An oil and gas reservoir water lock breaking chemical agent, a preparation method and application thereof

Abstract

The present application provides an oil and gas reservoir water lock chemical agent, a preparation method and application thereof. The oil and gas reservoir water lock chemical agent is prepared from raw materials including anionic fluorine surfactant, zwitterionic surfactant, synergistic adjuvant and solvent; the anionic fluorine surfactant is 1-40% of the total weight of the oil and gas reservoir water lock chemical agent; the zwitterionic surfactant is 1-40% of the total weight of the oil and gas reservoir water lock chemical agent; the synergistic adjuvant is 0.5-20% of the total weight of the oil and gas reservoir water lock chemical agent; and the rest is solvent. The prepared water lock chemical agent has mutual interaction and synergistic effect among the components, greatly reduces the surface tension of water, can regulate the surface of strong water-wet matrix to neutral wetting, has low apparent viscosity and low cost, and has better stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas reservoir exploitation and the field of oil and gas reservoir formation protection and formation repair, and further relates to an oil and gas reservoir water lock resolving chemical agent, a preparation method and application thereof. BACKGROUND

[0002] Water lock damage is a common problem in the process of oil and gas reservoir development. For example, in the process of drilling, well completion, well repair and production operation, due to the introduction of a large amount of construction fluid, the phenomenon of retention of foreign fluid in the porous medium often occurs, which significantly reduces the reservoir permeability and the relative permeability of oil and gas. For another example, in the later stage of oil and gas reservoir development, as the production time is prolonged, the production pressure difference of some high-pressure low-yield wells will gradually increase, which causes the bound water in the formation outside the reservoir to gradually flow into the near wellbore zone, resulting in water lock. In addition, the concept of water lock damage in oil and gas reservoirs can also be extended to liquid lock damage. For example, in natural gas reservoirs, especially in condensate natural gas reservoirs, due to the continuous production of condensate oil in the process of gas well production, the condensate oil gradually condenses and accumulates at the bottom of the natural gas well. When the accumulated water and condensate oil at the bottom of the well cannot be carried out of the wellhead with the gas flow, reverse seepage will occur in the capillary pores in the low permeability formation, resulting in water lock damage and condensate damage, which affects the productivity of the gas well, which belongs to liquid lock damage. Especially in low permeability oil and gas reservoirs, due to the characteristics of low porosity and low permeability of the reservoir, the flow channel of the fluid is narrow, the seepage resistance is large, and the interaction force between the interfaces is large, which makes the water lock and liquid lock damage particularly prominent.

[0003] Once water lock damage occurs, it will greatly affect the productivity of the oil and gas reservoir. Therefore, how to prevent and resolve water lock damage is one of the important issues for realizing stable and increased production of oil and gas fields.

[0004] There are two main reasons for water lock damage, including capillary self-suction and liquid phase retention, which are affected by fluid surface / interface tension, capillary wetting angle, and the pore throat radius of the formation rock, formation pressure, invasion depth of foreign fluid and fluid viscosity, etc. aggravate the occurrence of water lock damage and condensate damage. At present, the technical means for resolving water lock damage in oil and gas reservoirs include increasing the production pressure, thermal cleaning, formation fracturing and other physical means, but the most important method for resolving water lock is to use water lock resolving chemical agents. The working principle of water lock resolving chemical agents is to use surfactants and other agents to reduce the surface tension of water, regulate the wettability of the formation, etc., so as to promote the discharge of the blocked water in the oil and gas reservoir formation, thereby achieving the effect of resolving water lock damage. For natural gas reservoirs with condensate damage, the corresponding water lock resolving chemical agent needs to have good wettability regulation performance, so that the formation matrix is close to neutral wetting after treatment, thereby realizing the effect of discharging the fluid causing damage in the formation.

[0005] The main idea of the water lock releasing agent in the prior art is to reduce the surface tension, and less attention is paid to the properties of regulating wettability (contact angle data) and reducing viscosity or the performance is poor; in the newly reported technology, a new type of water lock releasing agent containing a biosurfactant is used, and the cost is high and the performance stability is poor. Therefore, it is necessary to study a chemical agent suitable for oil and gas reservoir water lock release, which can be prepared by using conventional surfactants, reduce the cost, improve the performance stability, and has the properties of low surface tension, good wettability, low viscosity and the like. SUMMARY

[0006] In order to solve the technical problems existing in the prior art, the present application provides an oil and gas reservoir water lock releasing chemical agent, a preparation method and application thereof.

