Temperature-resistant adhesive type supramolecular polymer gel plugging particle and preparation method and application thereof

Abstract

The application provides a temperature-resistant adhesion type supramolecular polymer gel plugging particle and a preparation method and application thereof, and belongs to the technical field of oil field chemicals. The temperature-resistant adhesion type supramolecular polymer gel plugging particle is prepared from the following raw materials in a mass percentage: 5-10% of a high molecular polymer, 10-20% of a methyl-containing organic compound, 1-5% of a natural high molecular material, 0.1-1% of a phenyl-containing compound, 1-5% of inorganic particles, 0.1-1% of an initiator, and the balance of water. The application introduces a bonding functional monomer with strong adhesion performance into the polymer gel, and cooperates with various temperature-resistant functional groups and various non-covalent bond interactions, so that the temperature resistance, strength and wall adhesion capacity of the polymer gel particle are improved. The obtained supramolecular polymer gel plugging particle is high in temperature resistance, high in strength, high in adhesion and capable of effectively plugging a fractured formation.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of temperature-resistant adhesive type supramolecular polymer gel plugging particles and its preparation method and application, belong to oilfield chemical technical field. BACKGROUND

[0002] With the sustained growth of demand for oil and gas, conventional oil and gas resources have been difficult to meet demand, shale oil and gas, tight oil and gas, coalbed methane and other unconventional oil and gas resources gradually into large-scale development stage, become effective supplement of conventional oil and gas resources.But unconventional oil and gas resources exploitation process accompanied by the occurrence of complex situation, among them, the well leakage problem is particularly prominent, seriously inhibit the efficiency and process of oil and gas exploration and development.

[0003] Well leakage refers to the phenomenon that various working fluids are lost to the formation through the loss channel during drilling.Once well leakage occurs, a series of serious consequences will be produced.Firstly, the large loss of drilling fluid increases the operation cost, accompanied by the frequent consumption of plugging materials, which further increases the economic cost.At the same time, well leakage will lead to a significant extension of drilling cycle, seriously affecting the operation progress, causing great waste of resources.More seriously, for oil and gas production layer, the loss of drilling fluid may contaminate the reservoir and block the oil and gas seepage channel, not only reducing the oil and gas production in the later stage, but also causing permanent damage to the reservoir, bringing huge economic losses to oil and gas development.According to the characteristics of the loss channel, well leakage can be divided into three types: porosity leakage, fracture leakage and solution leakage.In actual drilling process, fracture leakage is the most common and most harmful.Fracture leakage may be caused by naturally existing fractures in the formation, or may be induced by new fractures during drilling (excessive drilling fluid pressure).Due to the strong randomness and uncertainty of the distribution of fractures in the formation, the opening and position of the fractures cannot be accurately detected when the leakage occurs.Currently, the field plugging operation mainly relies on engineers to process according to limited data such as the position of the leakage, the leakage rate and the like, combined with past experience.This judgment method often leads to a certain deviation between the estimation of the fracture condition and the actual situation, resulting in low success rate of one-time plugging and repeated leakage.

[0004] The causes of fracture leakage are complex and diverse, which are influenced by the formation rock properties, ground stress distribution and drilling technology and other factors. These problems not only lead to the difficulty in effectively controlling the leakage, but also easily cause a series of downhole complex conditions such as well collapse, pipe sticking, well kick and the like, further increasing the risk and cost of drilling operation. At present, there are many patent literatures about the plugging materials suitable for the fractured leakage formation, for example, the Chinese patent document CN111732941A discloses a supramolecular gel plugging slurry and a preparation method thereof, the plugging slurry adopts polyvalent acrylamide, sodium chloride and inert materials, and the gelation time thereof is 4-8h. The Chinese patent document CN116023914A utilizes partially hydrolyzed polyacrylamide, chitosan, phosphoric acid diamine and other materials to prepare a gel plugging agent. Although these materials can achieve the plugging of the fractures to some extent, in the actual application, the plugging materials generally have the problem of insufficient retention capacity. The contact between the gel entering the leakage channel and the fracture wall surface is not close enough, and the interfacial adhesion is weak, which leads to the limited pressure bearing capacity of the polymer material to the fracture after plugging, and the polymer material is difficult to withstand the scouring and pressure change of the formation fluid, and cannot achieve long-term and effective plugging of the leakage channel.

[0005] In view of the many deficiencies of the existing plugging technology, it is of great significance to develop a polymer gel plugging particle with high temperature resistance, high strength and high adhesion. SUMMARY

[0006] In view of the deficiencies of the prior art, especially in view of the deficiencies of the existing gel plugging material such as insufficient temperature resistance and weak interfacial adhesion, the present application provides a temperature-resistant and adhesive supramolecular polymer gel plugging particle and a preparation method and application thereof. The present application introduces monomers with strong adhesion performance into the polymer gel, and cooperates with various temperature-resistant functional groups and various non-covalent bond interactions, so as to improve the temperature resistance, strength and wall adhesion capacity of the polymer gel particle, thereby obtaining a supramolecular polymer gel plugging particle with high temperature resistance, high strength and strong adhesion, which can effectively plug the fractured formation.

