Method for increasing production by microbial composite and application thereof

Abstract

The application belongs to the technical field of tertiary oil recovery, and particularly relates to a method for increasing production by microbial composite huff and puff and application thereof. The method for increasing production by microbial composite huff and puff comprises the following steps: (1) reservoir screening; (2) functional microbial system screening; and (3) physical model evaluation method. The application realizes the effects of the system and injection parameters by innovative indoor evaluation method, physical model displacement pressure and enhanced oil recovery. The application finally realizes the purposes of improving the channel blockage problem caused by high-wax crude oil and efficient development of high-wax crude oil in the reservoir, and the average single-well daily production is increased by more than 2t, and the economic efficiency is greater than 1:5.

Description

Technical Field

[0001] This invention belongs to the field of tertiary oil recovery technology, specifically relating to a method for enhancing oil production using microbial combined huff and puff and its application. Background Technology

[0002] With the continuous development of oil and gas resources, the properties of crude oil and reservoir conditions are becoming increasingly demanding. This type of reservoir not only has low permeability, but also exhibits the "double high" characteristics of high wax content and high asphaltene content in the crude oil.

[0003] Typically, the permeability of this type of reservoir is below 100 mD. The crude oil wax content is generally between 5% and 25%; the asphalt content is between 25% and 40%, and the viscosity of the underground crude oil at 50℃ is greater than 50 MPa·s. The coexistence of these two components leads to an increased wax precipitation point and decreased reservoir fluidity. For the development of this type of reservoir, fracturing is usually employed to release single-well productivity.

[0004] However, the single-well production capacity improvement effect of fracturing development is limited. The analysis suggests the following problems: 1. Existing evaluation methods only simulate reservoir development conditions, such as reservoir temperature and produced fluid composition, without considering the cold damage caused by the instantaneous low temperature after the injection of large doses of fluid during the application process, which further reduces the permeability of the near-wellbore zone; 2. Existing evaluation parameters only target crude oil properties and do not examine the flow dynamics and transport capacity of crude oil in porous media.

[0005] Microbial enhanced oil recovery (MEOR) utilizes the life activities and metabolic products of microorganisms in oil reservoirs to enhance crude oil production. This includes the biochemical processes of microbial growth, reproduction, and metabolism within the reservoir, as well as the migration of microbial cells, nutrient solutions, and metabolic products within the reservoir, and the alterations in the physical properties of rocks, oil, gas, and water caused by their interactions. MEOR is simple to implement and low-cost, making it an inexpensive and effective oil recovery technology that holds promise as one of the key technologies for stabilizing oil production, controlling water, and improving oil recovery rates in the later stages of oilfield development.

[0006] Chinese patent application No. 201310008012.4 discloses a method for improving the productivity of hydraulically fractured wells using a composite activator. This method involves introducing a composite activator A, comprising electron acceptors and nutrients, or a composite activator B, comprising microbial agents, into the target formation. In the target formation, the method selectively controls the proliferation and metabolic activity of microorganisms, removing formation contaminants and generating beneficial metabolites, thereby improving the productivity of the fractured well. This invention generates a microbial field in the reservoir space of the target formation, removing guar gum filter cake left from fracturing or heavy hydrocarbon contaminants caused by oil and gas production, improving the conductivity of the hydraulic fracture, and simultaneously generating beneficial microbial metabolites. This reduces the interfacial tension between the oil and water phases, emulsifies crude oil, and improves its fluidity, thereby improving the production enhancement effect of fracturing operations and increasing the productivity of the fractured well. However, this method only addresses the problem of polymer clogging of pores during fracturing and does not affect the crude oil in the reservoir, thus still resulting in a small increase in single-well productivity after the treatment.

[0007] Chinese patent application No. 201910788975.8 discloses an activator for targeted activation of core microorganisms and its application in microbial enhanced oil recovery (MEOR). The targeted activator is composed of yeast powder, soybean flour, trimethylammonium acetone, trace elements, nitric acid triacetic acid, corn starch, sodium polyphosphate, magnesium sulfate heptahydrate, and a target reservoir water sample. Compared with existing activator technologies, the activator provided by this invention can precisely and targetedly activate core microorganisms within the reservoir. These core microorganisms can directionally regulate the core metabolic pathways in the entire reservoir microbial community's metabolic activities, stabilizing the entire microbial community structure. Through the microbial community's own life activities, this reduces crude oil viscosity and pour point, improves crude oil fluidity, and increases crude oil recovery. This invention only focuses on the activation of endogenous microorganisms, primarily clarifying the effect by measuring the abundance of activated bacterial communities. Its effectiveness is not well-suited for low-temperature conditions of high-wax and high-colloidal asphalt crude oil. Summary of the Invention

[0008] Objective of the Invention: To address the shortcomings of existing technologies, this invention provides a method for enhancing oil production using a microbial combined huff and puff technique and its application, applicable to high-wax reservoirs. This invention includes microbial system screening and in-situ parameter optimization, encompassing reservoir screening conditions, system evaluation methods, and in-situ parameter optimization evaluation. This invention improves the channel blockage problem caused by cold damage in high-wax reservoirs, ultimately achieving efficient development of high-wax reservoirs within high-wax reservoirs.

[0009] Technical solution: A method for increasing yield using a combined microbial huff and puff technique, comprising the following steps:

[0010] (1) Reservoir screening;

[0011] (2) Screening of functional microbial systems;

[0012] (3) Physical model evaluation method.

[0013] The main design concept of this invention is as follows: Based on the evaluation of the biochemical performance of biological systems, this invention innovatively establishes a method for evaluating the state of crude oil after interaction under room temperature conditions. This method simulates the on-site injection process, more realistically representing the interaction effect between crude oil and the system under on-site conditions. It is simple to operate, and the indoor evaluation results are closer to the on-site effects, further improving the single-well success rate.

