Method for recycling heavy oil exploitation functional bacteria

Abstract

The application provides a thickened oil exploitation functional bacteria recycling method, comprising the following steps: determining functional bacteria matched with a viscosity-causing component of thickened oil; culturing a target culture medium corresponding to the functional bacteria by taking reservoir produced liquid as raw material; injecting the functional bacteria and the target culture medium into the reservoir; producing by opening the well to output the reservoir produced liquid; separating water and oil of the reservoir produced liquid to obtain produced water and produced oil; detecting the concentration of the functional bacteria in the produced water in real time, recording the detection result; and supplementing the functional bacteria and the target culture medium according to the detection result to make the concentration of the functional bacteria reach a preset concentration. The application solves the problem of low thickened oil exploitation efficiency in the prior art.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction technology, and more specifically, to a method for recycling functional bacteria used in heavy oil extraction. Background Technology

[0002] my country's heavy oil reservoirs are diverse in type and complex in formation. Due to their high viscosity and poor permeability, the overall development cost is relatively high. Currently, heavy oil development mainly employs thermal recovery technologies such as steam huff and puff, steam drive, and steam-assisted gravity drainage (SAGD). After decades of development, most domestic heavy oil reservoirs have entered the mid-to-late stages of development, with the heating radius approaching the theoretical limit. As the water cut of the reservoir increases, the oil-steam ratio decreases significantly. The development efficiency of some "thin, poor, and scattered" heavy oil reservoirs deteriorates sharply, with the oil-steam ratio dropping below 0.05 and the overall cost rising to around $80 per barrel. This has led to the complete shutdown of some inefficient reservoirs, and the scale of shutdowns is expanding year by year.

[0003] Microbial enhanced oil recovery (MEOR) is considered an important direction for oil recovery technology in the 21st century. China has been exploring MEOR technology for over 50 years. MEOR technology has shown expected effects such as viscosity reduction, oil production increase, and improved oil recovery in single-well huff and puff and field tests. However, in industrial applications, problems such as rapid decline in microbial activity and short effective period still exist, hindering further large-scale application. How to form a dominant microbial community and sustain its effect to improve MEOR efficiency is a pressing technical challenge that needs to be solved.

[0004] In other words, existing technologies for heavy oil extraction suffer from low efficiency. Summary of the Invention

[0005] The main objective of this invention is to provide a method for recycling functional bacteria in heavy oil extraction, so as to solve the problem of low efficiency in heavy oil extraction in the prior art.

[0006] To achieve the above objectives, the present invention provides a method for recycling functional bacteria in heavy oil extraction, comprising: identifying functional bacteria that match the viscosity-inducing components of heavy oil; cultivating a targeted culture medium corresponding to the functional bacteria using reservoir produced fluid as raw material; injecting the functional bacteria and the targeted culture medium into the reservoir; producing reservoir produced fluid by well opening; separating water and oil in the reservoir produced fluid to obtain produced water and produced oil; monitoring the concentration of functional bacteria in the produced water in real time and recording the monitoring results; and replenishing the functional bacteria and the targeted culture medium according to the monitoring results to ensure that the concentration of functional bacteria reaches a preset concentration.

[0007] Furthermore, the process of identifying functional bacteria that match the viscosity-inducing components of heavy oil includes: obtaining reservoir produced fluid; analyzing the composition of the reservoir produced fluid and extracting various hydrocarbon-degrading microorganisms from the reservoir produced fluid; conducting culture experiments on the hydrocarbon-degrading microorganisms and selecting functional bacteria that match the heavy oil from the various hydrocarbon-degrading microorganisms.

[0008] Furthermore, the process of culturing hydrocarbon-degrading microorganisms and selecting functional bacteria that match heavy oil from a variety of hydrocarbon-degrading microorganisms includes: culturing hydrocarbon-degrading microorganisms in a pre-set culture medium containing heavy oil; analyzing the changes in the composition of the pre-set culture medium; and selecting one hydrocarbon-degrading microorganism as a functional bacteria based on the changes in composition.

[0009] Furthermore, the process of selecting a hydrocarbon-degrading microorganism as a functional bacterium based on changes in composition includes: determining the changes in asphaltene content to judge the degree of degradation of heavy oil; determining the water-oil miscibility ratio to judge the degree of emulsification of heavy oil; and selecting the hydrocarbon-degrading microorganism corresponding to the highest degree of degradation and the highest degree of emulsification as the functional bacterium.