[0007] The technical scheme of the present application is as follows:

[0008] A temperature-resistant and adhesive supramolecular polymer gel plugging particle is prepared from the following raw materials in mass percentage: 5-10% of high molecular polymer, 10-20% of methyl-containing organic compound, 1-5% of natural high molecular material, 0.1-1% of phenyl-containing compound, 1-5% of inorganic particles, 0.1-1% of initiator, and the balance of water.

[0009] According to the application, preferably, the high molecular polymer is one or a combination of two or more of polyvinyl alcohol, hydroxyl-terminated polybutadiene and polyethylene glycol; the polyvinyl alcohol has a weight average molecular weight of 13000-23000, the hydroxyl-terminated polybutadiene has a number average molecular weight of 2700-4600, and the polyethylene glycol is PEG-800, PEG-1000, PEG-1450, PEG-2000, PEG-3000, PEG-4000, PEG-6000 or PEG-8000.

[0010] According to the application, preferably, the methyl-containing organic compound is a combination of one of 5-hydroxymethylfurfural, N-hydroxymethyl acrylamide and 4-(hydroxymethyl)imidazole and N,N-dimethyl acrylamide, and more preferably, a combination of N-hydroxymethyl acrylamide and N,N-dimethyl acrylamide; the mass ratio of the 5-hydroxymethylfurfural, N-hydroxymethyl acrylamide or 4-(hydroxymethyl)imidazole to N,N-dimethyl acrylamide is 1:25-35.

[0011] According to the application, preferably, the natural high molecular material is a mixture of sodium alginate and modified chitosan, and the mass ratio of the sodium alginate to the modified chitosan in the mixture is 1:1-5.

[0012] More preferably, the sodium alginate has a weight average molecular weight of 300000-400000.

[0013] More preferably, the modified chitosan is prepared by the following method:

[0014] (1) adding chitosan into an acidic solution and stirring to obtain solution A;

[0015] (2) adding a modified monomer into a solvent and stirring to obtain solution B;

[0016] (3) adding solution B into solution A to perform a first reaction, then adding a reducing agent to perform a second reaction, and then performing dialysis and freeze-drying to obtain the modified chitosan.

[0017] Preferably, in the preparation of the modified chitosan, the chitosan in step (1) has a weight average molecular weight of 100-200 kDa and a degree of deacetylation of ≥95%, the acidic solution is an aqueous acetic acid solution with a pH of 5, and the volume of the acidic solution to the mass of the chitosan is 40-60 mL:1 g.

[0018] Preferably, in the preparation of the modified chitosan, the modified monomer in step (2) is one or a combination of two of 1,2-dihydroxybenzene and 3,4-dihydroxybenzaldehyde.

[0019] Preferably, in the preparation of the modified chitosan, the solvent in step (2) is a mixed solution of water and methanol, and the volume ratio of water to methanol in the mixed solution is 1:1; the volume ratio of the solvent to the mass of the modifying monomer is 10-20 mL:1 g.

[0020] Preferably, in the preparation of the modified chitosan, the mass ratio of chitosan in solution A to the modifying monomer in solution B in step (3) is 1:1-5.

[0021] Preferably, in the preparation of the modified chitosan, the temperature of the first reaction in step (3) is 30-60℃, and the time of the first reaction is 10-15 h.

[0022] Preferably, in the preparation of the modified chitosan, the reducing agent in step (3) is one or a combination of two or more of sodium borohydride, potassium borohydride, and lithium borohydride; and the mass ratio of the reducing agent to chitosan is 1-3:1.

[0023] Preferably, in the preparation of the modified chitosan, the temperature of the second reaction in step (3) is 30-60℃, and the time of the second reaction is 5-7 h.

[0024] Preferably, in the preparation of the modified chitosan, the dialysis step in step (3) is to add the reaction solution into a dialysis bag and dialyze in deionized water; the molecular weight cut-off of the dialysis bag is 8000-14000 Da, and the dialysis time is 48-72 h; the temperature of the freeze-drying is -70~-50℃, and the time of the freeze-drying is 24-48 h.

[0025] Preferably, according to the present application, the phenyl-containing compound is one or a combination of two or more of 4-vinylaniline, 3-vinylaniline, and sodium p-styrenesulfonate.

[0026] Preferably, according to the present application, the inorganic particles are calcium carbonate.

[0027] Preferably, according to the present application, the initiator is one or a combination of two or more of benzoyl peroxide, lauryl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, ammonium persulfate, and potassium persulfate.

[0028] According to the present application, the preparation method of the temperature-resistant and adhesive supermolecular polymer gel plugging particles comprises the following steps:

[0029] (I) adding the high molecular polymer into water and stirring uniformly to obtain solution a;

[0030] (II) adding the methyl-containing organic compound, the natural high molecular material, the phenyl-containing compound, and the inorganic particles into solution a and stirring uniformly to obtain mixed solution b;

[0031] (III) adding initiator to the mixed solution b and stirring to obtain a gel solution; then, heating and solidifying to obtain a supramolecular polymer gel, drying, crushing to obtain the heat-resistant and adhesive supramolecular polymer gel plugging particle.