[0014] Invention Effects: The method for increasing yield using a microbial compound huff and puff technique disclosed in this invention and its application have the following beneficial effects:

[0015] By employing innovative indoor evaluation methods and combining physical model displacement pressure with enhanced oil recovery, the system's effects and injection parameters were clarified. Ultimately, this aimed to improve the channel blockage problem caused by high-wax crude oil, achieve efficient development of high-wax crude oil in reservoirs, increase average daily production per well by more than 2 tons, and achieve an economic efficiency greater than 1:5. Detailed Implementation

[0016] The specific embodiments of the present invention are described in detail below.

[0017] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.

[0018] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0019] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0020] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0021] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0022] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.

[0023] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.

[0024] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.

[0025] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0026] A method for increasing yield using a combined microbial spittoon and expiratory process includes the following steps:

[0027] (1) Reservoir screening;

[0028] (2) Screening of functional microbial systems;

[0029] (3) Physical model evaluation method.

[0030] Furthermore, the criteria for reservoir screening in step (1) are as follows:

[0031] The reservoir temperature is 30–120℃, the permeability is 10–500 mD, the oil layer thickness is greater than 3 m, the crude oil wax content is 2.5%–35%, the underground crude oil viscosity is ≤1000 mPa·s, the produced fluid salinity is less than 200,000 mg / L, and the crude oil pour point is higher than 25℃.

[0032] Furthermore, the screening of functional microbial systems in step (2) includes screening functional microorganisms and selecting a suitable activator system. For those skilled in the art, once the functional microorganisms are identified, the suitable activator system will naturally follow.

[0033] Furthermore, the parameters for screening the functional microbial system in step (2) include bacterial concentration, surface tension, wetting angle, crude oil viscosity reduction rate, pour point, and the state of crude oil after action at room temperature.

[0034] Furthermore, the steps for screening the functional microorganisms are as follows:

[0035] (21) The concentration of inorganic ions and total salinity in the produced fluid of the target reservoir were determined to determine the chemical composition of the produced fluid;

[0036] (22) Add nutrient solution to the product liquid, then add the product liquid to the anaerobic container, adjust the pH to 7, add exogenous functional bacteria with a volume concentration of 10-20%, and incubate at the oil reservoir temperature for at least 7 days.

[0037] (23) The bacterial concentration and solution properties of the culture medium were detected during the culture process;

[0038] (24) Based on the test results, bacteria concentrations ≥10 were screened. 7 Functional microorganisms with a bacterial count / ml, a bacterial suspension surface tension ≤29mN / m, and a bacterial suspension wetting angle ≤20°;

[0039] (25) The functional microorganisms screened in step (24) and their corresponding activator system are sequentially added to an anaerobic bottle containing formation water, and 20%-40% (by volume) of crude oil from the target block is added. After incubation for 2-5 days, the viscosity and pour point of the crude oil are tested, wherein:

[0040] After adding the functional microorganisms and activator system, if the crude oil viscosity reduction rate is ≥45% and the pour point change range is ≥3℃, then it meets the requirements and proceeds to step (26); otherwise, it does not meet the requirements.

[0041] (26) Screening and evaluation of cold damage systems:

[0042] For the functional microorganisms and their activator systems that were successfully screened in step (25), the optimal system was determined by the state of crude oil after treatment at room temperature. The method is as follows:

[0043] Add 30ml each of crude oil and liquid (formation water) to the anaerobic container, place it at the reservoir temperature and let it stand until the temperature is constant, then quickly add 40ml-45ml of the functional microorganisms and their activator system successfully screened in step (25). At this time, observe the state of crude oil under room temperature conditions, and clarify the effect under room temperature conditions according to the standards in the table below. The emulsification rating is divided into the following four levels according to the emulsification stability and the state of the emulsion oil droplets:

[0044]

[0045]

[0046] (27) When the emulsification rating is determined to be level three or above, the system can be used to evaluate and screen the best system, and the concentration to be used can be determined by comparing different emulsification performances.

[0047] Furthermore, in step (22), the nutrient solution is formulated with 1-3 g / L glucose, 3-5 g / L peptone, 0.1-0.3 g / L yeast powder, and 2-5 g / L glycerol.

[0048] Furthermore, the exogenous functional bacteria mentioned in step (22) are one or more of Bacillus cereus, hydrocarbon-loving bacteria, Pseudomonas aeruginosa, Bacillus cereus, Acinetobacter bacillus, thermophilic alkaliphiles and Pseudomonas aeruginosa.

[0049] Furthermore, the cultivation process described in step (23) takes 2-5 days.

[0050] Furthermore, the specific steps of step (3) are as follows:

[0051] A 10cm cemented core, consistent with reservoir conditions, was used, and saturated displacement was achieved using produced fluid and corresponding crude oil.

[0052] After saturation and improvement, the core samples were aged at the reservoir temperature for 3 days. Blank core samples were displaced using produced fluid, and the injection pressure was monitored during the displacement process. Samples were displaced using a microbial huff and puff system of a specific concentration, and the injection pressure was monitored during the process.

[0053] The injection rate for injecting blank samples and microbial systems is 10-15 ml / min, maintaining a high-speed, rapid injection state.

[0054] Place it back in the oil reservoir temperature and leave it for 2-7 days;

[0055] Finally, the produced fluid was used for secondary displacement at an injection rate of 1 ml / min. The displacement pressure and enhanced oil recovery data were observed, including:

[0056] When the displacement pressure decrease rate is greater than 50% and the enhanced oil recovery rate is ≥7%, the culture time at this time is the optimal well-closing cycle for the microbial ingestion and spit system.

[0057] The above-mentioned method of using microbial combined huff and puff to enhance production is applied to the exploitation of single wells in high-wax, low-permeability oil reservoirs.

