A sulfate-reducing bacteria bactericide and its application

Abstract

The present invention belongs to the technical field of wastewater treatment in petroleum engineering, and specifically relates to a sulfate-reducing bacteria bactericide and its application. The bactericide comprises the following components and their weight parts: 10-40 parts of dodecyl dimethyl benzyl ammonium chloride, 0-20 parts of glutaraldehyde, 10-30 parts of A bactericide, and 10-80 parts of water; A bactericide is any one of alkyl diquaternary ammonium salt, dodecylguanidine hydrochloride, and hydroxypropyl gemini quaternary ammonium salt modified guanidine. The sulfate-reducing bacteria bactericide of the present invention has a simple composition and a significant bactericidal effect on sulfate-reducing bacteria, especially alkali-resistant and mutated sulfate-reducing bacteria.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum engineering wastewater treatment, and specifically relates to a sulfate-reducing bacteria bactericide and application thereof. Background Art

[0002] There are a large number of sulfate-reducing bacteria (SRB) in oilfield wastewater and injection systems. The bacteria reduce sulfate to sulfide ions and reproduce in large numbers, causing corrosion damage to surface facilities and underground pipelines and sulfide pollution, causing huge economic losses to the oilfield.

[0003] Methods for inhibiting SRB include physical methods, chemical methods and biological methods. Physical methods include: using ionizing radiation, ultrasound or reflection radiation treatment; changing the medium environment and adjusting the pH value of the medium. When the pH value is lower than 4, SRB will stop growing; injecting highly mineralized water or salt water to reduce the water content inside the cells through osmotic pressure, which can inhibit the growth of SRB; injecting hot water periodically, etc. Biological methods use the symbiosis, competition and antagonism between microorganisms to prevent microbial corrosion of metals. Chemical methods mainly inhibit the reproduction of SRB by adding fungicides. Currently commonly used fungicides include quaternary ammonium salts and compound products; aldehyde fungicides, such as glutaraldehyde and acrolein; sulfur-containing compounds and matching products, such as dithiocyanate and isothiazolinone; oxidizing fungicides, such as triclosan, etc.; others such as quaternary phosphates.

[0004] Chinese patent application CN107488166A discloses a fungicide for sulfate-reducing bacteria in oilfield wastewater, which is prepared by reacting 1-propanol and 2,2,6-trimethyl-4-1,3-dioxacyclohexene-4-one to generate an intermediate, which is then split using a chiral reagent to obtain the final fungicide. The fungicide has a sterilization rate of more than 98% for sulfate-reducing bacteria in oilfield wastewater.

[0005] Chinese patent application CN102669103A discloses a fungicide for killing sulfate-reducing bacteria, wherein the weight percentages of the components are: industrial formaldehyde: 22.5%-25.0%; medical metronidazole: 2.5%-3.5%; industrial glutaraldehyde: 20.0%-25.05; water: the balance. Formaldehyde is highly toxic, and a large amount of the fungicide will pose a potential threat to the health of on-site workers.

[0006] Chinese invention patent CN105145631B discloses a sulfate-reducing bacteria inhibitor for oil storage tanks, which is composed of the following components by weight: 60-100 parts by weight of glutaraldehyde or acrolein, and / or 30-70 parts by weight of dodecyl dimethyl benzyl ammonium bromide or dodecyl dimethyl benzyl ammonium chloride; 15-20 parts by weight of lysozyme, and 20-30 parts by weight of protease; 10-20 parts by weight of di-o-phenylethylenediamine acetate, and / or 10-20 parts by weight of ethylenediamine disuccinate; 5-10 parts by weight of tetrakis hydroxymethyl phosphonium sulfate. The inhibitor contains lysozyme and protease, and the production cost is relatively high.

[0007] At present, with the long-term application of the sewage softening fine water treatment system, it is constantly found that the water output by the system also contains a large number of sulfate-reducing bacteria. The applicant has conducted tests on sulfate-reducing bacteria, pH value, oxygen content, sulfide, etc. at the production nodes of the sewage softening fine water treatment system, and collected microbial samples, enriched culture, strain isolation optimization, gene sequencing, comparison and analysis. For the first time, it was found on site that sulfate-reducing bacteria exceeded the standard in an alkaline environment with a high pH value of pH = 10-11, and there were differences and variations in the bacterial flora. For sulfate-reducing bacteria with stronger alkalinity resistance and stronger drug resistance, more effective fungicides are urgently needed.

