Microbial paraffin inhibitor and preparation method and application thereof

Abstract

The present application relates to the field of oil production, discloses a microbial wax removal and prevention agent, and a preparation method and application thereof, the microbial wax removal and prevention agent comprises a nutrient solution and microorganisms; the microorganisms comprise Exiguobacterium aurantiacum, and at least one of Bacillus stearothermophilus, Pseudomonas schneideri, Bacillus licheniformis and Rhodococcus ruber.The microbial wax removal and prevention agent is suitable for both ordinary wax-containing oil well wax removal and prevention and high calcium and magnesium wax-containing oil reservoir, has efficient wax dissolving and prevention effect, and has a wide application range.

Description

Technical Field

[0001] This invention relates to the field of oil extraction, specifically to a microbial wax-removing agent, a method for preparing the microbial wax-removing agent, the microbial wax-removing agent prepared by the method, and the application of the microbial wax-removing agent in waxy oil reservoirs for wax removal and / or improving oil recovery. Background Technology

[0002] The underlying cause of wax buildup in oil wells is the presence of wax in the crude oil; the higher the wax content, the more severe the wax buildup. Under reservoir conditions, due to the high temperature, the wax is dissolved in the crude oil. During extraction, as temperature and pressure decrease, the wax gradually precipitates from the crude oil, crystallizes, and deposits on the surface of the tubing, causing wax buildup. Waxing on the tubing, sucker rod, and pump increases the load on the pumping unit, reduces pump efficiency, decreases production, lowers productivity, shortens the effective life of the sucker rod, and in severe cases, even causes well shutdown. In some oil-producing blocks with severe wax buildup, wax removal and prevention costs can account for a large proportion of the total operating costs.

[0003] Mechanical wax removal, hot well washing, and chemical wax removal are the three traditional methods for preventing and removing wax from wax-containing oil wells, but each has its own shortcomings. Mechanical wax removal is difficult to install and repair, and the wax scraper is prone to detachment and damage, causing oil well accidents. Hot washing wax removal can easily cause well jamming if not operated properly, and can damage the oil layer in low-production wells. If the washing fluid is incompatible with the formation water, it will aggravate scale formation in the wellbore, and requires the use of large supporting vehicles, which is time-consuming and labor-intensive. Chemical wax removal agents generally pollute the environment and affect human health. Microbial wax removal technology is a technology that differs from the above three methods. Microbial wax removal technology is a technology that uses microbial wax removal agents to prevent and remove wax from oil wells. The mechanism of microbial wax removal mainly includes two aspects: on the one hand, the microbial cells adsorb onto the wellbore surface to form a bacterial protective film, thereby preventing wax crystals from adsorbing and accumulating on the metal surface; on the other hand, the degradation and emulsification of wax components in crude oil by the microbial cells prevents wax crystal formation, reduces tubing waxing, and extends the wax removal cycle. Compared with traditional physical and chemical dewaxing techniques, microbial dewaxing has the following characteristics: ① Simple construction conditions, no need for additional equipment investment, and easy operation. ② Low cost and significant economic benefits. Microbial dewaxing not only reduces or eliminates the need for hot washing or chemical dewaxing agents, but also increases liquid production, reduces water content, and increases oil production. ③ Microbial agents are non-toxic and harmless, do not damage the formation, and cause no environmental pollution.

[0004] Currently, while microbial wax removal and prevention is a mature technology and has been widely adopted, it still has some problems. In particular, in high-calcium and magnesium oil reservoirs, precipitation is prone to occur, which adversely affects the growth and metabolic rate of microorganisms, reducing the effectiveness of wax removal and prevention. Furthermore, the generated precipitation can easily form scale in the wellbore, clogging it and affecting the overall effectiveness. Therefore, there is currently no perfect microbial wax removal and prevention technology specifically designed for high-calcium and magnesium oil reservoirs.