[0058] In one embodiment

[0059] A method for increasing yield using a combined microbial spittoon and expiratory process includes the following steps:

[0060] (1) Reservoir screening;

[0061] (2) Screening of functional microbial systems;

[0062] (3) Physical model evaluation method.

[0063] Furthermore, the criteria for reservoir screening in step (1) are as follows:

[0064] The reservoir temperature is 30–120℃, the permeability is 10–500 mD, the oil layer thickness is greater than 3 m, the crude oil wax content is 2.5%–35%, the underground crude oil viscosity is ≤1000 mPa·s, the produced fluid salinity is less than 200,000 mg / L, and the crude oil pour point is higher than 25℃.

[0065] Furthermore, the screening of functional microbial systems in step (2) includes screening functional microorganisms and selecting a suitable activator system. For those skilled in the art, once the functional microorganisms are identified, the suitable activator system will naturally follow.

[0066] Furthermore, the parameters for screening the functional microbial system in step (2) include bacterial concentration, surface tension, wetting angle, crude oil viscosity reduction rate, pour point, and the state of crude oil after action at room temperature.

[0067] Furthermore, the steps for screening the functional microorganisms are as follows:

[0068] (21) The concentration of inorganic ions and total salinity in the produced fluid of the target reservoir were determined to determine the chemical composition of the produced fluid;

[0069] (22) Add nutrient solution to the product liquid, then add the product liquid to the anaerobic container, adjust the pH to 7, add exogenous functional bacteria with a volume concentration of 15%, and incubate at the oil reservoir temperature for 20 days.

[0070] (23) The bacterial concentration and solution properties of the culture medium were detected during the culture process;

[0071] (24) Based on the test results, bacteria concentrations ≥10 were screened. 7 Functional microorganisms with a bacterial count / ml, a bacterial suspension surface tension ≤29mN / m, and a bacterial suspension wetting angle ≤20°;

[0072] (25) The functional microorganisms screened in step (24) and their corresponding activator system were sequentially added to an anaerobic bottle containing formation water, and 30% (by volume) of crude oil from the target block was added. After culturing for 3 days, the viscosity and pour point of the crude oil were tested, where:

[0073] After adding the functional microorganisms and activator system, if the crude oil viscosity reduction rate is ≥45% and the pour point change range is ≥3℃, then it meets the requirements and proceeds to step (26); otherwise, it does not meet the requirements.

[0074] (26) Screening and evaluation of cold damage systems:

[0075] For the functional microorganisms and their activator systems that were successfully screened in step (25), the optimal system was determined by the state of crude oil after treatment at room temperature. The method is as follows:

[0076] Add 30ml each of crude oil and liquid (formation water) to the anaerobic container, place it at the reservoir temperature and let it stand until the temperature is constant, then quickly add 42ml of the functional microorganisms and their activator system successfully screened in step (25). At this time, observe the state of crude oil under room temperature conditions, and clarify the effect under room temperature conditions according to the standards in the table below. The emulsification rating is divided into the following four levels according to the emulsification stability and the state of the emulsified oil droplets:

[0077]

[0078] (27) When the emulsification rating is determined to be level three or above, the system can be used to evaluate and screen the best system, and the concentration to be used can be determined by comparing different emulsification performances.

[0079] Furthermore, in step (22), the nutrient solution is formulated with 2 g / L glucose, 4 g / L peptone, 0.2 g / L yeast powder, and 3 g / L glycerol.

[0080] Furthermore, the exogenous functional bacteria in step (22) are Pseudomonas. In another embodiment, the exogenous functional bacteria in step (22) are Bacillus subtilis, Hydrophila, Pseudomonas, Bacillus, Acinetobacter, thermophilic alkaliphiles, and Pseudomonas aeruginosa. In another embodiment, the exogenous functional bacteria in step (22) are Bacillus. In another embodiment, the exogenous functional bacteria in step (22) are Acinetobacter. In another embodiment, the exogenous functional bacteria in step (22) are thermophilic alkaliphiles. In another embodiment, the exogenous functional bacteria in step (22) are Pseudomonas aeruginosa.

[0081] Furthermore, the cultivation process described in step (23) takes 2-5 days.

[0082] Furthermore, the specific steps of step (3) are as follows:

[0083] A 10cm cemented core, consistent with reservoir conditions, was used, and saturated displacement was achieved using produced fluid and corresponding crude oil.

[0084] After saturation and improvement, the core samples were aged at the reservoir temperature for 3 days. Blank core samples were displaced using produced fluid, and the injection pressure was monitored during the displacement process. Samples were displaced using a microbial huff and puff system of a specific concentration, and the injection pressure was monitored during the process.

[0085] The injection rate for injecting blank samples and microbial systems is 10-15 ml / min, maintaining a high-speed, rapid injection state.

[0086] Place it back in the oil reservoir temperature and leave it for 2-7 days;

[0087] Finally, the produced fluid was used for secondary displacement at an injection rate of 1 ml / min. The displacement pressure and enhanced oil recovery data were observed, including:

[0088] When the displacement pressure decrease rate is greater than 50% and the enhanced oil recovery rate is ≥7%, the culture time at this time is the optimal well-closing cycle for the microbial ingestion and spit system.

[0089] The above-mentioned method of using microbial combined huff and puff to enhance production is applied to the exploitation of single wells in high-wax, low-permeability oil reservoirs.

[0090] In another embodiment

[0091] A method for increasing yield using a combined microbial spittoon and expiratory process includes the following steps:

[0092] (1) Reservoir screening;

[0093] (2) Screening of functional microbial systems;

[0094] (3) Physical model evaluation method.

[0095] Furthermore, the criteria for reservoir screening in step (1) are as follows:

[0096] The reservoir temperature is 30–120℃, the permeability is 10–500 mD, the oil layer thickness is greater than 3 m, the crude oil wax content is 2.5%–35%, the underground crude oil viscosity is ≤1000 mPa·s, the produced fluid salinity is less than 200,000 mg / L, and the crude oil pour point is higher than 25℃.