[0008] By increasing the frequency of system cleaning and adding conventional fungicides before external transport, SRB still exceeded the standard. Therefore, there is an urgent need for fungicides that can effectively inhibit mutated sulfate-reducing bacteria. Summary of the invention

[0009] The main purpose of the present invention is to provide a sulfate-reducing bacteria bactericide. The sulfate-reducing bacteria bactericide of the present invention can effectively inhibit sulfate-reducing bacteria, especially mutated sulfate-reducing bacteria with strong alkali resistance and drug resistance, and solves the problem that sulfate-reducing bacteria mutate, have enhanced alkali resistance and drug resistance, and are difficult to inhibit in the prior art during the softening treatment of oilfield wastewater.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] The present invention first provides a sulfate-reducing bacteria bactericide, which comprises the following components and their weight parts: 10-40 parts of dodecyl dimethyl benzyl ammonium chloride, 0-20 parts of glutaraldehyde, 10-30 parts of A bactericide, and 10-80 parts of water; the A bactericide is any one of alkyl diquaternary ammonium salt, dodecylguanidine hydrochloride, and hydroxypropyl gemini quaternary ammonium salt modified guanidine.

[0012] Furthermore, the fungicide comprises the following components and their weight parts: 10-30 parts of dodecyl dimethyl benzyl ammonium chloride, 10-20 parts of alkyl diquaternary ammonium salt, and 50-80 parts of water. The fungicide is named SH-1 fungicide.

[0013] Furthermore, the alkyl diquaternary ammonium salt has 10-18 carbon atoms in the alkyl group.

[0014] Furthermore, the fungicide comprises the following components and their weight parts: 10-20 parts of dodecyl dimethyl benzyl ammonium chloride, 10-20 parts of dodecyl guanidine hydrochloride, 4-15 parts of glutaraldehyde, and 45-76 parts of water. The fungicide is named SH-2 fungicide.

[0015] Furthermore, the fungicide comprises the following components and their weight parts: 10-20 parts of dodecyl dimethyl benzyl ammonium chloride, 10-20 parts of hydroxypropyl gemini quaternary ammonium salt modified guanidine, 4-20 parts of glutaraldehyde, and 40-76 parts of water. The fungicide is named SH-3 fungicide.

[0016] Furthermore, the number of carbon atoms in the alkyl group of the hydroxypropyl gemini quaternary ammonium salt modified guanidine is 10-18.

[0017] The present invention also provides the use of the above-mentioned sulfate-reducing bacteria bactericide in the softening treatment of oilfield wastewater.

[0018] Compared with the prior art, the present invention has the following technical advantages:

[0019] The sulfate-reducing bacteria bactericide of the present invention has a simple composition and has a significant bactericidal effect on sulfate-reducing bacteria, especially alkali-resistant and mutated sulfate-reducing bacteria. In the process of softening oilfield wastewater, only a small amount of the bactericide of the present invention needs to be added, and the sulfate-reducing bacteria in the treated water are less than or equal to 25 / mL, and the water quality can reach Class A; the treated water is injected back into the formation, which can greatly reduce the damage to the formation, and has significant antibacterial, anti-caking and anti-corrosion effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram of the sewage softening process of the present invention;

[0021] Figure 2 is the species distribution bar graph at the phylum level;

[0022] Figure 3 Heatmap of the community at the genus level;

[0023] Figure 4 It is the Chao Index chart;

[0024] Figure 5 It is the ace index chart;

[0025] Figure 6 is the Shannon index graph;

[0026] Figure 7 It is the Simpson index graph;

[0027] Figure 8 It is a weighted unifrac heat map;

[0028] Fig. 9 is the unweighted unifrac heatmap;

[0029] Fig.10 is PCoA based on weighted unifrac;

[0030] Fig.11 is PCoA based on unweighted unifrac;

[0031] Fig.12 It is the unweighted unifrac tree graph;

[0032] Fig.13 It is the unweighted unifrac tree graph;

[0033] Fig.14 is NMDS based on weighted unifrac;

[0034] Fig.15 is NMDS based on unweighted unifrac;

[0035] Fig.16 It is the heat map of the matrix of differences at the phylum level;

[0036] Fig.17 This is a combined analysis diagram of the sample clustering tree and histogram at the species level. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0039] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0040] Example 1

[0041] A sulfate-reducing bacteria bactericide is composed of the following components and their weight parts: 10 parts of dodecyl dimethyl benzyl ammonium chloride, 10 parts of dodecyl guanidine hydrochloride, 4 parts of glutaraldehyde and 76 parts of water.

