Environment-friendly biological unblocking liquid and application thereof

Abstract

The invention relates to the technical field of oil field yield increase and transformation, in particular to environment-friendly biological blockage removal liquid and application thereof, and aims to solve the problem that a current biological blockage removal product can only remove organic blockage. The environment-friendly biological unblocking liquid provided by the invention is prepared from the following components in percentage by mass: 2-5% of biological enzyme, 1-5% of surfactant, 1-5% of pH (Potential of Hydrogen) regulator and the balance of water. 1%-3% of a biological enzyme stabilizer; 3-5% of a chelating agent; 0.5%-1% of a surfactant; 0.5%-1% of a dispersion suspending agent; and the balance of water. The biological blockage removal liquid provided by the invention can effectively remove organic blockage of a stratum caused by wax and asphaltene precipitates, so that crude oil is released from the surfaces of rock particles, the flowing of the crude oil in pores of the stratum is improved by changing the wetting state of rock, and inorganic blockage is removed through permeation dispersion and chelation solubilization effects, so that the mechanical property of the stratum is improved. Mixed scales formed by mutual deposition of inorganic scales and organic matters (wax and asphaltene) are effectively removed, and the requirement for plugging removal of a complex scaling reservoir of an oil well is met.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield production enhancement and transformation, and in particular to an environmentally friendly biological plugging-removing liquid and application thereof. Background Art

[0002] As oilfield development enters the late stage of medium-high water content, the scaling problem of oil wells has become increasingly serious. The scaling problem of oil wells is seriously restricting the normal production and development of oilfields and causing significant economic losses. The scaling is mainly composed of inorganic scales such as calcium carbonate, calcium sulfate, and rust, as well as organic scales such as colloids, asphaltene, and wax. The current use of organic solvents for descaling is difficult to remove mixed scales, and there are problems such as high toxicity and low flash point. It is also difficult to achieve the purpose of simple hot well washing process.

[0003] Bioenzyme plugging removal technology is a new oil layer plugging removal technology that has emerged in the context of the rapid development of biotechnology in recent years. It has good safety and stability, does not harm operators, and does not pollute the environment. It does not corrode oil and gas field pipelines and pipes, and only undergoes biochemical reactions with crude oil, does not change the characteristics of crude oil, does not produce emulsification, and does not produce new derivatives. Therefore, after being injected into the formation, it will not block the oil layer due to scaling, nor will it pollute the oil layer. Therefore, it has been widely used in oil and gas field development. In recent years, there have been many introductions to bioenzyme plugging remover products and applications, mainly Apollo enzyme, LS bioenzyme, SUN-K500 bioenzyme, etc. The temperature resistance of enzyme products currently used on site is generally lower than 100°C, and they are more sensitive to mineralization. Some enzyme products have salting out when the mineralization is above 5000mg / L. When used alone, they are greatly affected by environmental factors. In addition, bioenzyme plugging removers only have a plugging removal effect on organic plugging materials such as wax and asphalt, and cannot remove inorganic scales such as calcium carbonate, calcium sulfate, and rust. Oil well blockages are not simple crystalline scales, but often mixed scales with complex components, including organic matter such as wax and asphalt, as well as inorganic impurities such as sand, rust, mud, and clay, which greatly limits their application in oil field deblocking technology. Summary of the invention

[0004] The purpose of the present invention is to provide an environmentally friendly biological plugging-removing fluid and its application to solve the shortcomings of the existing plugging-removing fluid system, remove organic and inorganic blockages, improve the flowability of crude oil, and achieve the purpose of removing formation blockages.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] The present invention provides an environmentally friendly biological plugging-removing liquid, comprising: the plugging-removing liquid is composed of the following components in mass percentage:

[0007] Biological enzyme 2%-5%;

[0008] Biological enzyme stabilizer 1%-3%;

[0009] Chelating agent 3-5%;

[0010] Surfactant 0.5%-1%;

[0011] Dispersing and suspending agent 0.5%-1%;

[0012] The balance is water.

[0013] Furthermore, the biological enzyme is a new type of glycoprotein substance produced by thermophilic Bacillus.