[0010] Furthermore, the process of cultivating targeted culture media corresponding to functional bacteria using reservoir produced fluid as raw material includes: establishing a nutrient solution system for the directional promotion of functional bacteria; and cultivating targeted culture media in the nutrient solution system.

[0011] Furthermore, the process of establishing a nutrient solution system for the targeted growth of functional bacteria includes: obtaining reservoir produced fluid; separating the water and oil in the reservoir produced fluid to obtain produced water and produced oil; and adding functional bacteria and a pre-set culture medium containing heavy oil to the produced water as the base liquid to form a nutrient solution system.

[0012] Furthermore, the process of culturing the targeted culture medium in the nutrient solution system includes: setting up multiple experimental systems with different concentrations and / or compositions of the preset culture medium; culturing multiple experimental systems; detecting the concentration and abundance of hydrocarbon-degrading microorganisms in the experimental system; and using the preset culture medium with a concentration of hydrocarbon-degrading microorganisms greater than the preset concentration and abundance as the targeted culture medium.

[0013] Furthermore, the process of cultivating multiple experimental systems includes: placing the experimental system in a shaker at 200 r / min for 7 days.

[0014] Furthermore, before injecting functional bacteria and targeted culture medium into the reservoir, the process also includes: sealing the water channeling channels in the reservoir; and adjusting the injection-production well pattern according to the distribution of the remaining oil.

[0015] Furthermore, the process of sealing water channeling in the reservoir includes: determining the recovery level of steam development; determining the sealing radius of the water channeling based on the recovery level; sealing the corresponding water channeling in descending order of sealing radius within the sealing range; and setting a buffer time for pump shutdown to ensure that the pump shutdown pressure remains stable within the preset pressure range.

[0016] Furthermore, the process of determining the sealing radius of the water channel based on the recovery rate includes: if the recovery rate is greater than or equal to 35% and the steam leakage frequency during steam injection is greater than the preset frequency, then the sealing range is determined to be greater than or equal to 20m and less than 35m; if the recovery rate is less than 35% and the steam leakage frequency is greater than the preset frequency, then the sealing range is determined to be greater than or equal to 5m and less than 20m.

[0017] Furthermore, before the process of producing reservoir produced fluid by well opening, the following steps are also included: if functional bacteria and targeted culture medium are injected into the oil well, the oil well is closed for a preset time to cultivate the functional bacteria; if functional bacteria and targeted culture medium are injected into the water well, they are injected using a slug injection method at a preset injection rate.

[0018] Furthermore, the process of supplementing functional bacteria and targeted culture medium according to the test results to bring the concentration of functional bacteria to a preset concentration includes: when the concentration of functional bacteria is lower than 1.0 × 10⁻⁶... 6 When the concentration of cfu / ml is reached, supplement with functional bacteria and targeted culture medium.

[0019] Furthermore, in the process of supplementing functional bacteria and targeted culture medium according to the test results to make the concentration of functional bacteria reach the preset concentration, the following steps are taken: the amount of targeted culture medium supplemented is 0.2%-0.3% of the standard amount.

[0020] Furthermore, the preset concentration is 1.0 × 10⁻⁶. 8 cfu / ml.

[0021] The method for recycling functional bacteria in heavy oil extraction using the technical solution of this invention includes: Step S10: identifying functional bacteria that match the viscosity-inducing components of heavy oil; Step S20: using reservoir produced fluid as raw material to cultivate a targeted culture medium corresponding to the functional bacteria; Step S30: injecting the functional bacteria and targeted culture medium into the reservoir; Step S40: opening a well to produce reservoir produced fluid; Step S50: separating water and oil in the reservoir produced fluid to obtain produced water and produced oil; Step S60: monitoring the concentration of functional bacteria in the produced water in real time and recording the monitoring results; Step S70: supplementing functional bacteria and targeted culture medium according to the monitoring results to make the concentration of functional bacteria reach a preset concentration.