[0032] According to the application, preferably, in the preparation of the gel plugging particle, the temperature of the stirring in step (I) is 60-100℃, the stirring time is 1-3h, and the stirring rate is 500-2500r / min; after uniform stirring, the solution a is obtained by natural cooling to room temperature.

[0033] According to the application, preferably, in the preparation of the gel plugging particle, the stirring time in step (II) is 12-24h, and the stirring rate is 1500-2500r / min.

[0034] According to the application, preferably, in the preparation of the gel plugging particle, the stirring time in step (III) is 2-6h, and the stirring rate is 1500-2500r / min.

[0035] According to the application, preferably, in the preparation of the gel plugging particle, the solidifying step in step (III) is: firstly, solidifying at 40-45℃ for 2-3h, then, solidifying at 55-65℃ for 2-3h, and finally, solidifying at 80-100℃ for 2-3h.

[0036] According to the application, preferably, in the preparation of the gel plugging particle, the drying temperature in step (III) is 40-80℃, and the drying time is 24-48h.

[0037] According to the application, in the preparation of the gel plugging particle, the specific particle size of the crushing in step (III) is mainly adjusted according to the site requirement, and is mainly in the range of 10-5000μm.

[0038] According to the application, the heat-resistant and adhesive supramolecular polymer gel plugging particle is used for plugging in the drilling process; preferably, the specific application steps are as follows: the obtained heat-resistant and adhesive supramolecular polymer gel plugging particle is added into the drilling fluid, and is drilled into the stratum, and the mass fraction of the heat-resistant and adhesive supramolecular polymer gel plugging particle in the drilling fluid is 1-15%.

[0039] The technical features and beneficial effects of the application are as follows:

[0040] 1. The supramolecular polymer gel plugging particles of the present invention form a complex and stable multiple supramolecular cross-linked network system. The high molecular polymer contains abundant hydroxyl groups, which are interconnected with the hydroxyl and carboxyl groups in the natural polymer material through intermolecular hydrogen bonds, thereby improving the structural strength. At the same time, the calcium ions produced by the dissolution of the inorganic particles undergo ionic cross-linking reactions with the natural polymer material, enhancing the stability of the network and giving the gel excellent mechanical strength and flexibility. In addition, in terms of improving heat resistance, the methyl groups provided by the methyl organic matter enhance the thermal stability of the system. Phenyl-containing compounds further improve the heat resistance of the gel by virtue of their rigid structure. Compared with traditional plugging materials with a single cross-linking mechanism, the supramolecular polymer gel of the present invention has made breakthroughs in structural integrity, heat resistance and performance stability, significantly expanding its scope of application under complex geological conditions.

[0041] 2. This invention introduces phenolic hydroxyl organic compounds, grafted onto natural polymer materials, to mimic the adhesion mechanism of mussel byssus protein. This binds to functional groups such as ions and hydroxyl groups on the rock surface, thereby tightly adhering the gel to the fracture surface. This property effectively addresses the insufficient retention capacity of traditional inert plugging materials in fractures, significantly enhancing the binding force between the gel particles and the fracture wall. The gel maintains a certain degree of adhesion despite the impact of formation fluids and pressure fluctuations, maintaining the plugging effect, ensuring long-term effectiveness, and reducing the risk of recurrent leaks.

[0042] 3. The present invention crushes the synthesized supramolecular polymer gel into particles and introduces inorganic particles into the system to form a rigid core. By regulating the concentration of inorganic particles, the structural strength of the gel particles can be precisely adjusted to meet the plugging requirements under different working conditions. The use of a pump-while-drilling operation method avoids the disadvantage of requiring the suspension of drilling operations for downhole cross-linked materials, greatly shortens the operation time, and significantly improves drilling efficiency. In terms of cost and production, the raw materials used in the present invention are widely available, low-cost, and the preparation process is simple and controllable, making it easy to achieve large-scale industrial production. This not only reduces the economic cost of plugging operations, but also lays a solid foundation for the widespread application of this technology in the field of oil and gas exploration and development, and has significant economic benefits and practical value.

[0043] 4. The present invention addresses the problem of leakage in fractured formations and provides a high-temperature resistant adhesive supramolecular polymer gel plugging particle. It achieves innovations in cross-linking mechanism, adhesion performance and construction technology, providing a new approach to solving the problem of underground leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the infrared spectrum of the temperature-resistant adhesive supramolecular polymer gel plugging particles prepared in Example 1.

[0045] Figure 2Thermogravimetric analysis diagram of the temperature-resistant adhesive type supramolecular polymer gel plugging particle prepared in Example 1.

[0046] Figure 3 Elastic modulus and loss modulus change diagram of the temperature-resistant adhesive type supramolecular polymer gel plugging particle prepared in Example 1 in Test Example 1 with angular frequency.

[0047] Figure 4 Maximum pressure-bearing capacity curve of the temperature-resistant adhesive type supramolecular polymer gel plugging particle prepared in Example 1 in Test Example 2.

