main difference between this comparative example and Example 1 is that a blank working solution without immobilized complex enzyme particles was used in the bio-enzyme working solution injection stage. The blank working solution contained hydroxysulfobetaine and C8-C... 10 The mass concentrations of alkyl glycosides, trehalose, ectoine, sodium citrate, and propylene glycol were the same as those used in the working solution of the bio-enzyme in Example 1, except that immobilized complex enzyme particles were not added.

[0072] Apart from the differences mentioned above, all other throughput process conditions are the same as in Example 1.

[0073] The test results of Examples 1-3 and Comparative Examples 1-4 are shown in Table 2.

[0074] Table 2: Test Results

[0075] Note: The enzyme activity data listed in Examples 1-3, Comparative Examples 2 and 3 are the enzyme activity retention rates per unit mass of recovered immobilized enzyme particles; the data listed in Comparative Example 1 are the total enzyme activity recovery rates of free enzymes. Due to the different forms of enzyme existence and calculation bases, the two are not compared in absolute numerical terms.

[0076] As shown in Table 2, the enzyme activity retention rates per unit mass of lipase and esterase recovered from the immobilized enzyme particles in Examples 1-3 were all above 83%, with recovery rates of 35.6%, 36.2%, and 33.4%, respectively. Example 1 and Comparative Example 4 used the same high-temperature active water slug, transitional active water slug, working enzyme solution (except for the immobilized composite enzyme particles), and post-displacement solution, and the same throughput conditions. Comparative Example 4 did not include immobilized composite enzyme particles. The recovery rate of Example 1 was 35.6%, while that of Comparative Example 4 was 15.2%, an increase of 20.4 percentage points, indicating that adding immobilized composite enzyme particles under these conditions could further improve the recovery rate. Since the slug temperature, surfactant concentration, slug volume, and simmering time in Examples 2 and 3 differed from those in Example 1, the recovery rate of Comparative Example 4 was not used as the enzyme-free baseline for Examples 2 and 3.

[0077] In Comparative Example 1, the total enzyme activity recovery rates of free lipase and free esterase were 11.4% and 8.7%, respectively, and the huff-and-puff recovery rate was only 18.2%, indicating that the effective total enzyme activity that the free enzyme system could recover under the core huff-and-puff conditions was low, and its recovery effect was significantly lower than that of Example 1.

[0078] In Comparative Example 2, without the genipin crosslinked carboxymethyl chitosan layer, the enzyme activity retention rate dropped to about 50%, and the recovery rate was 24.5%, indicating that the chitosan shell is beneficial to improving the enzyme activity retention of the immobilized dual enzymes under simulated formation water conditions.

[0079] In Comparative Example 3, the core inlet temperature at the start of the injection of the bio-enzyme working solution was higher than T. 50,24 When the temperature reached 6℃, or 78.6℃, while the injection temperature of the bio-enzyme working solution remained the same as in Example 1, the esterase (the weakest link in the system's thermal stability) activity retention rate decreased to 22.4%, and the recovery rate was only 21.1%, both significantly lower than in Example 1 (esterase activity retention rate 86.2%, recovery rate 35.6%). This indicates that the core inlet temperature during injection was higher than T. 50,24 During this period, the two enzymes underwent a higher temperature process, resulting in a significant decrease in both enzyme activity retention and harvest rate.