[0097] Furthermore, the screening of functional microbial systems in step (2) includes screening functional microorganisms and selecting a suitable activator system. For those skilled in the art, once the functional microorganisms are identified, the suitable activator system will naturally follow.

[0098] Furthermore, the parameters for screening the functional microbial system in step (2) include bacterial concentration, surface tension, wetting angle, crude oil viscosity reduction rate, pour point, and the state of crude oil after action at room temperature.

[0099] Furthermore, the steps for screening the functional microorganisms are as follows:

[0100] (21) The concentration of inorganic ions and total salinity in the produced fluid of the target reservoir were determined to determine the chemical composition of the produced fluid;

[0101] (22) Add nutrient solution to the product liquid, then add the product liquid to the anaerobic container, adjust the pH to 7, add exogenous functional bacteria with a volume concentration of 10%, and incubate at the oil reservoir temperature for 7 days.

[0102] (23) The bacterial concentration and solution properties of the culture medium were detected during the culture process;

[0103] (24) Based on the test results, bacteria concentrations ≥10 were screened. 7 Functional microorganisms with a bacterial count / ml, a bacterial suspension surface tension ≤29mN / m, and a bacterial suspension wetting angle ≤20°;

[0104] (25) The functional microorganisms screened in step (24) and their corresponding activator system were sequentially added to an anaerobic bottle containing formation water, and 20% (by volume) of crude oil from the target block was added. After culturing for 2 days, the viscosity and pour point of the crude oil were tested, where:

[0105] After adding the functional microorganisms and activator system, if the crude oil viscosity reduction rate is ≥45% and the pour point change range is ≥3℃, then it meets the requirements and proceeds to step (26); otherwise, it does not meet the requirements.

[0106] (26) Screening and evaluation of cold damage systems:

[0107] For the functional microorganisms and their activator systems that were successfully screened in step (25), the optimal system was determined by the state of crude oil after treatment at room temperature. The method is as follows:

[0108] Add 30ml each of crude oil and liquid (formation water) to the anaerobic container, place it at the reservoir temperature and let it stand until the temperature is constant, then quickly add 40ml-45ml of the functional microorganisms and their activator system successfully screened in step (25). At this time, observe the state of crude oil under room temperature conditions, and clarify the effect under room temperature conditions according to the standards in the table below. The emulsification rating is divided into the following four levels according to the emulsification stability and the state of the emulsion oil droplets:

[0109]

[0110] (27) When the emulsification rating is determined to be level three or above, the system can be used to evaluate and screen the best system, and the concentration to be used can be determined by comparing different emulsification performances.

[0111] Furthermore, in step (22), the nutrient solution is formulated with 1 g / L glucose, 3 g / L peptone, 0.1 g / L yeast powder, and 2 g / L glycerol.

[0112] Furthermore, the exogenous functional bacteria mentioned in step (22) are Bacillus geysersis.

[0113] Furthermore, the cultivation process described in step (23) takes 2 days.

[0114] Furthermore, the specific steps of step (3) are as follows:

[0115] A 10cm cemented core, consistent with reservoir conditions, was used, and saturated displacement was achieved using produced fluid and corresponding crude oil.

[0116] After saturation and improvement, the core samples were aged at the reservoir temperature for 3 days. Blank core samples were displaced using produced fluid, and the injection pressure was monitored during the displacement process. Samples were displaced using a microbial huff and puff system of a specific concentration, and the injection pressure was monitored during the process.

[0117] The injection rate for injecting blank samples and microbial systems was 10 ml / min, maintaining a high-speed, rapid injection state.

[0118] Place it back in the oil reservoir temperature and leave it for 2-7 days;

[0119] Finally, the produced fluid was used for secondary displacement at an injection rate of 1 ml / min. The displacement pressure and enhanced oil recovery data were observed, including:

[0120] When the displacement pressure decrease rate is greater than 50% and the enhanced oil recovery rate is ≥7%, the culture time at this time is the optimal well-closing cycle for the microbial ingestion and spit system.

[0121] The above-mentioned method of using microbial combined huff and puff to enhance production is applied to the exploitation of single wells in high-wax, low-permeability oil reservoirs.

[0122] In yet another embodiment

[0123] A method for increasing yield using a combined microbial spittoon and expiratory process includes the following steps:

[0124] (1) Reservoir screening;

[0125] (2) Screening of functional microbial systems;

[0126] (3) Physical model evaluation method.

[0127] Furthermore, the criteria for reservoir screening in step (1) are as follows:

[0128] The reservoir temperature is 30–120℃, the permeability is 10–500 mD, the oil layer thickness is greater than 3 m, the crude oil wax content is 2.5%–35%, the underground crude oil viscosity is ≤1000 mPa·s, the produced fluid salinity is less than 200,000 mg / L, and the crude oil pour point is higher than 25℃.

[0129] Furthermore, the screening of functional microbial systems in step (2) includes screening functional microorganisms and selecting a suitable activator system. For those skilled in the art, once the functional microorganisms are identified, the suitable activator system will naturally follow.

[0130] Furthermore, the parameters for screening the functional microbial system in step (2) include bacterial concentration, surface tension, wetting angle, crude oil viscosity reduction rate, pour point, and the state of crude oil after action at room temperature.

[0131] Furthermore, the steps for screening the functional microorganisms are as follows:

[0132] (21) The concentration of inorganic ions and total salinity in the produced fluid of the target reservoir were determined to determine the chemical composition of the produced fluid;

[0133] (22) Add nutrient solution to the product liquid, then add the product liquid to the anaerobic container, adjust the pH to 7, add exogenous functional bacteria with a volume concentration of 20%, and incubate at the oil reservoir temperature for at least 7 days.

