Method for determining remaining oil using microbial tropism and enhanced oil recovery method

Abstract

The application discloses a method for determining residual oil by using microbial tropism, which comprises the following steps: (1) selection of test oil reservoir; (2) simulation experiment; (3) determination of the relationship between the concentration of hydrocarbon bacteria and residual oil; (4) determination of residual oil in the test oil reservoir. A method for enhanced oil recovery comprises the following steps: determining the residual oil of at least one oil-water well in the test oil reservoir by the above method, and formulating corresponding measures for the oil-water well according to the distribution rule of the residual oil in the test oil reservoir. The application has the following beneficial effects: (1) the method is accurate, simple and reliable; (2) targeted improvement measures are formulated according to different residual oil saturations, and the method has target and purpose, thereby ensuring the effect on site; (3) the method is safe and environmentally friendly; (4) after the application on site, the single-well production of the oil reservoir is increased by more than 20%, the water content is reduced by more than 5%, the average oil production of a well group is increased by more than 10,000 tons, and the oil reservoir recovery rate is improved.

Description

Technical Field

[0001] This invention belongs to the field of tertiary oil recovery technology, specifically relating to a method for determining remaining oil using microbial tropism and an enhanced oil recovery method. Background Technology

[0002] After a long period of water injection development, the injected water advances along a fixed flow line, creating ineffective circulation. This results in variations in the location and degree of dispersion of residual oil between the injection wells and different oil wells. Therefore, how to determine the residual oil between different oil and water wells and effectively utilize it is a pressing development problem that oil fields urgently need to solve.

[0003] Currently, methods for determining residual oil mainly include single-well residual oil saturation determination, inter-well residual oil determination, and material balance methods. Single-well residual oil saturation determination methods include coring, tracer analysis, and logging. Inter-well residual oil determination methods include resistivity methods and inter-well tracer testing. However, different methods have varying applicability and accuracy, and the various methods involved require the use of corresponding testing and detection technologies, resulting in relatively high costs. Furthermore, some reagents used pose potential environmental hazards. Therefore, more accurate, effective, economical, and environmentally friendly new technologies are needed to achieve effective assessment of inter-well residual oil.

[0004] Microbial enhanced oil recovery (DEFR), a rapidly developing tertiary oil recovery technology, has been widely applied in various oilfields with good results. In particular, different types of functional bacteria can work synergistically to utilize crude oil in reservoirs, effectively extracting residual oil and thus increasing well production.

[0005] Chinese invention patent application CN 110452866 A discloses an activator for targeted activation of core microorganisms and its application in microbial enhanced oil recovery. Its main purpose is to provide an activator that can target and activate core microorganisms inside the reservoir, thereby regulating the core metabolic pathways in the metabolic activities of the entire reservoir microbial community, reducing crude oil viscosity and pour point, improving crude oil fluidity, and increasing crude oil recovery rate.

[0006] Chinese invention patent application CN112983367 A discloses the application and method of Toxoplasma gondii in the evaluation of the effect of microbial enhanced oil recovery field test. The effect of the microbial enhanced oil recovery field test is judged by measuring the change in the abundance of Toxoplasma gondii in the formation before and after microbial enhanced oil recovery.

[0007] The above patents propose various methods for microbial flooding from the perspective of activators or microorganisms, but they still have the following shortcomings: (1) The methods of the existing patents are all general activations of different functional microorganisms in the reservoir, which cannot achieve truly accurate and effective targeted activation of the remaining oil; (2) After microbial activation, they cannot achieve efficient effects on the remaining oil in different parts of the reservoir. Most of them, even if they are effective activating functional bacteria, will be ineffectively recycled out of the large channels with the injected water, which cannot achieve effective judgment of the remaining oil and accurately act on the remaining oil; (3) On-site detection of a certain special functional bacteria can reflect the activation, growth or migration and production of a certain functional bacteria, but it may not necessarily represent the good or bad of the on-site effect, nor can it represent the good or bad effect of the microorganisms on the remaining oil. Further investigation and evaluation are needed. Therefore, for the above patents, it is necessary to achieve efficient effects on different remaining oils in the reservoir by utilizing the growth and metabolism of microorganisms based on accurate analysis and judgment of the remaining oil.

[0008] The purpose of this invention is to inject hydrocarbon-loving microbial strains into the reservoir and use the concentration of hydrocarbon-loving bacteria in the produced fluid to determine the remaining oil status between the injection well and the oil well. This allows for the development of corresponding microbial oil displacement measures for different individual wells, thereby achieving accurate assessment of the remaining oil in the reservoir and efficient utilization of the remaining oil. Summary of the Invention

[0009] Objective of the Invention: To address the shortcomings of the existing technologies, this invention provides a method for determining remaining oil using microbial tropism and an enhanced oil recovery method. This method has the advantages of high accuracy, strong operability, and good field results, enabling efficient utilization of remaining oil in reservoirs and further improving the recovery rate by more than 15%.

[0010] Technical solution: A method for determining residual oil using microbial tropism, comprising the following steps:

[0011] (1) Screening of test reservoirs;

[0012] (2) Simulation experiment;

[0013] (3) Determining the relationship between hydrocarbon-loving bacteria concentration and residual oil;

[0014] (4) Determination of remaining oil in the test reservoir.

[0015] Furthermore, the conditions for selecting the test reservoir in step (1) are as follows: the test reservoir is a normally formed reservoir, the reservoir temperature is <90℃, the original formation pressure is <20MPa, and the permeability is >100×10⁻⁶. -3 μm 2 Formation water salinity <200,000 mg / L, crude oil viscosity <50,000 mPa·s, and original oil saturation >50%.

[0016] Furthermore, the specific steps of step (2) are as follows:

[0017] (21) The sand-filled core of the test reservoir was washed to produce a standard core of Φ38×600mm;

[0018] (22) Formation water in a vacuum-sealed, saturated test reservoir;

[0019] (23) Dehydrated and degassed crude oil from a saturated test reservoir;

[0020] (24) After aging and storage for 7 days, water flooding was performed once, and the core was water flooded to different residual oil saturation.

[0021] (25) Hydrophilic bacteria were injected into the core after one water flooding at a volume of 0.1 PV. The number of hydrophilic bacteria in the produced fluid was monitored after injection.

[0022] Furthermore, the hydrocarbon-loving bacteria is one of the following: hydrocarbon-degrading bacteria, symbiotic bacteria, spirochetes, halophilic bacteria, marine bacteria, hydrocarbon-loving pseudomonads, and hydrogen-producing bacteria.

[0023] Furthermore, the hydrocarbon-loving bacteria are hydrocarbon-degrading bacteria or marine bacteria.

