CN117004378A

CN117004378A - Neutral chelating enzyme operation workover fluid and preparation method thereof

Info

Publication number: CN117004378A
Application number: CN202310989782.5A
Authority: CN
Inventors: 盖海防; 武娜娜; 盖梦婷
Original assignee: Dongying Suncoo Petroleum Co ltd
Current assignee: Dongying Suncoo Petroleum Co ltd
Priority date: 2023-08-07
Filing date: 2023-08-07
Publication date: 2023-11-07

Abstract

The invention provides an operation workover fluid of neutral chelating enzyme, which comprises the following components in parts by weight: 12-30 parts of tetrasodium iminodisuccinate, 1-10 parts of aminotrimethylene phosphonic acid, 2-10 parts of amylase, 0.5-5 parts of protease, 5-15 parts of alkyl glucamide, 0.5-2 parts of coconut diethanolamide, 0.5-8 parts of trehalose, 1-5 parts of chitosan and 25-60 parts of deionized water. The invention also provides a preparation method of the operation workover fluid. In conclusion, the invention can carry out biodegradation, is environment-friendly, can effectively remove deposition blockage of inorganic scale and organic scale, eliminates emulsification blockage, improves the permeability of a well, has good swelling prevention, chelation and scale inhibition performances, removes and avoids water-sensitive and salt-sensitive injuries, and prolongs the effective period of operation.

Description

Neutral chelating enzyme operation workover fluid and preparation method thereof

Technical Field

The invention relates to the technical field of oilfield operation workover, in particular to an operation workover fluid of neutral chelating enzyme and a preparation method thereof.

Background

In order to solve the reservoir damage caused in the oilfield operation process and improve the oilfield operation yield increase and production efficiency, well repair liquid is generally utilized for matching treatment in the operation. There are many types of working workover fluids in the field today, such as: cleaning brine workover fluids, invisible acids, high density kill fluids, etc., but still have the following problems: clean saline water well servicing fluid reservoirs are less damaged, but the cleaning power is insufficient; the invisible acid has the effect of improving permeability, but is acidic in stratum environment, and is easy to cause stratum injury; the high-density well control fluid is generally added with barium sulfate to increase the density, so that the barium sulfate is easy to block, and the common acid cannot remove the barium sulfate.

For some wells with obvious scaling, hydrochloric acid, earthic acid and the like are often matched in the well repairing process, the reservoir framework is damaged by the too strong acidity to cause sand production, and the use of the strong acids is limited due to the influences of environmental protection, flowback, demulsification and gathering systems and the like.

An attack type workover fluid system for offshore oilfield workover and a preparation method and application thereof are disclosed in a patent with publication number of CN 107699220A; the patent with publication number CN 104531105B discloses a temporary plugging workover fluid for a low-pressure sandstone reservoir gas well and a preparation method thereof; a liquid compatible with both formation water and brine workover fluid and a method of making the same are disclosed in CN 108641689B. However, none of the above-mentioned patent technologies relates to the green environmental protection and synergistic performance of the well servicing fluid.

Disclosure of Invention

In view of the above, the invention provides a neutral chelating enzyme working workover fluid and a preparation method thereof, which can systematically solve the problems of scaling, waxing, corrosion, low yield and the like of oil, water and gas wells on the premise of safety and environmental protection, and achieve the purposes of improving the working workover efficiency, protecting oil reservoirs, increasing the yield and efficiency and prolonging the working period.

The technical scheme of the invention is realized as follows:

on the one hand, the invention provides a neutral chelating enzyme operation workover fluid, which comprises the following components in parts by weight: 12-30 parts of tetrasodium iminodisuccinate, 1-10 parts of aminotrimethylene phosphonic acid, 2-10 parts of amylase, 0.5-5 parts of protease, 5-15 parts of alkyl glucamide, 0.5-2 parts of coconut diethanolamide, 0.5-8 parts of trehalose, 1-5 parts of chitosan and 25-60 parts of deionized water.

