Drilling fluid biotoxicity evaluation method based on microalgae rapid chlorophyll fluorescence

Abstract

The invention discloses a drilling fluid biotoxicity evaluation method based on microalgae rapid chlorophyll fluorescence, and relates to the technical field of drilling fluid biotoxicity evaluation methods, the drilling fluid biotoxicity evaluation method comprises the following steps: S1, culturing microalgae in a photobioreactor, and activating and culturing the microalgae as a seed solution for later use; s2, taking the waste drilling fluid with different concentration gradients as experimental group culture conditions, setting a control group, and inoculating the control group into a photobioreactor filled with the seed solution for culture to obtain a culture system; s3, measuring Fv / Fm in rapid chlorophyll fluorescence parameters of the culture system; s4, calculating the inhibition ratio of the waste drilling fluid to the microalgae; s5, screening and determining the time required by the evaluation method; s6, EC50 of the concentrated control substance and EC50 of the waste drilling fluid are obtained according to the required time of the evaluation method, Fv / Fm in rapid chlorophyll fluorescence parameters is used as a detection index, the inhibition condition of microalgae can be more accurately represented, and the evaluation period is shortened.

Description

Technical Field

[0001] The invention relates to the technical field of drilling fluid biological toxicity evaluation methods, and in particular to a drilling fluid biological toxicity evaluation method based on microalgae rapid chlorophyll fluorescence. Background Art

[0002] With the increasing awareness of environmental protection, how to reduce the pollution of waste drilling fluid to the surrounding environment has become one of the key issues in the drilling industry. As the difficulty of drilling increases, the drilling fluid system is gradually improved, the technology continues to advance, and the composition of its chemical treatment agents becomes more complex. In the process of oil extraction, a large amount of waste drilling fluid is bound to be generated. Therefore, it is of great significance to develop environmentally friendly and high-performance drilling fluids. With the advancement of the research and development of environmentally friendly drilling fluids, the demand for cheaper and faster drilling fluid toxicity evaluation methods is gradually increasing, and the establishment of an innovative biological toxicity evaluation system has broad market potential.

[0003] PetroChina resolutely implements the national pollution prevention and control requirements, builds the "1+3" system for ecological environmental protection and development, and actively promotes the development of new drilling fluids that meet green environmental protection requirements. Drilling fluids are mainly composed of liquid phase, solid phase and chemical treatment agents. Because of their functions of carrying and suspending cuttings, maintaining the stability of the wellbore, protecting oil and gas layers, cooling and lubricating the drill bit, and transmitting water power, they have become an indispensable and important component in oil and gas drilling projects. With the gradual improvement of the drilling fluid system and the continuous advancement of technology, the composition of chemical treatment agents has become more complex. At present, the types of drilling fluids are mainly divided into water-based drilling fluids with good environmental protection and inhibition performance, oil-based drilling fluids suitable for shale gas extraction, ultra-high density and ultra-high temperature drilling fluids used in high-temperature deep wells, foam drilling fluids suitable for low-pressure layers and leak-prone layers, and synthetic-based drilling fluids with excellent thermal stability.

[0004] Waste drilling fluid is the main source of pollution in drilling projects. It usually contains water, clay, weighting materials, various chemical treatment agents, oil and drill cuttings. It is a complex multiphase stable suspended colloidal system. Most of the waste drilling fluid is alkaline. Depending on the type, it may contain pollutants such as hydrocarbons, various polymers, lignin sulfonates, heavy metal ions and impurities in barite. It is highly toxic and difficult to degrade. Direct discharge will seriously harm the environment.