[0024] Furthermore, the determination of the number of hydrocarbon-loving bacteria mentioned in step (25) is carried out using the quantitative real-time PCR method of molecular biology. The concentration is determined by the number of functional gene copies. The specific steps are as follows:

[0025] (251) Preparation of the real-time PCR reaction system:

[0026] The quantitative detection reaction system for hydrocarbon-loving bacteria is 20 μL, which includes 10 μL of real-time PCR reaction enzyme system, 0.2 μL each of 0.02 nmol / μL upstream and downstream primers, 1 μL of template DNA, and 8.6 μL of sterile water. Each sample is tested in 3 parallel experiments. The reaction solution is prepared in a 96-well sterile reaction plate.

[0027] The standard plasmid reaction system for constructing the standard curve is 20 μL, with the same composition as above, wherein 1 μL of template DNA is selected from 1×10⁻⁶. 2 copy / mL, 1×10 4 copy / mL, 1×10 6 copy / mL and 1×10 8 Four gradients of standard plasmid solutions were prepared at a ratio of 4 copies / mL, and each standard plasmid was used in three parallel experiments.

[0028] (252) Steps for Real-Time PCR Amplification

[0029] When the reaction primer Tm value is greater than or equal to 60℃, the amplification includes:

[0030] Step 1: Pre-denaturation at 95℃ for 3 minutes;

[0031] Step 2: Denature at 95℃ for 10s, anneal at 60℃ for 30s, repeat Step 2 40 times, and detect fluorescence signal during reaction at 60℃;

[0032] When the reaction primer Tm value is less than 60℃, the amplification includes:

[0033] S1: Pre-denaturation at 95℃ for 3 minutes;

[0034] S2: Denaturation at 95℃ for 10s, annealing at 30s, extension at 72℃ for 30s, repeat step 2 for 40 cycles, and detect fluorescence signal during reaction at 72℃.

[0035] (253) Analysis of Real-Time PCR Data:

[0036] A standard curve is plotted with the logarithm of the standard plasmid copy concentration on the x-axis and the measured Ct value on the y-axis. When quantifying hydrocarbon-loving bacteria samples, the hydrocarbon-loving bacteria gene copy concentration in the sample can be obtained from the standard curve based on the sample's Ct value.

[0037] Furthermore, in step (25), the concentration of hydrocarbon-loving bacteria injected is log functional gene copy number between 8 and 9.

[0038] Furthermore, in step (3), the relationship between the concentration of hydrocarbon-loving bacteria and the saturation of residual oil between oil and water wells is determined based on the number of hydrocarbon-loving bacteria in the produced fluid, and the saturation of residual oil between oil and water wells is determined based on the relationship between the concentration of hydrocarbon-loving bacteria and the residual oil.

[0039] The relationship between the concentration of hydrocarbon-loving bacteria in the produced fluid and the residual oil saturation between oil and water wells is shown in the table below, where: the concentration of hydrocarbon-loving bacteria is log functional gene copy number;

[0040] Table of Correlation between Hydrophilic Bacteria Concentration in Produced Fluid and Residual Oil Saturation Between Oil and Water Wells

[0041] Serial Number Residual oil saturation between oil and water wells Concentration of hydrocarbon-loving bacteria in the effluent 1 40％-45％ 2-3 2 30％-40％ 3-4 3 25％-30％ 4-5 4 20％-25％ 5-6 5 <20％ >7

[0042] Furthermore, step (4) includes the following steps:

[0043] (41) Hydrophilic bacteria were injected into the water injection wells of the test reservoir, wherein the concentration of the injected hydrophilic bacteria was log and the copy number of the functional gene was 8 to 9;

[0044] (42) Detect the concentration of hydrocarbon-loving bacteria in the oil well produced fluid. The detection cycle is 3-5 days and the number of detections is 8-10.

[0045] (43) Determine the remaining oil in the test reservoir based on the concentration of hydrocarbon-loving bacteria in the produced liquid and the relationship between the concentration of hydrocarbon-loving bacteria and the remaining oil determined in step (3).

[0046] An enhanced oil recovery method includes the following steps:

[0047] The remaining oil in at least one oil-water well in the test reservoir is determined using any of the methods described above. Based on the distribution pattern of the remaining oil in the test reservoir, corresponding measures for the oil-water wells are formulated. The concentration of hydrocarbon-loving bacteria in the produced fluid of the oil-water wells and the corresponding measures for the oil-water wells are shown in the table below.

[0048] Table of Correspondence between Hydrophilic Bacteria Concentration in Produced Fluid and Oil-Water Well Measures

[0049] Further, the hydroxylophilic functional bacteria activation system comprises 2.5-4.5 g / L corn steep liquor powder, 0.5-1.5 g / L potassium dihydrogen phosphate, 0.2-0.5 g / L sodium nitrate, 15-20 mL / L trace element solution, and the remainder being water, wherein:

[0050] Trace element liquid includes: N(CH2COOH)3 4~5g / L, MnCl2·4H2O 0.1~0.2g / L, KAl(SO4) 20.01~0.02g / L, NaCl 0.5~2g / L, Na2MoO4 0.01~0.05g / L, FeCl2·4H2O 0.2~0.6g / L, CoCl2·6H2O 0.05~0.2g / L, ZnCl2 0.05~0.2g / L, CaCl2 0.01~0.03g / L, H3BO3 0.01~0.03g / L.

[0051] Further, the bioactive surfactant-activating bacterial system comprises 10-15 g / L glucose, 1.2-2.4 g / L peptone, 0.6-1.2 g / L potassium dihydrogen phosphate, 0.1-0.4 g / L sodium chloride, 10-26 mL / L trace element solution, and the remainder being water, wherein:

[0052] Trace element liquid includes: N(CH2COOH)3 4~5g / L, MnCl2·4H2O 0.1~0.2g / L, KAl(SO4) 20.01~0.02g / L, NaCl 0.5~2g / L, Na2MoO4 0.01~0.05g / L, FeCl2·4H2O 0.2~0.6g / L, CoCl2·6H2O 0.05~0.2g / L, ZnCl2 0.05~0.2g / L, CaCl2 0.01~0.03g / L, H3BO3 0.01~0.03g / L.

[0053] Further, the polysaccharide-producing functional bacteria activation system comprises 5-15 g / L starch, 1-5 g / L soybean flour hydrolysate, 0.4-1.2 g / L dipotassium hydrogen phosphate, 0.1-0.3 g / L calcium chloride, 0.05-0.2 g / L magnesium sulfate, 15-30 mL / L trace element solution, and the remainder being water, wherein:

[0054] Trace element liquid includes: N(CH2COOH)3 4~5g / L, MnCl2·4H2O 0.1~0.2g / L, KAl(SO4) 20.01~0.02g / L, NaCl 0.5~2g / L, Na2MoO4 0.01~0.05g / L, FeCl2·4H2O 0.2~0.6g / L, CoCl2·6H2O 0.05~0.2g / L, ZnCl2 0.05~0.2g / L, CaCl2 0.01~0.03g / L, H3BO3 0.01~0.03g / L.