[0007] The water lock releasing chemical agent provided by the present application can reduce the surface tension of water, regulate the surface of a strong water-wet matrix to neutral wettability, and has the effect of reducing the viscosity of the fluid, so that the damage caused by the water lock and liquid lock of the oil and gas reservoir can be effectively eliminated.

[0008] The water lock releasing chemical agent provided by the present application can make the components interact with each other and synergistically by combining two types of surfactants. The anionic fluorine surfactant can fully exert the characteristics of ultra-high surface activity, greatly reduce the surface tension of the fluid, and the addition of the amphoteric surfactant can further improve the efficiency of the two types of surfactants. When the anionic fluorine surfactant and the amphoteric surfactant are used in a specific ratio, the arrangement of the composite system at the gas-liquid interface is more compact than that of a single surfactant, which can greatly improve the surface interfacial properties and wettability regulation ability of the system, and promote the reasonable adsorption of the surfactant composition on the surface of the matrix, effectively exert the wettability regulation ability, create a low-energy surface of the matrix, promote the discharge of the blocked water and oil in the formation, and play a good water lock releasing effect. In addition, the synergistic aid as a water structure breaker can destroy the interaction between water molecules to a certain extent, reduce the apparent viscosity of the whole system, improve the flowability of the damaging fluid, and further promote the elimination of water lock. The addition of the small molecule solvent can improve the solubility of the whole chemical agent system, and also partially reduce the viscosity of the system.

[0009] One of the purposes of the present application is to provide an oil and gas reservoir water lock releasing chemical agent.

[0010] The oil and gas reservoir water lock releasing chemical agent comprises an anionic fluorine surfactant, an amphoteric surfactant and a synergistic aid.

[0011] The oil and gas reservoir water lock releasing chemical agent comprises an anionic fluorine surfactant, an amphoteric surfactant and a synergistic aid.

[0012] The anionic fluorine surfactant is 1-40%, preferably 5-20%, based on 100% of the total weight of the oil and gas reservoir water lock releasing chemical agent.

[0013] Amphoteric surfactants, 1-40%; preferably 5-30%;

[0014] Synergistic adjuvant: 0.5-20%; preferably 5-10%.

[0015] In a preferred embodiment of the present invention,

[0016] The anionic fluorosurfactant is at least one of fluoroalkyl polyether acid salt and fluoroalkyl polyether ester salt;

[0017] The preferred structural formula of the anionic fluorosurfactant is:

[0018]

[0019] Where R is C1 to C 20 Alkylene, substituted C1-C 20 At least one of the alkylene groups, preferably, R is at least one of the C1-C6 alkylene groups or substituted C1-C6 alkylene groups;

[0020] n is an integer between 1 and 20, preferably an integer between 4 and 12;

[0021] x and y are each independently selected from any integer from 0 to 40, preferably from any integer from 2 to 20, and more preferably from any integer from 8 to 20;

[0022] X is selected from one of -COOM, -SO3M, -OSO3M, and -OPO3M2, with X preferably being -COOM or -SO3M, meaning the anionic fluorosurfactant is preferably at least one of fluoroalkyl polyether salts; wherein M is a cation with balanced charge, and M is preferably Na. + K + or NH4 + .

[0023] Anionic fluorosurfactants can be purchased directly or prepared using methods disclosed in the prior art. For example, nonionic fluorosurfactants can be prepared by reacting corresponding fluoroalkyl acyl chlorides with a certain proportion of propylene oxide and ethylene oxide, and then the corresponding anionic surfactants can be prepared by carboxylation, sulfonation, or other reactions.