[0005] For offshore drilling, the acute half-lethal concentration (LC) within 96 hours is generally used at home and abroad. 50 To indicate the toxicity of drilling fluid. my country's first-class sea area standard LC 50 ≥30000mg / kg. LC 50The smaller the value, the greater the toxicity of the drilling fluid. The American Petroleum Institute (API) recommends that the acute toxicity test method be used for the evaluation of drilling fluid toxicity, mainly including the mysid method, microbial toxicity method, bioaccumulation luminescence method and sea urchin fertilization method. Among them, the mysid method is a conventional test method officially approved by the United States Environmental Protection Agency. However, the mysid method has a long test time, cumbersome and time-consuming preparation process and method, and complex operation process. In addition, mysid is not widely distributed in my country, so it is not suitable for large-scale material screening. The luminescent bacteria method and the luminescent seaweed method have greatly optimized the problem of long test time. The luminescent bacteria method is simple, fast and cheap, and has been widely valued in the field of drilling fluid toxicity testing. The luminescent bacteria (Microtox) test technology uses Photobacterium phosphoreum as an acute toxicity test microorganism and uses the change of its luminescence intensity as an indicator to determine the biological toxicity of harmful and toxic substances in the environment. After adding toxic substances, the luminescent bacteria in the active period will be inhibited or even die, and the luminescence intensity will decrease or even be zero. The principle of the luminescent seaweed method is similar to it. However, considering that pH has a great influence on the growth of microalgae, this method requires that the pH range of the drilling fluid reserve solution is within 7.5-8, but in actual situations, the pH of the drilling fluid is likely to exceed this range. The microbial luminescence method needs to correct interference factors to be applicable to most systems, because the composition of the drilling fluid is complex and it may not be possible to correct the blank well. The rapid chlorophyll fluorescence parameters used in this method can more accurately characterize the inhibition of microalgae. The detection steps are simple and the detection time required is short, which can reduce the impact of the macroscopic physical and chemical properties of the drilling fluid itself on the biological toxicity evaluation.

[0006] In the study of drilling fluid toxicity evaluation using microalgae, fluorescence spectroscopy has gradually become one of the mainstream directions. In the prior art, the patent with authorization announcement number CN102031280B detects chlorophyll fluorescence by a fluorescence photometer and calculates the inhibition rate to characterize the degree of inhibition of microalgae. In this technology, in order to avoid interference peaks in the drilling fluid system, the fluorescence emission spectra of all components must be detected before the experiment, and subsequent operations can only be carried out after confirming that there are no interfering fluorescence peaks. This method uses the rapid chlorophyll parameters of microalgae as detection indicators. The rapid chlorophyll parameters have the characteristics of rapid measurement, non-destructive, easy to control conditions, not easily interfered, and a large amount of data can be obtained in one measurement, which can reduce the preliminary processing steps of the sample.

[0007] The patent application with the publication number CN110376146A uses Scenedesmus obliquus to detect the biological toxicity of sulfonamide antibiotics. The microalgae are cultured with gradient concentrations of sulfonamide antibiotics, and the absorbance values ​​after 0h and 96h are detected using a multifunctional microplate reader to establish a concentration-inhibition curve. The multifunctional microplate reader is a precision instrument and needs to be properly maintained in the laboratory and cannot be used for field testing of samples. The culture time required for this method is shorter, only 48h, and the detection conditions are simpler.

[0008] The patent application publication number CN116203003A discloses a quantitative analysis method for herbicide toxicity based on the full curve characteristics of microalgae OJIP. Through the exposure experiment of microalgae to different concentrations of herbicides, the dose-effect quantitative relationship curve is established and the toxicity of the herbicide is characterized by the 50% effect concentration. However, before the dose-effect quantitative relationship curve is established, the process of constructing a response index based on the full curve characteristics of the OJIP curve is slightly cumbersome, and the original data needs to be processed, so certain professional knowledge is required.

[0009] In view of this, this application is filed. Summary of the invention

[0010] The present invention provides a method for evaluating the biological toxicity of drilling fluid based on the rapid chlorophyll fluorescence of microalgae. v / F m As a detection indicator, it can more accurately characterize the inhibition of microalgae to solve the problems of cumbersome correction and long evaluation cycle in the existing technology.

[0011] The present invention is achieved through the following technical solutions:

[0012] This application proposes a drilling fluid biological toxicity evaluation method based on microalgae rapid chlorophyll fluorescence, comprising the following steps:

[0013] S1: Cultivate the microalgae in a photobioreactor and use it as seed solution after activation and cultivation;

[0014] S2: using drilling fluids of different concentration gradients as the culture conditions for the experimental group and setting up a control group, all of which are inoculated in a photobioreactor filled with the seed solution for culture to obtain a culture system;

[0015] S3: intermittently sampling the culture system, measuring and adjusting the pH of the culture system, and simultaneously measuring the F in the fast chlorophyll fluorescence parameter of the culture system v / F m ;

[0016] S4: F of the microalgae system without adding drilling fluid v / F m As a blank control, the inhibition rate of drilling fluid on microalgae was calculated;

[0017] S5: Statistically analyze the relationship between the microalgae inhibition rate and the control concentration of the control group and the relationship between the microalgae inhibition rate and the drilling fluid concentration, and combine the two analysis results to screen and determine the time required for this evaluation method;

[0018] S6: The time required for this evaluation method to obtain the EC of the control 50 and EC of drilling fluid50 , compared with the EC of the control 50 and EC of drilling fluid 50 That is, the biological toxicity of drilling fluid can be evaluated.