[0055] Furthermore, the polymer gel comprises 2-4 g / L polyacrylamide, 0.3-0.6 g / L chromium chloride, and 0.02-0.05 g / L citric acid.

[0056] Furthermore, the polymer gel comprises 3-6 g / L polyacrylamide, 0.5-0.8 g / L chromium chloride, and 0.05-0.08 g / L citric acid.

[0057] This invention utilizes the relationship between hydrocarbon-loving bacteria concentration and residual oil. Based on the unique tropism of hydrocarbon-loving bacteria towards crude oil, in areas with high residual oil abundance, hydrocarbon-loving bacteria are more likely to adsorb at the oil-water interface, resulting in a correspondingly lower concentration of hydrocarbon-loving bacteria detected in the produced fluid. Conversely, when the residual oil abundance is low, the adsorption of hydrocarbon-loving bacteria at the oil-water interface weakens, leading to an increase in the concentration of hydrocarbon-loving bacteria in the corresponding produced fluid. Based on this understanding, by injecting hydrocarbon-loving bacteria at a specific concentration and simultaneously detecting the hydrocarbon-loving bacteria in the produced fluid, the abundance of residual oil between oil and water wells can be determined. Furthermore, based on the residual oil situation between oil and water wells, measures can be formulated for different wells to increase single-well production, ultimately achieving the goal of utilizing residual oil and improving oil recovery.

[0058] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0059] (1) The method of detecting the concentration change of hydrocarbon-loving bacteria after injection is used to determine the remaining oil saturation, which has the advantages of accuracy, simplicity and reliability;

[0060] (2) Targeted improvement measures were formulated for different residual oil saturation levels, which were targeted and purposeful, and ensured the effectiveness on site;

[0061] (3) The method of detecting the concentration of biological bacteria to determine the saturation of residual oil eliminates the environmental hazards that may be caused by other methods and achieves the requirements of safety and environmental protection;

[0062] (4) After field application, the single well production of the reservoir increased by more than 20%, the water cut decreased by more than 5%, and the average oil production of the well group increased by more than 10,000 tons, which further improved the reservoir recovery rate. Detailed implementation method:

[0063] The specific embodiments of the present invention are described in detail below.

[0064] Example 1:

[0065] Overview of Test Block A in a certain oil production plant of Shengli Oilfield: Reservoir temperature 67℃, original formation pressure 12MPa, producing oil layer thickness 3.6m, permeability 850×10⁻⁶. -3 μm 2 The produced water salinity is 7500 mg / L, the underground crude oil viscosity is 130 mPa·s, the original oil saturation is 56%, the well group consists of 1 injection and 4 production wells, and the overall water cut is 86.5%.

[0066] A method for determining residual oil using microbial tropism includes the following steps:

[0067] (1) Screening of test reservoirs:

[0068] Block A meets the reservoir screening requirements;

[0069] (2) Simulation experiment;

[0070] (21) The sand-filled core of the test reservoir was washed to produce a standard core of Φ38×600mm;

[0071] (22) Formation water in a vacuum-sealed, saturated test reservoir;

[0072] (23) Dehydrated and degassed crude oil from a saturated test reservoir;

[0073] (24) After aging and storage for 7 days, water flooding was performed once, and the core was water flooded to different residual oil saturation.

[0074] (25) Hydrophilic bacteria were injected into the core after one water flooding at a volume of 0.1 PV. The number of hydrophilic bacteria in the produced fluid was monitored after injection.

[0075] (3) Determining the relationship between hydrocarbon-loving bacteria concentration and residual oil:

[0076] The relationship between hydrocarbon-loving bacteria concentration and residual oil saturation between oil and water wells can be determined by the amount of hydrocarbon-loving bacteria in the produced fluid.

[0077] The relationship between the concentration of hydrocarbon-loving bacteria in the produced fluid and the residual oil saturation between oil and water wells is shown in the table below, where: the concentration of hydrocarbon-loving bacteria is log functional gene copy number;

[0078] Table of Correlation between Hydrophilic Bacteria Concentration in Produced Fluid and Residual Oil Saturation Between Oil and Water Wells

[0079] Serial Number Residual oil saturation between oil and water wells Concentration of hydrocarbon-loving bacteria in the effluent 1 40％-45％ 2-3 2 30％-40％ 3-4 3 25％-30％ 4-5 4 20％-25％ 5-6 5 <20％ >7

[0080] (4) Determination of remaining oil in the test reservoir.

[0081] (41) Inject 0.1 PV of hydrocarbon-loving bacteria into the injection well in block A, wherein: the injection concentration of hydrocarbon-loving bacteria is log functional gene copy number is 8;

[0082] (42) The concentration of hydrocarbon-loving bacteria in the oil well produced fluid was detected. The detection cycle was 3 days and the number of detections was 8.

[0083] (43) The concentration of hydrocarbon-loving bacteria was detected in the produced fluid of four corresponding oil wells (A-1, A-2, A-3, A-4), and their residual oil saturation was determined as follows:

[0084] Table 3. Correlation between different concentrations of hydrocarbon-loving bacteria and residual oil saturation between oil and water wells.

[0085]

[0086] Furthermore, the hydrocarbon-loving bacteria is a hydrocarbon-degrading bacterium (Tistrella).

[0087] Furthermore, the determination of the number of hydrocarbon-loving bacteria mentioned in step (25) is carried out using the quantitative real-time PCR method of molecular biology. The concentration is determined by the number of functional gene copies. The specific steps are as follows:

[0088] (251) Preparation of the real-time PCR reaction system:

[0089] The quantitative detection reaction system for hydrocarbon-loving bacteria is 20 μL, which includes 10 μL of real-time PCR reaction enzyme system, 0.2 μL each of 0.02 nmol / μL upstream and downstream primers, 1 μL of template DNA, and 8.6 μL of sterile water. Each sample is tested in 3 parallel experiments. The reaction solution is prepared in a 96-well sterile reaction plate.

[0090] The standard plasmid reaction system for constructing the standard curve is 20 μL, with the same composition as above, wherein 1 μL of template DNA is selected from 1×10⁻⁶. 2 copy / mL, 1×10 4 copy / mL, 1×10 6 copy / mL and 1×10 8Four gradients of standard plasmid solutions were prepared at a ratio of 4 copies / mL, and each standard plasmid was used in three parallel experiments.

[0091] (252) Steps for Real-Time PCR Amplification

[0092] When the reaction primer Tm value is greater than or equal to 60℃, the amplification includes:

[0093] Step 1: Pre-denaturation at 95℃ for 3 minutes;

[0094] Step 2: Denature at 95℃ for 10s, anneal at 60℃ for 30s, repeat Step 2 40 times, and detect fluorescence signal during reaction at 60℃;

[0095] When the reaction primer Tm value is less than 60℃, the amplification includes:

[0096] S1: Pre-denaturation at 95℃ for 3 minutes;

[0097] S2: Denaturation at 95℃ for 10s, annealing at 30s, extension at 72℃ for 30s, repeat step 2 for 40 cycles, and detect fluorescence signal during reaction at 72℃.