[0024] Specific preparation methods are as follows:

[0025] With the corresponding commercially available fluoroalkyl acyl chloride as raw material, referring to the preparation method of polyoxyethylene polyoxypropylene ether nonionic surfactant in patent CN114479810A, add propylene oxide, ethylene oxide (determined according to the target molecular PO, EO number) with a certain molar ratio of fluoroalkyl acyl chloride, add 1-3wt% mass of alkaline catalyst of fluoroalkyl acyl chloride, and react at 100-180℃ for 6-12 hours, and nonionic fluorosurfactant can be obtained; with the prepared nonionic fluorosurfactant as raw material, referring to the synthesis method of anionic surfactant in patent CN103540303A, the nonionic fluorosurfactant and the catalyst are added into the reaction kettle according to the molar ratio of 1:1-5, alkalization is carried out at 20-100℃ for 1-10 hours, then sulfonating reagent or carboxylating reagent is added, the molar ratio of nonionic fluorosurfactant to sulfonating reagent or carboxylating reagent is 1:1-4, the temperature is increased to 50-100℃ and the reaction is continued for 1-20 hours, then hydrochloric acid is added for neutralization to pH<3, and oil-water separation is carried out, the oil phase is added into lye for neutralization, and finally ether carboxylate type fluorosurfactant is obtained.

[0026] In a preferred embodiment of the present application,

[0027] The amphoteric surfactant can be a commercially available product, preferably at least one of imidazoline surfactant, amino acid surfactant and betaine surfactant; more preferably betaine surfactant; the amphoteric surfactant is preferably R'3NCHC a H 2a+1 COOY, C b H 2b+1 R'2NR''COOY, C c H 2c+1 R'2NR''SO3Y; wherein R' is C1-8 alkyl and / or substituted alkyl; R'' is C1-10 alkylene or substituted alkylene; Y is a cation to balance the charge, Y is preferably Na + , K + or NH4 + ; a, b, c are independently selected from integers of 1-30;

[0028] The amphoteric surfactant is more preferably at least one of (CH3)3NCHC 12 H 25 COOK, C 16 H 33 (CH3)2NCH2COONa, C 14 H 29 N(CH3)2C2H4SO3Na, C8H 17 N(CH3)2CH2CH(OH)CH2SO3Na.

[0029] The synergistic adjuvant is at least one of urea, formamide, N-methyl acetamide, guanidine salt; preferably at least one of urea and formamide.

[0030] In a preferred embodiment of the present application,

[0031] The oil and gas reservoir water lock breaking chemical agent further comprises a solvent, and the amount of the solvent is the balance.

[0032] In a preferred embodiment of the present application,

[0033] The solvent is at least one of water and a small molecule organic solvent; preferably,

[0034] The water is at least one of deionized water and water containing inorganic minerals; and / or,

[0035] The small molecule organic solvent is at least one of a small molecule alcohol, a small molecule ether, a small molecule aldehyde, a small molecule ketone, a small molecule amine and a small molecule alcohol amine.

[0036] In a preferred embodiment of the present application,

[0037] The water containing inorganic minerals is at least one of tap water, river water, lake water and oil and gas field formation water; and / or,

[0038] The small molecule alcohol is at least one of C1-C6 monohydric alcohol, C2-C6 dihydric alcohol and C3-C6 polyhydric alcohol; preferably, the small molecule alcohol is at least one of C1-C3 monohydric alcohol, C2-C3 dihydric alcohol and glycerol; and / or,

[0039] The small molecule ether is at least one of C1-C6 monohydric ether; preferably, the small molecule ether is at least one of dimethyl ether, methyl vinyl ether, methyl ethyl ether, ethylene glycol methyl ether, ethyl vinyl ether and diethyl ether.

[0040] In a preferred embodiment of the present application,

[0041] When the solvent is water and a small molecule organic solvent, the mass ratio of the small molecule organic solvent to water is (0-10):10, preferably (1-10):10.

[0042] The second object of the present application is to provide a preparation method of the oil and gas reservoir water lock breaking chemical agent, comprising the following steps:

[0043] The anionic fluorine surfactant, the zwitterionic surfactant and the rest of the solvent are mixed and dissolved; then the synergistic agent and the rest of the solvent are added and stirred to obtain the oil and gas reservoir water lock resolving chemical agent; preferably, the mass of the part of the solvent accounts for 50-100% of the total mass of the solvent, and the rest of the solvent accounts for 0-50% of the total mass of the solvent.

[0044] The solvent is added in two steps because the aqueous solution of the surfactant can form a unique micellar structure; preferably, the two types of surfactants are first dissolved in water to form a stable combination, and then the synergistic agent is added.