[0022] Step S10 identifies the functional bacteria required for extraction. Based on the microbial community structure characteristics of different steam-affected areas, it allows for the screening of functional bacteria with the optimal ability to degrade heavy oil in the reservoir, maximizing the recovery of heavy oil. Step S20 cultivates a targeted culture medium for the functional bacteria, using reservoir produced fluid as one of the raw materials. This allows for the reuse of microorganisms in the produced water, avoiding direct waste of functional bacteria and improving their utilization rate. Step S30 injects the functional bacteria and targeted culture medium into the reservoir, enabling in-situ activation or growth promotion within the reservoir to form a dominant functional bacterial community, improving recovery efficiency and exhibiting higher targeted enhancement, long-term effectiveness, and resistance to interference in viscosity reduction. Steps S40 and S50 involve well opening and production, obtaining and separating the produced fluid. The produced oil recovery rate is higher, and the produced water contains functional bacteria that can be reused. By monitoring the concentration of functional bacteria in the produced water in real time through steps S60 and S70, and promptly replenishing functional bacteria and targeted culture medium when the preset concentration is not reached, the dominant bacterial colony conditions of the functional bacteria can be guaranteed, interference from other bacteria in the reservoir can be reduced, and the cold recovery capability of heavy oil microorganisms can be improved. The method for recycling functional bacteria in heavy oil extraction proposed in this application can achieve the expected effects of viscosity reduction, oil increase, and improved recovery rate, and can alleviate problems such as rapid decline in bacterial activity and short shelf life, thereby improving the low efficiency of heavy oil extraction and the large-scale application effect of microbial enhanced oil recovery. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0024] Figure 1 A flowchart of a method for recycling functional bacteria used in heavy oil extraction, according to an optional embodiment of the present invention, is shown. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0027] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0028] To address the problem of low efficiency in heavy oil extraction in existing technologies, this invention provides a method for recycling functional bacteria used in heavy oil extraction.

[0029] like Figure 1 As shown, the method for recycling functional bacteria in heavy oil extraction includes: Step S10: identifying functional bacteria that match the viscosity-inducing components of heavy oil; Step S20: using reservoir produced fluid as raw material to cultivate the corresponding targeted culture medium for the functional bacteria; Step S30: injecting the functional bacteria and targeted culture medium into the reservoir; Step S40: opening the well to produce reservoir produced fluid; Step S50: separating the water and oil in the reservoir produced fluid to obtain produced water and produced oil; Step S60: monitoring the concentration of functional bacteria in the produced water in real time and recording the test results; Step S70: replenishing the functional bacteria and targeted culture medium according to the test results to make the concentration of functional bacteria reach the preset concentration.

[0030] Step S10 identifies the functional bacteria required for extraction. Based on the microbial community structure characteristics of different steam-affected areas, it allows for the screening of functional bacteria with the optimal ability to degrade heavy oil in the reservoir, maximizing the recovery of heavy oil. Step S20 cultivates a targeted culture medium for the functional bacteria, using reservoir produced fluid as one of the raw materials. This allows for the reuse of microorganisms in the produced water, avoiding direct waste of functional bacteria and improving their utilization rate. Step S30 injects the functional bacteria and targeted culture medium into the reservoir, enabling in-situ activation or growth promotion within the reservoir to form a dominant functional bacterial community, improving recovery efficiency and exhibiting higher targeted enhancement, long-term effectiveness, and resistance to interference in viscosity reduction. Steps S40 and S50 involve well opening and production, obtaining and separating the produced fluid. The produced oil recovery rate is higher, and the produced water contains functional bacteria that can be reused. By monitoring the concentration of functional bacteria in the produced water in real time through steps S60 and S70, and promptly replenishing functional bacteria and targeted culture medium when the preset concentration is not reached, the dominant bacterial colony conditions of the functional bacteria can be guaranteed, interference from other bacteria in the reservoir can be reduced, and the cold recovery capability of heavy oil microorganisms can be improved. The method for recycling functional bacteria in heavy oil extraction proposed in this application can achieve the expected effects of viscosity reduction, oil increase, and improved recovery rate, and can alleviate problems such as rapid decline in bacterial activity and short shelf life, thereby improving the low efficiency of heavy oil extraction and the large-scale application effect of microbial enhanced oil recovery.

[0031] Specifically, the process of identifying functional bacteria that match the viscous components of heavy oil includes: obtaining reservoir produced fluid; analyzing the composition of the reservoir produced fluid and extracting various hydrocarbon-degrading microorganisms from the produced fluid; conducting culture experiments on the hydrocarbon-degrading microorganisms and selecting functional bacteria that match the heavy oil from among the various hydrocarbon-degrading microorganisms. Through the extraction and culture of hydrocarbon-degrading microorganisms in the reservoir produced fluid, hydrocarbon-degrading microorganisms that play a significant role in the degradation of heavy oil in the reservoir can be screened based on the microbial community structure characteristics of different steam-affected areas. Furthermore, functional bacteria that match the specific reservoir can be selected from among a variety of hydrocarbon-degrading microorganisms.