[0098] (253) Analysis of Real-Time PCR Data:

[0099] A standard curve is plotted with the logarithm of the standard plasmid copy concentration on the x-axis and the measured Ct value on the y-axis. When quantifying hydrocarbon-loving bacteria samples, the hydrocarbon-loving bacteria gene copy concentration in the sample can be obtained from the standard curve based on the sample's Ct value.

[0100] Furthermore, in step (25), the concentration of hydrocarbon-loving bacteria injected is log functional gene copy number of 8.

[0101] An enhanced oil recovery method includes the following steps:

[0102] The remaining oil in four oil and water wells of the test reservoir was determined using the methods described above. Based on the distribution pattern of the remaining oil in the test reservoir, corresponding measures for the oil and water wells were formulated. The concentration of hydrocarbon-loving bacteria in the produced fluid of the oil and water wells and the corresponding measures for the oil and water wells are shown in the table below.

[0103] Table of Correspondence between Hydrophilic Bacteria Concentration in Produced Fluid and Oil-Water Well Measures

[0104]

[0105] Based on the correlation between the concentration of hydrocarbon-loving bacteria in the produced fluid and the residual oil saturation between oil and water wells, production enhancement measures for different oil wells are determined.

[0106] The concentration of hydrocarbon-loving bacteria in the produced fluid of well A-1 is 2-3, and the remaining oil saturation is 40%-45%. The preferred measure is to activate the hydrocarbon-loving functional bacteria by injecting a hydrocarbon-loving functional bacteria activation system, which includes 3.6 g / L corn steep liquor powder, 1.5 g / L potassium dihydrogen phosphate, 0.2 g / L sodium nitrate, and 15 mg / L trace element solution.

[0107] The concentration of hydrocarbon-loving bacteria in the produced fluid of well A-2 is 3-4, and the residual oil saturation is 30%-40%. The preferred approach is to activate the hydrocarbon-loving bacteria and the bio-surfactant-producing bacteria, injecting them separately into the hydrocarbon-loving bacteria activation system and the bio-surfactant-producing bacteria activation system.

[0108] The activation system for hydrocarbon-loving functional bacteria consisted of 3.6 g / L corn steep liquor powder, 1.5 g / L potassium dihydrogen phosphate, 0.2 g / L sodium nitrate, and 15 mg / L trace element solution. The activation system for surfactant-producing functional bacteria consisted of 10 g / L glucose, 2.4 g / L peptone, 1.2 g / L potassium dihydrogen phosphate, 0.4 g / L sodium chloride, and 26 mL / L trace element solution.

[0109] The concentration of hydrocarbon-loving bacteria in the produced fluid of well A-3 is 2-3, and the remaining oil saturation is 40%-45%. The preferred measure is to activate the hydrocarbon-loving functional bacteria. The injected activation system consists of 3.6 g / L corn steep liquor powder, 1.5 g / L potassium dihydrogen phosphate, 0.2 g / L sodium nitrate, and 15 mL / L trace element solution.

[0110] The concentration of hydrocarbon-loving bacteria in the produced fluid of well A-4 is 4-5, and the residual oil saturation is 25%-30%. The preferred approach is to activate the bio-surfactant and bio-polysaccharide-producing functional bacteria by injecting them into the bio-surfactant-producing functional bacteria activation system and the bio-polysaccharide-producing functional bacteria activation system, respectively.

[0111] The bioactive surfactant-producing functional bacteria activation system consisted of 10 g / L glucose, 2.4 g / L peptone, 1.2 g / L potassium dihydrogen phosphate, 0.4 g / L sodium chloride, and 26 mg / L trace element solution.

[0112] The polysaccharide-producing functional bacteria activation system consisted of 5 g / L starch, 5 g / L soybean flour hydrolysate, 1.2 g / L dipotassium hydrogen phosphate, 0.3 g / L calcium chloride, 0.1 g / L magnesium sulfate, and 26 mL / L trace element solution.

[0113] The injection volume for different oil wells is designed according to the volume specified in conventional microbial single-well production enhancement measures. The construction process involves a high-pressure pump truck injecting different activation systems from the oil wells into the formation, including:

[0114] In this embodiment, the trace element solution includes: N(CH2COOH)3 4 g / L, MnCl2·4H2O 0.1 g / L, KAl(SO4)2 0.01 g / L, NaCl 0.5 g / L, Na2MoO4 0.01 g / L, FeCl2·4H2O 0.2 g / L, CoCl2·6H2O 0.05 g / L, ZnCl2 0.05 g / L, CaCl2 0.01 g / L, and H3BO3 0.01 g / L.

[0115] 4. Effect Analysis

[0116] After the field test, the overall water cut of the block decreased from 86.5% to 73.7%, a reduction of 12.8 percentage points. Production increased from 11.1 t / d before implementation to 16.2 t / d, with the well group increasing crude oil production by 1.2 × 10⁻⁶ tons. 4 The field test results were good.

[0117] Post-implementation effects

[0118]

[0119] Example 2:

[0120] Overview of Test Block B in a certain oil production plant of Shengli Oilfield: Reservoir temperature 78℃, original formation pressure 17MPa, producing oil layer thickness 3.1m, permeability 460×10⁻⁶ -3 μm 2 The produced water salinity is 17500 mg / L, the underground crude oil viscosity is 210 mPa·s, the original oil saturation is 58.9%, the well group is 1 injection and 3 production, and the overall water cut is 96.5%.

[0121] A method for determining residual oil using microbial tropism includes the following steps:

[0122] (1) Screening of test reservoirs;

[0123] The conditions in test block B meet the requirements for reservoir screening.

[0124] (2) Simulation experiment;

[0125] (21) The sand-filled core of the test reservoir was washed to produce a standard core of Φ38×600mm;

[0126] (22) Formation water in a vacuum-sealed, saturated test reservoir;

[0127] (23) Dehydrated and degassed crude oil from a saturated test reservoir;

[0128] (24) After aging and storage for 7 days, water flooding was performed once, and the core was water flooded to different residual oil saturation.

[0129] (25) Hydrophilic bacteria were injected into the core after one water flooding at a volume of 0.1 PV. The number of hydrophilic bacteria in the produced fluid was monitored after injection.

[0130] (3) Determining the relationship between hydrocarbon-loving bacteria concentration and residual oil:

[0131] The relationship between hydrocarbon-loving bacteria concentration and residual oil saturation between oil and water wells can be determined by the amount of hydrocarbon-loving bacteria in the produced fluid.