[0005] CN102093868A discloses a microbial wax-removing and preventing agent composed of an expanded culture medium of Rhodococcus ruber Z25 and a wax-removing and preventing nutrient solution, which is then injected into the oil wellbore for wax removal and prevention. However, the reported growth temperature of this strain is relatively low, only able to grow and metabolize at 20-50℃, and unable to grow and metabolize at 50-90℃ to reduce or dissolve wax; while the temperature of wax-containing oil reservoirs is generally high, exceeding the growth and metabolic range of this strain.

[0006] The microbial wax removal method described in CN107255024A is applicable to reservoirs with temperatures below 90℃, but it does not mention high-calcium-magnesium waxy reservoirs. Summary of the Invention

[0007] The purpose of this invention is to provide a microbial wax-removing and wax-preventing agent suitable for high-calcium and magnesium wax-containing reservoirs, a method for preparing the microbial wax-removing and wax-preventing agent, the microbial wax-removing and wax-preventing agent prepared by the method, and the application of the microbial wax-removing and wax-preventing agent in wax-containing reservoirs for wax removal and / or improving oil recovery. This microbial wax-removing and wax-preventing agent has a high efficiency in dissolving and preventing wax, is suitable for wax removal and wax-preventing treatment in wax-containing reservoirs under higher temperature conditions, is also suitable for high-calcium and magnesium wax-containing reservoirs, and can also improve oil recovery, thus having a wide range of applications.

[0008] To achieve the above objectives, the first aspect of the present invention provides a microbial wax remover, the microbial wax remover comprising a nutrient solution and microorganisms;

[0009] The microorganisms include *Exiguobacterium aurantiacum*, and at least one of *Bacillus stearothermophilus*, *Pseudomonas schneideri*, *Bacillus licheniformis*, and *Rhodococcus ruber*.

[0010] Preferably, the preservation number of the *Microbacterium aureum* is CGMCC No. 14606;

[0011] The accession number of the thermophilic steatobacterium is ATCC 7953;

[0012] The accession number of the *Pseudomonas schlegelii* strain is ATCC 17588;

[0013] The Bacillus licheniformis has the accession number ATCC 21415;

[0014] The accession number of the Rhodococcus is ATCC 17896.

[0015] The second aspect of the present invention provides a method for preparing a microbial wax-removing agent, the method comprising: mixing a nutrient solution with microorganisms and then optionally fermenting the mixture to obtain a microbial wax-removing agent;

[0016] The microorganisms include *Exiguobacterium aurantiacum*, and at least one of *Bacillus stearothermophilus*, *Pseudomonas schneideri*, *Bacillus licheniformis*, and *Rhodococcus ruber*.

[0017] The third aspect of the present invention provides a microbial dewaxing agent prepared by the method described above.

[0018] The fourth aspect of the present invention provides the application of the microbial wax-removing agent as described above in wax-containing reservoirs for wax removal and / or enhanced oil recovery.

[0019] Preferably, the waxy oil reservoir is a high-calcium-magnesium waxy oil reservoir, wherein the calcium ion content is above 500 mg / L and the magnesium ion content is above 2000 mg / L in the high-calcium-magnesium waxy oil reservoir.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The microbial wax-removing and wax-preventing agent of the present invention has a high-efficiency wax-dissolving and wax-preventing effect, which can extend the maintenance cycle of wells that are prone to wax blockage, reduce the number of hot washes, reduce the load of oil pumps, and at the same time increase crude oil production to a certain extent.

[0022] (2) The microbial wax removal and prevention agent described in this invention can be applied to various types of waxy oil reservoirs. It is suitable for wax removal and prevention construction in waxy oil reservoirs under higher temperature conditions, as well as construction in high calcium and magnesium waxy oil reservoirs. In particular, it can prevent or alleviate the problem of wax removal and prevention in high calcium and magnesium waxy oil reservoirs, improve the wax removal and prevention effect, and is targeted, highly operable, and widely applicable. It can solve the production problem of wax-blocked oil reservoirs.

