Flexible sealant for oil and gas well as well as preparation method and application of flexible sealant

Abstract

The invention provides a flexible sealant for oil and gas wells and a preparation method and application thereof, and belongs to the technical field of treating agents for oil and gas wells, the flexible sealant for oil and gas wells comprises the following raw materials by weight: 100 parts of modified nitrile latex, 1-5 parts of an activator, 5-20 parts of a terminator, and 1-2 parts of a stabilizer. The flexible sealant for the oil and gas well is stable in performance, resistant to temperature, high in pressure resistance and capable of meeting the plugging requirement of the oil and gas well.

Description

Technical Field

[0001] The present invention relates to the technical field of treatment agents for oil and gas wells, and in particular to a flexible sealant for oil and gas wells, a preparation method thereof, and an application thereof. Background Art

[0002] Well leakage is a process in which a large amount of oil and gas resources leak from pipeline cracks during the exploitation of oil and gas, and it is a problem often encountered in downhole operations. The leakage of oil and gas pipelines will waste oil and gas resources, cause a large amount of economic losses, and the plugging work of oil wells also requires a lot of time to complete, resulting in unnecessary waste. The downhole environment around the oil pipe is complex, containing substances such as crude oil, groundwater, sand and gravel, acids, alkalis, high molecular polymers, drilling fluids, wax, etc. The working conditions are high temperature and high pressure, and the wear and corrosion are very serious. The leakage of oil wells will cause crude oil to leak into the formation under the action of pressure difference. The occurrence of this phenomenon will not only bring great difficulties to the exploration and development of oil and gas resources, but may even lead to more serious hazards, endangering people's lives and property, and also damaging the local environmental quality, etc. The complexity of the well leakage problem has always been a major engineering and technical problem that plagues oil exploration and development at home and abroad and has not been completely solved so far.

[0003] The treatment of well leakage has always been a difficult problem in oil and gas exploitation, especially the well leakage problem of complex underground oil wells is more serious and needs to be solved as soon as possible. When encountering karst, fractured, and fissured complex geological layers, serious oil and gas leakage is very likely to occur, a large amount of oil and gas resources are lost from the cracks, and the oil and gas production efficiency is low. Using traditional plugging agents for plugging has very poor effects, and a large amount of plugging materials are wasted, costing a huge amount. According to past plugging experience, the plugging problems of fractured, porous formations and highly permeable geological formations are the most difficult to handle. At present, the production of most oil and gas fields has entered the middle and late stages. Due to long-term overexploitation, a large amount of vacuum has been formed underground, and the pressure of the oil and gas layers has changed greatly. Some oil layers are depleted. Due to a large amount of water injection, the formation pressure has increased, and high pressure has been formed after long-term accumulation, and in severe cases, it will even exceed the upper layer pressure. Coupled with the aging of the oil pipes over the years, well leakage accidents are very likely to occur.

[0004] Traditional repair methods mainly focus on mechanical repair and chemical plugging. Mechanical repair includes rig operation, remote control vehicle operation, and rerouting of leakage circuits, etc. Mechanical repair is time-consuming and laborious, and at the same time, the repair cost is high; while chemical plugging mainly uses cement slurry plugging, bridging material plugging, and compound plugging. Cement slurry plugging requires clear leakage electricity. Bridging material plugging can only plug the leakage points with large cracks, while the compound has a large molecular weight, poor rheology, strong viscosity, and is not easy to be squeezed into small spaces such as screw threads. At the same time, it will solidify at positions where plugging is not required, resulting in problems such as cumbersome subsequent cleaning processes.

[0005] Traditional sealants only seal leaks by blocking the leak points with particulate matter. The differential pressure-activated sealant works through a completely different process. The reaction of the sealant is similar to blood coagulation in a wound. The differential pressure-activated sealant remains in a fluid state in any hydraulic system. When the sealant passes through the leakage site, under the action of the pressure difference, the sealant reacts and quickly seals the leak point. A large number of tests have proven that the sealant does not damage the original equipment in the gas well.

[0006] At present, the differential pressure-activated sealants mainly consist of rubber latex, nitrile latex, vulcanized latex, and polymer latex. However, the above products have poor heat resistance and will age and deteriorate at high temperatures. Some products also have poor oil resistance and a short service life in the oil pipe, making them unsuitable for use in plugging leaks in oil and gas wells. Summary of the Invention

[0007] One of the purposes of the present invention is to provide a flexible sealant for oil and gas wells. By using specific oil-resistant and heat-resistant latex materials, a flexible sealant with strong sealing performance, high temperature resistance, good thermal stability, strong compressive capacity, and good rheology is obtained to meet the needs of plugging oil and gas wells.