[0042] The application of the sulfate-reducing bacteria bactericide in the softening treatment process of oilfield wastewater, such as Figure 1 As shown, the specific steps include:

[0043] Step 1. When the oilfield wastewater enters the softening tank for softening treatment, the pH value of the aqueous solution in the softening tank is first adjusted to 10.6, and then a flocculant is added for sedimentation to obtain low-hardness softened water;

[0044] Step 2. When the low-hardness softened water enters the acid-base neutralization tank, the pH value of the aqueous solution in the acid-base neutralization tank is adjusted to 9.0; after passing through the multi-media filter, 50 mg / L of the bactericide described in Example 1 is added, and then filtered through a metal membrane filter, and then transported to the water injection tank;

[0045] Step 3. The sediment mud discharged from the softening tank is discharged into the sedimentation tank, and then transported to the mud press for solid-liquid separation, and then transported out after forming mud cake;

[0046] Step 4. Drain the clean water from the upper part of the sludge tank into the clean water tank for recycling.

[0047] Example 2

[0048] A sulfate-reducing bacteria bactericide is composed of the following components and their weight parts: 13 parts of dodecyl dimethyl benzyl ammonium chloride, 14 parts of dodecyl guanidine hydrochloride, 5 parts of glutaraldehyde and 68 parts of water.

[0049] The application of the sulfate-reducing bacteria bactericide in the softening treatment process of oilfield wastewater comprises the following steps:

[0050] Step 1. When the oilfield wastewater enters the softening tank for softening treatment, the pH value of the aqueous solution in the softening tank is first adjusted to 10.8, and then a flocculant is added for sedimentation to obtain low-hardness softened water;

[0051] Step 2. When the low-hardness softened water enters the acid-base neutralization tank, the pH value of the aqueous solution in the acid-base neutralization tank is adjusted to 8.9; after passing through the multi-media filter, 55 mg / L of the bactericide described in Example 2 is added, and then filtered through a metal membrane filter, and then transported to the water injection tank;

[0052] Step 3. The sediment mud discharged from the softening tank is discharged into the sedimentation tank, and then transported to the mud press for solid-liquid separation, and then transported out after forming mud cake;

[0053] Step 4. Drain the clean water from the upper part of the sludge tank into the clean water tank for recycling.

[0054] Example 3

[0055] A sulfate-reducing bacteria bactericide is composed of the following components in parts by weight: 20 parts of dodecyl dimethyl benzyl ammonium chloride, 20 parts of dodecyl guanidine hydrochloride, 15 parts of glutaraldehyde, and 55 parts of water.

[0056] The application of the sulfate-reducing bacteria bactericide in the softening treatment process of oilfield wastewater comprises the following steps:

[0057] Step 1. When the oilfield wastewater enters the softening tank for softening treatment, the pH value of the aqueous solution in the softening tank is first adjusted to 11, and then a flocculant is added for sedimentation to obtain low-hardness softened water;

[0058] Step 2. When the low-hardness softened water enters the acid-base neutralization tank, the pH value of the aqueous solution in the acid-base neutralization tank is adjusted to 9.0; after passing through the multi-media filter, 50 mg / L of the bactericide described in Example 3 is added, and then filtered through a metal membrane filter, and then transported to the water injection tank;

[0059] Step 3. The sediment mud discharged from the softening tank is discharged into the sedimentation tank, and then transported to the mud press for solid-liquid separation, and then transported out after forming mud cake;

[0060] Step 4. Drain the clean water from the upper part of the sludge tank into the clean water tank for recycling.

[0061] Example 4

[0062] A sulfate-reducing bacteria bactericide comprises the following components and their weight parts: 10 parts of dodecyl dimethyl benzyl ammonium chloride, 10 parts of dodecyl (dodecyl) diquaternary ammonium salt, and 80 parts of water.

[0063] The application of the sulfate-reducing bacteria bactericide in the softening treatment process of oilfield wastewater comprises the following steps:

[0064] Step 1. When the oilfield wastewater enters the softening tank for softening treatment, the pH value of the aqueous solution in the softening tank is first adjusted to 10.7, and then a flocculant is added for sedimentation to obtain low-hardness softened water;

[0065] Step 2. When the low-hardness softened water enters the acid-base neutralization tank, the pH value of the aqueous solution in the acid-base neutralization tank is adjusted to 8.8; after passing through the multi-media filter, 48 mg / L of the bactericide described in Example 4 is added, and then filtered through a metal membrane filter, and then transported to the water injection tank;

[0066] Step 3. The sediment mud discharged from the softening tank is discharged into the sedimentation tank, and then transported to the mud press for solid-liquid separation, and then transported out after forming mud cake;

[0067] Step 4. Drain the clean water from the upper part of the sludge tank into the clean water tank for recycling.