[0048] Figure 5 Sealing strength curve of the temperature-resistant adhesive type supramolecular polymer gel plugging particle prepared in Example 1 in Test Example 2.

[0049] Figure 6 Surface adhesion macroscopic photo of the temperature-resistant adhesive type supramolecular polymer gel plugging particle prepared in Example 1 in Test Example 3 to different materials. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be described in detail below, and the described embodiments are only a part of the embodiments of the present application, not all.

[0051] The weight average molecular weight of the chitosan used in the embodiments is 200 kDa, and the degree of deacetylation is 95%.

[0052] The polyvinyl alcohol used in the embodiments is PVA1792.

[0053] The weight average molecular weight of the sodium alginate used in the embodiments is 360000.

[0054] Example 1

[0055] A temperature-resistant adhesive type supramolecular polymer gel plugging particle is prepared from the following raw materials in mass percentage: 8% of a high molecular polymer, 15.5% of a methyl-containing organic compound, 2% of a natural high molecular material, 0.5% of a phenyl-containing compound, 1.5% of an inorganic particle, 0.1% of an initiator, and the rest is water.

[0056] The high molecular polymer is polyvinyl alcohol.

[0057] The methyl-containing organic compound is a combination of N-hydroxymethyl acrylamide and N,N-dimethyl acrylamide, and the mass ratio of N-hydroxymethyl acrylamide to N,N-dimethyl acrylamide is 1:30.

[0058] The phenyl-containing compound is p-styrenesulfonic acid sodium salt.

[0059] The inorganic particle is calcium carbonate.

[0060] the initiator is potassium persulfate;

[0061] the natural high molecular material is a mixture of sodium alginate and modified chitosan, and the mass ratio of sodium alginate to modified chitosan in the mixture is 1:1;

[0062] The modified chitosan is prepared by the following method:

[0063] (1) First, 2g of chitosan is weighed and added to 100mL of an acetic acid aqueous solution with pH=5, and stirred uniformly at a speed of 1000r / min to obtain solution A;

[0064] (2) 6g of 3,4-dihydroxybenzaldehyde is weighed and placed in a mixed solution of water and methanol (the volume of the mixed solution is 100mL, and the volume ratio of water to methanol in the mixed solution is 1:1), and stirred uniformly to obtain solution B;

[0065] (3) Solution B obtained in step (2) is added to solution A obtained in step (1), and continuously stirred for 12h at 30℃, then 4g of sodium borohydride is added to the obtained reaction solution, and continuously stirred for 6h at 40℃, to obtain a white precipitate, then the obtained reaction solution is added to a dialysis bag with a molecular weight cut-off of 14000Da, and dialyzed in deionized water for 48h, and then freeze-dried at -70℃ for 24h to obtain modified chitosan.

[0066] The preparation method of the temperature-resistant adhesive supermolecular polymer gel plugging particle described above comprises the following steps:

[0067] (I) High molecular polymer is added to water, and stirred at 95℃ and a speed of 500r / min for 2h, and then naturally cooled to room temperature to obtain solution a;

[0068] (II) Methyl-containing organic compounds, natural high molecular materials, phenyl-containing compounds, and inorganic particles are added to solution a, and continuously stirred at a speed of 2000r / min for 24h to obtain mixed solution b;

[0069] (III) An initiator is added to mixed solution b, and continuously stirred at a speed of 1500r / min for 2h to obtain a gel-forming solution; the gel-forming solution is placed in a water bath, and solidified by stepwise heating at 40-60-80℃, with each temperature maintained for 2h, to obtain a supermolecular polymer gel; the obtained gel material is placed in a vacuum drying oven, and dried at 40℃ for 48h, then taken out, crushed, to obtain temperature-resistant adhesive supermolecular polymer gel plugging particles.

[0070] The infrared spectrum of the temperature-resistant adhesive supermolecular polymer gel plugging particle obtained in this example is shown in Figure 1 , which isFigure 1 It can be seen that the wide peak presented at 3200-3700cm -1 is due to OH stretching vibration of high molecular polymer, which contains OH stretching vibration of natural high molecular material, and NH2 and -N-H stretching vibration; the absorption peak at 2870cm -1 is attributed to C-H methyl stretching vibration; the absorption peaks at 1474cm -1 , 1400cm -1 , 1280cm -1 and 840cm -1 correspond to amide I band (C=O stretching vibration), amide II band (N-H deformation vibration and C-N stretching vibration) and amide III band (C=C stretching vibration on benzene ring and C-O stretching vibration on phenolic hydroxyl group), respectively.