[0032] Specifically, the process of culturing hydrocarbon-degrading microorganisms and selecting functional bacteria that match heavy oil from a variety of hydrocarbon-degrading microorganisms includes: culturing the hydrocarbon-degrading microorganisms in a pre-set culture medium containing heavy oil; analyzing the changes in the composition of the pre-set culture medium; and selecting one hydrocarbon-degrading microorganism as the functional bacteria based on the changes in composition. By culturing hydrocarbon-degrading microorganisms in a pre-set culture medium containing heavy oil, the changes in the composition of the pre-set culture medium can be analyzed, thereby determining the hydrocarbon-degrading microorganism with the optimal ability to degrade heavy oil.

[0033] Optionally, the preset culture medium is an inorganic salt culture medium, in which petroleum hydrocarbons corresponding to heavy oil are added.

[0034] Specifically, the process of selecting a hydrocarbon-degrading microorganism as a functional bacterium based on changes in composition includes: determining changes in asphaltenes content to assess the degree of degradation of heavy oil; determining the water-oil miscibility ratio to assess the degree of emulsification of heavy oil; and selecting the hydrocarbon-degrading microorganism corresponding to the highest degree of degradation and emulsification as the functional bacterium. The degree of emulsification can be assessed by visually observing the miscibility of the oil and water phases or by measuring the dispersed particle size of the oil phase, selecting hydrocarbon-degrading microorganisms from those with a particle size of less than 10 μm accounting for more than 60%. The microorganism with the largest reduction in asphaltenes content is determined to have the highest degree of degradation.

[0035] Specifically, the process of cultivating targeted culture media for functional bacteria using reservoir produced fluid as raw material includes: establishing a nutrient solution system for the targeted growth of functional bacteria; and culturing the targeted culture medium in the nutrient solution system. By establishing a nutrient solution system for the targeted growth of functional bacteria, environmental conditions can be provided for the growth of functional bacteria. Cultivating the targeted culture medium in the nutrient solution system can obtain the advantageous growth conditions for the functional bacteria and reduce the interference of other bacteria in the reservoir.

[0036] Specifically, the process of establishing a nutrient solution system for targeted growth of functional bacteria includes: obtaining reservoir produced fluid; separating the water and oil in the reservoir produced fluid to obtain produced water and produced oil; and adding functional bacteria and a pre-prepared culture medium containing heavy oil to the produced water as the base liquid to form the nutrient solution system. By utilizing the produced water in the reservoir produced fluid, the functional bacteria in the produced water are recycled at a high concentration, while simultaneously providing conditions for the preparation of the targeted culture medium.

[0037] Specifically, the process of culturing the targeted culture medium in the nutrient solution system includes: setting up multiple experimental systems with different concentrations and / or compositions of preset culture media; culturing multiple experimental systems; detecting the concentration and abundance of hydrocarbon-degrading microorganisms in the experimental systems; and using the preset culture medium corresponding to a hydrocarbon-degrading microorganism concentration and abundance greater than the preset concentration and abundance as the targeted culture medium. By adjusting the composition and concentration of the preset culture medium to obtain a targeted culture medium with a hydrocarbon-degrading microorganism concentration and abundance greater than the preset concentration and abundance, it is beneficial for the functional bacteria to have higher targeted enhancement, long-term effect, and anti-interference ability in viscosity reduction in oil reservoirs.

[0038] Optionally, the process of culturing multiple experimental systems includes: placing the experimental system in a shaker at 200 r / min for 7 days.

[0039] It should be noted that the petroleum hydrocarbons in the pre-set culture medium will not be adjusted. During the culture process, the other components will change according to the concentration of residual nutrients; if any are lacking, they must be replenished to the original concentration.

[0040] Specifically, before injecting functional bacteria and targeted culture medium into the reservoir, the process includes: sealing the water channel in the reservoir; and adjusting the injection-production well pattern according to the distribution of remaining oil. By sealing the water channel and adjusting the injection-production well pattern according to the distribution of remaining oil, it is possible to ensure that the remaining oil in the non-water channel direction is swept away at a higher injection pressure during the injection of functional bacteria. This helps the injected functional bacteria to contact the remaining heavy oil in the reservoir and form internal and external activation, thereby creating a microbial reservoir condition dominated by heterocyclic hydrocarbon degrading microorganisms and improving the oil displacement effect of functional bacteria.