[0045] The third object of the present application is to provide an application of the oil and gas reservoir water lock resolving chemical agent in the oil and gas reservoir water lock damage.

[0046] The skilled in the art can use the existing water lock resolving construction process, for example, but not limited to, the anionic fluorine surfactant, the zwitterionic surfactant and the synergistic agent are diluted with water to an effective concentration of 0.001%-10w.t.% and then a certain amount of the water lock resolving agent is injected into the oil, water and gas well. The water can be selected from deionized water and / or water containing inorganic minerals, specifically, the water containing inorganic minerals can be selected from at least one of tap water, river / lake water and oil and gas field formation water. The water lock resolving chemical agent provided by the present application can be used in combination with the existing acidizing construction of the oil and gas reservoir, and the hydrochloric acid and the corrosion inhibitor system have no negative effect on the performance of the water lock resolving chemical agent.

[0047] In a preferred embodiment of the present application,

[0048] The oil and gas reservoir water lock resolving chemical agent is diluted with water to a mass concentration of 0.001%-10%, preferably 0.01%-2%, for example, 0.05%, 0.1%, 0.5%, 1%, 1.5% and 2% when used.

[0049] Compared with the prior art, the present application has the following advantages:

[0050] The water lock releasing chemical agent provided by the application can make the components interact with each other and synergistically reduce the surface tension of water by combining anionic fluorine surfactant and zwitterionic surfactant, and can reduce the surface tension of water to less than 20 mN / m. Moreover, the strong water-wet substrate surface can be regulated to neutral wetting, thereby promoting the discharge of the blocking fluid in the formation. Further, by controlling the specific ratio of the anionic fluorine surfactant and the zwitterionic surfactant, the obtained surfactant composition has a more compact arrangement at the gas-liquid interface than the single surfactant, and can greatly improve the interfacial properties and wetting regulation ability of the system. Especially when the zwitterionic surfactant is added in a suitable proportion, the reasonable adsorption of the chemical agent system on the negatively charged substrate surface can be effectively controlled, the strong water-wet surface can be effectively regulated to neutral, the discharge of the blocking fluid in the formation can be promoted, and the water lock damage of the oil and gas reservoir can be effectively released. The addition of the synergistic aid can reduce the apparent viscosity of the whole system and improve the flowability of the damage fluid, thereby further promoting the release of water lock. The addition of the small molecule solvent can improve the solubility of the system and also partially reduce the viscosity of the system.

[0051] The water lock releasing chemical agent prepared by the application has better stability, good temperature resistance and salt resistance, can maintain stable performance under the condition of 120 DEG C and below and 100000 mg / L NaCl mineralization, has a wide temperature and salinity adaptation range, and can be used in water lock releasing construction in various formation conditions.

[0052] The anionic fluorine surfactant and the zwitterionic surfactant used in the application are conventional industrial surfactants, and have low cost. At present, biological surfactants are usually produced and separated by fermentation process of microorganisms, and the production cost is higher than that of chemically synthesized surfactants. Moreover, due to the limitation of production process and separation technology, the purity and effective component ratio of the commercial products may have certain batch differences. DETAILED DESCRIPTION

[0053] Hereinafter, the application will be specifically described in combination with specific embodiments. It is necessary to point out that the following embodiments are only used for further illustration of the application, and cannot be understood as the limitation of the protection scope of the application. Some non-essential improvements and adjustments of the application made by the person skilled in the art according to the content of the application still belong to the protection scope of the application.

[0054] The raw materials used in the examples are all conventional commercially available raw materials; the raw materials used in the examples and comparative examples, if not specifically limited, are all disclosed in the prior art, for example, can be directly purchased or prepared according to the preparation method disclosed in the prior art. For example, the anionic fluorinated surfactant can be prepared by reacting the corresponding fluorinated alkyl acyl chloride with a certain proportion of propylene oxide and ethylene oxide to obtain a non-ionic fluorinated surfactant, and then by carboxylation, sulfonation and the like to obtain the corresponding anionic surfactant; the zwitterionic surfactant is commercially available.