In the invention, the volume concentration of the iminodisuccinic acid is 98%, the volume concentration of the aminotrimethylene phosphonic acid is more than or equal to 50%, the content of effective substances of amylase and protease is 99%, the volume concentration of alkyl glucamide is more than 50%, the volume concentration of coconut diethanolamide is more than 98%, and the purity of trehalose and chitosan is 99.9%. All the components can be purchased directly from the market, and the concentration, purity and content of the effective substances are all the specifications of the commercial products.

Preferably, the operation workover fluid comprises the following components in parts by weight: 18 parts of tetrasodium iminodisuccinate, 5 parts of aminotrimethylene phosphonic acid, 6 parts of amylase, 3 parts of protease, 8 parts of alkyl glucamide, 1.2 parts of coconut diethanolamide, 2.5 parts of trehalose, 2 parts of chitosan and 36 parts of deionized water.

On the other hand, the invention also provides a preparation method applied to the operation workover fluid, which comprises the following steps:

grinding the mixture of trehalose and chitosan through a 210-mesh screen, and vacuum drying to obtain a mixture I;

step two, heating deionized water, adding the mixture I, and uniformly stirring to obtain a mixture II;

adding alkyl glucamide and tetrasodium iminodisuccinate into the mixture II, uniformly mixing, adding amylase and protease, and continuously uniformly mixing to obtain a mixture III;

and step four, amino trimethylene phosphonic acid and coconut diethanolamide are sequentially added into the mixture three, and after uniform mixing, ultrasonic treatment is carried out to obtain the neutral chelating enzyme operation workover fluid.

In the first step, the mixture of trehalose and chitosan is ground for 5-10min by using a solid grinder, and is dried for 4.5-5.5h at the temperature of 40-50 ℃ through a 210-mesh screen to obtain a first mixture, and the first mixture is placed in a dryer for standby.

In the second step, deionized water is added into a reaction device, the temperature is raised to 90-98 ℃, the first mixture is added into a solid charging port, and the stirring is carried out for 16-24min by using a stirrer at the rotating speed of 45-55r/min, so as to obtain the second mixture.

In the third step, alkyl glucamide and tetrasodium iminodisuccinate are added into the mixture II, stirring is continued for 26-35min, cooling is carried out to 28-36 ℃, amylase and protease are added, stirring is continued for 25-35min, and heating is stopped after all solid materials are dissolved, so that a mixture III is obtained.

In the fourth step, amino trimethylene phosphonic acid and coconut diethanolamide are sequentially added into the mixture III through a liquid feed inlet, the rotation speed of a stirrer is adjusted to be 40-45r/min, and the stirring is carried out for 0.8-1.3h, so that all raw materials are uniformly mixed, and the stirring is stopped, thus obtaining a mixture IV. The conditions of the ultrasonic treatment are as follows: the frequency is 15-25kHz, and the ultrasonic treatment is carried out for 12-18min.

Preferably, in the invention, the stirrer adopts a triclinic blade type stirrer.

The invention has the following action principle:

in the working workover fluid, tetra sodium iminodisuccinate and amino trimethylene phosphonic acid are used as chelating agents to prevent scaling of system equipment and pipelines; after the system equipment and the pipeline are treated and protected, the liquid in the pipeline is further required to be treated, so that amylase and protease are added into the operation workover fluid to treat gel in water, polymers, scraps, mudstones and the like in an oil reservoir; further, after the system equipment, the pipeline and the liquid in the pipeline are treated, the invention also treats the greasy dirt on the two-phase interface through the alkyl glucamide to eliminate the organic pollutant in the reservoir; although alkyl glucamide can treat greasy dirt on the interface of two phases, the corrosion resistance of the metal surface is inevitably affected, so in order to protect the metal surface, the invention adds coconut diethanolamide which is adsorbed on the metal surface to form an adsorption protective film, so that the metal is not corroded by water, oxygen and the like; further, the swelling of the clay is prevented by chitosan; furthermore, the raw materials are combined together to treat oil stains on the pipeline, liquid in the pipeline and two-phase interfaces together so as to achieve the purposes of improving the operation well workover efficiency and protecting the oil reservoir, but after the raw materials are combined together, the stability needs to be adjusted so as to bring the maximum effect or the maximum application range of the operation well workover fluid into play.