[0132] The relationship between the concentration of hydrocarbon-loving bacteria in the produced fluid and the residual oil saturation between oil and water wells is shown in the table below, where: the concentration of hydrocarbon-loving bacteria is log functional gene copy number;

[0133] Table of Correlation between Hydrophilic Bacteria Concentration in Produced Fluid and Residual Oil Saturation Between Oil and Water Wells

[0134] Serial Number Residual oil saturation between oil and water wells Concentration of hydrocarbon-loving bacteria in the effluent 1 40％-45％ 2-3 2 30％-40％ 3-4 3 25％-30％ 4-5 4 20％-25％ 5-6 5 <20％ >7

[0135] (4) Determination of remaining oil in the test reservoir:

[0136] (41) Hydrophilic bacteria are injected into the water injection wells in Block B, wherein: the concentration of hydrophilic bacteria injected is log and the copy number of functional genes is 9;

[0137] (42) The concentration of hydrocarbon-loving bacteria in the oil well produced fluid was detected. The detection cycle was 5 days and the number of detections was 10.

[0138] (43) The concentration of hydrocarbon-degrading bacteria was detected in the produced fluid of three corresponding oil wells (B-1, B-2, B-3), and their residual oil saturation was determined as follows:

[0139] Correlation between different concentrations of hydrocarbon-loving bacteria and residual oil saturation between oil and water wells

[0140]

[0141] Furthermore, the hydrocarbon-loving bacterium is Marinobacter.

[0142] Furthermore, the determination of the number of hydrocarbon-loving bacteria mentioned in step (25) is carried out using the quantitative real-time PCR method of molecular biology. The concentration is determined by the number of functional gene copies. The specific steps are as follows:

[0143] (251) Preparation of the real-time PCR reaction system:

[0144] The quantitative detection reaction system for hydrocarbon-loving bacteria is 20 μL, which includes 10 μL of real-time PCR reaction enzyme system, 0.2 μL each of 0.02 nmol / μL upstream and downstream primers, 1 μL of template DNA, and 8.6 μL of sterile water. Each sample is tested in 3 parallel experiments. The reaction solution is prepared in a 96-well sterile reaction plate.

[0145] The standard plasmid reaction system for constructing the standard curve is 20 μL, with the same composition as above, wherein 1 μL of template DNA is selected from 1×10⁻⁶. 2 copy / mL, 1×10 4 copy / mL, 1×10 6 copy / mL and 1×10 8 Four gradients of standard plasmid solutions were prepared at a ratio of 4 copies / mL, and each standard plasmid was used in three parallel experiments.

[0146] (252) Steps for Real-Time PCR Amplification

[0147] When the reaction primer Tm value is greater than or equal to 60℃, the amplification includes:

[0148] Step 1: Pre-denaturation at 95℃ for 3 minutes;

[0149] Step 2: Denature at 95℃ for 10s, anneal at 60℃ for 30s, repeat Step 2 40 times, and detect fluorescence signal during reaction at 60℃;

[0150] When the reaction primer Tm value is less than 60℃, the amplification includes:

[0151] S1: Pre-denaturation at 95℃ for 3 minutes;

[0152] S2: Denaturation at 95℃ for 10s, annealing at 30s, extension at 72℃ for 30s, repeat step 2 for 40 cycles, and detect fluorescence signal during reaction at 72℃.

[0153] (253) Analysis of Real-Time PCR Data:

[0154] A standard curve is plotted with the logarithm of the standard plasmid copy concentration on the x-axis and the measured Ct value on the y-axis. When quantifying hydrocarbon-loving bacteria samples, the hydrocarbon-loving bacteria gene copy concentration in the sample can be obtained from the standard curve based on the sample's Ct value.

[0155] Furthermore, in step (25), the concentration of hydrocarbon-loving bacteria injected is log functional gene copy number of 9.

[0156] An enhanced oil recovery method includes the following steps:

[0157] The remaining oil in the three oil and water wells in Block B was determined using the above method. Based on the distribution pattern of remaining oil in the experimental reservoir, corresponding measures for the oil and water wells were formulated. The concentration of hydrocarbon-loving bacteria in the produced fluid of the oil and water wells and the corresponding measures are shown in the table below.

[0158] Table of Correspondence between Hydrophilic Bacteria Concentration in Produced Fluid and Oil-Water Well Measures

[0159]

[0160] Based on the correlation between the concentration of hydrocarbon-loving bacteria in the produced fluid and the residual oil saturation between oil and water wells, production enhancement measures for different oil wells are determined.

[0161] The produced fluid from well B-1 has a hydrocarbon-loving bacteria concentration of 5-6 and a residual oil saturation of 20%-25%. The preferred approach is to activate the bio-surfactant and polymeric weak gel, injecting the bio-surfactant functional bacteria activation system and the polymeric weak gel, respectively.

[0162] The bioactive surfactant-producing functional bacteria activation system includes: glucose 15g / L, peptone 1.2g / L, potassium dihydrogen phosphate 0.6g / L, sodium chloride 0.1g / L, and trace element solution 10mL / L;

[0163] The polymeric gel contains 3 g / L polyacrylamide, 0.5 g / L chromium chloride, and 0.05 g / L citric acid.

[0164] The concentration of hydrocarbon-loving bacteria in the produced fluid of well B-2 is 3-4, and the residual oil saturation is 30%-40%. The preferred approach is to activate the hydrocarbon-loving bacteria and the bio-surfactant-producing functional bacteria by injecting them into the hydrocarbon-loving bacteria activation system and the bio-surfactant-producing functional bacteria activation system, respectively.

[0165] The hydroxylophilic functional bacteria activation system consisted of 2.5 g / L corn steep liquor powder, 0.5 g / L potassium dihydrogen phosphate, 0.3 g / L sodium nitrate, and 18 mg / L trace element solution.

[0166] The bioactive surfactant-activated bacteria activation system consisted of 15 g / L glucose, 1.2 g / L peptone, 0.6 g / L potassium dihydrogen phosphate, 0.1 g / L sodium chloride, and 10 mL / L trace element solution.

[0167] The concentration of hydrocarbon-loving bacteria in the produced fluid of well B-3 is >7, and the residual oil saturation is <20%. The preferred approach is to activate the bio-surfactant and polymer gel, injecting the bio-surfactant functional bacteria activation system and the polymer gel respectively.

[0168] The bioactive surfactant-producing functional bacteria activation system consisted of 15 g / L glucose, 1.2 g / L peptone, 0.6 g / L potassium dihydrogen phosphate, 0.1 g / L sodium chloride, and 10 mL / L trace element solution.

[0169] The polymer gel contains 2 g / L polyacrylamide, 0.3 g / L chromium chloride, and 0.02 g / L citric acid.

[0170] In this embodiment, the trace element solution includes: N(CH2COOH)3 5 g / L, MnCl2·4H2O 0.2 g / L, KAl(SO4)2 0.02 g / L, NaCl 2 g / L, Na2MoO4 0.05 g / L, FeCl2·4H2O 0.6 g / L, CoCl2·6H2O 0.2 g / L, ZnCl2 0.2 g / L, CaCl2 0.03 g / L, and H3BO3 0.03 g / L.