[0023] (3) The microbial wax remover in this invention has low sensitivity to formation oil, does not pollute the environment, and does not damage the formation. Detailed Implementation

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] The first aspect of this invention provides a microbial wax remover, the microbial wax remover comprising a nutrient solution and microorganisms;

[0026] The microorganisms include *Exiguobacterium aurantiacum*, and at least one of *Bacillus stearothermophilus*, *Pseudomonas schneideri*, *Bacillus licheniformis*, and *Rhodococcus ruber*.

[0027] Preferably, the microorganism comprises *Microbacterium aureum*, and at least two of *Bacillus stearothermophilus*, *Pseudomonas schrenckii*, *Bacillus licheniformis*, and *Rhodococcus rubrum*.

[0028] Preferably, the total viable bacteria count in the microbial wax remover is 1*102. 7 CFU / mL or higher, preferably 1*10 8 CFU / mL or higher.

[0029] Preferably, the viable count of *Microbacterium aureum* in the microbial wax remover is 1*103. 7 CFU / mL or higher, for example, 1*10 7 2*10 7 4*10 7 6*10 7 8*107 1*10 8 CFU / mL and above, and any range between any two values.

[0030] Preferably, the viable count of *Bacillus stearothermophilus* is 1*10-1. 7 CFU / mL or higher, for example, 1*10 7 2*10 7 4*10 7 6*10 7 8*10 7 1*10 8 CFU / mL and above, and any range between any two values.

[0031] Preferably, the viable count of *Pseudomonas stearothermiae* is 1*10-1. 7 CFU / mL or higher, for example, 1*10 7 2*10 7 4*10 7 6*10 7 8*10 7 1*10 8 CFU / mL and above, and any range between any two values.

[0032] Preferably, the viable count of Bacillus licheniformis is 1*10-1. 7 CFU / mL or higher, for example, 1*10 7 2*10 7 4*10 7 6*10 7 8*10 7 1*10 8 CFU / mL and above, and any range between any two values.

[0033] Preferably, the viable count of Rhodococcus is 1*10⁻⁶. 7 CFU / mL or higher, for example, 1*10 7 2*10 7 4*10 7 6*10 7 8*10 7 1*10 8 CFU / mL and above, and any range between any two values.

[0034] Preferably, the preservation number of the *Microbacterium aureum* is CGMCC No. 14606, and its detailed information can be found in CN109554303A.

[0035] Preferably, the thermophilic lipobacterium has the accession number ATCC 7953.

[0036] Preferably, the preservation number of the *Pseudomonas schrenckii* is ATCC 17588.

[0037] Preferably, the Bacillus licheniformis has the accession number ATCC 21415.

[0038] Preferably, the Rhodococcus rubrum has the accession number ATCC 17896. All four strains are commercially available.

[0039] Preferably, the microorganism is a combination of *Microbacterium aureum*, *Bacillus stearothermophilus*, *Pseudomonas schrenckii*, and *Bacillus licheniformis*; a combination of *Microbacterium aureum*, *Bacillus stearothermophilus*, and *Bacillus licheniformis*; a combination of *Microbacterium aureum*, *Pseudomonas schrenckii*, and *Bacillus licheniformis*; a combination of *Microbacterium aureum*, *Bacillus stearothermophilus*, *Bacillus licheniformis*, and *Rhodococcus erythropoietin*; a combination of *Microbacterium aureum*, *Bacillus stearothermophilus*, and *Rhodococcus erythropoietin*; or a combination of *Microbacterium aureum*, *Bacillus stearothermophilus*, *Pseudomonas schrenckii*, *Bacillus licheniformis*, and *Rhodococcus erythropoietin*.

[0040] In a preferred embodiment of the present invention, the microorganisms comprise *Exiguobacterium aurantiacum*, *Bacillus stearothermophilus*, *Pseudomonas schneideri*, and *Bacillus licheniformis*, wherein the preservation number of *Exiguobacterium aurantiacum* is CGMCC No. 14606; the preservation number of *Bacillus stearothermophilus* is ATCC 7953; the preservation number of *Pseudomonas schneideri* is ATCC 17588; the preservation number of *Bacillus licheniformis* is ATCC 21415; and the preservation number of *Rhodococcus rubescens* is ATCC 17896.