The neutral chelating enzyme of the invention has the following beneficial effects compared with the prior art:

1. safe and environment-friendly

The components are safe: the biological degradation can be carried out, cl, F, S, P, si is not contained, no harm is caused to staff, equipment, natural environment and stratum, and the environment-friendly requirement is met;

ultra low corrosion: the pH is neutral, non-acid and non-alkali, and the pipeline is protected from corrosion;

self-demulsification: the process can be directly carried out without affecting the demulsification and gathering system, and after demulsification, the oil-water separation interface is clear, see figure 1.

2. Yield and efficiency increasing

Yield increase: effectively remove the deposition blockage of inorganic scale and organic scale, and eliminate the emulsification blockage; replacing the crude oil at the micro-pore throat, and releasing the water lock; the water lock blockage in the microporous roar dense core is eliminated, and the permeability of the well is improved.

Synergy: the quick flowback shortens the operation recovery period; the anti-corrosion and scale-inhibiting device effectively protects the pipeline, avoids the oil reservoir from being blocked by the rust scale, and prolongs the well repair and production increase period.

3. Reservoir protection

Eliminating five-sensitivity injury (acid sensitivity, alkali sensitivity, salt sensitivity, water sensitivity and quick sensitivity), operating in the whole neutral environment, and having mild reaction, without excessively exciting the oil reservoir and excessively unblocking to cause sand production and particle migration of the oil reservoir. Has good anti-swelling, chelating and scale inhibiting properties, and can relieve and avoid water sensitivity and salt sensitivity injury, and prolong the effective period of operation.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a demulsification diagram of a working well servicing fluid of a neutral chelating enzyme of the invention;

FIG. 2 is a photograph of a neutral chelating enzyme of the present invention after 24 hours of placement of N80 steel plate in the working workover fluid;

FIG. 3 is a photograph of 24 hours after N80 steel sheet was placed in the working fluid of comparative example 14.

Detailed Description

The following description of the embodiments of the present invention will clearly and fully describe the technical aspects of the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.

Example 1

The neutral chelating enzyme operation workover fluid comprises the following components in parts by weight: 12 parts of tetrasodium iminodisuccinate, 1 part of aminotrimethylene phosphonic acid, 2 parts of amylase, 0.5 part of protease, 5 parts of alkyl glucamide, 0.5 part of coconut diethanolamide, 0.5 part of trehalose, 0.1 part of chitosan and 25 parts of deionized water.

The preparation method of the operation workover fluid comprises the following steps:

grinding the mixture of trehalose and chitosan for 5min by using a solid grinder, and vacuum drying for 4.5h at 40 ℃ through a 210-mesh screen to obtain a mixture I, and placing the mixture I in a dryer for standby.

Adding deionized water into a reaction device, heating to 90 ℃, adding the mixture I into a solid charging port, and stirring for 16min at the rotating speed of 45r/min by using a triclinic blade paddle type stirrer to obtain a mixture II.

Adding alkyl glucamide and tetrasodium iminodisuccinate into the mixture II, continuously stirring for 26min, cooling to 28 ℃, adding amylase and protease, continuously stirring for 25min, and stopping heating after all solid materials are completely dissolved to obtain a mixture III.

And step four, amino trimethylene phosphonic acid and coconut diethanolamide are sequentially added into the mixture three through a liquid feed inlet, the rotating speed of a triclinic blade type stirrer is adjusted to be 40r/min, and stirring is carried out for 0.8h, so that all raw materials are uniformly mixed, and stirring is stopped, thus obtaining a mixture four.

And fifthly, performing ultrasonic treatment on the mixture IV at the frequency of 15kHz for 12 minutes to obtain the neutral chelating enzyme operation workover fluid.