[0068] Example 5

[0069] A sulfate-reducing bacteria bactericide comprises the following components and their weight parts: 30 parts of dodecyl dimethyl benzyl ammonium chloride, 20 parts of octadecyl diquaternary ammonium salt, and 50 parts of water.

[0070] The application of the sulfate-reducing bacteria bactericide in the softening treatment process of oilfield wastewater comprises the following steps:

[0071] Step 1. When the oilfield wastewater enters the softening tank for softening treatment, the pH value of the aqueous solution in the softening tank is first adjusted to 10.9, and then a flocculant is added for sedimentation to obtain low-hardness softened water;

[0072] Step 2. When the low-hardness softened water enters the acid-base neutralization tank, the pH value of the aqueous solution in the acid-base neutralization tank is adjusted to 8.9; after passing through the multi-media filter, 50 mg / L of the bactericide described in Example 5 is added, and then filtered through a metal membrane filter, and then transported to the water injection tank;

[0073] Step 3. The sediment mud discharged from the softening tank is discharged into the sedimentation tank, and then transported to the mud press for solid-liquid separation, and then transported out after forming mud cake;

[0074] Step 4. Drain the clean water from the upper part of the sludge tank into the clean water tank for recycling.

[0075] Example 6

[0076] A sulfate-reducing bacteria bactericide comprises the following components and their weight parts: 12 parts of dodecyl dimethyl benzyl ammonium chloride, 15 parts of dodecyl diquaternary ammonium salt, and 73 parts of water.

[0077] The application of the sulfate-reducing bacteria bactericide in the softening treatment process of oilfield wastewater comprises the following steps:

[0078] Step 1. When the oilfield wastewater enters the softening tank for softening treatment, the pH value of the aqueous solution in the softening tank is first adjusted to 10.7, and then a flocculant is added for sedimentation to obtain low-hardness softened water;

[0079] Step 2. When the low-hardness softened water enters the acid-base neutralization tank, the pH value of the aqueous solution in the acid-base neutralization tank is adjusted to 8.9; after passing through the multi-media filter, 46 mg / L of the bactericide described in Example 6 is added, and then filtered through a metal membrane filter, and then transported to the water injection tank;

[0080] Step 3. The sediment mud discharged from the softening tank is discharged into the sedimentation tank, and then transported to the mud press for solid-liquid separation, and then transported out after forming mud cake;

[0081] Step 4. Drain the clean water from the upper part of the sludge tank into the clean water tank for recycling.

[0082] Example 7

[0083] A sulfate-reducing bacteria bactericide comprises the following components and their weight parts: 10 parts of dodecyl dimethyl benzyl ammonium chloride, 10 parts of hydroxypropyl gemini quaternary ammonium salt modified guanidine, 4 parts of glutaraldehyde, and 76 parts of water.

[0084] The application of the sulfate-reducing bacteria bactericide in the softening treatment process of oilfield wastewater comprises the following steps:

[0085] Step 1. When the oilfield wastewater enters the softening tank for softening treatment, the pH value of the aqueous solution in the softening tank is first adjusted to 11.1, and then a flocculant is added for sedimentation to obtain low-hardness softened water;

[0086] Step 2. When the low-hardness softened water enters the acid-base neutralization tank, the pH value of the aqueous solution in the acid-base neutralization tank is adjusted to 9.0; after passing through the multi-media filter, 52 mg / L of the bactericide described in Example 7 is added, and then filtered through a metal membrane filter, and then transported to the water injection tank;

[0087] Step 3. The sediment mud discharged from the softening tank is discharged into the sedimentation tank, and then transported to the mud press for solid-liquid separation, and then transported out after forming mud cake;

[0088] Step 4. Drain the clean water from the upper part of the sludge tank into the clean water tank for recycling.

[0089] Example 8

[0090] A sulfate-reducing bacteria bactericide comprises the following components and their weight parts: 13 parts of dodecyl dimethyl benzyl ammonium chloride, 14 parts of hydroxypropyl gemini quaternary ammonium salt modified guanidine, 15 parts of glutaraldehyde, and 68 parts of water.

[0091] The application of the sulfate-reducing bacteria bactericide in the softening treatment process of oilfield wastewater comprises the following steps:

[0092] Step 1. When the oilfield wastewater enters the softening tank for softening treatment, the pH value of the aqueous solution in the softening tank is first adjusted to 10.8, and then a flocculant is added for sedimentation to obtain low-hardness softened water;

[0093] Step 2. When the low-hardness softened water enters the acid-base neutralization tank, the pH value of the aqueous solution in the acid-base neutralization tank is adjusted to 8.8; after passing through the multi-media filter, 55 mg / L of the bactericide described in Example 8 is added, and then filtered through a metal membrane filter, and then transported to the water injection tank;

[0094] Step 3. The sediment mud discharged from the softening tank is discharged into the sedimentation tank, and then transported to the mud press for solid-liquid separation, and then transported out after forming mud cake;

[0095] Step 4. Drain the clean water from the upper part of the sludge tank into the clean water tank for recycling.