[0134] (23) The bacterial concentration and solution properties of the culture medium were detected during the culture process;

[0135] (24) Based on the test results, bacteria concentrations ≥10 were screened. 7 Functional microorganisms with a bacterial count / ml, a bacterial suspension surface tension ≤29mN / m, and a bacterial suspension wetting angle ≤20°;

[0136] (25) The functional microorganisms screened in step (24) and their corresponding activator system were sequentially added to an anaerobic bottle containing formation water, and 40% (by volume) of crude oil from the target block was added. After culturing for 5 days, the viscosity and pour point of the crude oil were tested, where:

[0137] After adding the functional microorganisms and activator system, if the crude oil viscosity reduction rate is ≥45% and the pour point change range is ≥3℃, then it meets the requirements and proceeds to step (26); otherwise, it does not meet the requirements.

[0138] (26) Screening and evaluation of cold damage systems:

[0139] For the functional microorganisms and their activator systems that were successfully screened in step (25), the optimal system was determined by the state of crude oil after treatment at room temperature. The method is as follows:

[0140] Add 30ml each of crude oil and liquid (formation water) to the anaerobic container, place it at the reservoir temperature and let it stand until the temperature is constant, then quickly add 45ml of the functional microorganisms and their activator system successfully screened in step (25). At this time, observe the state of crude oil under room temperature conditions, and clarify the effect under room temperature conditions according to the standards in the table below. The emulsification rating is divided into the following four levels according to the emulsification stability and the state of the emulsified oil droplets:

[0141]

[0142]

[0143] (27) When the emulsification rating is determined to be level three or above, the system can be used to evaluate and screen the best system, and the concentration to be used can be determined by comparing different emulsification performances.

[0144] Furthermore, in step (22), the nutrient solution is formulated with 3 g / L glucose, 5 g / L peptone, 0.3 g / L yeast powder, and 5 g / L glycerol.

[0145] Furthermore, the exogenous functional bacteria mentioned in step (22) are hydrocarbon-loving bacteria.

[0146] Furthermore, the cultivation process described in step (23) takes 5 days.

[0147] Furthermore, the specific steps of step (3) are as follows:

[0148] A 10cm cemented core, consistent with reservoir conditions, was used, and saturated displacement was achieved using produced fluid and corresponding crude oil.

[0149] After saturation and improvement, the core samples were aged at the reservoir temperature for 3 days. Blank core samples were displaced using produced fluid, and the injection pressure was monitored during the displacement process. Samples were displaced using a microbial huff and puff system of a specific concentration, and the injection pressure was monitored during the process.

[0150] The injection rate for injecting blank samples and microbial systems was 12 ml / min, maintaining a high-speed, rapid injection state.

[0151] Place it back in the oil reservoir temperature and leave it for 2-7 days;

[0152] Finally, the produced fluid was used for secondary displacement at an injection rate of 1 ml / min. The displacement pressure and enhanced oil recovery data were observed, including:

[0153] When the displacement pressure decrease rate is greater than 50% and the enhanced oil recovery rate is ≥7%, the culture time at this time is the optimal well-closing cycle for the microbial ingestion and spit system.

[0154] The above-mentioned method of using microbial combined huff and puff to enhance production is applied to the exploitation of single wells in high-wax, low-permeability oil reservoirs.

[0155] Example 1

[0156] A method for increasing yield using a combined microbial spittoon and expiratory process includes the following steps:

[0157] (1) Reservoir screening:

[0158] In a certain block A, the reservoir temperature is 110℃, the underground crude oil viscosity is 138mN / m, the crude oil pour point is 37℃, the reservoir permeability is 10mD, the pressure is 17MPa, the target layer thickness is 3m, and the formation water salinity is 126000mg / L, which meets the screening criteria for microbial flooding in the test well area.

[0159] (2) Screening of functional microbial systems;

[0160] ① Ion testing of reservoir produced fluids

[0161] The concentration of inorganic ions and total salinity in the produced fluid of the target reservoir were measured to determine the chemical composition of the produced fluid. The salinity of 126,000 mg / L was less than the required 200,000 mg / L, indicating suitable conditions for the growth and metabolism of functional microorganisms.

[0162] Table 1. Ion Test Analysis of Produced Liquid from Block A Reservoir

[0163]

[0164]

[0165] ② Screening of exogenous functional bacteria

[0166] Add 3 g / L glucose, 2.7 g / L peptone, and 0.3 g / L yeast extract to the above-mentioned product liquid. Simultaneously, adjust the pH to 7 using sodium hydroxide, then place the solution in an anaerobic bottle and sterilize. Next, add one bottle each of exogenous bacteria at a volume concentration of 20%, including *Bacillus geysersis*, *Hydrogentodoxacarb*, *Pseudomonas*, *Bacillus*, *Acinetobacter*, thermophilic alkaliphiles, and *Pseudomonas aeruginosa*. Incubate at reservoir temperature for 5 days, observing changes in bacterial concentration and culture medium properties. Based on the results, select functional microorganisms with a bacterial concentration ≥10⁷ CFU / ml, a surface tension ≤29 mN / m, and a wetting angle ≤20° after culture, meeting the screening criteria, including *Bacillus geysersis*, *Bacillus*, and *Acinetobacter*.

[0167] Table 2. Evaluation results of exogenous functional bacteria screening

[0168]

[0169]

[0170] (3) Screening of activator systems

[0171] Three culture media were selected to evaluate the activation system, with formulations consisting of high sugar, high nitrogen, or average nutrition, respectively. The corresponding indicators for *Bacillus cereus*, *Acinetobacter*, and *Bacillus* met the requirements of crude oil viscosity reduction ≥45% and freezing point change ≥3℃. After comparing the effects of different systems, system three was selected as the optimal activation system.