[0014] Furthermore, the thermophilic Bacillus is thermophilic Bacillus DM-2.

[0015] Furthermore, the glycoprotein substance is composed of glucose, lysine, alanine, valine, methionine and glycine.

[0016] Furthermore, the biological enzyme stabilizer is composed of one or two of sodium dodecyl alcohol polyoxyethylene ether sulfate and disodium ethylenediaminetetraacetate.

[0017] Furthermore, the chelating agent is one or two of polyepoxysuccinic acid, S-carboxyethyl sulfosuccinic acid, and polyaspartic acid.

[0018] Furthermore, the surfactant is composed of one or two of fluorinated heavy alkyl benzene sulfonate, lignin sulfonate, and petroleum sulfonate.

[0019] Furthermore, the dispersing suspending agent is composed of one or two of sodium butylnaphthalene sulfonate, sodium dodecyl sulfate, and sodium tripolyphosphate.

[0020] Furthermore, the use process of the environmentally friendly biological plugging-removing liquid is to mix various additives according to proportions, add a certain amount of water to dissolve and dilute them, and then use them.

[0021] In a second aspect, the present invention provides a use of the environmentally friendly biological plugging-removing fluid in removing plugging in scaling reservoirs of oil wells.

[0022] Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

[0023] 1. Biological enzymes can change the wetting state of rocks, making the rock wettability become water-wet, reducing the wetting angle and the interfacial tension of rock particles, increasing the oil phase permeability, reducing the flow resistance of crude oil in the formation pores, and removing organic blockages in oil wells; biological enzyme stabilizers can maintain the activity of biological enzymes and avoid the failure of biological enzymes; surfactants can effectively reduce the interfacial tension of the plugging remover surface, avoid the adsorption of the plugging remover in the formation, and reduce the plugging removal effect; chelating agents mainly react with scale to form stable water-soluble compounds that can dissolve inorganic blockages; dispersing and suspending agents disperse and suspend the scale in the scale remover. Even if the chelating agent does not react with it, it can bring the scale out of the wellbore or formation.

[0024] 2. The environmentally friendly biological unblocking liquid provided by the present invention has excellent descaling rate and cleaning rate. The product of the present invention aims to unblock and unclog pore throats to restore reservoir permeability, and effectively removes inorganic blocking substances such as carbonates, metal oxides, and organic scales such as colloids, asphaltene and wax in the reservoir. In addition, the use of the product of the present invention does not damage the reservoir skeleton, and the waste liquid after unblocking does not need to be returned for treatment, and the pump can be started to produce oil after unblocking. Compared with traditional pickling unblocking, biological enzyme unblocking and organic solvents, the product of the present invention is safe and reliable, green and environmentally friendly, and effectively solves the inorganic-organic mixed scale existing in oil wells, and solves the problem that current biological unblocking products can only remove organic blockages. It is of great significance to ensure safe production and long-term oil production.

[0025] 3. Compared with the prior art, the present invention has significant effects, which are specifically manifested in:

[0026] (1) The environmentally friendly biological plugging-removing liquid system developed by the present invention has good safety and stability, does not harm the operating personnel, and does not cause pollution to the environment; (2) The plugging-removing agent developed by the present invention has excellent comprehensive performance, and only undergoes biochemical reactions with crude oil, does not change the properties of crude oil, does not produce emulsification, and does not produce new derivatives. Therefore, after being injected into the formation, it will not block the oil layer due to scaling, nor will it pollute the oil layer, and can be reused; (3) The use of high-temperature resistant biological enzymes can withstand the formation temperature, and can play a biological catalytic function under high-temperature formation conditions to remove formation blockages; restore or improve the oil and gas production capacity of oil and gas wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 Oilfield scale samples used in the test examples and comparative examples;

[0029] Figure 2 This is the infrared spectrum of oilfield scale sample;

[0030] Figure 3 is the TGA spectrum;

[0031] Figure 4 This is the XRF spectrum of the scale sample. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0033] Embodiment 1:

[0034] Formula of plugging solution (by weight percentage):

[0035] Biological enzyme 2%;

[0036] Sodium dodecyl alcohol polyoxyethylene ether sulfate 1%;