[0096] Example 9

[0097] A sulfate-reducing bacteria bactericide comprises the following components and their weight parts: 20 parts of dodecyl dimethyl benzyl ammonium chloride, 20 parts of hydroxypropyl gemini quaternary ammonium salt modified guanidine, 20 parts of glutaraldehyde, and 40 parts of water.

[0098] The application of the sulfate-reducing bacteria bactericide in the softening treatment process of oilfield wastewater comprises the following steps:

[0099] Step 1. When the oilfield wastewater enters the softening tank for softening treatment, the pH value of the aqueous solution in the softening tank is first adjusted to 10.9, and then a flocculant is added for sedimentation to obtain low-hardness softened water;

[0100] Step 2. When the low-hardness softened water enters the acid-base neutralization tank, the pH value of the aqueous solution in the acid-base neutralization tank is adjusted to 9.0; after passing through the multi-media filter, 52 mg / L of the bactericide described in Example 9 is added, and then filtered through a metal membrane filter, and then transported to the water injection tank;

[0101] Step 3. The sediment mud discharged from the softening tank is discharged into the sedimentation tank, and then transported to the mud press for solid-liquid separation, and then transported out after forming mud cake;

[0102] Step 4. Drain the clean water from the upper part of the sludge tank into the clean water tank for recycling.

[0103] (I) Detection of sulfate-reducing bacteria at each node in the softening water treatment process

[0104] When pile 74 station was in normal operation, on-site sampling and testing were carried out for 5 days from September 15 to September 19, 2019, to test the SRB, pH, sulfide, dissolved oxygen and other indicators at each node. The experimental data are shown in Tables 1 and 2.

[0105] Table 1 SRB bacteria detection table of sewage along the 74th station of pile

[0106]

[0107]

[0108] Table 2 Sewage detection table along the 74th station of pile

[0109]

[0110]

[0111] (1) The pH value of the incoming water is about 7, and the SRB range is 6 to 250 / ml. The engineering design pH value is controlled at about 10.0-10.5 to control the survival and growth of SRB bacteria. The test data shows that after adding alkali to soften, the pH value at the outlet of the softening tank is about 10.20, and the SRB range is 2.5×10 2 ~2.5×10 4 / ml, combined with the SRB value of the mud outlet of 2.5×10 4 ~2.5×10 5 / ml, it is preliminarily inferred that there are bacterial growth and mutation in the sludge at the bottom of the softening tank;

[0112] (2) The neutralization tank uses hydrochloric acid to adjust the pH value to 9.0 and the SRB value to 6×10 2 ~2.5×10 4 / ml, slightly more bacteria than in the softening tank;

[0113] (3) The pH value of the diamond filter tank is 9.0, and the SRB value is 2.5×10 3 ~2.5×10 4 / ml, which is an order of magnitude higher than that of the neutralization tank outlet. Combined with the SRB value of 6×10 2 ~ 2.5×10 4 / ml, it can be preliminarily inferred that the trapped sediment particles cannot be completely backwashed clean, and the diamond abrasive filter material may be contaminated;

[0114] (4) The pH value at the outlet of the metal membrane filter tank is 9.00, and the SRB value is 2.5×10 2 ~2.5×10 3 / ml, which is one order of magnitude lower than that of the diamond abrasive filter, indicating that the metal membrane filter has a certain retention effect.

[0115] (5) The sewage in the sewage pool comes from the upper part of the sludge pool, and the SRB value is 2.5×10 3 ~2.3×10 3 / ml, and the mud outlet (2.5×10 4 ~2.5×10 5 / ml), the SRB value is reduced by one order of magnitude, which is related to the open oxygenation of the sludge tank.

[0116] (6) The wastewater from the backwash buffer tank and the sewage from the sewage pool enters the softening recovery tank (the sewage from the sewage pool is pumped into the softening recovery tank 24 hours a day, and the backwash is pumped into the softening recovery tank once every 12 hours. After settling in the buffer tank for a period of time, it is pumped into the softening recovery tank). The SRB value is 2.5×10 2 ~2.5×10 3 Pieces / ml.