[0172] Table 3 Composition of different activator systems

[0173]

[0174] Table 4. Screening and evaluation results of different activator systems

[0175]

[0176]

[0177] (4) Screening of optimal concentration for cold injury system

[0178] The selected functional microorganisms, including Bacillus subtilis, Acinetobacter, and Bacillus subtilis, along with an activator system, were added to an anaerobic flask at an oil-water volume ratio of 30 ml each. The oil sample was placed at reservoir temperature and allowed to stand until the temperature stabilized. Then, 30 ml of the selected system was rapidly added using a syringe, resulting in a final system concentration of 10-30%. The state of the crude oil was then observed at room temperature. The evaluation results are shown in the table below: According to the emulsification rating requirements, the selected Bacillus subtilis and its corresponding nutrient system achieved an emulsification rating of level four, which is the final system for field application; the optimal injection concentration of the system is 30%.

[0179] Table 5. Emulsification Evaluation Effects of Different Systems

[0180]

[0181]

[0182] (5) Screening of well shut-in cycle

[0183] Using 10cm cemented cores, saturation displacement was performed with produced fluid and corresponding crude oil. After saturation, the cores were aged at reservoir temperature for 3 days. Blank cores were displaced using produced fluid, with monitoring of injection pressure changes during the displacement process. Samples were displaced using a microbial huff and puff system containing 30% *Bacillus subtilis* and System 3. The injection rate for both the blank sample and the microbial system was 10-15 ml / min, maintaining a high-speed injection. The cores were then placed back at reservoir temperature for 2-7 days. Finally, a second displacement was performed using produced fluid at an injection rate of 1 ml / min. The displacement pressure and enhanced oil recovery (EOR) data were observed for different well-closing times. The results showed that a 5-day well-closing time with 30% *Bacillus subtilis* and System 3 as the microbial huff and puff system was the optimal huff and puff cycle.

[0184] Table 6 Comparison of Displacement Parameters for Different Well-Stopping Cycles

[0185]

[0186]

[0187] (6) Field application and effect analysis

[0188] The prepared 30% Bacillus subtilis and system three were injected into the annulus of the oil well casing, and the well shut-in period was selected as 5 days according to the functional bacteria. The peak daily oil production of a single well increased from 2.5t to 5.3t, while the water cut did not increase significantly. The oil production of a single well during the cycle reached 1820t, and the input-output ratio was greater than 1:5.2.

[0189] Example 2

[0190] A method for increasing yield using a combined microbial spittoon and expiratory process includes the following steps:

[0191] (1) Reservoir screening: In a certain block B, the reservoir temperature is 80℃, the underground crude oil viscosity is 375mN / m, the crude oil pour point is 40℃, the reservoir permeability is 150mD, the pressure is 12MPa, the target layer thickness is 5m, and the formation water salinity is 73600mg / L, which meets the screening criteria for microbial flooding in the test well area.

[0192] (2) Screening of functional microbial systems;

[0193] ① Ion testing of reservoir produced fluids

[0194] The concentration of inorganic ions and total salinity in the produced fluid of the target reservoir were measured to determine the chemical composition of the produced fluid. The salinity of 73,600 mg / L was less than the required 200,000 mg / L. Therefore, it is suitable for the growth and metabolism of exogenous functional bacteria.

[0195] Table 7 Analysis of Ion Tests in Produced Liquid from Reservoir Block A Table 7.

[0196]

[0197]

[0198] ② Screening and evaluation of exogenous functional bacteria

[0199] Add 3 g / L glucose, 2.7 g / L peptone, and 0.3 g / L yeast extract to the above-mentioned product liquid. Simultaneously, adjust the pH to 7 using sodium hydroxide, then place the liquid in an anaerobic bottle and sterilize. Next, add one bottle each of exogenous bacteria at a volume concentration of 20%, including *Bacillus geysersis*, *Hydrogentodoxacarb*, *Pseudomonas*, *Bacillus*, *Acinetobacter*, thermophilic alkaliphiles, and *Pseudomonas aeruginosa*. Incubate at reservoir temperature for 5 days, observing changes in bacterial concentration and culture medium properties. Based on the results, select functional microorganisms with a bacterial concentration ≥10⁷ CFU / ml, a surface tension ≤29 mN / m, and a wetting angle ≤20° after culturing *Bacillus geysersis*, *Hydrogentodoxacarb*, and *Pseudomonas* that meet the screening criteria.

[0200] Table 8. Evaluation results of screening for exogenous functional bacteria

[0201]

[0202]

[0203] (3) Screening of activator systems

[0204] Three culture media were selected to evaluate the activation system, with formulations consisting of high sugar, high nitrogen, or average nutrition, respectively. The corresponding indicators for *Bacillus cereus*, *Hydrogentodoxacarb*, and *Pseudomonas* met the requirements of crude oil viscosity reduction ≥45% and freezing point change ≥3℃. After comparing the effects of different systems, System 1 was selected as the optimal activation system.

[0205] Table 9 Composition of different activator systems

[0206]

[0207] Table 10 Screening and evaluation results of different activator systems

[0208]

[0209] (4) Screening of optimal concentration for cold injury system

[0210] The selected functional microorganisms, including *Bacillus subtilis*, *Hydrogentodoxacarb*, *Pseudomonas*, and activator system one, were added to an anaerobic flask at an oil-to-water volume ratio of 30 ml each. The oil sample was placed at reservoir temperature and allowed to stand until the temperature stabilized. Then, 45 ml of the selected system was rapidly added using a syringe, resulting in a final system concentration of 10-30%. The state of the crude oil was then observed at room temperature. The evaluation results are shown in the table below: According to the emulsification rating requirements, the selected hydrophilic bacteria and its corresponding nutrient system achieved an emulsification rating of Level III, making it the final system for field application; the optimal injection concentration of the system was 10%.