Example 2

The neutral chelating enzyme operation workover fluid comprises the following components in parts by weight: 30 parts of tetrasodium iminodisuccinate, 10 parts of aminotrimethylene phosphonic acid, 10 parts of amylase, 5 parts of protease, 15 parts of alkyl glucamide, 2 parts of coconut diethanolamide, 8 parts of trehalose, 5 parts of chitosan and 60 parts of deionized water.

grinding the mixture of trehalose and chitosan for 10min by using a solid grinder, and vacuum drying the mixture for 5.5h at 50 ℃ through a 210-mesh screen to obtain a mixture I, and placing the mixture I in a dryer for standby.

Adding deionized water into a reaction device, heating to 98 ℃, adding the mixture I into a solid charging port, and stirring for 24min by using a triclinic blade paddle stirrer at the rotating speed of 55r/min to obtain a mixture II.

Adding alkyl glucamide and tetrasodium iminodisuccinate into the mixture II, continuously stirring for 35min, cooling to 36 ℃, adding amylase and protease, continuously stirring for 35min, and stopping heating after all solid materials are completely dissolved to obtain a mixture III.

And step four, amino trimethylene phosphonic acid and coconut diethanolamide are sequentially added into the mixture three through a liquid feed inlet, the rotating speed of a triclinic blade type stirrer is adjusted to be 45r/min, stirring is carried out for 1.3 hours, all raw materials are uniformly mixed, and stirring is stopped, so that a mixture four is obtained.

And fifthly, performing ultrasonic treatment on the mixture IV at the frequency of 25kHz for 18min to obtain the neutral chelating enzyme operation workover fluid.

Example 3

The neutral chelating enzyme operation workover fluid comprises the following components in parts by weight: 18 parts of tetrasodium iminodisuccinate, 5 parts of aminotrimethylene phosphonic acid, 6 parts of amylase, 3 parts of protease, 8 parts of alkyl glucamide, 1.2 parts of coconut diethanolamide, 2.5 parts of trehalose, 2 parts of chitosan and 36 parts of deionized water.

grinding the mixture of trehalose and chitosan for 7min by using a solid grinder, and vacuum drying for 4.9h at 42 ℃ through a 210-mesh screen to obtain a mixture I, and placing the mixture I in a dryer for standby.

Adding deionized water into a reaction device, heating to 92 ℃, adding the mixture I into a solid charging port, and stirring for 18min at the rotating speed of 50r/min by using a triclinic blade paddle type stirrer to obtain a mixture II.

Adding alkyl glucamide and tetrasodium iminodisuccinate into the mixture II, continuously stirring for 30min, cooling to 31 ℃, adding amylase and protease, continuously stirring for 28min, and stopping heating after all solid materials are completely dissolved to obtain a mixture III.

And step four, amino trimethylene phosphonic acid and coconut diethanolamide are sequentially added into the mixture three through a liquid feed inlet, the rotating speed of a triclinic blade type stirrer is adjusted to be 42r/min, stirring is carried out for 1h, all raw materials are uniformly mixed, and stirring is stopped, so that a mixture four is obtained.

And fifthly, performing ultrasonic treatment on the mixture IV at the frequency of 20kHz for 14 minutes to obtain the neutral chelating enzyme operation workover fluid.

Example 4

The neutral chelating enzyme operation workover fluid comprises the following components in parts by weight: 26 parts of tetrasodium iminodisuccinate, 7 parts of aminotrimethylene phosphonic acid, 8 parts of amylase, 3.5 parts of protease, 11 parts of alkyl glucamide, 1.6 parts of coconut diethanolamide, 6 parts of trehalose, 4 parts of chitosan and 52 parts of deionized water.

grinding the mixture of trehalose and chitosan for 8min by using a solid grinder, and vacuum drying the mixture for 5.2h at 44 ℃ through a 210-mesh screen to obtain a mixture I, and placing the mixture I in a dryer for standby.

Adding deionized water into a reaction device, heating to 96 ℃, adding the mixture I into a solid charging port, and stirring for 21min at a rotating speed of 52r/min by using a triclinic blade paddle type stirrer to obtain a mixture II.

Adding alkyl glucamide and tetrasodium iminodisuccinate into the mixture II, continuously stirring for 32min, cooling to 33 ℃, adding amylase and protease, continuously stirring for 32min, and stopping heating after all solid materials are completely dissolved to obtain a mixture III.