[0019] Preferably, the microalgae include Tetraselmis subcordiformis and / or Chlorella vulgaris and / or Scenedesmus and / or Chlamydomonas reinhardtii, and the photobioreactor is a bubbling column photobioreactor.

[0020] Preferably, the inoculation volume ratio of the microalgae in the photobioreactor in S1 is 10% to 30%, and the activation culture time is 3 to 7 days.

[0021] Preferably, the gradient concentration of the drilling fluid in S2 is 0-1000 mg / L, and the control substance of the control group is the standard poison SDS, and the concentration gradient is 0-15 mg / L.

[0022] Preferably, the initial inoculation density OD of the control in the drilling fluid in S2 and the control group is 680 It is 0.5~0.8.

[0023] Preferably, the intermittent sampling method in S3 includes daily sampling, and the pH needs to be adjusted within the range of 7 to 8.

[0024] Preferably, the calculation method of the inhibition rate in S4 is: (F of microalgae without adding drilling fluid v / F m - Adding microalgae to drilling fluid v / F m ) / F without adding microalgae to drilling fluid v / F m .

[0025] Preferably, the statistics and analysis in S5 include statistically drawing a curve or table of the relationship between the microalgae inhibition rate and the control concentration, and a curve or table of the relationship between the microalgae inhibition rate and the drilling fluid concentration.

[0026] Preferably, the screening in S5 includes finding a culture time at which the microalgae inhibition rate satisfies a good positive correlation with the control and the drilling fluid concentration, and the culture time is the time required by the evaluation method.

[0027] Preferably, the control concentration in S6 is EC 50 and EC of drilling fluid 50 They are respectively the half-effective control concentration corresponding to a microalgae inhibition rate of 50% and the half-effective drilling fluid concentration corresponding to a microalgae inhibition rate of 50%.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] The present invention relates to a method for evaluating the biological toxicity of drilling fluid based on the rapid chlorophyll fluorescence parameters of marine microalgae, which is beneficial to the on-site rapid evaluation of the biological toxicity of drilling fluid and promotes environmental protection construction. v / F m As a detection indicator, it can more accurately characterize the inhibition of microalgae. This technology greatly shortens the detection time, the algae species are cheap and easy to obtain, and the biological toxicity detection is more targeted, and the characterization results are less affected by the physical and chemical properties of the drilling fluid itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0031] Figure 1 A curve diagram showing the relationship between the microalgae inhibition rate and the SDS concentration on the second day provided in an embodiment of the present invention;

[0032] Figure 2 A curve diagram showing the relationship between the microalgae inhibition rate on the second day and the concentration of the waste drilling fluid provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0036] The fast chlorophyll fluorescence induction kinetic curve, or OJIP curve, contains a lot of useful information about the photosynthetic apparatus (especially photosystem II). The OJIP curve has the characteristics of fast measurement, no damage, easy control of conditions, and a large amount of data can be obtained in one measurement. In the photosynthesis process of plants, photosystem II uses the absorbed light energy to split water and transfers the released electrons to plastoquinone. The fast chlorophyll fluorescence parameter F v / F m This ratio is defined as the maximum photochemical efficiency of photosystem II under light adaptation. The embodiment of the present invention uses the F in the fast chlorophyll fluorescence parameter. v / F m As a detection indicator, it can more accurately characterize the inhibition of microalgae, specifically:

[0037] The embodiment of the present invention provides a method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae, comprising the following steps:

[0038] S1: Cultivating microalgae in a photobioreactor, and using the activated culture as seed solution for later use; the microalgae include Tetraselmis subcordiformis and / or Chlorella and / or Scenedesmus and / or Chlamydomonas reinhardtii, the photobioreactor is a bubbling column photobioreactor, the inoculation volume ratio of the microalgae in the photobioreactor is 10% to 30%, and the activation culture time is 3 to 7 days;