[0171] The injection volume for different oil wells was designed according to the volume specified in conventional microbial single-well production enhancement measures. The construction process involved injecting different activation systems from the oil wells into the formation using a high-pressure pump truck. The injection volume for polymer gel and polymer gel was designed according to the volume specified in conventional oil well water shut-off measures. The construction was completed using conventional profile control and water shut-off equipment from the oilfield.

[0172] 4. Effect Analysis

[0173] After the field test, the overall water cut of the block decreased from 95.4% to 89.5%, a reduction of 5.9 percentage points. Production increased from 4.7 t / d before implementation to 8.2 t / d, with the well group increasing crude oil production by 1.03 × 10⁻⁶ tons. 4 The field test results were good.

[0174] Post-implementation effects

[0175]

[0176] Example 3:

[0177] Overview of Test Block C in a certain oil production plant of Shengli Oilfield: Reservoir temperature 37℃, original formation pressure 4MPa, producing oil layer thickness 13.6m, permeability 2850×10⁻⁶. -3 μm 2 The produced water salinity is 10,500 mg / L, the underground crude oil viscosity is 830 mPa·s, the original oil saturation is 60%, the well group consists of 1 injection and 4 production wells, and the overall water cut is 92.6%.

[0178] A method for determining residual oil using microbial tropism includes the following steps:

[0179] (1) Screening of test reservoirs;

[0180] Block C meets the reservoir screening requirements;

[0181] (2) Simulation experiment;

[0182] Furthermore, the specific steps of step (2) are as follows:

[0183] (21) The sand-filled core of the test reservoir was washed to produce a standard core of Φ38×600mm;

[0184] (22) Formation water in a vacuum-sealed, saturated test reservoir;

[0185] (23) Dehydrated and degassed crude oil from a saturated test reservoir;

[0186] (24) After aging and storage for 7 days, water flooding was performed once, and the core was water flooded to different residual oil saturation.

[0187] (25) Hydrophilic bacteria were injected into the core after one water flooding at a volume of 0.1 PV. The number of hydrophilic bacteria in the produced fluid was monitored after injection.

[0188] (3) Determining the relationship between hydrocarbon-loving bacteria concentration and residual oil;

[0189] The relationship between hydrocarbon-loving bacteria concentration and residual oil saturation between oil and water wells can be determined by the amount of hydrocarbon-loving bacteria in the produced fluid.

[0190] The relationship between the concentration of hydrocarbon-loving bacteria in the produced fluid and the residual oil saturation between oil and water wells is shown in the table below, where: the concentration of hydrocarbon-loving bacteria is log functional gene copy number;

[0191] Table of Correlation between Hydrophilic Bacteria Concentration in Produced Fluid and Residual Oil Saturation Between Oil and Water Wells

[0192] Serial Number Residual oil saturation between oil and water wells Concentration of hydrocarbon-loving bacteria in the effluent 1 40％-45％ 2-3 2 30％-40％ 3-4 3 25％-30％ 4-5 4 20％-25％ 5-6 5 <20％ >7

[0193] (4) Determination of remaining oil in the test reservoir:

[0194] (41) Hydrophilic bacteria were injected into the water injection wells of the test reservoir, wherein: the concentration of hydrophilic bacteria injected was log and the copy number of functional genes was 8;

[0195] (42) The concentration of hydrocarbon-loving bacteria in the oil well produced fluid was detected. The detection cycle was 4 days and the number of detections was 9.

[0196] (43) 0.1 PV of hydrocarbon-degrading bacteria (Tistrella) was injected into the water injection wells (C-1, C-2, C-3, C-4) in block C. The concentration of hydrocarbon-degrading bacteria was detected in the produced fluid of the four corresponding oil wells, and the residual oil saturation was determined as follows:

[0197] Correlation between different concentrations of hydrocarbon-loving bacteria and residual oil saturation between oil and water wells

[0198]

[0199] Furthermore, the hydrocarbon-loving bacteria is a hydrocarbon-degrading bacterium (Tistrella).

[0200] Furthermore, the determination of the number of hydrocarbon-loving bacteria mentioned in step (25) is carried out using the quantitative real-time PCR method of molecular biology. The concentration is determined by the number of functional gene copies. The specific steps are as follows:

[0201] (251) Preparation of the real-time PCR reaction system:

[0202] The quantitative detection reaction system for hydrocarbon-loving bacteria is 20 μL, which includes 10 μL of real-time PCR reaction enzyme system, 0.2 μL each of 0.02 nmol / μL upstream and downstream primers, 1 μL of template DNA, and 8.6 μL of sterile water. Each sample is tested in 3 parallel experiments. The reaction solution is prepared in a 96-well sterile reaction plate.

[0203] The standard plasmid reaction system for constructing the standard curve is 20 μL, with the same composition as above, wherein 1 μL of template DNA is selected from 1×10⁻⁶. 2 copy / mL, 1×10 4 copy / mL, 1×10 6 copy / mL and 1×10 8 Four gradients of standard plasmid solutions were prepared at a ratio of 4 copies / mL, and each standard plasmid was used in three parallel experiments.

[0204] (252) Steps for Real-Time PCR Amplification

[0205] When the reaction primer Tm value is greater than or equal to 60℃, the amplification includes:

[0206] Step 1: Pre-denaturation at 95℃ for 3 minutes;

[0207] Step 2: Denature at 95℃ for 10s, anneal at 60℃ for 30s, repeat Step 2 40 times, and detect fluorescence signal during reaction at 60℃;

[0208] When the reaction primer Tm value is less than 60℃, the amplification includes:

[0209] S1: Pre-denaturation at 95℃ for 3 minutes;

[0210] S2: Denaturation at 95℃ for 10s, annealing at 30s, extension at 72℃ for 30s, repeat step 2 for 40 cycles, and detect fluorescence signal during reaction at 72℃.

[0211] (253) Analysis of Real-Time PCR Data:

[0212] A standard curve is plotted with the logarithm of the standard plasmid copy concentration on the x-axis and the measured Ct value on the y-axis. When quantifying hydrocarbon-loving bacteria samples, the hydrocarbon-loving bacteria gene copy concentration in the sample can be obtained from the standard curve based on the sample's Ct value.

[0213] Furthermore, in step (25), the concentration of hydrocarbon-loving bacteria injected is log functional gene copy number of 8.

[0214] An enhanced oil recovery method includes the following steps:

[0215] The remaining oil in four oil and water wells of the test reservoir was determined using the above method. Based on the distribution pattern of the remaining oil in the test reservoir, corresponding measures for the oil and water wells were formulated. The concentration of hydrocarbon-loving bacteria in the produced fluid of the oil and water wells and the corresponding measures for the oil and water wells are shown in the table below.

[0216] Table of Correspondence between Hydrophilic Bacteria Concentration in Produced Fluid and Oil-Water Well Measures

[0217]

[0218] Based on the correlation between the concentration of hydrocarbon-loving bacteria in the produced fluid and the residual oil saturation between oil and water wells, production enhancement measures for different oil wells are determined.