And step four, amino trimethylene phosphonic acid and coconut diethanolamide are sequentially added into the mixture three through a liquid feed inlet, the rotating speed of a triclinic blade type stirrer is adjusted to be 42r/min, stirring is carried out for 1.1h, all raw materials are uniformly mixed, and stirring is stopped, so that a mixture four is obtained.

And fifthly, performing ultrasonic treatment on the mixture IV at the frequency of 23kHz for 17min to obtain the neutral chelating enzyme operation workover fluid.

Comparative example 1

On the basis of example 3, tetrasodium iminodisuccinate and aminotrimethylene phosphonic acid in the working workover fluid were deleted, and the other conditions were identical.

Comparative example 2

On the basis of example 3, tetrasodium iminodisuccinate was deleted from the working workover fluid, all other conditions being identical.

Comparative example 3

On the basis of example 3, the amino trimethylene phosphonic acid in the working workover fluid was deleted, and the other conditions were identical.

Comparative example 4

On the basis of example 3, the chelating agent disodium EDTA was used to replace tetra sodium iminodisuccinate and aminotrimethylene phosphonic acid in the working well servicing fluid, and the disodium EDTA was 23 parts (total amount of tetra sodium iminodisuccinate and aminotrimethylene phosphonic acid), all other conditions were identical.

Comparative example 5

On the basis of example 3, amylase and protease in the working workover fluid were deleted, and the other conditions were identical.

Comparative example 6

On the basis of example 3, amylase was removed from the working workover fluid, and the other conditions were identical.

Comparative example 7

On the basis of example 3, the protease in the working workover fluid was deleted, and the other conditions were identical.

Comparative example 8

On the basis of example 3, the alkyl glucamide in the working workover fluid was deleted, and the other conditions were identical.

Comparative example 9

The alkyl glucosamide in the working fluid was replaced with an equivalent amount of alkyl glycoside based on example 3, with the other conditions being identical.

Comparative example 10

Based on example 3, coconut diethanolamide in the working workover fluid was removed and the other conditions were identical.

Comparative example 11

On the basis of example 3, equal amounts of sodium alkylbenzene sulfonate were used to replace coconut diethanolamide in the working workover fluid, all other conditions being identical.

Comparative example 12

Based on the embodiment 3, the chitosan in the operation workover fluid is deleted, and other conditions are consistent.

Comparative example 13

the first step is consistent with the second step;

sequentially adding alkyl glucamide, tetrasodium iminodisuccinate, amylase and protease into the mixture II, continuously adding amino trimethylene phosphonic acid and coconut diethanolamide, continuously stirring for 120min under the condition of the rotating speed of 42r/min, cooling to 31 ℃, then performing ultrasonic treatment with the frequency of 20kHz and performing ultrasonic treatment for 14min to obtain the neutral chelating enzyme operation workover fluid.

Other conditions were consistent.

Comparative example 14

Selecting conventional well repairing liquid, wherein the well repairing liquid consists of a clay stabilizer, a high-valence metal ion chelating agent, a corrosion inhibition bactericide and an aqueous solution, and the clay stabilizer is potassium chloride with the mass fraction of 2% -2.5%; the high-valence metal ion chelating agent is a mixture of ethylenediamine tetraacetic acid disodium salt, hydrofluoric acid and benzoic anhydride, and the mass fraction is 0.3-1.5%; the mass fraction of the corrosion inhibition bactericide is 0.8% -1.5%; the balance being aqueous solution.

Comparative example 15

On the basis of example 3, trehalose in the working workover fluid was deleted, and the other conditions were identical.

The working well servicing fluids prepared in the examples and comparative examples above were subjected to performance measurements, the measurement indexes including pH, interfacial tension, anti-swelling rate, corrosion rate, enzymatic degradation rate, wash oil rate, natural sedimentation dehydration rate, and permeability recovery value. The criteria for the above criteria are shown in Table 1.

Table 1 Performance Standard for each index

The evaluation method of the index comprises the following steps: (the volume concentration of the sample solution was 60% and the volume concentration of the sample stock solution was 100%)

1. pH value: taking a sample stock solution, and measuring by using wide pH test paper.