[0008] Another purpose of the present invention is to provide a preparation method of the flexible sealant for oil and gas wells.

[0009] The third purpose of the present invention is to provide an application of the flexible sealant for oil and gas wells.

[0010] In order to achieve the above purposes of the present invention, the following technical solutions are specifically adopted:

[0011] In the first aspect, the present invention provides a flexible sealant for oil and gas wells, which comprises the following raw materials in parts by weight: 100 parts of modified nitrile latex, 1 - 5 parts (preferably 2 parts) of activator, 5 - 20 parts (preferably 5 parts) of terminator, and 1 - 2 parts (preferably 1 part) of stabilizer.

[0012] The following is a detailed description of each part:

[0013] Modified nitrile latex:

[0014] The modified nitrile latex is at least one selected from hydrogenated nitrile latex, sulfonated nitrile latex, and oxidized nitrile latex.

[0015] The addition amount of the modified nitrile latex is 100 parts by weight.

[0016] Activator:

[0017] The activator is at least one selected from inorganic salt aqueous solutions and organic salt aqueous solutions.

[0018] There is no specific limitation on the inorganic salts, which can be inorganic salts known in the art, such as magnesium sulfate, sodium chloride, etc., but not limited thereto.

[0019] There is no specific limitation on the organic salts, which can be organic salts known in the art, such as sodium acetate, sodium acetate, etc., but not limited thereto.

[0020] Preferably, the mass concentration of the inorganic salt aqueous solution is 0.1%-1%;

[0021] Preferably, the mass concentration of the organic salt aqueous solution is 1%-2%.

[0022] The addition amount of the activator is 1-5 parts by weight, such as 1, 2, 3, 4, 5 parts by weight, but not limited thereto.

[0023] Terminator:

[0024] The terminator is an aqueous solution of a non-ionic surfactant, and the non-ionic surfactant is preferably a non-ionic surfactant of the OP series or the SP series.

[0025] Exemplary OP series non-ionic surfactants may include OP-4, OP-7, OP-9, OP-10, OP-13, OP-15, OP-20, OP-30, OP-40, OP-50, etc., but not limited thereto.

[0026] Exemplary SP series non-ionic surfactants may include SP-20, SP-20, SP60, SP-80, etc., but not limited thereto.

[0027] Preferably, the mass concentration of the aqueous solution of the OP series non-ionic surfactant is 0.2%-1%;

[0028] Preferably, the mass concentration of the aqueous solution of the SP series non-ionic surfactant is 0.1%-0.5%.

[0029] The addition amount of the terminator is 5-20 parts by weight, such as 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20 parts by weight, but not limited thereto.

[0030] Stabilizer:

[0031] The stabilizer is a high molecular polymer, preferably at least one selected from PAM (polyacrylamide), K-PAM (potassium polyacrylate), CMC (sodium carboxymethyl cellulose), XC (xanthan gum), AMMA (acrylonitrile / methyl methacrylate copolymer), MBS (methyl methacrylate, butadiene, styrene terpolymer).

[0032] The addition amount of the stabilizer is 1-2 parts by weight, such as 1, 1.5, 2 parts by weight, but not limited thereto.

[0033] In a second aspect, the present invention provides a method for preparing the above flexible sealant for oil and gas wells, comprising the following steps:

[0034] (1) Using the modified nitrile latex as the continuous phase, adding the activator thereto and stirring;

[0035] (2) Adding the terminator to the obtained continuous phase and stirring;

[0036] (3) Adding the stabilizer to the obtained continuous phase and stirring to obtain a flexible sealant for oil and gas wells.

[0037] The present invention uses modified nitrile latex as a functional monomer, an inorganic salt solution or an organic salt aqueous solution as an initiator, a nonionic surfactant aqueous solution as a terminator, and a high molecular polymer as a stabilizer, and is synthesized by a stepwise synthesis method.

[0038] The definitions of the modified nitrile latex, the activator, the terminator, and the stabilizer are the same as those described above.

[0039] In some embodiments, in step (1), the addition rate of the activator is less than or equal to 3 g / min; and / or

[0040] The stirring time is greater than or equal to 20 min.