[0219] The concentration of hydrocarbon-loving bacteria in the produced fluid of well C-1 is >7, and the residual oil saturation is <20%. The preferred approach is to activate the bio-surfactant and polymer gel, injecting the bio-surfactant functional bacteria activation system and the polymer gel respectively.

[0220] The bioactive surfactant-producing functional bacteria activation system consisted of 12 g / L glucose, 2 g / L peptone, 1 g / L potassium dihydrogen phosphate, 0.2 g / L sodium chloride, and 20 mL / L trace element solution.

[0221] The polymer gel contains 4 g / L polyacrylamide, 0.6 g / L chromium chloride, and 0.05 g / L citric acid.

[0222] The C-2 well's produced fluid has a hydrocarbon-loving bacteria concentration of 3-4 and a residual oil saturation of 30%-40%. The preferred approach is to activate the hydrocarbon-loving bacteria and the bio-surfactant-producing bacteria by injecting them into the hydrocarbon-loving bacteria activation system and the bio-surfactant-producing bacteria activation system, respectively.

[0223] The activating system for hydrocarbon-loving functional bacteria consisted of 4.9 g / L corn steep liquor powder, 1 g / L potassium dihydrogen phosphate, 0.5 g / L sodium nitrate, and 20 ml / L trace element solution.

[0224] The bioactive surfactant-activated bacteria activation system consisted of 12 g / L glucose, 2 g / L peptone, 1 g / L potassium dihydrogen phosphate, 0.2 g / L sodium chloride, and 20 mL / L trace element solution.

[0225] The C-3 well's produced fluid has a hydrocarbon-loving bacteria concentration of 2-3 and a residual oil saturation of 40%-45%. The preferred method is to activate the hydrocarbon-loving bacteria by injecting them into a hydrocarbon-loving bacteria activation system, wherein:

[0226] The activating system for hydrocarbon-loving functional bacteria consisted of 4.9 g / L corn steep liquor powder, 1 g / L potassium dihydrogen phosphate, 0.5 g / L sodium nitrate, and 20 ml / L trace element solution.

[0227] The C-4 well's produced fluid has a hydrocarbon-loving bacteria concentration of 5-6 and a residual oil saturation of 20%-25%. The preferred approach is to activate the bio-surfactant and a polymer-based weak gel, injecting the bio-surfactant functional bacteria activation system and the polymer-based weak gel, respectively.

[0228] The bioactive surfactant-producing functional bacteria activation system consisted of 12 g / L glucose, 2 g / L peptone, 1 g / L potassium dihydrogen phosphate, 0.2 g / L sodium chloride, and 20 mL / L trace element solution.

[0229] The polymeric gel contains 6 g / L polyacrylamide, 0.8 g / L chromium chloride, and 0.08 g / L citric acid.

[0230] In this embodiment, the trace element solution includes: N(CH2COOH)3 4.5g / L, MnCl2·4H2O 0.15g / L, KAl(SO4)2 0.015g / L, NaCl 1g / L, Na2MoO4 0.02g / L, FeCl2·4H2O 0.4g / L, CoCl2·6H2O 0.1g / L, ZnCl2 0.1g / L, CaCl2 0.02g / L, and H3BO3 0.02g / L.

[0231] The injection volume for different oil wells was designed according to the volume specified in conventional microbial single-well production enhancement measures. The construction process involved injecting different activation systems from the oil wells into the formation using a high-pressure pump truck. The injection volume for polymer gel and polymer gel was designed according to the volume specified in conventional oil well water shut-off measures. The construction was completed using conventional profile control and water shut-off equipment from the oilfield.

[0232] 4. Effect Analysis

[0233] After the field test, the overall water cut of the block decreased from 92.6% to 86.2%, a reduction of 6.4 percentage points. Production increased from 6.8 t / d before implementation to 10.5 t / d, and the well group increased crude oil production by 1.3 × 10⁻⁶ tons. 4 The field test results were good.

[0234] Table 8. Effects after implementation

[0235]

[0236]

[0237] Examples 4-8

[0238] Similar to Example 1, the only difference lies in the different block environments of the test reservoirs, which lead to different hydrocarbon-loving bacteria:

[0239] Hydrocarbonophiles Example 4 Alternaria Example 5 Spirulina Example 6 Halomonas Example 7 Pseudomonas hydrophila Example 8 Hydrogen-producing bacteria (Tepidiphilus)

[0240] 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 enhanced oil recovery, characterized in that, Includes the following steps: The residual oil in at least one oil-water well in the test reservoir was determined using a method based on microbial tropism. Corresponding measures for the oil-water wells were then formulated based on the distribution pattern of residual oil in the test reservoir. The concentration of hydrocarbon-loving bacteria in the produced fluid of the oil-water wells and the corresponding measures are shown in the table below. Table of Correspondence between Hydrophilic Bacteria Concentration in Produced Fluid and Oil-Water Well Measures The method of determining the remaining oil in at least one oil-water well in the test reservoir using microbial tropism includes the following steps: (1) Screening of test reservoirs; (2) Simulation experiment; (3) Determining the relationship between hydrocarbon-loving bacteria concentration and residual oil; (4) Determination of the remaining oil in the test reservoir.

2. The enhanced oil recovery method as described in claim 1, characterized in that, The conditions for selecting the test reservoir in step (1) are: the test reservoir is a normally formed reservoir, the reservoir temperature is <90℃, the original formation pressure is <20MPa, and the permeability is >100×10⁻⁶. -3 μm 2 Formation water salinity < 200,000 mg / L, crude oil viscosity < 50,000 mPa•s, and original oil saturation > 50%.

3. The enhanced oil recovery method as described in claim 1, characterized in that, Step (2) consists of the following steps: (21) The sand-filled core of the test reservoir was washed to produce a standard core of Φ38×600mm; (22) Formation water in a vacuum-sealed, saturated test reservoir; (23) Dehydrated and degassed crude oil from a saturated test reservoir; (24) After aging and storage for 7 days, water flooding was carried out once, and the core was water flooded to different residual oil saturation; (25) Hydrophilic bacteria were injected into the core after one water flooding at a volume of 0.1 PV. The number of hydrophilic bacteria in the produced fluid was monitored after injection.

4. The enhanced oil recovery method as described in claim 3, characterized in that, The hydrocarbon-loving bacteria are one of the following: hydrocarbon-degrading bacteria, symbiotic bacteria, spirochetes, halophilic bacteria, marine bacteria, hydrocarbon-loving pseudomonads, and hydrogen-producing bacteria.

5. The enhanced oil recovery method as described in claim 4, characterized in that, The hydrocarbon-loving bacteria are hydrocarbon-degrading bacteria or marine bacteria.