2. Surface interfacial tension: the sample solution was taken and measured using a fully automated surface tension meter.

3. Expansion preventing rate: and measuring the anti-swelling volume of the sample by using a centrifugal method, and calculating the anti-swelling rate according to a formula.

4. Corrosion rate: 200g of sample solution is taken to soak a standard N80 steel sheet (the material of the N80 steel sheet is the same as that of a downhole tubular column), and the steel sheet is placed in a water bath at 90 ℃ for 24 hours. The corrosion rate was calculated from the mass of the N80 steel sheet before and after the reaction. See fig. 2.

5. Erosion rate: the sample solution is respectively added with solid calcium carbonate and a calcium sulfate reagent (the mass ratio of the sample solution to the reagent is 100:2), and the mixture is placed in a water bath at 90 ℃ for 24 hours. And calculating the corrosion rate according to the mass of the calcium carbonate and calcium sulfate reagents before and after the reaction.

6. Enzymatic degradation rate: preparing 0.35% of guar gum base solution, and adding a cross-linking agent to form gel capable of hanging. At 170s with a six-speed viscometer ^-1 Determination of initial gel viscosity as mu ₁ . Taking 100mL of jelly, adding the sample stock solution, placing in a water bath kettle with the constant temperature of 50 ℃ for 2h, and measuring the colloid viscosity to be mu ₂ . The enzyme-catalyzed degradation rate was calculated from the change in colloidal viscosity.

7. Wash oil ratio: the oil sand is prepared by mixing artificial oil stain (83% of crude oil, 12% of asphalt oil and 5% of paraffin) and quartz sand according to the proportion of 1.5:1. Taking 3.0g of newly-prepared oil sand into a 50mL colorimetric tube, adding 10mL of sample solution, placing in a constant-temperature water bath at 60 ℃, taking out, shaking for 10 times at intervals of 0.5h, placing for lh together, and taking out. The oil stains on the liquid level and the pipe wall are dipped with cotton, the eluate is carefully poured off, 20mL of distilled water is measured by a cylinder at 20 ℃ and poured into a colorimetric tube, the distilled water and the residual sample are fully mixed, the oil stains on the liquid level and the pipe wall are dipped with the cotton, the eluate is carefully poured off, and the steps are repeated until the eluate is in a transparent state. Adding petroleum ether with boiling range of (60-90) deg.C into the colorimetric tube, shaking thoroughly, and diluting to scale. And (3) taking petroleum ether as a blank, testing absorbance on a spectrophotometer, and calculating the oil washing rate according to the residual oil quantity.

8. Natural sedimentation dehydration rate: adding 50ml of sample solution into a conical flask, adding 50ml of crude oil, stirring the solution at a rotating speed of 1500 revolutions for 10min to obtain oil emulsion, pouring into a measuring cylinder with a plug, standing for 2h, and calculating the natural sedimentation dehydration rate according to the volume of water discharged from the lower part of the measuring cylinder.

9. Permeability recovery value: the core was taken out to have a diameter of 2.5cm and a length of 3.0cm. Brine is introduced forward at 70 ℃ to determine permeability K ₁ The method comprises the steps of carrying out a first treatment on the surface of the Then 2pv crude oil is introduced to form a blockage; reversely introducing a sample solution with a specified concentration for 6pv, and soaking for 24 hours (70 ℃ environment); brine is positively introduced, and the permeability K of the brine after unblocking is measured ₂ . And calculating a permeability recovery value.

Table 2 results of measurement of pH value, interfacial tension, anti-swelling Rate and Corrosion Rate

TABLE 3 determination of erosion Rate, enzymatic degradation Rate, wash Rate, natural sedimentation Desorption Rate and permeability recovery values

The data in tables 2 and 3 show that:

the tetrasodium iminodisuccinate belongs to an environment-friendly chelating agent, is green and degradable, and can effectively prevent metal ions such as calcium, magnesium and the like from forming precipitates in chemical reaction, thereby preventing system equipment and pipelines from scaling, gradually removing the original scaling, having certain dispersing capacity on the scale and improving the dispersibility of the scale.