[0055] Example 1

[0056] Preparation of anionic fluorinated surfactant: add propylene oxide with a molar ratio of 1:10 to fluorinated alkyl acyl chloride, and add ethylene oxide with a molar ratio of 1:16 to fluorinated alkyl acyl chloride, add a basic catalyst with a mass of 2% of the fluorinated alkyl acyl chloride, react at 150°C for 10 hours to obtain a non-ionic fluorinated surfactant; add the obtained non-ionic fluorinated surfactant and a basic catalyst according to a molar ratio of 1:3 into a reaction kettle, and alkalify at 50°C for 4 hours, then add a carboxylation reagent, wherein the molar ratio of the non-ionic fluorinated surfactant to the carboxylation reagent is 1:2, continue to react at 80°C for 10 hours, then add hydrochloric acid to neutralize to pH <3, and perform oil-water separation, add a lye to the oil phase for neutralization, and finally obtain an anionic fluorinated surfactant C 10 F 21 CH2O(PO) 10 (EO) 16 C3H6COONa;

[0057] The water lock release chemical is composed of the following mass fraction of raw materials: anionic fluorinated surfactant C 10 F 21 CH2O(PO) 10 (EO) 16 C3H6COONa 20%, zwitterionic surfactant (CH3)3NCHC 12 H 25 COOK 30%, formamide 5%, solvent 45%, the solvent is deionized water, methyl vinyl ether and ethanol with a mass ratio of 4:1:1.

[0058] Preparation method: mix the above two surfactants and half of the solvent, stir to completely dissolve; supplement formamide and the remaining solvent, stir to mix uniformly, and obtain a water lock release chemical.

[0059] Example 2

[0060] Preparation of anionic fluorosurfactant: the difference from Example 1 is that the molar ratio of fluoroalkyl acid chloride to propylene oxide to ethylene oxide is 1:8:8, and sulfonating reagent is selected in the synthesis of anionic surfactant; other conditions are the same as in Example 1, and anionic fluorosurfactant C4F9CH2O(PO)8(EO)8C2H4SO3Na is prepared.

[0061] The water lock release chemical agent is composed of the following raw materials with mass fraction: anionic fluorosurfactant C4F9CH2O(PO)8(EO)8C2H4SO3Na 10%, zwitterionic surfactant C 16 H 33 (CH3)2NCH2COONa 20%, urea 10%, and solvent 60%, and the solvent is deionized water and ethanol with mass ratio of 1:1.

[0062] The preparation method of the water lock release chemical agent is the same as in Example 1.

[0063]

Example 3

[0064] Preparation of anionic fluorosurfactant: the difference from Example 1 is that the molar ratio of fluoroalkyl acid chloride to propylene oxide to ethylene oxide is 1:4:10; other conditions are the same as in Example 1, and anionic fluorosurfactant C6F 13 CH2O(PO)4(EO) 10 CH2OPO3Na2 is prepared.

[0065] The water lock release chemical agent is composed of the following raw materials with mass fraction: anionic fluorosurfactant C6F 13 CH2O(PO)4(EO) 10 CH2OPO3Na2 5%, zwitterionic surfactant C 14 H 29 N(CH3)2C2H4SO3Na 15%, N-methyl acetamide 8%, and solvent 72%, and the solvent is deionized water.

[0066] The preparation method of the water lock release chemical agent is the same as in Example 1.

[0067]

Example 4

[0068] Preparation of anionic fluorosurfactant: the difference from Example 1 is that the molar ratio of fluoroalkyl acid chloride to propylene oxide to ethylene oxide is 1:12:18; other conditions are the same as in Example 1, and anionic fluorosurfactant C 12 F 25 CH2O(PO) 12 (EO) 18 CH2COONa is prepared.

[0069] The water lock release chemical is composed of the following raw materials by mass fraction: anionic fluorinated surfactant C 12 F 25 CH2O(PO) 12 (EO) 18 CH2COONa 20%, zwitterionic surfactant C8H 17 N(CH3)2CH2CH(OH)CH2SO3Na 10%, urea 5%, solvent 65%, and the solvent is deionized water and methanol in a mass ratio of 10:1.

[0070] The preparation method of the water lock release chemical is the same as that of Example 1.