[0117] In summary, the nodes where SRB bacteria exceeded the standard were: softening tank sewage, corundum filter media and backwash water quality; the corundum filter media was likely to be contaminated, and sewage passing through would cause secondary pollution, and the backwashing effect was not obvious, so the filter media needed to be cleaned regularly. SRB bacteria were not effectively suppressed at a pH value of about 10.2 in the softening tank, and it was necessary to conduct an indoor pH adjustment experiment on the incoming water to eliminate interference from other factors on site and examine the effect of pH on SRB alone.

[0118] (II) Investigating the effect of pH on SRB bacteria

[0119] The incoming water was adjusted to different pH values ​​with 30% NaOH, and the bactericidal effect of pH value on SRB bacteria in the incoming water of the sewage system of Pile 74 Station and the effluent of the softening tank was investigated. The results are shown in Tables 3 and 4 respectively.

[0120] Table 3 Pile 74 station water pH adjustment experiment

[0121]

[0122] Table 4 pH value adjustment experiment of softening tank outlet water at station 74

[0123]

[0124]

[0125] It can be seen from Tables 3 and 4 that for the water from Pile 74 Station, adjusting the pH value indoors has a significant inhibitory effect on SRB bacteria. When the pH reaches 9, the SRB content is 25 / mL; but for the water out of the softening tank, the pH value has no effect on SRB inhibition, indicating that the bacteria in the softening tank water have enhanced adaptability to high pH values ​​in the dynamic environment of continuous replenishment of new water, and the effect of conventional fungicides on SRB bacteria needs to be further investigated.

[0126] (III) Investigating the effects of fungicides on SRB bacteria

[0127] Take the water from the softening tank on site, and screen the fungicides indoors. At the on-site temperature of 40°C, take different types of fungicides and select different dosing concentrations to investigate their bactericidal effects on SRB bacteria in the water from the softening tank to determine the appropriate dosing concentration. The test results are shown in Table 5.

[0128] Table 5 Fungicide screening evaluation

[0129]

[0130]

[0131] SRB content of softening tank outlet water 6×10 2 / mL, the on-site fungicide has a poor sterilization effect on the softening tank effluent within the detection concentration range, and the conventional SJ fungicide has no effect on it. Considering that the bacterial community may have evolved, the next step is to isolate and identify the strain.

[0132] (IV) Microbial flora isolation and community diversity analysis

[0133] Water and mud samples were collected along the route of pile 74, and strains were separated from the samples to investigate the differences in microbial communities among the samples.

[0134] Table 6 Microbial community analysis sample names and numbers

[0135] Sample No. Sampling location 1# Pile Western Union filter water outlet 2# Pile 74 water 3# Pile 74 softening tank water outlet 4# Pile 74 sewage recovery tank water outlet 1# Mud sample: Softening tank center tube 2# Mud sample: Mud pool bottom

[0136] (1) Community structure composition bar graph

[0137] Based on the results of taxonomic analysis, we can know the taxonomic comparison of one or more samples at each taxonomic level. The results include two pieces of information: what kind of microorganisms are contained in the sample; the number of sequences of each microorganism in the sample, that is, the relative abundance of each microorganism. Figure 2 It can be seen that the community structure of samples 3 and 4 at the phylum classification level is significantly different from that of the other two groups.

[0138] (2) Community Heatmap

[0139] The community heatmap can use color changes to reflect the data information in a two-dimensional matrix or table. It can intuitively represent the size of the data value with a defined color depth. Data is often clustered according to the abundance similarity between species or samples as needed, and the clustered data is represented on the heatmap. Figure 3 It can be seen that the abundance similarity clustering between species or samples at the genus classification level of samples 3 and 4 is significantly different from that of the other two groups.

[0140] (3) Alpha-diversity analysis

[0141] Alpha diversity includes Chao index, Ace index, Shannon index and Simpson index. The larger the first three indexes are and the smaller the last index is, the richer the species in the sample are.

[0142] The Chao index and ACE index reflect the species richness of the community in the sample, which simply refers to the number of species in the community without considering the abundance of each species in the community. The dilution curves corresponding to these two indices can also reflect whether the sample sequencing volume is sufficient. If the curve tends to be flat or reaches a plateau, it can be considered that the sequencing depth has basically covered all species in the sample; otherwise, it means that the species diversity in the sample is high and there are still many species that have not been detected by sequencing.

[0143] Depend on Figure 4 , Figure 5 It can be seen that the number of samples 3 and 4 in the community is significantly smaller than that of the other two groups.

[0144] The Shannon index and the Simpson index reflect the species diversity of the community, which is affected by the species richness and species evenness in the sample community. Under the same species richness, the greater the evenness of each species in the community, the greater the diversity of the community.