[0041] In some embodiments, in step (2), the addition rate of the terminator is less than or equal to 3 g / min; and / or

[0042] The stirring time is greater than or equal to 30 min.

[0043] In some embodiments, in step (3), the addition rate of the stabilizer is less than or equal to 3 g / min; and / or

[0044] The stirring time is greater than or equal to 30 min.

[0045] In some embodiments, the activator is prepared by dissolving an inorganic salt or an organic salt in water, and the stirring time during the preparation process is greater than or equal to 5 min; the stirring time during the preparation process of the organic salt solution is greater than or equal to 10 min.

[0046] In some embodiments, the terminator is prepared by dissolving a nonionic surfactant in water, and the stirring time during the preparation process is greater than or equal to 10 min.

[0047] In some embodiments, the stabilizer is a high molecular polymer, and the stirring time during the preparation process is greater than or equal to 30 min.

[0048] In a specific embodiment, the method for preparing the flexible sealant for oil and gas wells comprises the following steps:

[0049] Under stirring conditions, an inorganic salt aqueous solution or an organic salt aqueous solution is added to the hydrogenated nitrile rubber latex at a rate of 3 g / min, and stirred at a speed of 600 r / min for 20 min;

[0050] Under stirring conditions, an aqueous solution of a non-ionic surfactant is added to the above continuous phase at a rate of 3 g / min, and stirred at a speed of 600 r / min for 30 min;

[0051] Under stirring conditions, a stabilizer is added to the above continuous phase at a rate of 3 g / min, and stirred at a speed of 1000 r / min for 30 min; the target product is obtained.

[0052] In a third aspect, the present invention provides an application of the flexible sealant for oil and gas wells in well leakage repair.

[0053] The sealant can initiate a polymerization reaction under pressure difference to polymerize the originally liquid sealant into a flexible solid sealing material.

[0054] Beneficial effects

[0055] 1. The synthesis method of the present invention is simple, the number of required compounds for synthesis is small, the price is low, and it is easy to produce;

[0056] 2. The flexible sealant for oil and gas wells provided by the present invention has stable performance, strong oil resistance, temperature resistance and pressure resistance, and can meet the requirements of oil and gas well plugging;

[0057] 3. The flexible sealant for oil and gas wells provided by the present invention has good sealing effect, simple operating conditions, and ensures the use temperature range: 0 - 100 °C, viscosity less than 10 mPa·s, the bearing pressure strength after the sealant is cured is 35 MPa, and the pressure drop within 30 min ≤ 0.5 MPa.

[0058] The present invention has been described in detail above, but the above embodiments are essentially illustrative only and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the foregoing prior art or the content of the invention or the following examples. Description of the drawings

[0059] Figure 1 Shows the particle size distribution diagrams of Examples 1 - 8;

[0060] Figure 2 Shows the particle size distribution diagrams of Examples 9 - 16;

[0061] Figure 3 Shows the particle size distribution diagrams of Comparative Examples 1 - 8;

[0062] Figure 4 Shows the schematic diagram of the seal effect verification test of Examples 1 - 8;

[0063] Figure 5 Shows a physical picture of the sealant before curing in the comparative example;

[0064] Figure 6 Shows a physical picture of the sealant before curing in the example;

[0065] Figure 7 Shows a physical picture of the sealant after curing in the example;

[0066] Figure 8 Shows a physical picture of the casing head;

[0067] Figure 9 Shows a physical picture of the removed casing head. Detailed implementation manners

[0068] The present invention will be further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

[0069] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are all conventional raw materials, reagents, and methods in the art.

[0070] The raw materials involved in the examples and comparative examples are as follows:

[0071] Hydrogenated nitrile latex is purchased from Shanghai Yuanxiang Industry Co., Ltd.;

[0072] OP-10 and SP-80 are purchased from Hai'an Petrochemical Factory, Jiangsu Province;

[0073] XC stabilizer is purchased from Ordos Zhongxuan Biochemical Co., Ltd.

[0074] Examples 1-8 Preparation of flexible sealant for oil and gas wells

[0075] A flexible sealant for oil and gas wells, comprising the following components in parts by weight: 100 parts of hydrogenated nitrile latex, 2 parts of activator, 5 parts of terminator, and 1 part of XC stabilizer.

[0076] The specific situations of the activators and terminators used in each example are shown in Table 1.