[0041] Each strain can be cultured in accordance with conventional methods in this field, which will not be elaborated here.

[0042] Preferably, the nutrient solution comprises yeast extract, peptone, magnesium sulfate, sodium nitrate, and water.

[0043] Preferably, by weight, the nutrient solution contains 0.1-2 wt% yeast extract, 1-4 wt% peptone, 0.1-1 wt% magnesium sulfate, and 0.5-3 wt% sodium nitrate. The nutrient solution may be sterilized under conventional conditions, which will not be elaborated further. The pH of the nutrient solution is neutral, for example, 6.5-7.5.

[0044] The nutrient solution may also be the product of the above-mentioned nutrient solution after microbial fermentation, and the conditions and methods of the microbial fermentation are described in the second aspect.

[0045] Preferably, the microbial wax remover further comprises microbial metabolites.

[0046] The components of the wax remover can be placed individually or mixed together.

[0047] Preferably, the method for evaluating the wax-preventing rate of the microbial wax-repellent agent comprises the following specific steps:

[0048] (1) Degrease the hanging tablet (A3 steel sheet) with petroleum ether, then wash it with anhydrous ethanol, take out the test piece, wipe it dry with filter paper, place it in a desiccator for 4 hours and weigh it to 0.1 mg;

[0049] (2) Weigh 160g of paraffin sample and place it in an Erlenmeyer flask. Heat it until it becomes molten and mix it thoroughly.

[0050] (3) Add 1% by volume of microbial wax remover to the conical flask and mix well;

[0051] (4) Hang the A3 steel sheet inside the conical flask and let it stand in a 30℃ biochemical incubator for 5 days;

[0052] (5) Remove the tablets and weigh them after 4 hours in a desiccator, to a weight of 0.1 mg;

[0053] (6) Calculate the anti-wax rate using the following formula;

[0054]

[0055] Where: F—wax-preventing rate, %; M1—scraping material quality difference without microbial wax-preventing agent, g; M2—scraping material quality difference with microbial wax-preventing agent, g;

[0056] (7) Microbial wax remover with a wax removal rate of ≥70% is qualified.

[0057] Preferably, the specific steps of the evaluation method for the wax dissolution rate of the microbial wax-removing agent wax balls are as follows:

[0058] (1) Melt the paraffin wax and pour it into two hemispherical metal molds. After cooling for 1 minute, press the two hemispherical metal molds together.

[0059] (2) Put it into a small beaker and place it in a constant temperature water bath at (58~60)℃. After 10 minutes, take it out and wait for the wax to cool completely. Then, gently rotate the mold, take out the wax ball and weigh it to an accuracy of 0.01g.

[0060] (3) Control the temperature of the constant temperature water bath at 45℃±1℃, add 100mL of microbial anti-wax agent and wax balls to the conical flask, and place it in a biochemical incubator for shaking culture. Observe and record the time t taken for the wax balls to dissolve completely, accurate to 1h;

[0061] (4) Calculate the wax melting rate using the following formula.

[0062]

[0063] Where: γ—wax dissolving rate, g / h; mb—mass of wax ball, g; t—time taken for the wax ball to completely dissolve, h;

[0064] (5) The wax dissolving rate of microbial wax remover is ≥0.4g / h to be considered qualified.

[0065] The second aspect of the present invention provides a method for preparing a microbial wax-removing agent, the method comprising: mixing a nutrient solution with microorganisms and then optionally fermenting the mixture to obtain a microbial wax-removing agent;

[0066] The microorganisms include *Exiguobacterium aurantiacum*, and at least one of *Bacillus stearothermophilus*, *Pseudomonas schneideri*, *Bacillus licheniformis*, and *Rhodococcus ruber*.

[0067] For a description of the microorganisms and specific strains, please refer to the first aspect, which will not be repeated here.