[0211] Table 11 Emulsification Evaluation Effects of Different Systems

[0212]

[0213] (5) Composite system injection process

[0214] Using 10cm cemented cores, saturation displacement was performed with produced fluid and corresponding crude oil. After saturation, the cores were aged at reservoir temperature for 3 days. Blank cores were displaced using produced fluid, with monitoring of injection pressure changes during the displacement process. Samples were displaced using a microbial huff and puff system containing 10% hydrocarbon-loving bacteria and System 1. The injection rate for both the blank sample and the microbial system was 10-15 ml / min, maintaining a high-speed injection. The cores were then placed back at reservoir temperature for 2-7 days. Finally, a second displacement was performed using produced fluid at an injection rate of 1 ml / min, and the displacement pressure and enhanced oil recovery (EOR) data were observed at different well-closing times. From an economic perspective, a well-closing time of 2 days for the 10% hydrocarbon-loving bacteria and System 1 microbial huff and puff system is considered the optimal huff and puff cycle.

[0215] Table 12 Comparison of Displacement Parameters for Different Well-Stopping Cycles

[0216]

[0217]

[0218] (6) Field application of microbial anti-adsorption system

[0219] The prepared 10% hydrocarbon-loving bacteria and system 1 were injected into the annulus of the oil well casing, and the well shut-in period was selected as 2 days according to the functional bacteria. The peak daily oil production of a single well increased from 1.5t to 3.7t, while the water cut did not increase significantly. The oil production of a single well during the cycle reached 1039t, and the input-output ratio was greater than 1:5.0.

[0220] Example 3

[0221] A method for increasing yield using a combined microbial spittoon and expiratory process includes the following steps:

[0222] (1) Reservoir screening: In a certain block C, the reservoir temperature is 60℃, the underground crude oil viscosity is 705mN / m, the crude oil pour point is 33℃, the reservoir permeability is 400mD, the pressure is 8MPa, the target layer thickness is 5m, and the formation water salinity is 60000mg / L, which meets the screening criteria for microbial flooding in the test well area.

[0223] (2) Screening of functional microbial systems;

[0224] ① Ion testing of reservoir produced fluids

[0225] The concentration of inorganic ions and total salinity in the produced fluid of the target reservoir were measured to determine the chemical composition of the produced fluid. The salinity of 42,000 mg / L was less than the required 100,000 mg / L. Therefore, it is suitable for the growth and metabolism of exogenous functional bacteria.

[0226] Table 13 Ion Test Analysis of Produced Liquid from Block A Reservoir 13

[0227]

[0228] ② Screening and evaluation of exogenous functional bacteria

[0229] Add 3 g / L glucose, 2.7 g / L peptone, and 0.3 g / L yeast extract to the above-mentioned product liquid. Simultaneously, adjust the pH to 7 using sodium hydroxide, then place the solution in an anaerobic bottle and sterilize. Next, add one bottle each of exogenous bacteria at a volume concentration of 20%, including *Bacillus cereus*, *Hydrogentodoxacarb*, *Pseudomonas*, *Bacillus*, *Acinetobacter*, thermophilic alkaliphiles, and *Pseudomonas aeruginosa*. Incubate at reservoir temperature for 5 days, observing changes in bacterial concentration and culture medium properties. Based on the results, select functional microorganisms with a bacterial concentration ≥10⁷ CFU / ml, a surface tension ≤29 mN / m, and a wetting angle ≤20° for *Pseudomonas*, *Acinetobacter*, and *Pseudomonas aeruginosa*, meeting the screening criteria.

[0230] Table 14. Evaluation results of screening for exogenous functional bacteria

[0231]

[0232]

[0233] (3) Screening of activator systems

[0234] Three culture media were selected to evaluate the activation system, with formulations consisting of high sugar, high nitrogen, or average nutrition, respectively. The corresponding indicators for Pseudomonas, Acinetobacter, and Pseudomonas aeruginosa met the requirements of crude oil viscosity reduction ≥45% and freezing point change ≥3℃. After comparing the effects of different systems, System 2 was selected as the optimal activation system.

[0235] Table 15 Composition of different activator systems

[0236]

[0237] Table 16 Screening and evaluation results of different activator systems

[0238]

[0239] (4) Screening and evaluation of cold damage systems

[0240] The selected functional microorganisms, including *Pseudomonas aeruginosa*, *Acinetobacter*, and *Pseudomonas aeruginosa*, and activator system one, were added to an anaerobic flask at an oil-water volume ratio of 30 ml each. The oil sample was placed at reservoir temperature and allowed to stand until the temperature stabilized. Then, 45 ml of the selected system was quickly added using a syringe, resulting in a final system concentration of 10-30%. The state of the crude oil was then observed at room temperature. The evaluation results are shown in the table below: According to the emulsification rating requirements, the selected *Pseudomonas aeruginosa* and its corresponding nutrient system achieved an emulsification rating of level four, making it suitable for final field application; the optimal injection concentration of the system was 20%.

[0241] Table 17 Emulsification Evaluation Effects of Different Systems

[0242]

[0243] (5) Screening of well shut-in cycle

[0244] Using 10cm cemented core samples, saturation displacement was performed with produced fluid and corresponding crude oil. After saturation, the core samples were aged at reservoir temperature for 3 days. Blank core samples were displaced using produced fluid, with monitoring of injection pressure changes during the displacement process. Samples were displaced using a microbial huff and puff system containing 20% ​​*Pseudomonas aeruginosa* and System II. The injection rate for both the blank sample and the microbial system was 10-15 ml / min, maintaining a high-speed injection. The samples were then placed back at reservoir temperature for 2-7 days. Finally, a second displacement was performed using produced fluid at an injection rate of 1 ml / min, and the displacement pressure and enhanced oil recovery (EOR) data were observed at different well-closing times. From an economic perspective, a well-closing time of 7 days using 20% ​​*Pseudomonas aeruginosa* and System II as the microbial huff and puff system is considered the optimal huff and puff cycle.