[0041] Specifically, the process of sealing water channel passages in an oil reservoir includes: determining the recovery level of steam development; determining the sealing radius and range of the water channel passages based on the recovery level; sealing the corresponding water channel passages sequentially from largest to smallest within the sealing range; and setting a preset buffer time for pump shutdown to ensure that the pump shutdown pressure remains stable within the preset pressure range. Since the sealing is adaptive based on the size and dimensions of the water channel passages, within the sealing range, the plugging agent first enters the water channel passage with the largest sealing radius, and after solidification, it enters the next smaller water channel passage, until all water channel passages within the sealing range are sealed. This is beneficial for increasing the contact area between functional bacteria and the remaining oil in the reservoir, activating a large number of endogenous bacteria in the heavy oil. After sealing, the pump is shut down for observation; the pump head pressure stabilizes within the preset pressure range three minutes after shutdown to ensure the sealing effect.

[0042] Specifically, determining the sealing radius for blocking water channeling based on the recovery rate includes the following: if the recovery rate is greater than or equal to 35% and the steam channeling frequency during steam injection is greater than a preset frequency, the sealing range is determined to be greater than or equal to 20m and less than 35m; if the recovery rate is less than 35% and the steam channeling frequency is greater than the preset frequency, the sealing range is determined to be greater than or equal to 5m and less than 20m. Sealing water channeling channels of different radii based on the recovery rate and steam channeling frequency promotes contact between functional bacteria and the remaining heavy oil in the reservoir.

[0043] Specifically, before well production to generate reservoir produced fluids, the process includes: if functional bacteria and targeted culture medium are injected into the oil well, the well is shut down for a preset time to cultivate the functional bacteria; if functional bacteria and targeted culture medium are injected into the water well, they are injected using a slug injection method at a preset injection rate. Injecting functional bacteria into the oil well and shutting it down ensures sufficient time for bacterial growth and contact with crude oil, and prevents dilution of nutrients. Optionally, the well shutdown period for microbial propagation can be 7-30 days. Injecting and cultivating the bacteria in oil and water wells using different methods caters to various oil and gas extraction scenarios, offering greater applicability, and both aim to ensure an optimal growth environment for the functional bacteria and activate a large number of endogenous bacteria in heavy oil.

[0044] Specifically, the process of supplementing functional bacteria and targeted culture medium according to the test results to bring the concentration of functional bacteria to the preset concentration includes: when the concentration of functional bacteria is lower than 1.0 × 10⁻⁶... 6 When the concentration of CFU / ml is reached, functional bacteria and targeted culture medium are supplemented. Real-time monitoring is performed after oil-water separation to ensure the concentration of bacteria in the aqueous phase, guaranteeing optimal conditions for the growth of functional bacteria. The production water is maintained to ensure high levels of functional microorganisms after cyclic injection and production, creating conditions conducive to microbial turnover. The produced water can also be reused for cultivating targeted culture medium and functional bacteria.

[0045] Specifically, the process of supplementing functional bacteria and targeted culture medium based on test results to achieve the preset concentration of functional bacteria includes supplementing targeted culture medium at 0.2%-0.3% of the standard amount. Timely supplementation of targeted culture medium can ensure the growth of the added functional bacteria and ensure timely improvement in oil recovery.

[0046] Specifically, the preset concentration is 1.0 × 10⁻⁶. 8 cfu / ml.

[0047] This application achieves enhanced viscosity-reducing properties, longer-lasting effects, and stronger resistance to interference through targeted screening of functional bacteria, control of functional and dominant bacterial concentrations during the injection-production system, and effective activation of new functional bacteria. The recycling of effective functional bacteria and their products in the reservoir produced fluid reduces the continuous input of microorganisms and effectively activates dominant functional bacteria in heavy oil, lowering the input cost of microorganisms. Furthermore, because the reservoir produced fluid is effectively reinjected, it does not cause environmental pollution. Microbial cold recovery significantly reduces steam input, resulting in significant carbon reduction and efficiency gains. Using hot water at a temperature not exceeding 60℃ for microbial flooding increases the recovery rate by 15 percentage points.