[0068] The nutrient solution can be used directly after mixing with microorganisms, or it can be used after fermentation. Preferably, the method includes: mixing the nutrient solution with microorganisms and then fermenting to obtain a microbial wax remover.

[0069] Preferably, the fermentation conditions include: a temperature of 30-45℃, for example, any range of 30, 32, 34, 36, 38, 40, 42, 45℃, or any two of these values; and a time of 2-4 days, for example, any range of 2, 2.5, 3, 3.5, 4 days, or any two of these values. The fermentation process can be performed by fermenting individual strains separately, with the fermentation broths of each strain mixed before use, or by fermenting all strains together and using the resulting product directly.

[0070] The third aspect of the present invention provides a microbial dewaxing agent prepared by the method described above.

[0071] The fourth aspect of the present invention provides the application of the microbial wax-removing agent as described above in wax-containing reservoirs for wax removal and / or enhanced oil recovery.

[0072] The waxy reservoir can be a conventional oil well in the art. Preferably, the applicable oil well meets the following conditions: the oil well is a pumping well with a bottom temperature ≤100℃, the pH value of its produced fluid is 6-9, and the comprehensive water content in its produced fluid is 20%-98%; the oil well has not undergone chemical dewaxing measures within half a month before the use of microbial dewaxing agent.

[0073] The application method of the microbial wax remover can be the conventional application method in the art. Preferably, the application method of the microbial wax remover includes the following steps:

[0074] (1) The wellbore is pretreated by hot washing with an electric heating sucker rod; (2) Two to seven days after the wellbore is pretreated, a microbial dewaxing agent is added to the wellbore. The injection volume and frequency can be adjusted according to the actual situation. For example, injection can be carried out every 2-3 days, once a month, without needing to shut down the well.

[0075] Preferably, the waxy oil reservoir is a high-calcium-magnesium waxy oil reservoir, wherein the calcium ion content is above 500 mg / L and the magnesium ion content is above 2000 mg / L in the high-calcium-magnesium waxy oil reservoir.

[0076] The present invention will be described in detail below through embodiments.

[0077] Unless otherwise specified, all reagents and materials used in the following examples were commercially available.

[0078] The nutrient solution formula is as follows: 0.5 wt% yeast extract, 2 wt% peptone, 0.5 wt% magnesium sulfate, 1 wt% sodium nitrate; pH 7, with the remainder being water. The preparation method is as follows: First, add the yeast extract, peptone, magnesium sulfate, sodium nitrate, and water to a fermenter and stir well; then heat to 121℃ and sterilize for 20 minutes, then cool to 30-40℃ to obtain the nutrient solution.

[0079] Example 1

[0080] This example illustrates the preparation of a microbial wax-removing agent.

[0081] Strains that do not antagonize each other (growth is not significantly inhibited) were selected through preliminary experiments and used in the preparation of the wax-removing agent in the following examples. The sources of the strains are shown in Table 1.

[0082] Table 1

[0083] serial number strain name source 1# Microbacterium aureum CGMCC No. 14606 2# Thermophilic Bacillus stearothermophilus ATCC 7953 3# Pseudomonas schrenckii ATCC 17588 4# Bacillus licheniformis ATCC 21415 5# Rhodococcus ATCC 17896 6# Bacillus licheniformis laboratory strains 7# Microbacterium aureum ATCC 35652

[0084] The strains described above, stored in a -80°C freezer with glycerol, were removed and streaked onto prepared LB agar plates to activate single colonies. Single colonies were then obtained by static incubation at 37°C for 1 day. A single colony was picked and inoculated into liquid LB agar and cultured at 37°C and 200 rpm on a shaker until OD reached [value missing]. 600nm If the number of viable cells is greater than 1 (logarithmic growth phase), adjust the viable cell count to 1*10^6. 8 After reaching approximately CFU / mL, it is used as a seed culture for later use.