[0071]

Comparative Example 1

[0072] The difference from Example 1 is that the zwitterionic surfactant (CH3)3NCHC 12 H 25 COOK is not added, and an equivalent amount of anionic fluorinated surfactant C 10 F 21 CH2O(PO) 10 (EO) 16 C3H6COONa is replaced, i.e., the mass fraction of the anionic fluorinated surfactant is 50%;

[0073] The other raw material compositions and preparation methods are the same as those of Example 1, and the water lock release chemical is obtained.

[0074]

Comparative Example 2

[0075] The difference from Example 1 is that the anionic fluorinated surfactant C 10 F 21 CH2O(PO) 10 (EO) 16 C3H6COONa is not added, and an equivalent amount of zwitterionic surfactant (CH3)3NCHC 12 H 25 COOK is replaced, i.e., the mass fraction of the zwitterionic surfactant is 50%;

[0076] The other raw material compositions and preparation methods are the same as those of Example 1, and the water lock release chemical is obtained.

[0077]

Comparative Example 3

[0078] The difference from Example 1 is that the formamide is not added, and an equivalent amount of solvent is added to make up, i.e., the mass fraction of the solvent is 50%;

[0079] The other raw material compositions and preparation methods are the same as those of Example 1, and the water lock release chemical is obtained.

[0080] Comparative Example 4

[0081] The water lock releasing chemical was prepared by using the following raw materials with the mass fraction: anionic fluorine surfactant C 10 F 21 CH2O(PO) 10 (EO) 16 C3H6COONa 2.5%, zwitterionic surfactant (CH3)3NCHC 12 H 25 COOK 45%, solvent 52.5%, the solvent is deionized water, methyl vinyl ether and ethanol with a mass ratio of 4:1:1.

[0082] The water lock releasing chemical was prepared by using the following raw materials with the mass fraction: anionic fluorine surfactant C

[0083] The water lock releasing chemicals prepared in Examples 1-4 and Comparative Examples 1-4 were respectively diluted with deionized water to an effective concentration of 0.1 w.t.%, and the surface tension of each water lock releasing agent was determined according to "GB / T 22237-2008 Determination of surface tension of surfactants", and the determination results are shown in Table 1.

[0084] Table 1

[0085] Sample Surface tension (mN / m) Example 1 15.5 Example 2 15.9 Example 3 16.8 Example 4 16.1 Comparative Example 1 17.1 Comparative Example 2 28.7 Comparative Example 3 16.4 Comparative Example 4 27.9

[0086] As can be seen from Table 1, the surfactant composition provided in Examples 1-4 has a lower surface tension. Especially, as can be seen from the comparison of Example 1 and Comparative Examples 1-2, the combination of anionic fluorine surfactant and zwitterionic surfactant can greatly reduce the surface tension of water due to the synergistic effect between the components.

[0087] The contact angles of the water lock releasing chemicals prepared in Examples 1-4 and Comparative Examples 1-4 were tested to evaluate the ability of the water lock releasing agent for oil and gas reservoirs to regulate the wettability of the formation.

[0088] Specifically, a hydrophilic quartz piece was selected as the test substrate, and the quartz piece was cleaned with an alcohol solvent and ultrapure water for multiple times. The ultrapure water was almost completely spread on the quartz piece for testing, and the contact angle was less than 5°. The water lock releasing chemicals prepared in Examples 1-4 and Comparative Examples 1-4 were respectively diluted with deionized water to an effective concentration of 0.1 w.t.% to obtain test solutions, and the quartz piece was immersed in the solution for 24 h and then naturally dried. (1) The contact angle of water and the treated quartz piece was tested, and the test results are shown in Table 2; (2) the glass piece was immersed in water, and the contact angle of n-octane in water and the glass piece was tested, and the test results are shown in Table 3.

[0089] Table 2

[0090] Sample Contact angle 1 (°) Example 1 105.9 Example 2 99.1 Example 3 98.2 Example 4 95.9 Comparative Example 1 69.5 Comparative Example 2 51.8 Comparative Example 3 92.1 Comparative Example 4 70.0

[0091] Table 3

[0092] Sample Contact angle 2 (°) Example 1 103.7 Example 2 102.5 Example 3 100.2 Example 4 100.9 Comparative Example 1 79.7 Comparative Example 2 22.3 Comparative Example 3 98.1 Comparative Example 4 52.2

[0093] As can be seen from Tables 2 and 3, the water lock releasing chemical agents provided by Examples 1 to 4 can regulate the surface of a strong water-wet substrate to neutral wetness. In particular, as can be seen from the comparison between Example 1 and Comparative Examples 1 to 2, the combination of an anionic fluorinated surfactant and a zwitterionic surfactant can exhibit a synergistic effect due to the interaction between the components, and can exhibit a wetness regulating performance that is significantly better than that of a single chemical agent.