[0071] The thermal stability of the temperature-resistant adhesive supramolecular polymer gel plugging particles obtained in the embodiment was characterized by a thermal gravimetric analyzer. The control experiment range was room temperature to 800℃, the heating rate was 5℃ / min, and the test was performed in an N2 environment. The experimental results are shown in Figure 2 In the room temperature to 100℃ range, the particles showed slight thermal weight loss, which was due to the volatilization of a small amount of water contained in the sample. As the temperature continued to rise, the gel system began to decompose at 232℃, at which time the flexible chain segments in the molecular structure began to depolymerize, resulting in a significant increase in the mass loss rate. In the 232℃ to 500℃ temperature range, the gel particle structure showed significant weight loss, indicating that the molecular chain segments were broken in large quantities. In this stage, the mass change rate fluctuated to a certain extent. When the temperature was in the range of 500℃ to 800℃, the sample did not show obvious weight loss, and the mass change rate gradually stabilized. At the end of the experiment, the final residual mass fraction of the sample was 18%. The above results prove that the molecular structure of the supramolecular polymer gel plugging particles obtained in the embodiment can still maintain integrity in a high temperature environment, and has excellent heat resistance.

[0072] Example 2

[0073] A temperature-resistant adhesive supramolecular polymer gel plugging particle was prepared as described in Example 1, except that the content of the methyl-containing organic compound was 11%, and the other conditions and preparation steps were the same as in Example 1.

[0074] Example 3

[0075] A temperature-resistant adhesive supramolecular polymer gel plugging particle was prepared as described in Example 1, except that the content of the phenyl-containing compound was 0.1%, and the other conditions and preparation steps were the same as in Example 1.

[0076] Example 4

[0077] A temperature-resistant adhesive type supramolecular polymer gel plugging particle is as described in Embodiment 1, except that the mass ratio of sodium alginate and modified chitosan in the natural polymer material is 1:3, and other conditions and preparation steps are the same as in Embodiment 1.

[0078] Embodiment 5

[0079] A temperature-resistant adhesive type supramolecular polymer gel plugging particle is as described in Embodiment 1, except that the high molecular polymer is 5%, and other conditions and preparation steps are the same as in Embodiment 1.

[0080] Embodiment 6

[0081] A temperature-resistant adhesive type supramolecular polymer gel plugging particle is as described in Embodiment 1, except that the high molecular polymer is changed to PEG-6000, and other conditions and preparation steps are the same as in Embodiment 1.

[0082] Embodiment 7

[0083] A temperature-resistant adhesive type supramolecular polymer gel plugging particle is as described in Embodiment 1, except that the methyl-containing organic compound is changed to a combination of 5-hydroxymethyl furfural and N, N-dimethyl acrylamide, and other conditions and preparation steps are the same as in Embodiment 1.

[0084] Embodiment 8

[0085] A temperature-resistant adhesive type supramolecular polymer gel plugging particle is as described in Embodiment 1, except that the phenyl-containing compound is changed to 3-vinyl aniline, and other conditions and preparation steps are the same as in Embodiment 1.

[0086] Embodiment 9

[0087] A temperature-resistant adhesive type supramolecular polymer gel plugging particle is as described in Embodiment 1, except that the high molecular polymer is 10%, the methyl-containing organic compound is 20%, the natural polymer material is 5%, the phenyl-containing compound is 1%, the inorganic particles are 5%, the initiator is 1%, and the balance is water, and other conditions and preparation steps are the same as in Embodiment 1.

[0088] Embodiment 10

[0089] A temperature-resistant adhesive type supramolecular polymer gel plugging particle is as described in Embodiment 1, except that the high molecular polymer is 5%, the methyl-containing organic compound is 10%, the natural polymer material is 1%, the phenyl-containing compound is 0.1%, the inorganic particles are 1%, the initiator is 0.1%, and the balance is water, and other conditions and preparation steps are the same as in Embodiment 1.

[0090] Embodiment 11

[0091] A temperature resistant adhesive type supramolecular polymer gel lost circulation control particle as described in Example 1, except that the modified monomer of chitosan is changed to 1,2-dihydroxybenzene, and other conditions and preparation steps are the same as in Example 1.

[0092] Comparative Example 1

[0093] A supramolecular polymer gel lost circulation control particle as described in Example 1, except that no methyl-containing organic compound is added, and the omitted component is replaced with the same amount of water, and other preparation steps and conditions are the same as in Example 1.

[0094] Comparative Example 2

[0095] A supramolecular polymer gel lost circulation control particle as described in Example 1, except that no high molecular polymer is added, and the omitted component is replaced with the same amount of water, and other preparation steps and conditions are the same as in Example 1.

[0096] Comparative Example 3

[0097] A supramolecular polymer gel lost circulation control particle as described in Example 1, except that no natural high molecular material is added, and the omitted component is replaced with the same amount of water, and other preparation steps and conditions are the same as in Example 1.

[0098] Comparative Example 4

[0099] A supramolecular polymer gel lost circulation control particle as described in Example 1, except that the natural high molecular material is only modified chitosan, and other preparation steps and conditions are the same as in Example 1.

[0100] Comparative Example 5

[0101] A supramolecular polymer gel lost circulation control particle as described in Example 1, except that the natural high molecular material is only sodium alginate, and other preparation steps and conditions are the same as in Example 1.

[0102] Comparative Example 6

[0103] A supramolecular polymer gel lost circulation control particle as described in Example 1, except that no phenyl-containing compound is added, and the omitted component is replaced with the same amount of water, and other preparation steps and conditions are the same as in Example 1.