[0048] Example 1

[0049] In this embodiment, 15 hydrocarbon-degrading microorganisms for oil production were extracted from the reservoir and screened and evaluated. After being cultured for 7 days in a shaker at 200 r / min using a pre-set culture medium, bacteria 1-2, 6-1, and 6-2 were selected based on the crude oil emulsification characteristics and bacterial concentration. The degree of degradation and emulsification of the crude oil by the three bacteria was evaluated, and bacteria 6-2 was selected as the functional bacteria for the well area.

[0050] Specifically, the preset culture medium is selected as an inorganic salt culture medium, and the components can be: 0.2-1.0 g / L sodium nitrate, 0.1-0.5 g / L ammonium sulfate, 0.01-0.05 g / L magnesium chloride, 3-10 g / L petroleum hydrocarbons, 0.3-1.0 g / L dipotassium hydrogen phosphate, 0.2-1.0 g / L sodium hydrogen phosphate, and 0.05-0.3 g / L yeast extract.

[0051] Specifically, produced fluid from the reservoir is obtained, and water and oil are separated to obtain produced water and produced oil. Using the produced water as a base solution, functional bacteria and a pre-prepared culture medium containing heavy oil are added and cultured on a shaker at 200 rpm for 7 days. The concentration and composition of the pre-prepared culture medium are adjusted, selecting hydrocarbon-degrading microorganisms with a concentration greater than 1 × 10⁻⁶. 8 The pre-set culture medium with cfu / ml and abundance greater than 60% is the target culture medium.

[0052] Specifically, based on the distribution of remaining oil, the corner wells of the original nine-point reverse steam-drive well network were converted into microbial reinjection wells, forming a new five-point reverse microbial injection-production well network. This aims to increase the contact area between functional bacteria and the remaining reservoir oil, and activate a large number of endogenous bacteria in heavy oil. After sealing the water channel, the pump was stopped for 5 minutes, and the pump stop pressure stabilized at around 2.5 MPa.

[0053] After adopting the functional bacteria recycling method for heavy oil extraction proposed in this application, the content of key viscosity-inducing components of heavy oil, namely gum and asphaltenes, decreased from the original 42.3% to 27.9%, effectively reducing crude oil viscosity, improving crude oil fluidity, and increasing oil production efficiency and capacity.

[0054] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0055] 1. This application achieves higher targeted enhancement, long-lasting effect and anti-interference of viscosity reduction function through targeted screening of functional bacteria, control of functional bacteria concentration and dominant bacteria concentration during injection and collection system, and effective activation of new functional bacteria.

[0056] 2. The recycling of effective functional bacteria and products in the reservoir produced fluid reduces the continuous input of microorganisms and effectively activates the dominant functional bacteria in heavy oil, thereby reducing the input cost of microorganisms.

[0057] 3. Since the produced fluid from the reservoir is effectively reinjected, it will not cause environmental pollution. Microbial cold extraction can significantly reduce steam input, resulting in significant carbon reduction and efficiency improvement benefits.