The amino trimethylene phosphonic acid has good chelation, low limit inhibition and lattice distortion effect. Can prevent scale formation, especially calcium carbonate scale formation, of scale forming salts in water. Meanwhile, the corrosion inhibitor has good corrosion inhibition effect and plays a role in reducing corrosion and scaling of metal equipment or pipelines.

Example 3 compared with comparative examples 1-4, tetrasodium iminodisuccinate and aminotrimethylene phosphonic acid were selected as chelating agents, which have good corrosion and do not produce secondary precipitation; common chelating agents, such as disodium EDTA and tetrasodium EDTA, have poor corrosion, and although they can reduce equipment, pipeline precipitation and scale formation, the chelating agents themselves can also produce secondary precipitation during the reaction.

The amylase can reduce gel concentration and polymerization in injected water, improve permeability of water phase and promote development of carbonate hydrocarbon reservoirs.

The protease can degrade polymer, detritus, mudstone and other sediment garbage in the oil reservoir, enlarge the permeability of the oil layer, improve the quality of the oil layer reservoir and increase the oil and gas yield.

Example 3 the effect of amylase and protease on wash oil rate, permeability, enzyme catalyzed degradation rate was greater compared to comparative examples 5-7.

The alkyl glucamide is green and nontoxic, is easy to biodegrade, can be directionally adsorbed on a two-phase interface, reduces surface interfacial tension, has good wetting and cleaning effects on oil dirt, can eliminate organic pollutants in a reservoir, and promotes biodegradation.

Example 3 shows that the effect of the non-alkyl glucamide on the surface tension, interfacial tension, and natural settling dehydration rate is greater than that of comparative examples 8-9.

The coconut diethanolamide has good anti-corrosion effect, and polar groups in molecules can be tightly adsorbed on the surface of metal by virtue of charge effect to form an adsorption protective film, so that the metal is not corroded by water, oxygen and the like. Can be used together with alkyl glucamide to effectively improve the cleaning force.

Example 3 in comparison to comparative examples 10-11, it can be seen that coconut diethanolamide affects corrosion rate.

Chitosan is a natural product, has good stability and viscosity performance, and can effectively prevent clay from swelling.

Trehalose has non-reducibility, stability and freezing resistance, has a protective effect on biological macromolecules, has very good stability on heat, acid and alkali, can stabilize a formula system, and ensures that the formula of the system is suitable for extreme environments such as high temperature, high salt, acid and alkali.

Example 3 in comparison with comparative example 13, it can be seen that in the present invention, alkyl glucamide and tetrasodium iminodisuccinate; amylase and protease repair; aminotrimethylene phosphonic acid and coconut diethanolamide; the three components are added for three times, so that the mixing uniformity of the components can be improved, the final index effects of the operation workover fluid are improved, and the problems that sediment, flocculation or layering is generated due to uneven mixing in the preparation process of the operation workover fluid, and the indexes of the operation workover fluid are influenced are avoided.

As can be seen from comparative example 14, the working workover fluid of the present invention has various indexes superior to those of the working workover fluid of the prior art.

In addition, as can be seen from fig. 2 and 3, the surface of the neutral chelating enzyme working workover fluid is bright as new after 24 hours after the N80 steel sheet is placed in the working workover fluid; in comparative example 14, the conventional working well servicing fluid, the N80 steel sheet was left for 24 hours and then rust was attached to the surface.

The working fluids prepared in example 3 and comparative example 15 were subjected to performance tests at 0℃and 40℃and 60℃and 80℃and 100℃and 120℃and 150℃and 160℃respectively, and the test results are shown in tables 4 and 5.

TABLE 4 measurement results of pH, interfacial tension, anti-swelling Rate, corrosion Rate

TABLE 5 determination of erosion Rate, enzymatic degradation Rate, wash Rate, natural sedimentation Desorption Rate and permeability recovery values

/>

The data in tables 4 and 5 show that:

the working workover fluid in example 3 still meets the standard in all indexes at 150 ℃ and is lower than the standard requirement in all indexes at 160 ℃, which indicates that the working workover fluid can be suitable for the well depth environment of more than 5000 meters. The working workover fluid in comparative example 15 has various indexes lower than standard requirements at 80 ℃ and indicates that the working workover fluid can only adapt to well depths within 2000 meters. Thus, the addition of trehalose has a great influence on the stability of the working workover fluid.