[0145] Depend on Figure 6 , Figure 7 It can also be reflected that the community richness and diversity of samples 3 and 4 are significantly lower than those of the other two groups.

[0146] (4) Beta-diversity analysis

[0147] Different from Alpha diversity analysis, Beta diversity analysis is used to compare the differences in species diversity between a pair of samples. The content of each group in the sample is analyzed, and then the Beta diversity value between different samples is calculated.

[0148] There are many indices that can measure Beta diversity, the most commonly used ones are Bray-Curtis, weighted unifrac, and unweighted unifrac.

[0149] 1)(un)weighted.unifrac weighted analysis

[0150] UniFrac analysis uses the evolutionary information between the sequences of each sample to compare whether there are significant differences in the microbial community in a specific evolutionary lineage. UniFrac can be used to evaluate beta diversity, that is, to compare and analyze samples pairwise to obtain the unifrac distance matrix between samples.

[0151] Unweighted unifrac can detect the presence of changes between samples, while weighted unifrac can further quantitatively detect the variations that occur in different lineages between samples.

[0152] Table 7 Weighted unifrac difference matrix

[0153] 1 1_mud 2 2_mud 3 4 1 0 0.538713 0.185855 0.561589 0.795779 0.776554 1_mud 0.538713 0 0.560805 0.320173 0.774647 0.720011 2 0.185855 0.560805 0 0.604718 0.8038 0.790132 2_mud 0.561589 0.320173 0.604718 0 0.689335 0.650615 3 0.795779 0.774647 0.8038 0.689335 0 0.087576 4 0.776554 0.720011 0.790132 0.650615 0.087576 0

[0154] By visualizing Table 7, we can get Figure 8 ;

[0155] Table 8 Unweighted unifrac difference matrix

[0156]

[0157]

[0158] By visualizing Table 8, we can get Fig. 9 ;

[0159] From Table 7, Table 8, Figure 8 , Fig. 9 It can be seen that the darker red color represents a large difference in microbial communities, that is, samples 3, 4 and water samples 1, 2 have huge differences in different lineages; the differences in orange-red or orange-yellow colors are in the middle, that is, the differences between samples 3, 4 and mud samples 1, 2 are slightly smaller than those of water samples 1, 2, but still have certain differences.

[0160] 2) PCoA based on (un)weighted.unifrac

[0161] The distance matrix obtained by Unifrac analysis can be used in a variety of analysis methods, and can be analyzed by multivariate statistical method PCoA to intuitively display the similarities and differences in microbial evolution in different environmental samples.

[0162] PCoA (principal co-ordinates analysis) is a visualization method for studying data similarities or differences. After sorting a series of eigenvalues ​​and eigenvectors, PCoA can find the most important coordinates in the distance matrix. The result is a rotation of the data matrix. It does not change the relative position relationship between sample points, but only changes the coordinate system. PCoA can be used to observe differences between individuals or groups.

[0163] Depend on Fig.10 , Fig.11It can be seen that in the first principal component, samples 3 and 4 are quite different from the other four samples in terms of microbial evolution. In the second principal component, samples 1 and 2 are quite different from mud samples 1# and 2#, with 3 and 4 being in the middle.

[0164] 3) Multi-sample similarity tree analysis based on (un)weighted.unifrac

[0165] The distance matrix obtained by Unifrac analysis can be used in a variety of analysis methods. Graphic visualization processing such as constructing evolutionary trees through the unweighted group average method (UPGMA) in hierarchical clustering can intuitively display the similarities and differences in microbial evolution in different environmental samples.

[0166] UPGMA (Unweighted pair group method with arithmetic mean) assumes that all nucleotides / amino acids have the same mutation rate during evolution, that is, there is a molecular clock. The evolutionary distance between samples can be observed by the distance between branches and the distance of clusters.

[0167] Depend on Fig.12 , 13 It can be seen that samples 3 and 4 are not on the same branch as the other four samples, and the differences are relatively large.

[0168] 4) Non-metric multidimensional scaling analysis based on (un)weighted.unifrac

[0169] Non-metric multidimensional scaling is a data analysis method that simplifies the research objects (samples or variables) in multidimensional space to low-dimensional space for positioning, analysis and classification, while retaining the original relationship between objects. It is suitable for situations where it is impossible to obtain accurate similarity or dissimilarity data between research objects, and only hierarchical relationship data between them can be obtained. Its characteristic is that the species information contained in the sample is reflected in the multidimensional space in the form of points, and the degree of difference between different samples is reflected by the distance between points, and finally a spatial positioning point map of the sample is obtained. By Fig.14 , 15 It can be seen that after weighting, samples 3 and 4 are far away from samples 1 and 2, with greater differences, and also have certain differences from mud samples 1# and 2#.