[0085] Following the method described in Table 2, seed liquids of one or more microorganisms were added to the nutrient solution (10% by volume of seed liquid for inoculation; when inoculating multiple microorganisms, the inoculation was carried out at a ratio of 1:1 for each type of seed liquid, with a total inoculation amount of 10% by volume). After constant temperature fermentation at 37°C for 72 hours, a microbial wax-removing agent was obtained.

[0086] Table 2

[0087]

[0088]

[0089] Example 2

[0090] This example illustrates the wax-preventing rate of microbial wax removers under high-calcium and magnesium-free conditions.

[0091] The wax-preventing rates of the wax-repellent agents Q1-7 and W1-15 prepared in Example 1 were determined.

[0092] The anti-wax rate of microbial wax removal was determined by the hanging plate method. The amount of wax deposited on the hanging plate was measured for paraffin with and without the addition of microbial anti-wax removal agent. The anti-wax rate of the microbial anti-wax removal agent was calculated. The specific operation is as follows.

[0093] The A3 steel strips were degreased with petroleum ether, then washed with anhydrous ethanol. The strips were removed, dried with filter paper, and weighed after 4 hours in a desiccator. 160g of paraffin sample was weighed and placed in an Erlenmeyer flask, heated to a molten state, and thoroughly mixed. 1% (v / v) of a microbial anti-wax agent was added to the flask and mixed well. The A3 steel strips were then placed inside the flask and incubated at 30°C for 5 days. The strips were removed, weighed after 4 hours in a desiccator, and the anti-wax rate (without calcium and magnesium) of the microbial anti-wax agent was determined, as shown in Table 3.

[0094] The procedure was carried out as described above, except that 1% by volume of microbial wax remover, 6000 mg / L of CaCl2, and 6000 mg / L of MgCl2 were added to the conical flask. The wax removal rate of the microbial wax remover (high calcium and magnesium) was measured and is shown in Table 3.

[0095] Table 3

[0096]

[0097]

[0098] As shown in Table 3, microbial wax removers W1, W2, and W7 exhibit good wax-preventing effects in both high-calcium and magnesium-free environments, especially W1. W8 shows good wax-preventing effects in calcium-free environments, but its wax-preventing rate is lower under high-calcium and magnesium conditions.

[0099] Example 3

[0100] This example illustrates the wax dissolution rate of microbial wax-removing agents under high-calcium and low-calcium-magnesium conditions.

[0101] The wax dissolution rate of the wax-removing agents Q1-7 and W1-15 prepared in Example 1 was measured.

[0102] The time it takes for wax balls to dissolve in a microbial wax-removing agent is measured, and the wax dissolution rate of the microbial wax-removing agent is calculated.

[0103] (1) Calcium- and magnesium-free group

[0104] After melting paraffin wax, pour it into two hemispherical metal molds. After cooling for 1 minute, press the two hemispherical metal molds together. Place the molds into a small beaker and put them in a constant temperature water bath at (58-60)℃. After 10 minutes, remove the beaker and allow the wax to cool completely. Gently rotate the mold to remove the wax ball and weigh it. Control the temperature of the constant temperature water bath at 45℃. Add 100mL of microbial wax-dissolving agent and the wax ball to a conical flask and place it in an incubator at 45℃ with shaking. Observe and record the time t taken for the wax ball to completely dissolve. The wax dissolving rate of the microbial wax-dissolving agent is shown in Table 4.

[0105] Table 4

[0106]

[0107]

[0108] (2) High calcium and magnesium group

[0109] After melting paraffin wax, pour it into two hemispherical metal molds. After cooling for 1 minute, press the two hemispherical metal molds together. Place the molds into a small beaker and put them in a constant temperature water bath at (58-60)℃. After 10 minutes, remove the beaker and allow the wax to cool completely. Gently rotate the mold to remove the wax ball and weigh it. Control the temperature of the constant temperature water bath at 45℃. Add 100mL of microbial wax-removing agent and wax balls to a conical flask, along with 6000mg / L CaCl2 and 6000mg / L MgCl2. Place the flask in an incubator and shake at 45℃. Observe and record the time t taken for the wax ball to completely dissolve. The wax dissolution rate of the microbial wax-removing agent under high calcium and magnesium conditions is shown in Table 5.