From the data, the operation workover fluid is neutral, non-acidic and non-basic, and can protect pipelines from corrosion; the well repairing liquid has good surface interfacial tension, swelling resistance, corrosion rate, enzyme catalytic degradation rate, oil washing rate, natural sedimentation dehydration rate and permeability recovery value by the synergistic function of the special formula composition of the iminodisuccinate tetrasodium, the aminotrimethylene phosphonic acid, the amylase, the protease, the alkyl glucamide, the coconut diethanolamide, the chitosan and the deionized water; meanwhile, the stability of the operation workover fluid is high through the action of trehalose, and the adaptive temperature range is wider.

The invention can be applied to the operation well cleaning, well completion production and daily unblocking of production wells (oil, gas and water), can stably protect oil reservoirs and protection equipment, and is compatible and matched with various well entering liquids. Inorganic scale and organic scale in a shaft and a near-wellbore zone are safely and effectively removed in a neutral environment, so that the permeability is improved, and the operation well repairing efficiency and the oil and gas well yield are improved.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims

1. The utility model provides a neutral chelating enzyme's operation workover fluid which characterized in that: the coating comprises the following components in parts by weight: 12-30 parts of tetrasodium iminodisuccinate, 1-10 parts of aminotrimethylene phosphonic acid, 2-10 parts of amylase, 0.5-5 parts of protease, 5-15 parts of alkyl glucamide, 0.5-2 parts of coconut diethanolamide, 0.5-8 parts of trehalose, 1-5 parts of chitosan and 25-60 parts of deionized water.

2. The neutral chelatase working workover fluid of claim 1, wherein: the coating comprises the following components in parts by weight: 18 parts of tetrasodium iminodisuccinate, 5 parts of aminotrimethylene phosphonic acid, 6 parts of amylase, 3 parts of protease, 8 parts of alkyl glucamide, 1.2 parts of coconut diethanolamide, 2.5 parts of trehalose, 2 parts of chitosan and 36 parts of deionized water.

3. The neutral chelatase working workover fluid of claim 1, wherein: the volume concentration of the iminodisuccinic acid tetrasodium is 98%, the volume concentration of the aminotrimethylene phosphonic acid is more than or equal to 50%, the content of effective substances of amylase and protease is 99%, the volume concentration of alkyl glucamide is more than 50%, the volume concentration of coconut diethanolamide is more than 98%, and the purities of trehalose and chitosan are 99.9%.

4. A method for preparing the operation workover fluid applied to claim 1, which is characterized by comprising the following steps:

5. The method for preparing the operation workover fluid according to claim 4, wherein: in the first step, a mixture of trehalose and chitosan is ground for 5-10min by using a solid grinder, and is dried in vacuum for 4.5-5.5h at the temperature of 40-50 ℃ to obtain a first mixture.

6. The method for preparing the operation workover fluid according to claim 4, wherein: in the second step, deionized water is added into a reaction device, the temperature is raised to 90-98 ℃, the first mixture is added into a solid charging port, and stirring is carried out for 16-24min at the rotating speed of 45-55r/min, so as to obtain the second mixture.

7. The method for preparing the operation workover fluid according to claim 4, wherein: in the third step, alkyl glucamide and tetrasodium iminodisuccinate are added into the mixture II, stirred for 26-35min, cooled to 28-36 ℃, amylase and protease are added, and stirring is continued for 25-35min, so that a mixture III is obtained.

8. The method for preparing the operation workover fluid according to claim 4, wherein: in the fourth step, the mixing conditions are as follows: stirring at 40-45r/min for 0.8-1.3 hr; the conditions of the ultrasonic treatment are as follows: the frequency is 15-25kHz, and the ultrasonic treatment is carried out for 12-18min.