[0037] Polyepoxysuccinic acid 3%;

[0038] Fluorinated heavy alkylbenzene sulfonate 0.8%;

[0039] Sodium butylnaphthalenesulfonate 0.5%;

[0040] Add 93 parts of water with a mineralization degree of 20×104 mg / L into a beaker, and then add 2 parts of biological enzymes, 1 part of sodium dodecyl alcohol polyoxyethylene ether sulfate, 3 parts of polyepoxysuccinic acid, 0.8 parts of fluorinated heavy alkylbenzene sulfonate, and 0.5 parts of sodium butylnaphthalene sulfonate in sequence, stir evenly, and obtain biological enzyme composite plugging remover 1#.

[0041] Embodiment 2:

[0042] Formula of plugging solution (by weight percentage):

[0043] Biological enzyme 5%;

[0044] EDTA disodium 3%;

[0045] S-Carboxyethylsulfosuccinic acid 5%;

[0046] Petroleum sulfonate 1.0%;

[0047] Sodium dodecyl sulfate 0.6%;

[0048] Add 85 parts of 20×104 mg / L water into a beaker, then add 5 parts of biological enzyme, 3 parts of disodium ethylenediaminetetraacetate, 5 parts of S-carboxyethyl sulfosuccinic acid, 1 part of petroleum sulfonate, and 0.6 parts of sodium dodecyl sulfate in sequence, stir evenly, and obtain biological enzyme composite plugging remover 2#.

[0049] Embodiment 3:

[0050] Formula of plugging solution (by weight percentage):

[0051] Bioenzyme 3%;

[0052] Sodium dodecyl alcohol polyoxyethylene ether sulfate 2%;

[0053] Polyaspartic acid 4%;

[0054] Lignin sulfonate 0.7%;

[0055] Sodium tripolyphosphate 0.8%;

[0056] Add 85 parts of mineralization 20×104 mg / L into a beaker, then add 3 parts of biological enzyme, 2 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate, 4 parts of polyaspartic acid, 0.7 parts of lignin sulfonate, and 0.8 parts of sodium tripolyphosphate in sequence, stir evenly, and obtain biological enzyme composite plugging remover 3#.

[0057] Embodiment 4:

[0058] Formula of plugging solution (by weight percentage):

[0059] Bioenzyme 4%;

[0060] EDTA disodium 3%;

[0061] Polyepoxysuccinic acid 5%;

[0062] Fluorinated heavy alkylbenzene sulfonate 1.0%;

[0063] Sodium butylnaphthalenesulfonate 1.0%;

[0064] Add 87 parts of water with a mineralization degree of 20×104 mg / L into a beaker, and then add 4 parts of biological enzymes, 3 parts of disodium ethylenediaminetetraacetate, 5 parts of polyepoxysuccinic acid, 1 part of fluorinated heavy alkylbenzene sulfonate, and 1 part of sodium butylnaphthalene sulfonate in sequence, stir evenly, and obtain biological enzyme composite plugging remover 4#.

[0065] Embodiment 5:

[0066] Formula of plugging solution (by weight percentage):

[0067] Biological enzyme 5%;

[0068] Sodium lauryl alcohol polyoxyethylene ether sulfate 2%

[0069] S-Carboxyethylsulfosuccinic acid 4%;

[0070] Lignin sulfonate 0.6%;

[0071] Sodium butylnaphthalenesulfonate 0.8%;

[0072] Add 89 parts of water with a mineralization degree of 20×104 mg / L into a beaker, and then add 5 parts of biological enzymes, 2 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate, 4 parts of S-carboxyethyl sulfosuccinic acid, 0.6 parts of lignin sulfonate, and 0.8 parts of sodium butylnaphthalene sulfonate in sequence, stir evenly, and obtain biological enzyme composite plugging remover 5#.

[0073] Related test methods:

[0074] (1) Temperature resistance test: The biological plugging solution is heated to a specified temperature, left for 12 hours, and then taken out for evaluation experiments.

[0075] (2) Scale sample analysis: Infrared spectroscopy, TGA, and XRF spectrum tests are performed on oilfield scale samples.