6. The enhanced oil recovery method as described in claim 3, characterized in that, The determination of the number of hydrocarbon-loving bacteria mentioned in step (25) is carried out by using the quantitative real-time PCR method of molecular biology to track and judge the concentration by the number of functional gene copies. The specific steps are as follows: (251) Preparation of the real-time PCR reaction system: The quantitative detection reaction system for hydrocarbon-loving bacteria is 20 μL, which includes 10 μL of real-time PCR enzyme system, 0.2 μL each of 0.02 nmol / μL upstream and downstream primers, 1 μL of template DNA, and 8.6 μL of sterile water. Each sample is tested in 3 parallel experiments. The reaction solution is prepared in a 96-well sterile reaction plate. The standard plasmid reaction system for constructing the standard curve consisted of 20 μL, including 10 μL of real-time PCR enzyme system, 0.2 μL each of 0.02 nmol / μL forward and reverse primers, 1 μL of template DNA, and 8.6 μL of sterile water. 1 μL of the template DNA was selected from 1×10⁻⁶ ppm. 2 copy / mL, 1×10 4 copy / mL, 1×10 6 copy / mL and 1×10 8 Four gradients of standard plasmid solutions were prepared at a ratio of 4 copies / mL, and each standard plasmid was used in three parallel experiments. (252) Steps for Real-Time PCR Amplification When the reaction primer Tm value is greater than or equal to 60 ℃, the amplification includes: Step 1: Pre-denaturation at 95 ℃ for 3 min; Step 2: Denaturation at 95 ℃ for 10 s, annealing at 60 ℃ for 30 s, repeat Step 2 40 times, and detect fluorescence signal during reaction at 60 ℃; When the Tm value of the reaction primers is less than 60 °C, the amplification includes: S1: Pre-denaturation at 95 ℃ for 3 min; S2: Denaturation at 95 ℃ for 10 s, annealing at 30 s, extension at 72 ℃ for 30 s, repeat step 2 40 times, and detect fluorescence signal during reaction at 72 ℃; (253) Analysis of real-time PCR data: A standard curve is plotted with the logarithm of the standard plasmid copy concentration on the x-axis and the measured Ct value on the y-axis. When quantifying hydrocarbon-loving bacteria samples, the hydrocarbon-loving bacteria gene copy concentration in the sample can be obtained from the standard curve based on the sample's Ct value.

7. The enhanced oil recovery method as described in claim 3, characterized in that, In step (25), the concentration of hydrocarbon-loving bacteria injected is log functional gene copy number of 8-9.

8. The enhanced oil recovery method as described in claim 1, characterized in that, In step (3), the relationship between the concentration of hydrocarbon-loving bacteria and the saturation of residual oil between oil and water wells is determined based on the number of hydrocarbon-loving bacteria in the produced fluid. Based on the relationship between the concentration of hydrocarbon-loving bacteria and the residual oil, the saturation of residual oil between oil and water wells is determined. The relationship between the concentration of hydrocarbon-loving bacteria in the produced fluid and the residual oil saturation between oil and water wells is shown in the table below, where: the concentration of hydrocarbon-loving bacteria is log functional gene copy number; Table of Correspondence between Hydrophilic Bacteria Concentration in Produced Fluid and Residual Oil Saturation Between Oil and Water Wells 9. The enhanced oil recovery method as described in claim 1, characterized in that, Step (4) includes the following steps: (41) Hydrophilic bacteria were injected into the water injection wells of the test reservoir, wherein the concentration of the injected hydrophilic bacteria was log and the copy number of the functional gene was 8 to 9; (42) Detect the concentration of hydrocarbon-loving bacteria in the oil well produced fluid. The detection cycle is 3-5 days and the number of detections is 8-10 times. (43) Determine the remaining oil in the test reservoir based on the concentration of hydrocarbon-loving bacteria in the produced liquid and the relationship between the concentration of hydrocarbon-loving bacteria and the remaining oil determined in step (3).

10. The enhanced oil recovery method as described in claim 1, characterized in that, The aforementioned hydrocarbon-loving functional bacteria activation system comprises 2.5-4.5 g / L corn steep liquor powder, 0.5-1.5 g / L potassium dihydrogen phosphate, 0.2-0.5 g / L sodium nitrate, 15-20 mL / L trace element solution, and the remainder being water. The trace element solution includes: N(CH2COOH)3 4~5 g / L, MnCl2·4H2O 0.1~0.2 g / L, KAl(SO4)2 0.01~0.02 g / L, NaCl 0.5~2 g / L, Na2MoO4 0.01~0.05 g / L, FeCl2·4H2O 0.2~0.6 g / L, CoCl2·6H2O 0.05~0.2 g / L, ZnCl2 0.05~0.2 g / L, CaCl2 0.01~0.03 g / L, and H3BO3 0.01~0.03 g / L.

11. The enhanced oil recovery method as described in claim 1, characterized in that, The aforementioned bioactive surfactant-activated bacterial activation system comprises 10-15 g / L glucose, 1.2-2.4 g / L peptone, 0.6-1.2 g / L potassium dihydrogen phosphate, 0.1-0.4 g / L sodium chloride, 10-26 mL / L trace element solution, and the remainder being water. The trace element solution includes: N(CH2COOH)3 4~5 g / L, MnCl2·4H2O 0.1~0.2 g / L, KAl(SO4)2 0.01~0.02 g / L, NaCl 0.5~2 g / L, Na2MoO4 0.01~0.05 g / L, FeCl2·4H2O 0.2~0.6 g / L, CoCl2·6H2O 0.05~0.2 g / L, ZnCl2 0.05~0.2 g / L, CaCl2 0.01~0.03 g / L, and H3BO3 0.01~0.03 g / L.

12. The enhanced oil recovery method as described in claim 1, characterized in that, The polysaccharide-producing functional bacteria activation system comprises 5-15 g / L starch, 1-5 g / L soybean flour hydrolysate, 0.4-1.2 g / L dipotassium hydrogen phosphate, 0.1-0.3 g / L calcium chloride, 0.05-0.2 g / L magnesium sulfate, 15-30 mL / L trace element solution, and the remainder being water. The trace element solution includes: N(CH2COOH)3 4~5 g / L, MnCl2·4H2O 0.1~0.2 g / L, KAl(SO4)2 0.01~0.02 g / L, NaCl 0.5~2 g / L, Na2MoO4 0.01~0.05 g / L, FeCl2·4H2O 0.2~0.6 g / L, CoCl2·6H2O 0.05~0.2 g / L, ZnCl2 0.05~0.2 g / L, CaCl2 0.01~0.03 g / L, and H3BO3 0.01~0.03 g / L.

13. The enhanced oil recovery method as described in claim 1, characterized in that, The polymer gel comprises 2-4 g / L polyacrylamide, 0.3-0.6 g / L chromium chloride, and 0.02-0.05 g / L citric acid.

14. The enhanced oil recovery method as described in claim 1, characterized in that, The polymer gel comprises 3-6 g / L polyacrylamide, 0.5-0.8 g / L chromium chloride, and 0.05-0.08 g / L citric acid.

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