[0170] 5) Bray-Curtis distance analysis based on species information

[0171] Bray-Curtis distance is a commonly used indicator to reflect the difference between two communities. The calculation of Bray-Curtis distance does not consider the evolutionary distance between sequences, but only considers the presence of species in the sample. The value of Bray-Curtis distance is between 0 and 1, and the larger the value, the greater the difference between the samples. Fig.16 It can be seen that samples 3 and 4 have large differences between communities and 1# and 2# mud samples at the phylum level, and have certain differences with samples 1 and 2 at the phylum level.

[0172] 6) Combined analysis of multi-sample similarity tree and histogram

[0173] Depend on Fig.17 It can be seen that samples 3 and 4 are very different from the other four samples at the species level.

[0174] The above analysis shows that the effluent from the Pile 74 softening tank and the softening recovery tank are significantly different from the effluent from the Pile Western Union filter, the inlet water from Pile 74, the sludge from the center tube of the softening tank, and the sludge from the bottom of the sludge pool in terms of bacterial composition and distribution: there are significant changes in the types and contents of microorganisms; there are significant differences in the community composition at each classification level; and further quantitative variations occur in different lineages between samples.

[0175] Water samples with an imported sulfate-reducing bacteria count of 2500-25000 / ml from a primary filtration device for softening fine water treatment of produced water from an on-site oil field were taken to investigate the effects of the bactericide described in Example 1 (SH-2 type), the bactericide described in Example 4 (SH-1 type), and the bactericide described in Example 7 (SH-3 type). The concentrations of the various bactericides were 40 mg / l, 50 mg / l, and 60 mg / l, respectively. The specific bactericidal effects are shown in Table 9 below.

[0176] Table 9 Indoor sterilization effect of SH-1, SH-2 and SH-3 fungicides

[0177]

[0178] Table 9 shows that when the three fungicides described in Example 1, Example 4 and Example 7 are added indoors at 40-50 mg / mL, the SRB bacteria are controlled within 25 / mL; the bactericidal effects of the above fungicides are significantly better than those of 1227 fungicide.

[0179] The field test investigated the bactericidal effect of the fungicide, and the results are shown in Tables 10, 11 and 12 below respectively.

[0180] Table 10 Effect of adding medicine in the field test of the fungicide formulation described in Example 1

[0181]

[0182]

[0183] From October 8, 2019 to October 20, 2019, the on-site agent optimization test was carried out after the filter for 13 consecutive days. It can be seen from Table 10 that the bactericide described in Example 1 has a good effect in controlling SRB bacteria in the sewage of Pile 74 Station. When the dosage of the reinjection water is 45 mg / L, the SRB bacteria is controlled within 6 / mL, which meets the production requirements.

[0184] Table 11 Effect of adding medicine in the field test of the fungicide formulation described in Example 4

[0185]

[0186]

[0187] From November 1, 2019 to November 21, 2019, the on-site agent optimization test was carried out after the filter for 13 consecutive days. It can be seen from Table 11 that the bactericide described in Example 4 has a good effect in controlling SRB bacteria in the sewage of Pile 74 Station. When the dosage of the reinjection water is 45 mg / L, the SRB bacteria are controlled within 25 / mL, which meets the production requirements.

[0188] Table 12 Effect of adding fungicide in field test of Example 7

[0189]

[0190] From December 25, 2019 to January 6, 2020, the field was subjected to a reagent optimization test after the filter for 13 consecutive days. As can be seen from Table 12, the fungicide described in Example 7 had a good effect in controlling SRB bacteria in the sewage of Pile 74 Station. When the dosage of the reinjection water was 45 mg / L, the SRB bacteria were controlled within 25 / mL, which met the production requirements.

[0191] From December 18, 2019 to March 24, 2021, the water quality of station 74 was tested on site 15 times. As can be seen from Table 13, the fungicides mentioned above have a good effect in controlling SRB bacteria in the sewage of station 74.

[0192] Table 13 Results of on-site external water quality testing at station 74

[0193]

[0194] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. Application of a sulfate-reducing bacteria bactericide in the softening treatment of oilfield wastewater, characterized in that The invention is composed of the following components and their weight parts: 10 parts of dodecyl dimethyl benzyl ammonium chloride, 10 parts of dodecyl guanidine hydrochloride, 4 parts of glutaraldehyde and 76 parts of water.

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