[0094] The water lock releasing chemical agents prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were diluted to an effective concentration of 0.1 w.t.%, and the viscosity was tested according to GB / T 22235-2008, and the results are shown in Table 4.

[0095] Table 4

[0096] Sample Viscosity (mPa-s) Example 1 0.89 Example 2 0.88 Example 3 0.95 Example 4 0.91 Comparative Example 1 0.92 Comparative Example 2 0.93 Comparative Example 3 1.08 Comparative Example 4 1.02

[0097] In summary, the lower the surface tension, the easier it is for the water lock to be removed from the capillary channels caused by damage; the more neutral the wettability of the formation, the less likely it is for fluids such as water and condensate to adhere to the surface of the formation substrate, thereby causing the water lock damage to be removed as soon as possible; the lower the viscosity of the fluid, the faster the water lock damage is removed. The viscosity of the water lock releasing chemical agents prepared in Examples 1 to 4 diluted to 0.1 w.t.% is 0.89 mPa·s to 0.95 mPa·s, which is lower than that of Comparative Examples 3 and 4 (1.08 mPa·s and 1.02 mPa·s, respectively), and the fluid has a lower viscosity and a faster liquid removal rate.

[0098] The water lock releasing chemical agents prepared in Examples 1 to 4 have a synergistic effect due to the interaction between the components, can significantly reduce the surface tension of water to less than 20 mN / m, can regulate the surface of a strong water-wet substrate to neutral wetness, and can promote the removal of the blocking fluid in the formation; the apparent viscosity of the entire system is low, which can improve the flowability of the damage-causing fluid and further promote the removal of the water lock; and the anionic fluorinated surfactant and the zwitterionic surfactant used in the present application are conventional industrial surfactants, have a low cost, have good temperature resistance and salt resistance, have better stability, and are conducive to use and promotion in practice.

Claims

1. A chemical agent for dewatering oil and gas reservoirs, comprising anionic fluorinated surfactants, amphoteric surfactants, and synergistic agents; Assuming the total weight of water-locking chemicals in oil and gas reservoirs is 100%, Anionic fluorinated surfactants: 1-40%; Amphoteric surfactants: 1-40%; Synergistic additives: 0.5-20%; The anionic fluorosurfactant is at least one of fluoroalkyl polyether salts and fluoroalkyl polyether ester salts; the structural formula of the anionic fluorosurfactant is: (I) in, R is C1~C 20 Alkylene, substituted C1~C 20 At least one of the alkylene groups; n is an integer between 1 and 20; x and y are each independently selected from any integer from 2 to 40; X is selected from one of —COOM, —SO3M, —OSO3M, and —OPO3M2, where M is a cation with a balanced charge; The zwitterionic surfactant is R'3NCHC a H 2a+1 COOY, C b H 2b+1 R'2NR''COOY、C c H 2c+1 At least one of R'2NR''SO3Y; wherein R' is a C1-8 alkyl and / or substituted alkyl; R'' is a C1-10 alkylene or substituted alkylene; Y is a cation with balanced charge; a, b, and c are each independently selected from integers from 1 to 30; The synergistic agent is at least one of urea, formamide, N-methylacetamide, and guanidine salt.

2. The oil and gas reservoir water-lock breaking chemical agent as described in claim 1, characterized in that: Based on the total weight of the reservoir water-lock breaking chemicals as 100%, the reservoir water-lock breaking chemicals include: Anionic fluorinated surfactants: 5-20%; Amphoteric surfactants: 5-30%; Synergistic additives: 1-10%.

3. The oil and gas reservoir water-lock breaking chemical agent as described in claim 1, characterized in that: In formula (I), R is at least one of C1-C6 alkylene or substituted C1-C6 alkylene; n is an integer between 4 and 12; x and y are each independently selected from any integer from 2 to 20; M is Na + K + or NH4 + .