[0076] (3) Descaling rate test: Weigh a certain mass of scale samples and place them in stoppered test tubes. Heat them in a water bath to melt the scale samples. Rotate the test tubes and cool them so that they are evenly adsorbed on the test tube walls. Add 20 ml of deblocking solution to each test tube and heat them at 60°C. Observe the dissolution at different times. Pour out the solution, dry and weigh it, and calculate the descaling rate.

[0077] Analysis of the scale samples shows that the main components of the oilfield scale samples are calculated by mass fraction: 47%-48% asphalt, 30%-31% ferrous tetrasulfide, 2%-2.5% calcium carbonate, 18%-19% ferrous sulfide, and 1%-1.5% calcium silicate. It is a mixed scale composed of organic and inorganic components.

[0078] Table 1 Biological plugging removal performance test of liquid

[0079] Comparative Example

[0080] The performance test of the biological plugging remover products on the market showed that the temperature resistance of the products is generally lower than 100°C (including 100°C), and the removal rate for mixed scale is low.

[0081] Table 2 Test of the existing biological plugging removal performance

[0082] It can be seen from Table 1 that the biological plugging removal liquid prepared in the embodiment of the present invention has a temperature resistance of ≥200°C and a mixed scale plugging removal rate of ≥95.0%. Compared with the existing biological plugging removal liquid products, the biological plugging removal liquid prepared in the embodiment of the present invention has a higher temperature resistance and a higher mixed scale plugging removal rate.

[0083] The biological plugging-removing fluid provided by the present invention can effectively remove organic blockages in formations caused by wax and asphaltene precipitation, release crude oil from the surface of rock particles, improve the flow of crude oil in formation pores by changing the wetting state of rocks, and remove inorganic blockages by osmotic dispersion and chelating solubilization, effectively removing mixed scale formed by mutual deposition of inorganic scale and organic matter (wax, asphaltene), meeting the needs of deblocking complex scaling reservoirs in oil wells.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An environmentally friendly biological plugging removal liquid, characterized in that: include: The plugging removal liquid is composed of the following components in percentage by mass: Biological enzyme 2%-5%; Biological enzyme stabilizer 1%-3%; Chelating agent 3-5%; Surfactant 0.5%-1%; Dispersing and suspending agent 0.5%-1%; The balance is water.

2. The environmentally friendly biological plugging removal liquid according to claim 1, characterized in that: The biological enzyme is a new type of glycoprotein substance produced by thermophilic Bacillus.

3. The environmentally friendly biological plugging removal liquid according to claim 2, characterized in that: The thermophilic Bacillus is thermophilic Bacillus DM-2.

4. The environmentally friendly biological plugging removal liquid according to claim 2, characterized in that: The glycoprotein substances are composed of glucose, lysine, alanine, valine, methionine and glycine.

5. The environmentally friendly biological plugging removal liquid according to claim 1, characterized in that: The biological enzyme stabilizer is composed of one or two of sodium dodecyl alcohol polyoxyethylene ether sulfate and disodium ethylenediaminetetraacetate.

6. The environmentally friendly biological plugging removal liquid according to claim 1, characterized in that: The chelating agent is one or two of polyepoxysuccinic acid, S-carboxyethyl sulfosuccinic acid and polyaspartic acid.

7. The environmentally friendly biological plugging removal liquid according to claim 1, characterized in that: The surfactant is composed of one or two of fluorinated heavy alkyl benzene sulfonate, lignin sulfonate and petroleum sulfonate.

8. The environmentally friendly biological plugging removal liquid according to claim 1, characterized in that: The dispersing suspending agent is composed of one or two of sodium butylnaphthalene sulfonate, sodium dodecyl sulfate and sodium tripolyphosphate.

9. The environmentally friendly biological plugging removal liquid according to claim 1, characterized in that: The process of using the environmentally friendly biological plugging-removing liquid is to mix various additives according to proportions, add a certain amount of water to dissolve and dilute them, and then use them.

10. Use of the environmentally friendly biological plugging-removing fluid according to any one of claims 1 to 9 in removing plugging in scaling reservoirs of oil wells.

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