[0058] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0059] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0060] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recycling functional bacteria used in heavy oil extraction, characterized in that, include: Identify functional bacteria that match the viscosity-inducing components of heavy oil; Using reservoir produced fluid as raw material, a targeted culture medium corresponding to the functional bacteria was cultured. The functional bacteria and the targeted culture medium were injected into the oil reservoir; Wells are opened for production to generate fluids from the reservoir. The produced fluid from the reservoir is separated into water and oil to obtain produced water and produced oil; The concentration of the functional bacteria in the extracted water is monitored in real time, and the monitoring results are recorded. Based on the test results, supplement the functional bacteria and the targeted culture medium to bring the concentration of the functional bacteria to a preset concentration; The process of determining the functional bacteria that match the viscosity-inducing components of heavy oil includes: Obtain reservoir produced fluid; The composition of the produced fluid from the reservoir was analyzed, and various hydrocarbon-degrading microorganisms were extracted from the produced fluid. Culture experiments were conducted on the hydrocarbon-degrading microorganisms to select the functional bacteria that matched the heavy oil from a variety of hydrocarbon-degrading microorganisms; The process of culturing the hydrocarbon-degrading microorganisms and selecting the functional bacteria that match the heavy oil from a variety of hydrocarbon-degrading microorganisms includes: The hydrocarbon-degrading microorganisms were cultured in a pre-defined culture medium containing the heavy oil. Analyze the changes in the composition of the preset culture medium; Based on the changes in the composition, one of the hydrocarbon-degrading microorganisms was selected as the functional bacteria; The process of selecting a hydrocarbon-degrading microorganism as the functional bacterium based on the changes in composition includes: Determine the changes in asphaltene content to assess the degree of degradation of the heavy oil; Determine the water-oil miscibility ratio and assess the degree of emulsification of the heavy oil; The hydrocarbon-degrading microorganisms corresponding to the highest degree of degradation and the highest degree of emulsification are designated as the functional bacteria. The process of culturing the targeted culture medium corresponding to the functional bacteria using reservoir produced fluid as raw material includes: Establish a nutrient solution system for the targeted growth promotion of the aforementioned functional bacteria; The targeted culture medium is cultured in the nutrient solution system; The process of establishing the nutrient solution system for the targeted growth of the functional bacteria includes: Obtain the produced fluid from the reservoir; The produced fluid from the reservoir is separated into water and oil to obtain produced water and produced oil; Using the extracted water as the base liquid, the functional bacteria and a pre-set culture medium containing the heavy oil are added to form the nutrient solution system; The process of culturing the targeted culture medium in the nutrient solution system includes: Set up multiple experimental systems with different concentrations and / or different compositions of the preset culture medium; Cultivate multiple sets of the aforementioned experimental systems; The concentration and abundance of hydrocarbon-degrading microorganisms in the experimental system were detected. The preset culture medium corresponding to the concentration of hydrocarbon-degrading microorganisms being greater than the preset bacterial concentration and the abundance being greater than the preset abundance is used as the target culture medium for cultivation.

2. The method for recycling functional bacteria in heavy oil extraction according to claim 1, characterized in that, The process of culturing multiple experimental systems includes: placing the experimental system in a shaker at 200 r / min and culturing it for 7 days.

3. The method for recycling functional bacteria in heavy oil extraction according to claim 1, characterized in that, Prior to the process of injecting the functional bacteria and the targeted culture medium into the reservoir, the method further includes: Block the water channeling pathways of the reservoir; Adjust the injection and production well pattern according to the distribution of remaining oil.

4. The method for recycling functional bacteria in heavy oil extraction according to claim 3, characterized in that, The process of sealing the water channel in the oil reservoir includes: Determine the extent of steam recovery in steam development; Based on the extraction level, determine the sealing radius of the water flow channel to block the sealing range; Within the blocking range, the corresponding water flow channels are blocked sequentially according to the blocking radius from large to small. The pump shutdown has a preset buffer time to ensure that the pump shutdown pressure remains stable within the preset pressure range.

5. The method for recycling functional bacteria in heavy oil extraction according to claim 4, characterized in that, The process of determining the sealing radius for blocking the water leakage channel based on the extraction level includes: If the extraction rate is greater than or equal to 35%, and the frequency of steam leakage during steam injection is greater than the preset frequency, then the sealing range is determined to be greater than or equal to 20m and less than 35m. If the extraction rate is less than 35% and the frequency of gas leakage is greater than the preset frequency, then the blocking range is determined to be greater than or equal to 5m and less than 20m.

6. The method for recycling functional microorganisms used in heavy oil extraction according to any one of claims 1 to 5, characterized in that, Prior to the well-opening production process to produce the reservoir produced fluid, the process also includes: If the functional bacteria and the targeted culture medium are injected into the oil well, the oil well is shut down for a preset time to cultivate the functional bacteria; If the functional bacteria and the targeted culture medium are injected into the well, they are injected using a slug injection method at a preset injection rate.

7. The method for recycling functional microorganisms used in heavy oil extraction according to any one of claims 1 to 5, characterized in that, The process of supplementing the functional bacteria and the targeted culture medium according to the detection results to bring the concentration of the functional bacteria to a preset concentration includes: when the concentration of the functional bacteria is lower than 1.0 × 10⁻⁶. 6 When the cfu / ml level is reached, the functional bacteria and the targeted culture medium are supplemented.

8. The method for recycling functional bacteria in heavy oil extraction according to claim 7, characterized in that, The process of supplementing the functional bacteria and the targeted culture medium according to the test results to make the concentration of the functional bacteria reach the preset concentration includes: supplementing the targeted culture medium in an amount of 0.2%-0.3% of the standard amount.

9. The method for recycling functional microorganisms used in heavy oil extraction according to any one of claims 1 to 5, characterized in that, The preset concentration is 1.0 × 10⁻⁶. 8 cfu / ml.

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