[0077] Table 1

[0078] Serial number Activator Terminator Example 1 (1#) Magnesium sulfate aqueous solution (concentration: 0.5%) OP-10 (concentration: 0.2%) Example 2 (2#) Magnesium sulfate aqueous solution (concentration: 0.5%) OP-10 (concentration: 1%) Example 3 (3#) Magnesium sulfate aqueous solution (concentration: 0.5%) SP-80 (concentration: 0.1%) Example 4 (4#) Magnesium sulfate aqueous solution (concentration: 0.5%) SP-80 (concentration: 0.5%) Example 5 (5#) Magnesium sulfate aqueous solution (concentration: 1%) OP-10 (concentration: 0.2%) Example 6 (6#) Magnesium sulfate aqueous solution (concentration: 1%) OP-10 (concentration: 1%) Example 7 (7#) Magnesium sulfate aqueous solution (concentration: 1%) SP-80 (concentration: 0.1%) Example 8 (8#) Magnesium sulfate aqueous solution (concentration: 1%) SP-80 (concentration: 0.5%)

[0079] Preparation method:

[0080] Under stirring conditions, 2 g of magnesium sulfate aqueous solution was added to 100 g of hydrogenated nitrile latex at a rate of 3 g / min, and stirred at a speed of 600 r / min for 20 min;

[0081] Under stirring conditions, 5 g of terminator was added to the above continuous phase at a rate of 3 g / min, and stirred at 600 r / min for 30 min;

[0082] Under stirring conditions, 1 g of XC stabilizer was added to the above continuous phase at a rate of 3 g / min, and stirred at 1000 r / min for 30 min; the target product was obtained.

[0083] Examples 9 and 10

[0084] The difference between Example 9 (9#) and Example 1 is that the hydrogenated nitrile latex is replaced by oxidized nitrile latex.

[0085] The difference between Example 10 (10#) and Example 7 is that the hydrogenated nitrile latex is replaced by oxidized nitrile latex.

[0086] Examples 11 and 12

[0087] The difference between Example 11 (11#) and Example 1 is that the hydrogenated nitrile latex is replaced by sulfonated nitrile latex.

[0088] The difference between Example 12 (12#) and Example 7 is that the hydrogenated nitrile latex is replaced by sulfonated nitrile latex.

[0089] Examples 13 and 14

[0090] The difference between Example 13 (13#) and Example 1 is that the activator used is an aqueous solution of sodium acetate.

[0091] The difference between Example 14 (14#) and Example 7 is that the activator used is an aqueous solution of sodium acetate.

[0092] Serial number Activator Terminator Example 13 Sodium acetate aqueous solution (concentration: 1%) OP-10 (concentration: 0.2%) Example 14 Sodium acetate aqueous solution (concentration: 2%) SP-80 (concentration: 0.1%)

[0093] Examples 15 and 16

[0094] The difference between Example 15 (15#) and Example 1 is that the stabilizer used is CMC.

[0095] The difference between Example 16 (16#) and Example 7 is that the stabilizer used is CMC.

[0096] Comparative Examples 1-8

[0097] The difference between Comparative Examples 1-4 and Example 1 is that the addition rate of the activator was changed, and 2 g of aqueous magnesium sulfate solution was added to 100 g of hydrogenated nitrile latex at different addition rates, and stirred at 600 r / min for 20 min.

[0098]

[0099]

[0100] The differences between Comparative Examples 5-8 and Example 7 lie in that the addition rate of the activator is changed, and 2 g of magnesium sulfate aqueous solution is added to 100 g of hydrogenated nitrile rubber latex at different addition rates, and stirred at a speed of 600 r / min for 20 min.

[0101]

[0102] Comparative Examples 9, 10

[0103] The difference between Comparative Example 9 (Comparison 9#) and Example 1 is that the hydrogenated nitrile rubber latex is replaced with nitrile rubber latex.

[0104] The difference between Comparative Example 10 (Comparison 10#) and Example 7 is that the hydrogenated nitrile rubber latex is replaced with nitrile rubber latex.

[0105] Performance evaluation

[0106] I. Particle Size Distribution Evaluation

[0107] The particle size distribution was observed by a microscope, and its particle size distribution was measured with a Malvern laser particle size analyzer and statistically analyzed. The statistical results are shown in Table 2, Figure 1 , Figure 2 , Figure 3 as shown.