4. The oil and gas reservoir water-lock breaking chemical agent as described in claim 3, characterized in that: x and y are each independently selected from any integers between 8 and 20.

5. The oil and gas reservoir water-lock breaking chemical agent as described in claim 1, characterized in that: The amphoteric surfactant Y is Na. + K + or NH4 + .

6. The oil and gas reservoir water-lock breaking chemical agent as described in claim 5, characterized in that: The zwitterionic surfactant is (CH3)3NCHC 12 H 25 COOK, C 16 H 33 (CH3)2NCH2COONa, C 14 H 29 N(CH3)2C2H4SO3Na、C8H 17 At least one of N(CH3)2CH2CH(OH)CH2SO3Na.

7. The oil and gas reservoir water-lock breaking chemical agent as described in claim 1, characterized in that: The oil and gas reservoir water-lock-breaking chemical agent also includes a solvent, with the solvent amount being the remainder.

8. The oil and gas reservoir water-lock breaking chemical agent as described in claim 7, characterized in that: The solvent is at least one of water and small molecule organic solvents.

9. The oil and gas reservoir water-lock breaking chemical agent as described in claim 8, characterized in that: The water is at least one of deionized water and water containing inorganic minerals; and / or, The small molecule organic solvent is at least one of small molecule alcohols, small molecule ethers, small molecule aldehydes, small molecule ketones, small molecule amines, and small molecule alcoholamines.

10. The oil and gas reservoir water-lock breaking chemical agent as described in claim 9, characterized in that: The water containing inorganic minerals is at least one of tap water, river water, lake water, and formation water from oil and gas fields; and / or, The small molecule alcohol is at least one selected from C1-C6 monohydric alcohols, C2-C6 dihydric alcohols, and C3-C6 polyhydric alcohols; and / or, The small molecule ether is at least one of C1 to C6 monomethyl ethers.

11. The oil and gas reservoir water-lock breaking chemical agent as described in claim 10, characterized in that: The small molecule alcohol is at least one selected from C1-C3 monohydric alcohols, C2-C3 dihydric alcohols, and glycerol; and / or, The small molecule ether is at least one of methyl ether, methyl vinyl ether, methyl ethyl ether, ethylene glycol methyl ether, ethyl vinyl ether, and ethyl ether.

12. The oil and gas reservoir water-lock breaking chemical agent as described in claim 8, characterized in that: When the solvent is water and a small molecule organic solvent, the mass ratio of the small molecule organic solvent to water is (0~10):

10.

13. The oil and gas reservoir water-lock breaking chemical agent as described in claim 12, characterized in that: The mass ratio of the small molecule organic solvent to water is (1~10):

10.

14. A method for preparing a water-lock breaking chemical agent for oil and gas reservoirs as described in any one of claims 1 to 13, the method comprising the following steps: The anionic fluorinated surfactant, the amphoteric surfactant, and a portion of the solvent are mixed and dissolved; then the synergist and the remaining solvent are added, and the mixture is stirred and mixed evenly to obtain the oil and gas reservoir water-lock breaking chemical agent.

15. The method for preparing the water-locking chemical agent for oil and gas reservoirs as described in claim 14, characterized in that: The initial portion of the solvent accounts for 50-100% of the total solvent mass, while the remaining solvent accounts for 0-50% of the total solvent mass.

16. The application of a water-lock-removing chemical agent for oil and gas reservoirs as described in any one of claims 1 to 13 in the removal of water-lock damage in oil and gas reservoirs.

17. The application as described in claim 16 in relieving water-lock damage in oil and gas reservoirs, characterized in that: The oil and gas reservoir dewatering chemical agent is diluted with water to a mass concentration of 0.001% to 10%, based on the sum of the mass fractions of anionic fluorinated surfactants, amphoteric surfactants, and synergistic agents.

18. The application as described in claim 17 in relieving water-lock damage in oil and gas reservoirs, characterized in that: The oil and gas reservoir dewatering chemical agent is diluted with water to a mass concentration of 0.01% to 2%, based on the sum of the mass fractions of anionic fluorinated surfactants, amphoteric surfactants, and synergistic agents.

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