[0039] S2: The drilling fluids with different concentration gradients are used as the experimental group culture conditions, and a control group is set up, and they are all inoculated in a photobioreactor filled with the seed solution for culture to obtain a culture system; the gradient concentration of the drilling fluid is 0-1000 mg / L, the control substance of the control group is the standard poison SDS, and the concentration gradient is 0-15 mg / L, and the initial inoculation density OD of the drilling fluid and the control substance of the control group is 680 0.5~0.8;

[0040] S3: intermittently sampling the culture system, measuring and adjusting the pH of the culture system, and simultaneously measuring the F in the fast chlorophyll fluorescence parameter of the culture system v / F m ; The intermittent sampling method includes daily sampling, and the pH needs to be adjusted within the range of 7 to 8;

[0041] S4: F of the microalgae system without adding drilling fluid v / F m As a blank control, the inhibition rate of drilling fluid on microalgae was calculated; the inhibition rate was calculated as follows: (F of microalgae without adding drilling fluid v / F m - Adding microalgae to drilling fluid v / F m ) / F without adding microalgae to drilling fluidv / F m ;

[0042] S5: Statistically analyzing the relationship between the microalgae inhibition rate and the control concentration of the control group and the relationship between the microalgae inhibition rate and the drilling fluid concentration, and combining the two analysis results to screen and determine the required time of the evaluation method; the statistics and analysis include statistically drawing a curve or table of the relationship between the microalgae inhibition rate and the control concentration, and a curve or table of the relationship between the microalgae inhibition rate and the drilling fluid concentration; the screening includes finding the culture time when the microalgae inhibition rate satisfies a good positive correlation with the control and the drilling fluid concentrations, and the culture time is the required time of the evaluation method;

[0043] S6: The time required by this evaluation method to obtain the EC concentration of the control 50 EC of spent drilling fluid 50 , compared with the EC of the control 50 EC of spent drilling fluid 50 That is, the biological toxicity of drilling fluid can be evaluated; the EC 50 and EC of drilling fluid 50 They are respectively the half-effective control concentration corresponding to a microalgae inhibition rate of 50% and the half-effective drilling fluid concentration corresponding to a microalgae inhibition rate of 50%.

[0044] Example

[0045] The embodiment of the present invention provides a method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae, comprising the following steps:

[0046] S1: Cultivating microalgae in a photobioreactor, and using the activated culture as seed solution for later use; the microalgae is Tetraselmis subcordiformis, the photobioreactor is a bubbling column photobioreactor, the inoculation ratio of the microalgae in the photobioreactor is 25%, and the activation culture time is 5 days;

[0047] S2: The waste drilling fluid with different concentration gradients is used as the experimental group culture condition, and a control group is set up, and they are all inoculated in the photobioreactor filled with the seed liquid for culture to obtain a culture system; the gradient concentration of the waste drilling fluid is 0 mg / L, 500 mg / L, 750 mg / L and 1000 mg / L, the control of the control group is the standard poison SDS, and the concentration gradient is 0 mg / L, 5 mg / L, 10 mg / L and 15 mg / L, and the initial inoculation density OD of the waste drilling fluid and the control of the control group is 680 is 0.6;

[0048] S3: intermittently sampling the culture system, measuring and adjusting the pH of the culture system, and simultaneously measuring the F in the rapid chlorophyll fluorescence parameter of the culture system v / Fm ; The intermittent sampling method includes daily sampling, and the pH needs to be adjusted within the range of 7 to 8, that is, if the pH of the system exceeds 8, it is adjusted to 7 with a trace amount of acid;

[0049] S4: F of the microalgae system without adding waste drilling fluid v / F m As a blank control, the inhibition rate of the waste drilling fluid on the microalgae was calculated; the calculation method of the inhibition rate is: (the F of the microalgae without adding the waste drilling fluid v / F m - Adding waste drilling fluid microalgae to F v / F m ) / F without adding waste drilling fluid microalgae v / F m ;