[0110] Table 5

[0111]

[0112]

[0113] As can be seen from Tables 4 and 5, the microbial wax removers W1, W2, W7, W8, W10 and W15 have good wax-dissolving effects in both high calcium and magnesium environments and non-high calcium and magnesium environments, especially microbial wax remover W1, which has an excellent wax-dissolving effect.

[0114] Example 4

[0115] This embodiment illustrates a method for removing wax using a microbial wax-removing agent.

[0116] A microbial dewaxing agent was used in an oil well prone to wax blockage. The well's temperature was 85℃, the pH of the produced fluid was 6.5, the overall water cut was 91.4%, the concentration of calcium and magnesium ions was 5421 mg / L, the salinity was 34452 mg / L, and the water type was CaCl2. No chemical dewaxing measures had been taken in the well for the two weeks prior to the application of the microbial dewaxing agent.

[0117] First, the wax-blocked well was treated with an electrically heated sucker rod for hot washing. Three days after treatment, a microbial wax-removing agent, W1, was injected into the wellbore at a concentration of 1.26m. 3 One month later, inject microbial wax remover W1 1.26m. 3 A total of three rounds of injections were made.

[0118] After the field test of the well was completed, the effect was evaluated: the hot washing cycle of the oil well was extended by 320 days, the number of hot washing wells was reduced by 18, the wax content was reduced by 69.3%, and the oil production increased by 675 tons.

[0119] In summary, this invention addresses the technical deficiencies of existing technologies. In particular, it addresses the problem of wax removal and prevention in high-calcium, magnesium-containing wax reservoirs. The microbial wax removal and prevention agent in this invention has low sensitivity to formation oil quality, does not pollute the environment, and does not damage the formation. It is especially effective in removing and preventing wax from high-calcium, magnesium-containing wax reservoirs.

[0120] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A microbial wax remover, characterized in that, The microbial wax-removing agent comprises a nutrient solution and microorganisms; the microorganisms include *Microbacterium aureum* (…). Exiguobacterium aurantiacum ), and thermophilic steatobacterium ( Bacillus stearothermophilus ), Pseudomonas schrenckii ( Pseudomonas schneideri ), Bacillus licheniformis ( Bacillus licheniformis ) and Rhodococcus ( Rhodococcus ruber At least two of the following; The preservation number of the *Microbacterium aureum* is CGMCC No. 14606; The accession number of the thermophilic steatobacterium is ATCC 7953; The accession number of the *Pseudomonas schlegelii* strain is ATCC 17588; The Bacillus licheniformis has the accession number ATCC 21415; The accession number of the Rhodococcus is ATCC 17896.

2. The microbial wax remover according to claim 1, wherein, The microorganisms are combinations of *Microbacterium aureum*, *Bacillus stearothermophilus*, *Pseudomonas schrenckii*, and *Bacillus licheniformis*; combinations of *Microbacterium aureum*, *Bacillus stearothermophilus*, and *Bacillus licheniformis*; combinations of *Microbacterium aureum*, *Pseudomonas schrenckii*, and *Bacillus licheniformis*; combinations of *Microbacterium aureum*, *Bacillus stearothermophilus*, *Bacillus licheniformis*, and *Rhodococcus rubrum*; combinations of *Microbacterium aureum*, *Bacillus stearothermophilus*, and *Rhodococcus rubrum*; or combinations of *Microbacterium aureum*, *Bacillus stearothermophilus*, *Pseudomonas schrenckii*, *Bacillus licheniformis*, and *Rhodococcus rubrum*. And / or, the viable bacteria count in the microbial wax remover is 1*102 7 CFU / mL or higher.

3. The microbial wax remover according to claim 2, wherein, The viable bacteria count in the microbial dewaxing agent is 1*103 8 CFU / mL or higher.