[0104] Comparative Example 7

[0105] A supramolecular polymer gel lost circulation control particle as described in Example 1, except that no inorganic particles are added, and the omitted component is replaced with the same amount of water.

[0106] Test Example 1

[0107] In order to better understand the strength of the gel particles, the supermolecular polymer gels were prepared according to the steps of Examples 1-11 and Comparative Examples 1-7, respectively, and the gels were made into cylinders with a diameter of 30 mm and a thickness of 3 mm. After drying (drying at 40℃ for 48h), the cylinders were placed in a drilling fluid (the drilling fluid formula was 4% bentonite slurry, i.e. the mass ratio of bentonite to water was 4g:100mL) for 1h, and then taken out. The structural strength of the gels was characterized using a rheometer instrument, with a scanning frequency of 1-15Hz and an angular frequency range of 0.1-100rad·s. -1 ,

[0108] The graph of the elastic modulus and the loss modulus of the temperature-resistant adhesive supermolecular polymer gel plugging particles obtained in Example 1 versus the angular frequency is shown in Figure 3 , Figure 3 As can be seen from the graph, as the angular frequency increases, the elastic modulus and the loss modulus of the gel gradually increase. When the angular frequency is 84rad·s -1 , the elastic modulus and the loss modulus reach maximum values of 10981Pa and 4383Pa, respectively, which is mainly due to the crosslinking between multiple molecules in the gel, which enables the gel to maintain high strength under high shear rate.

[0109] The maximum elastic modulus and loss modulus of the temperature-resistant adhesive supermolecular polymer gel plugging particles obtained in Examples 1-11 and Comparative Examples 1-7 are shown in Table 1.

[0110] Table 1 Maximum elastic modulus and loss modulus of the plugging particles obtained in Examples 1-11 and Comparative Examples 1-7

[0111]

[0112] As can be seen from Table 1, the supermolecular polymer gel plugging particles prepared in Example 1 have high strength. The proportion of the methyl-containing organic compound is reduced in Example 2, and the strength of the obtained plugging particles decreases, mainly because the methyl-containing organic compound is one of the key monomers participating in the polymerization reaction to construct the polymer network. When the concentration is reduced, the number of polymer chains participating in the polymerization to form the polymer network decreases, and the length of the molecular chain may also be shortened. In this case, the density of the polymer network decreases, and it cannot effectively resist external force deformation as when the concentration is high, thereby causing the gel elastic modulus to decrease. The proportion of the phenyl-containing compound is reduced in Example 3, and the strength of the obtained gel particles decreases, which is mainly because the phenyl-containing compound participates in the formation of the polymer network during the polymerization, and the change in the concentration thereof affects the growth of the polymer chain, crosslinking, and the arrangement mode between the molecular chains. When the concentration is reduced, the integrity and compactness of the polymer network are destroyed, thereby causing the elastic modulus to decrease. In Example 4, the proportion of the modified chitosan in the natural high molecular material is increased, which causes the concentration of the phenolic hydroxyl group to greatly increase, the viscosity of the system to increase, and the gel elastic modulus to slightly decrease. In Example 5, the content of the high molecular polymer is reduced, the crosslinking density of the polymer network is reduced, the structural strength and elasticity of the gel are weakened, and finally the elastic modulus decreases. In Example 6, polyethylene glycol is used instead of polyvinyl alcohol, and the interaction with other components in the system is relatively weak, so that the gel is more likely to deform when subjected to stress, and the elastic modulus decreases. In Example 7, the type of the methyl-containing organic compound is changed, which may cause the network structure formed thereby to be not dense and complete, and the stress cannot be effectively dispersed and transmitted when subjected to stress, thereby causing the elastic modulus to decrease. In Example 8, 3-vinyl aniline is used instead of sodium p-styrenesulfonate, 3-vinyl aniline is not easy to ionize under general conditions, and cannot provide similar ionic interactions. When subjected to external force, the molecular chains are more likely to slide, and the elastic modulus may decrease. In Example 9, the content of each component is increased, the number of polymer chains generated increases, and the length of the molecular chain increases. The molecular chains are more likely to entangle, the friction and constraint between the molecular chains are increased, and the change in the elastic modulus is slightly fluctuated. In Example 10, the content of each component is reduced, the number of molecules participating in the polymerization reaction decreases, and the elastic modulus decreases. In Example 11, the modified monomer of chitosan is changed, the conformation of the chitosan molecule is changed, the synergistic effect between the molecular chains is weakened when the gel is subjected to stress, the stress cannot be effectively dispersed, and thereby the elastic modulus decreases.