[0108] Table 2 Statistical Table of Particle Size Distribution of Different Formulations

[0109]

[0110]

[0111] 9# 10# 11# 12# 13# 14# 15# 16# < 100μm 2％ 11％ 2％ 12％ 4％ 15％ 6％ 10％ 100 - 300μm 4％ 16％ 6％ 18％ 8％ 18％ 9％ 18％ 300 - 500μm 10％ 20％ 12％ 20％ 15％ 19％ 16％ 16％ 500 - 800μm 18％ 22％ 20％ 25％ 22％ 22％ 25％ 23％ 800 - 1000μm 21％ 17％ 22％ 20％ 23％ 25％ 20％ 22％ > 1000μm 45％ 14％ 38％ 5％ 28％ 1％ 24％ 11％

[0112]

[0113] Experimental Results:

[0114] Examples 9# and 10# show that the particle size distributions of oxidized nitrile and hydrogenated nitrile are similar;

[0115] Examples 11# and 12# show that the particle size distributions of sulfonated nitrile and hydrogenated nitrile are similar;

[0116] Examples 13# and 14# show that the particles produced are smaller when sodium acetate is used as the activator than when magnesium sulfate is used as the activator;

[0117] Examples 15# and 16# show that the particle size distributions are similar when CMC is used as the stabilizer and XC is used as the stabilizer.

[0118] Comparative Examples 1-8 show that by changing the addition rate, the system demulsifies and solidifies within a short time. As the addition rate increases, the proportion of the part with a particle size > 1000 μm increases (as Figure 3 shown), and after increasing the stirring rate, the system quickly demulsifies and a uniformly dispersed emulsion cannot be formed.

[0119] II. Verification of the Sealing Effect of the Sealant

[0120] Before sealing, turn on the vacuum pump. The 40-mesh sieve can freely pass clear water, and the clear water flows out in a stream with a large flow rate. The pressure of the vacuum pump is 0 MPa. After pouring the prepared flexible sealant into the Buchner funnel, the flow rate decreases with time. After 5 minutes, dripping starts, with a speed of 1 drop per 45 s. After half an hour, dripping stops, and the pressure of the vacuum pump stabilizes at the maximum negative pressure of -0.1 MPa, indicating that the sieve is completely sealed at this pressure, as Figure 4 shown.

[0121] Figure 6 、 Figure 7 are the physical pictures of the sealant before sealing and the seal removed after sealing. It shows that the prepared sealant can aggregate to form a seal under a pressure difference and effectively seal the leakage point.

[0122] However, Comparative Examples 1-8 have completely solidified and cannot be operated, as Figure 5 shown.

[0123] III. Verification of the Tooling Effect

[0124] The casing head tooling experiment was carried out (the physical picture of the casing head is as Figure 8 shown), and the test process is as follows:

[0125] (1) Manually create a crack of 1 mm (manually create a 1-mm-wide through scratch on the sealing rubber ring);

[0126] (2) Test the leakage rate of clear water, apply a pressure of 35 MPa, and measure the pressure drop for 30 min / 12 h;

[0127] (3) Plug the agent for plugging. After adding the plugging agent, apply a pressure of 35 MPa and hold the pressure for more than 12 h, and record the pressure drop value;

[0128] (4) Test the pressure of the plugging agent. Raise the pressure to 35 MPa and measure the pressure drop for 30 min / 12 h;

[0129] (5) Test the pressure of clear water. Raise the pressure to 35 MPa and measure the pressure drop for 30 min / 12 h.

[0130] The results are shown in Table 3.

[0131] Table 3 Statistics of the Plugging Effects of Different Formulations

[0132]

[0133]

[0134] The experimental results show that the flexible sealant can form an elastic plugging layer at the leakage point (as Figure 9 shown), and the flexible sealant has an obvious sealing effect on the casing head leakage and has good pressure-bearing capacity.

[0135] IV. Temperature resistance of the system

[0136] The temperature resistance test of the sealant product was carried out using a high-temperature aging tank, and the test results are shown in Table 4.

[0137] Table 4 Temperature resistance test results of flexible sealants with different formulations

[0138]

[0139]

[0140] It can be seen from the results that when the temperature is below 100 °C, the product will not undergo instability solidification reaction; for some samples, when the temperature is between 100 and 120 °C, the product shows a reaction but still has good fluidity; for some samples, when the temperature reaches 120 °C, reactions occur between the colloidal particles in the system and large particles appear.

[0141] It can be seen from Comparative Examples 9-10 that if modified nitrile is not used, the temperature resistance is about 25 °C. At 40 °C, large particles appear, but it still has fluidity. At 50 °C, it has solidified and the surface is dark yellow and cannot be used.