4. The microbial wax remover according to any one of claims 1-3, wherein, The nutrient solution contains yeast extract, peptone, magnesium sulfate, sodium nitrate, and water.

5. The microbial wax remover according to claim 4, wherein, By weight, the nutrient solution contains 0.1-2 wt% yeast extract, 1-4 wt% peptone, 0.1-1 wt% magnesium sulfate, and 0.5-3 wt% sodium nitrate.

6. The microbial wax remover according to claim 4, wherein, The microbial dewaxing agent also contains microbial metabolites.

7. The microbial wax remover according to any one of claims 1-3 and 5, wherein, The microbial dewaxing agent also contains microbial metabolites.

8. A method for preparing a microbial wax-removing agent, characterized in that, The method includes: mixing nutrient solution with microorganisms and then optionally fermenting the mixture to obtain a microbial wax remover; The microorganisms include *Microbacterium aureum* (…). Exiguobacterium aurantiacum ), and thermophilic steatobacterium ( Bacillus stearothermophilus ), Pseudomonas schrenckii ( Pseudomonas schneideri ), Bacillus licheniformis ( Bacillus licheniformis ) and Rhodococcus ( Rhodococcus ruber At least two of the following; The preservation number of the *Microbacterium aureum* is CGMCC No. 14606; The accession number of the thermophilic steatobacterium is ATCC 7953; The accession number of the *Pseudomonas schlegelii* strain is ATCC 17588; The Bacillus licheniformis has the accession number ATCC 21415; The accession number of the Rhodococcus is ATCC 17896.

9. The preparation method according to claim 8, wherein, The fermentation conditions include a temperature of 30-45℃ and a time of 2-4 days.

10. The preparation method according to claim 8 or 9, wherein, The combination of the microorganisms *Microbacterium aureum*, *Bacillus stearothermophilus*, *Pseudomonas schrenckii*, and *Bacillus licheniformis*, or the combination of *Microbacterium aureum*, *Bacillus stearothermophilus*, and *Bacillus licheniformis*, or the combination of *Microbacterium aureum*, *Bacillus stearothermophilus*, *Bacillus licheniformis*, and *Rhodococcus rubrum*, or the combination of *Microbacterium aureum*, *Bacillus stearothermophilus*, *Pseudomonas schrenckii*, *Bacillus licheniformis*, and *Rhodococcus rubrum*. And / or, the total viable count in the microbial wax remover is 1*102 7 CFU / mL or higher.

11. The preparation method according to claim 10, wherein, The total viable bacteria count in the microbial desiccant is 1*10⁻⁶. 8 CFU / mL or higher.

12. The preparation method according to claim 10, wherein, The nutrient solution contains yeast extract, peptone, magnesium sulfate, sodium nitrate, and water.

13. The preparation method according to claim 12, wherein, By weight, the nutrient solution contains 0.1-2 wt% yeast extract, 1-4 wt% peptone, 0.1-1 wt% magnesium sulfate, and 0.5-3 wt% sodium nitrate.

14. The preparation method according to any one of claims 8, 9, and 11, wherein, The nutrient solution contains yeast extract, peptone, magnesium sulfate, sodium nitrate, and water.

15. The preparation method according to claim 14, wherein, By weight, the nutrient solution contains 0.1-2 wt% yeast extract, 1-4 wt% peptone, 0.1-1 wt% magnesium sulfate, and 0.5-3 wt% sodium nitrate.

16. The microbial dewaxing agent prepared by the method according to any one of claims 8-15.

17. The application of the microbial wax-removing agent according to any one of claims 1-7 and 16 in wax-containing oil reservoirs for wax removal and / or enhanced oil recovery; The waxy oil reservoir is a high-calcium, high-magnesium waxy oil reservoir, wherein, In the aforementioned high-calcium and high-magnesium waxy oil reservoir, the calcium ion content is above 500 mg / L and the magnesium ion content is above 2000 mg / L.

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