[0050] S5: Statistically analyze the relationship between the microalgae inhibition rate and the control concentration of the control group and the relationship between the microalgae inhibition rate and the concentration of the waste drilling fluid, and combine the two analysis results to screen and determine the required time of the evaluation method; the statistics and analysis include statistically drawing a curve or table of the relationship between the microalgae inhibition rate and the control concentration, and a curve or table of the relationship between the microalgae inhibition rate and the waste drilling fluid concentration; the screening includes finding the culture time when the microalgae inhibition rate satisfies a good positive correlation with the control and the waste drilling fluid concentrations, and the culture time is the required time of the evaluation method;

[0051] S6: The time required by this evaluation method to obtain the EC concentration of the control 50 EC of spent drilling fluid 50 , compared with the control concentration of EC 50 EC of spent drilling fluid 50 That is, the biological toxicity of drilling fluid can be evaluated; the EC concentration of the control substance is 50 EC of spent drilling fluid 50 They are respectively the half-effective control concentration corresponding to a microalgae inhibition rate of 50% and the half-effective waste drilling fluid concentration corresponding to a microalgae inhibition rate of 50%.

[0052] Experimental Results

[0053] Measuring the fast chlorophyll fluorescence parameter F in the culture system v / F m The measurement was performed using an AquenPen AP110-C handheld algae fluorescence detector at room temperature of 20-25°C. The results are shown in Tables 1 and 2, which are the effects of the concentration of the waste drilling fluid on the fluorescence intensity of the algae recorded during the experiment of the embodiment of the present invention. v / F m The influence of SDS concentration on F v / F m Impact of:

[0054] Table 1 Effect of waste drilling fluid concentration on F v / F m Impact

[0055]

[0056] Table 2 Effect of SDS concentration on F v / F m Impact

[0057]

[0058] The F without adding waste drilling fluid microalgae system v / F m As a blank control, the inhibition rate of the waste drilling fluid on microalgae was calculated = (the F of microalgae without waste drilling fluid added v / F m - Adding waste drilling fluid microalgae to F v / F m ) / F without adding waste drilling fluid microalgae v / F m ). The relationship between the microalgae inhibition rate and the SDS concentration and the relationship between the microalgae inhibition rate and the waste drilling fluid concentration were plotted as shown in Table 3 and Table 4, respectively.

[0059] Table 3 Relationship between microalgae inhibition rate and waste drilling fluid concentration

[0060]

[0061] Table 4 Relationship between microalgae inhibition rate and SDS concentration

[0062]

[0063] Combined with Table 3 and Table 4, the culture time at which the microalgae inhibition rate satisfies a good positive correlation with the concentration of SDS and waste drilling fluid is found, which is the time required for this method. In the embodiment of the present invention, the second day is selected as the required time. The results are shown in Tables 5 and 6. Figure 1 and Figure 2 As shown:

[0064] Table 5 Relationship between microalgae inhibition rate and SDS concentration on the second day

[0065]

[0066] The data in Table 5 are plotted into a curve, such as Figure 1 As shown, we can get Y = 0.65339*(1-EXP(-000283*X)), where X is the SDS concentration and Y is the inhibition rate. 2=0.94683, the inhibition rate was calculated by using the experimentally obtained Fv / Fm parameter as a reference, and the EC value of the standard poison SDS with low biological toxicity acting on Tetraselmis subcordiformis was obtained in the experiment. 50 It is 512.47mg / L.

[0067] Table 6 Relationship between microalgae inhibition rate and waste drilling fluid concentration on the second day

[0068]

[0069] The data in Table 6 are plotted into a curve, such as Figure 2 As shown, we can get Y = 1 / (1.8357 + 95159.59735 * 0.98362^x), where x is the concentration of the waste drilling fluid, Y is the inhibition rate, and the fitting degree R 2 =0.99805, the EC corresponding to the effect of drilling fluid wastewater on Tetraselmis subcordiformis was obtained in the experiment 50 The result is 803.80 mg / L. This result is greater than the EC of the standard poison SDS 50 The results showed that the biological toxicity of drilling fluid wastewater to Tetraselmis subcordiformis was lower than that of the standard toxicant SDS, and it could be one of the bases for evaluating the environmental performance of drilling fluid.