[0142] V. Temperature resistance of the plugging layer

[0143] The heat-resistant aging performance of the formed plugging layer also determines the sealing duration of channeling prevention. Materials with good temperature resistance can maintain the long-term sealing of the channeling point. In the experiment, samples of the formed plugging layer were taken for heat aging test. The test shows that the color of the sample becomes slightly darker after aging at 120 °C for 72 h, but it still has good elasticity. After aging at 130 °C for a short time, the sample is dark yellow and only maintains a small amount of elasticity.

[0144] The evaluation results of the performance of the differential pressure-activated sealant show that the sealant has the ability of differential pressure activation. The results of the high-pressure plugging test show that a sealing layer can be formed at the leakage points of damaged Φ6 screw threads and slits less than 0.5 mm, and this sealing layer can withstand a differential pressure of 35 MPa. When the temperature is below 100 °C, the product will not undergo instability solidification reaction; when the temperature reaches 120 °C, some products show reactions, but still have good fluidity; when the temperature reaches 120 °C, reactions occur between the rubber particles in some product systems, and large particles appear. The color of the formed sealing layer sample becomes slightly darker after aging at 120 °C for 72 h, but still has good elasticity, while the elasticity becomes poor after aging at 130 °C for a short time.

[0145] 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 foregoing embodiments, those of ordinary skill in the art should understand that: within the scope of the spirit and essence defined by the claims of the present invention, the technical solutions described in the foregoing embodiments can be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A flexible sealant for oil and gas wells, characterized in that, The flexible sealant for oil and gas wells comprises the following raw materials in parts by weight: 100 parts of modified nitrile latex, 1-5 parts of activator, 5-20 parts of terminator, and 1-2 parts of stabilizer.

2. The flexible sealant for oil and gas wells according to claim 1, characterized in that, The modified nitrile latex is at least one selected from hydrogenated nitrile latex, sulfonated nitrile latex, and oxidized nitrile latex.

3. The flexible sealant for oil and gas wells according to claim 1, characterized in that, The activator is at least one selected from aqueous inorganic salt solutions and aqueous organic salt solutions.

4. The flexible sealant for oil and gas wells according to claim 3, characterized in that, The inorganic salt is at least one selected from magnesium sulfate and sodium chloride; The organic salt is at least one selected from sodium acetate and sodium acetate; Preferably, the mass concentration of the aqueous inorganic salt solution is 0.1%-1%; Preferably, the mass concentration of the aqueous organic salt solution is 1%-2%.

5. The flexible sealant for oil and gas wells according to claim 1, characterized in that, The terminator is an aqueous solution of a non-ionic surfactant, and the non-ionic surfactant is preferably a non-ionic surfactant of the OP series or the SP series.

6. The flexible sealant for oil and gas wells according to claim 5, characterized in that, The non-ionic surfactant of the OP series is at least one selected from OP-4, OP-7, OP-9, OP-10, OP-13, OP-15, OP-20, OP-30, OP-40, and OP-50; The non-ionic surfactant of the SP series is at least one selected from SP-20, SP-20, SP60, and SP-80; Preferably, the mass concentration of the aqueous solution of the non-ionic surfactant of the OP series is 0.2%-1%; Preferably, the mass concentration of the aqueous solution of the non-ionic surfactant of the SP series is 0.1%-0.5%.

7. The flexible sealant for oil and gas wells according to claim 1, characterized in that, The stabilizer is a polymer, preferably at least one selected from PAM, K-PAM, CMC, XC, AMMA, and MBS.

8. A preparation method of the flexible sealant for oil and gas wells according to any one of claims 1 - 7, characterized in that, It includes the following steps: (1) Using the modified nitrile latex as the continuous phase, adding the activator and stirring; (2) Adding the terminator to the obtained continuous phase and stirring; (3) Adding the stabilizer to the obtained continuous phase and stirring to obtain the flexible sealant for oil and gas wells.

9. The preparation method according to claim 8, characterized in that, In step (1), the addition rate of the activator is less than or equal to 3 g / min; the stirring time is greater than or equal to 20 min; and / or In step (2), the addition rate of the terminator is less than or equal to 3 g / min; the stirring time is greater than or equal to 30 min; and / or In step (3), the addition rate of the stabilizer is less than or equal to 3 g / min; the stirring time is greater than or equal to 30 min.

10. Application of the flexible sealant for oil and gas wells according to any one of claims 1 - 7 in well leakage repair.

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