[0245] Table 18 Comparison of Displacement Parameters for Different Well-Stopping Cycles

[0246] Well-sealing cycle / day Displacement pressure (MPa) Increase recovery rate / % 2 3 5.3 5 2 7.1 7 2 7.3

[0247] (5) On-site application and effect analysis.

[0248] The prepared 20% Pseudomonas aeruginosa and System II were injected into the annulus of the oil well casing, and the well shut-in period was selected as 7 days according to the functional bacteria. The peak daily oil production of a single well increased from 1.2t to 3.9t, and the oil production of a single well during the cycle reached 1290t, with an input-output ratio greater than 1:5.0.

[0249] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method for increasing yield using a microbial compound huff and puff technique, characterized in that, The steps are as follows: (1) Reservoir screening; (2) Screening of functional microbial systems; (3) Physical model evaluation method.

2. The method for increasing yield using a microbial compound huff and puff process as described in claim 1, characterized in that, The criteria for reservoir screening in step (1) are as follows: The reservoir temperature is 30–120℃, the permeability is 10–500 mD, the oil layer thickness is greater than 3 m, the crude oil wax content is 2.5%–35%, the underground crude oil viscosity is ≤1000 mPa·s, the produced fluid salinity is less than 200,000 mg / L, and the crude oil pour point is higher than 25℃.

3. The method for increasing yield using a microbial compound huff and puff process as described in claim 1, characterized in that, The functional microbial system screening in step (2) includes the screening of functional microorganisms and the selection of an appropriate activator system.

4. The method for increasing yield using a microbial compound huff and puff process as described in claim 1, characterized in that, The parameters for screening the functional microbial system in step (2) include bacterial concentration, surface tension, wetting angle, crude oil viscosity reduction rate, pour point, and the state of crude oil after action at room temperature.

5. The method for increasing yield using a microbial compound huff and puff process as described in claim 3, characterized in that, The steps for screening functional microorganisms are as follows: (21) The concentration of inorganic ions and total salinity in the produced fluid of the target reservoir were determined to determine the chemical composition of the produced fluid; (22) Add nutrient solution to the product liquid, then add the product liquid to the anaerobic container, adjust the pH to 7, add exogenous functional bacteria with a volume concentration of 10-20%, and incubate at the oil reservoir temperature for at least 7 days. (23) The bacterial concentration and solution properties of the culture medium were detected during the culture process; (24) Based on the test results, bacteria concentrations ≥10 were screened. 7 Functional microorganisms with a bacterial count / ml, a bacterial suspension surface tension ≤29mN / m, and a bacterial suspension wetting angle ≤20°; (25) The functional microorganisms screened in step (24) and their corresponding activator system are sequentially added to an anaerobic bottle containing formation water, and 20%-40% (by volume) of crude oil from the target block is added. After incubation for 2-5 days, the viscosity and pour point of the crude oil are tested, wherein: After adding the functional microorganisms and activator system, if the crude oil viscosity reduction rate is ≥45% and the pour point change range is ≥3℃, then it meets the requirements and proceeds to step (26); otherwise, it does not meet the requirements. (26) Screening and evaluation of cold damage systems: For the functional microorganisms and their activator systems that were successfully screened in step (25), the optimal system was determined by the state of crude oil after treatment at room temperature. The method is as follows: Add 30ml each of crude oil and liquid to the anaerobic container, place it at the reservoir temperature and let it stand until the temperature is constant, then quickly add 40ml-45ml of the functional microorganisms and their activator system successfully screened in step (25). At this time, observe the state of crude oil under room temperature conditions, and clarify the effect under room temperature conditions according to the standards in the table below. The emulsification rating is divided into the following four levels according to the emulsification stability and the state of the emulsion oil droplets: (27) When the emulsification rating is determined to be level three or above, the system can be used to evaluate and screen the best system, and the concentration to be used can be determined by comparing different emulsification performances.

6. The method for increasing yield using a microbial compound huff and puff process as described in claim 5, characterized in that, In step (22), the nutrient solution is formulated with 1-3 g / L glucose, 3-5 g / L peptone, 0.1-0.3 g / L yeast powder, and 2-5 g / L glycerol.

7. The method for increasing yield using a microbial compound huff and puff process as described in claim 5, characterized in that, The exogenous functional bacteria mentioned in step (22) are one or more of Bacillus terrestris, Hydrophila, Pseudomonas, Bacillus, Acinetobacter, thermophilic alkaliphila, and Pseudomonas aeruginosa.

8. The method for increasing yield using a microbial compound huff and puff process as described in claim 5, characterized in that, The cultivation process described in step (23) takes 2-5 days.

9. The method for increasing yield using a microbial compound huff and puff process as described in claim 1, characterized in that, The specific steps of step (3) are as follows: A 10cm cemented core, consistent with reservoir conditions, was used, and saturated displacement was achieved using produced fluid and corresponding crude oil. After saturation and improvement, the core samples were aged at the reservoir temperature for 3 days. Blank core samples were displaced using produced fluid, and the injection pressure was monitored during the displacement process. Samples were displaced using a microbial huff and puff system of a specific concentration, and the injection pressure was monitored during the process. The injection rate for injecting blank samples and microbial systems is 10-15 ml / min, maintaining a high-speed, rapid injection state. Place it back in the oil reservoir temperature and leave it for 2-7 days; Finally, the produced fluid was used for secondary displacement at an injection rate of 1 ml / min. The displacement pressure and enhanced oil recovery data were observed, including: When the displacement pressure decrease rate is greater than 50% and the enhanced oil recovery rate is ≥7%, the culture time at this time is the optimal well-closing cycle for the microbial ingestion and spit system.

10. The application of the microbial combined huff and puff method as described in any one of claims 1-9 in the exploitation of single wells in high-wax, low-permeability oil reservoirs.

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