[0080] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0082] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A method for high-temperature active water-based bio-enzyme huff and puff recovery of heavy oil, characterized in that, Includes the following steps: S1. Inject a high-temperature active water slug at a temperature of 95–125°C into the target oil layer. The high-temperature active water slug contains hydroxysulfobetaine and C8-C... 10 Alkyl glycosides; S2. After the high-temperature active water slug injection is completed, a transitional active water slug with a temperature of 50-75°C is injected into the target oil layer. The transitional active water slug contains hydroxysulfobetaine and C8-C 10 Alkyl glycosides, and the transition active aqueous septum contains hydroxysulfobetaine and C8-C 10 The total mass concentration of alkyl glycosides is lower than that of hydroxysulfobetaine and C8-C in the high-temperature active water slug. 10 Total mass concentration of alkyl glycosides; continuous injection of the transitional active water slug to reduce the bottomhole injection port temperature below the 24-hour thermal inactivation threshold T of the bio-enzyme working fluid. 50,24 ; S3, when the temperature at the bottom injection port is lower than T 50,24 When injecting oil into the target oil layer at a temperature lower than T... 50,24 The bio-enzyme working solution is then injected, followed by a post-displacement fluid, the temperature of which at the bottom-hole injection port is lower than T. 50,24 ; S4. After completing the injection of the post-displacement fluid, shut in the well and allow it to simmer, then start production. The bio-enzyme working solution contains immobilized composite enzyme particles, which include an aminated mesoporous silica carrier, lipase and esterase covalently immobilized on the aminated mesoporous silica carrier by glutaraldehyde, and a genipin crosslinked carboxymethyl chitosan layer coating the outer surface of the aminated mesoporous silica carrier. The T 50,24 The process involves: using target formation water, or simulated formation water prepared based on the measured ion types, ion concentrations, and total mineralization of the target formation water, to prepare test samples with the same composition and mass concentration of each component as the bio-enzyme working solution used in step S3. These samples are then incubated at different temperatures for 24 hours each. The temperatures corresponding to a 50% residual enzyme activity for both lipase and esterase are determined, and the lower of the two temperatures is taken as T. 50,24 .

2. The method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil according to claim 1, characterized in that, The lipase and esterase are covalently immobilized within the pores of the aminated mesoporous silica carrier using glutaraldehyde.

3. The method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil according to claim 1, characterized in that, When the bio-enzyme working solution is injected in step S3, the temperature at the bottom of the well is higher than that at T. 50,24 The temperature is 3-5°C lower; the injection temperature of the bio-enzyme working solution is 45-65°C.

4. The method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil according to claim 1, characterized in that, The bio-enzyme working solution also includes a composite surfactant, a protein protectant, a salt-tolerant agent, and a polyol; the composite surfactant includes hydroxysulfobetaine and C8-C 10 Alkyl glycoside; the protein protectant includes trehalose and ectoine; the salt-tolerant agent is sodium citrate; the polyol is propylene glycol.

5. The method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil according to claim 1, characterized in that, In step S1, the high-temperature activated water slug contains hydroxysulfonate betaine and C8-C 10 The total mass concentration of alkyl glycosides is 0.20–0.80%; in step S2, the hydroxysulfonate betaine and C8-C in the transition active water slug are... 10 The total mass concentration of alkyl glycosides is 0.05–0.20%, and the transition active aqueous septum contains hydroxysulfobetaine and C8-C... 10 The total mass concentration of alkyl glycosides is lower than that of hydroxysulfobetaine and C8-C in the high-temperature active water slug. 10 Total mass concentration of alkyl glycosides.

6. The method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil according to claim 1, characterized in that, Determine the T 50,24 At that time, the relationship between the residual enzyme activity of the lipase and esterase and the incubation temperature was established, and the temperature corresponding to 50% residual enzyme activity of the lipase and esterase was determined. When the temperature corresponding to 50% residual enzyme activity is between two adjacent test temperatures, the temperature is determined by linear interpolation based on the two adjacent test temperatures and their corresponding residual enzyme activity.

7. The method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil according to claim 1, characterized in that, The bottom injection port temperature is obtained by actual measurement using a temperature detection device installed downhole; or, it is calculated using a wellbore heat transfer model based on the wellhead injection temperature, injection rate, well depth, wellbore structure, target oil layer temperature, and wellbore heat transfer parameters.

8. The method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil according to claim 1, characterized in that, Based on the effective pore volume Vp of the target treatment area, the injection volume of the high-temperature active water slug is 0.25Vp to 0.40Vp, the injection volume of the transition active water slug is 0.10Vp to 0.20Vp, the injection volume of the bio-enzyme working solution is 0.15Vp to 0.30Vp, and the injection volume of the post-displacement solution is 0.05Vp to 0.15Vp.

9. The method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil according to claim 1, characterized in that, The temperature of the post-displacement fluid at the bottom of the well is 45-60℃; after the injection of the post-displacement fluid is completed, the well is shut down for 48-120 hours. After the shut-down is completed, the well is started for production, and the bottom flow pressure is gradually reduced within 24-72 hours from the start of the well.

10. The method for high-temperature active water bio-enzyme huff and puff recovery of heavy oil according to claim 1, characterized in that, In steps S1 and S2, the hydroxysulfonate betaine reacts with the C8-C... 10 The mass ratio of alkyl glycosides was 3:2.

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