[0113] In Comparative Example 1, no methyl-containing organic compound was added, the number of polymer chains generated in the polymerization reaction was reduced, the gel network structure became loose and incomplete, and it was difficult to withstand external force, resulting in a decrease in the elastic modulus. In Comparative Example 2, no high molecular polymer was added, the long-chain molecules of the high molecular polymer could interweave with each other in the system, providing a basic framework for the attachment and crosslinking of other components. When the high molecular polymer was removed, this basic framework was missing in the system, and other components were difficult to form a stable and continuous network structure, resulting in a decrease in strength. In Comparative Example 3, no natural high molecular material was added, the degree of crosslinking reaction was reduced, the synergistic effect disappeared, the crosslinking density and overall performance of the gel decreased, and the elastic modulus also decreased. In Comparative Example 4, the natural high molecular material was only modified chitosan, the crosslinking points formed by sodium alginate in the system disappeared, the crosslinking density decreased, the network structure became loose, and when subjected to external force, the relative sliding between molecular chains was more likely to occur, resulting in a decrease in the elastic modulus of the gel. In Comparative Example 5, the natural high molecular material was only sodium alginate, the polymer network structure of the gel became incomplete, the uniformity and compactness of the network were affected, and the elastic modulus decreased. In Comparative Example 6, no phenyl-containing compound was added, the distribution of crosslinking points might become uneven, or the degree of crosslinking reaction might be partially missing, resulting in a decrease in the integrity and stability of the gel network structure. In Comparative Example 7, no inorganic particles were added, and calcium carbonate particles could act as a physical crosslinking point in the gel, interweaving and adsorbing with polymer molecular chains, making the polymer network structure more compact and uniform. When the particles were removed, the molecular chains were more likely to slide and deform under external force, resulting in a decrease in the elastic modulus of the gel.

[0114] Test Example 2

[0115] Gel particle pressure-bearing strength test:

[0116] (I) In order to explore the plugging performance of the supermolecular polymer gel plugging particle to the fracture, the pressure-bearing capacity of the plugging particle was tested by means of a high temperature and high pressure plugging displacement device. A water dispersion liquid of the plugging particle with a mass fraction of 5% (particle size of 1000-2000 μm) was configured, injected into a steel column fracture core with a fracture width of 3 mm, and then placed at 100°C for 1 h. After the particles were adhered to the wall, clean water was injected, and then a constant flow was injected. The change of the outlet pressure was recorded in real time. The specific steps are as follows:

[0117] 1) Adjust the temperature device of the plugging instrument to 100°C.

[0118] 2) After the steel column fracture core with a fracture width of 3 mm and a length of 30 cm was assembled, it was placed in the core holder and injected with a confining pressure of 20 MPa.

[0119] 3) The clean water was injected into the plugging instrument device at a flow rate of 5.99 mL / min until the clean water flowed out stably at the outlet.

[0120] 4) inject the water dispersion of plugging particles into the plugging instrument device at an injection rate of 5.99 mL / min, after the outlet section stably flows out the water dispersion of plugging particles, stop injection, after standing for 1 h, continue to inject clean water at a rate of 5.99 mL / min, and observe the pressure change.

[0121] The maximum pressure-bearing capacity curve of the temperature-resistant adhesive type supramolecular polymer gel plugging particles obtained in Example 1 is shown in Figure 4 It can be seen from Figure 4 that the maximum breakthrough pressure of the gel is 6.19 MPa, indicating that the plugging particles have good pressure-bearing effect on the fracture. The maximum breakthrough pressures of the plugging particles obtained in Examples 1-11 and Comparative Examples 1-7 are shown in Table 2.

[0122] Table 2 Maximum breakthrough pressures of plugging particles prepared in different examples and comparative examples

[0123]

[0124] (II) replace the displacement mode of (I) with a constant pressure mode, that is, after standing for 1 h in step 4), inject clean water at a rate of 5.99 mL / min until the pressure reaches a set value (the set values are 3 MPa, 4 MPa and 5 MPa, respectively), the pressure on the flat-flow pump is maintained at the set value, and the pressure change is recorded in real time using software for 150 s at the set value, and the results are shown in Figure 5 It can be seen from Figure 5 that the gel particles maintain stable pressure at each stage, which is due to the adhesion performance of the gel particles to the core wall surface, and the adhesion performance between the wall surface and the particles is good.

[0125] Test Example 3

[0126] Adhesion test

[0127] Prepare the supramolecular polymer gel according to the steps of Example 1, and make the gel into a cylinder with a diameter of 30 mm and a thickness of 3 mm. After drying (drying at 40°C for 48 h), place it in the drilling fluid (the drilling fluid formula is 4% bentonite-based slurry, that is, the mass ratio of bentonite to water is 4g:100mL) for 1 h, and then take it out for adhesion experiments on standard core slices, polypropylene, glass and other materials. The results are shown in Figure 6 Due to the multiple supramolecular interactions and the action of phenolic hydroxyl groups in the system, the gel particles can adhere to the surfaces of different materials, which also explains the reason why the particles can maintain high strength pressure-bearing strength.