[0070] Compared with conventional biological toxicity experiments, the evaluation method provided by the embodiment of the present invention shortens the detection time, can directly use waste drilling fluid as experimental material on site, the detection instrument is portable, the method is less affected by the physical and chemical properties of the drilling fluid itself, and can better characterize the inhibition of microalgae. That is, the embodiment of the present invention can use a handheld rapid chlorophyll fluorescence detector for detection, the detection instrument is portable and easy to operate, and can directly use waste drilling fluid as experimental material on site. It is relatively easy to implement rapid toxicity detection using this method, and it has the potential to become a mainstream method for promotion.

[0071] In general, the rapid chlorophyll fluorescence parameter used in this method can more accurately characterize the inhibition of microalgae. The detection steps are simple and the required detection time is short. It can reduce the influence of the macroscopic physicochemical properties of the drilling fluid itself on the biological toxicity evaluation. At the same time, the embodiment of the present invention simplifies the subsequent data processing process, making the method more widely applicable. Therefore, in the field of biological toxicity evaluation of waste drilling fluid using microalgae as model organisms, the evaluation method based on this parameter has research value and potential.

[0072] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae. It is characterized in that The following steps are involved: S1: Cultivate the microalgae in a photobioreactor and use it as seed solution after activation and cultivation; S2: using drilling fluids of different concentration gradients as the culture conditions for the experimental group and setting up a control group, all of which are inoculated in a photobioreactor filled with the seed solution for culture to obtain a culture system; S3: intermittently sampling the culture system, measuring and adjusting the pH of the culture system, and simultaneously measuring the F in the fast chlorophyll fluorescence parameter of the culture system v / F m ; S4: F of the microalgae system without adding drilling fluid v / F m As a blank control, the inhibition rate of drilling fluid on microalgae was calculated; S5: Statistically analyze the relationship between the microalgae inhibition rate and the control concentration of the control group and the relationship between the microalgae inhibition rate and the drilling fluid concentration, and combine the two analysis results to screen and determine the time required for this evaluation method; S6: The time required for this evaluation method to obtain the EC of the control 50 and EC of drilling fluid 50 , compared with the EC of the control 50 and EC of drilling fluid 50 That is, the biological toxicity of drilling fluid can be evaluated.

2. The method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae according to claim 1, It is characterized in that The microalgae include Tetraselmis subcordiformis and / or Chlorella and / or Scenedesmus and / or Chlamydomonas reinhardtii, and the photobioreactor is a bubbling column photobioreactor.

3. The method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae according to claim 1, It is characterized in that In S1, the inoculation volume ratio of the microalgae in the photobioreactor is 10% to 30%, and the activation culture time is 3 to 7 days.

4. The method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae according to claim 1, It is characterized in that The gradient concentration of the drilling fluid in S2 is 0-1000 mg / L, and the control substance of the control group is the standard poison SDS, and the concentration gradient is 0-15 mg / L.

5. The method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae according to claim 1, It is characterized in that Initial inoculation density OD of the control in the drilling fluid and control group in S2 680 It is 0.5~0.

8.

6. According to claim 1, a method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae, It is characterized in that The intermittent sampling method in S3 includes daily sampling, and the pH needs to be adjusted within the range of 7 to 8.

7. The method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae according to claim 5, It is characterized in that The calculation method of the inhibition rate described in S4 is: (F of microalgae without adding drilling fluid v / F m - Adding microalgae to drilling fluid v / F m ) / F without adding microalgae to drilling fluid v / F m .

8. The method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae according to claim 1, It is characterized in that The statistics and analysis in S5 include statistically drawing a curve or table of the relationship between the microalgae inhibition rate and the control concentration, and a curve or table of the relationship between the microalgae inhibition rate and the drilling fluid concentration.

9. The method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae according to claim 8, It is characterized in that The screening in S5 includes finding out the culture time at which the microalgae inhibition rate satisfies a good positive correlation with the control and the drilling fluid concentration, and the culture time is the time required by the evaluation method.

10. The method for evaluating the biological toxicity of drilling fluid based on rapid chlorophyll fluorescence of microalgae according to claim 9, It is characterized in that EC of the control in S6 50 and EC of drilling fluid 50 They are respectively the half-effective control concentration corresponding to a microalgae inhibition rate of 50% and the half-effective drilling fluid concentration corresponding to a microalgae inhibition rate of 50%.

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