Claims

1. A temperature resistant, adhesive, supramolecular polymer gel plugging particle, characterized in that, Prepared from raw materials including the following mass percentages: 5-10% of high molecular polymer, 10-20% of methyl-containing organic compound, 1-5% of natural polymer material, 0-1% of phenyl-containing compound, 1-5% of inorganic particles, 0-1% of initiator, and the rest of water; The high molecular polymer is polyvinyl alcohol; the methyl-containing organic compound is a combination of N-hydroxymethyl acrylamide and N,N-dimethyl acrylamide, the mass ratio of the N-hydroxymethyl acrylamide to the N,N-dimethyl acrylamide being 1:25-35; the natural polymer material is a mixture of sodium alginate and modified chitosan, the mass ratio of the sodium alginate to the modified chitosan in the mixture being 1:1-5; The modified chitosan is prepared according to the following method: (1) adding chitosan into an acidic solution, stirring uniformly to obtain solution A; the acidic solution is an acetic acid aqueous solution with a pH of 5; (2) adding a modified monomer into a solvent, stirring uniformly to obtain solution B; the modified monomer is one or a combination of 1,2-dihydroxybenzene and 3,4-dihydroxybenzaldehyde; the solvent is a mixed solution of water and methanol; (3) adding solution B into solution A to perform a first reaction; then continuously adding a reducing agent to perform a second reaction, and then performing dialysis and freeze-drying to obtain the modified chitosan; the mass ratio of the chitosan in solution A to the modified monomer in solution B is 1:1-5; the reducing agent is one or a combination of more than two of sodium borohydride, potassium borohydride, and lithium borohydride; the mass ratio of the reducing agent to the chitosan is 1-3:1; The phenyl-containing compound is one or a combination of more than two of 4-vinylaniline, 3-vinylaniline, and sodium p-styrenesulfonate; the inorganic particles are calcium carbonate; the initiator is one or a combination of more than two of benzoyl peroxide, lauryl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, ammonium persulfate, and potassium persulfate; The preparation method of the temperature-resistant adhesive supermolecular polymer gel plugging particle includes the following steps: (I) adding high molecular polymer into water, stirring uniformly to obtain solution a; (II) adding methyl-containing organic compound, natural polymer material, phenyl-containing compound, and inorganic particles into solution a, stirring uniformly to obtain mixed solution b; (III) adding an initiator into mixed solution b to perform stirring to obtain a gel-forming solution; Then, performing solidification by heating to obtain a supermolecular polymer gel, and then performing drying and crushing to obtain the temperature-resistant adhesive supermolecular polymer gel plugging particle.

2. The temperature resistant, adhesive, supramolecular polymer gel plugging particle of claim 1, wherein, The weight average molecular weight of the polyvinyl alcohol is 13000-23000.

3. The temperature resistant, adhesive, supramolecular polymer gel plugging particle of claim 1, wherein, The weight average molecular weight of the sodium alginate is 300000-400000.

4. The temperature resistant, adhesive, supramolecular polymer gel plugging particle of claim 1, wherein, In the preparation of the modified chitosan, in step (1), the weight average molecular weight of the chitosan is 100-200 kDa, and the degree of deacetylation is ≥95%; the volume of the acidic solution to the mass of the chitosan is 40-60 mL:1 g; in step (2), the volume ratio of water to methanol in the mixed solution is 1:1; the volume of the solvent to the mass of the modified monomer is 10-20 mL:1 g.

5. The temperature resistant, adhesive, supramolecular polymer gel based lost circulation material particle of claim 1, wherein, In the preparation of the modified chitosan, the first reaction in step (3) is carried out at a temperature of 30-60 DEG C for 10-15 h; the second reaction is carried out at a temperature of 30-60 DEG C for 5-7 h; the dialysis step is carried out by adding the reaction solution into a dialysis bag and dialyzing in deionized water; the dialysis bag has a molecular weight cut-off of 8000-14000 Da, and the dialysis is carried out for 48-72 h; the freeze-drying is carried out at a temperature of -70 to -50 DEG C for 24-48 h.

6. The temperature resistant, adhesive, supramolecular polymer gel based lost circulation material particle of claim 1, wherein, In the preparation of the gel plugging particles, the stirring in step (I) is carried out at a temperature of 60-100 DEG C for 1-3 h at a stirring speed of 500-2500 r / min; after the stirring, the solution a is obtained by cooling to room temperature; the stirring in step (II) is carried out for 12-24 h at a stirring speed of 1500-2500 r / min.

7. The temperature resistant, adhesive, supramolecular polymer gel based lost circulation material particle of claim 1, wherein, In the preparation of the gel plugging particles, the stirring in step (III) is carried out for 2-6 h at a stirring speed of 1500-2500 r / min; the solidification is carried out by first solidifying at 40-45 DEG C for 2-3 h, then solidifying at 55-65 DEG C for 2-3 h, and finally solidifying at 80-100 DEG C for 2-3 h; the drying is carried out at a temperature of 40-80 DEG C for 24-48 h.

8. Use of the temperature resistant, adhesive, supramolecular polymer gel plugging particles according to any one of claims 1 to 7 for plugging in the process of drilling a well, characterized in that, The application steps are as follows: the obtained temperature-resistant adhesive type supramolecular polymer gel plugging particles are added into a drilling fluid, and the drilling fluid enters into a formation while drilling; the mass fraction of the temperature-resistant adhesive type supramolecular polymer gel plugging particles in the drilling fluid is 1-15%.

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