Temperature and pH simultaneous coupling response gel material and application thereof

Abstract

The invention provides a temperature and pH simultaneous coupling response gel material and application thereof. The gel material comprises an acrylic acid terpolymer and an AM / NVP / DMDAAC copolymer. The gel material can automatically identify a leakage layer, is self-adaptive to a leakage channel, can quickly stop in a high-pressure saline water layer, and has an excellent leakage-proof and leakage-stopping effect.

Description

Technical Field

[0001] The present invention belongs to the field of oil and gas exploration, and relates to a gel material, in particular to a gel material with simultaneous temperature and pH coupling response and its application. Background Art

[0002] With the expansion of oil and gas exploration and development into deep, ultra-deep and unconventional oil and gas fields, drilling and completion engineering faces many severe technical challenges. In particular, severe lost circulation occurring in fractured formations has become a "bottleneck" problem for drilling and completion technology.

[0003] The lost circulation time of the group company accounts for 70% of all drilling complex lost time, and the economic loss reaches billions of yuan. The existing lost circulation prevention and control technologies generally have the defects of poor applicability and low success rate. There is an urgent need to carry out special research to form a series of lost circulation prevention and control technologies suitable for fractured lost circulation, so as to provide strong technical support for "safe, efficient, economic" drilling and completion and accelerating the exploration and development process.

[0004] In fracture-cavity reservoirs, the dissolution pores and large caves formed by paleokarstification are the main reservoir spaces, and the tectonic fractures and dissolution fractures are the main flow channels. The reservoir burial depth is 5300 - 7000m, the formation temperature is 70 - 90°C, the formation water salinity is 2×10 4 ~20×10 4 mg / L, and the pH value is about 7.4. Summary of the Invention

[0005] To solve the technical problems existing in the prior art, the present invention provides a gel material with simultaneous temperature and pH coupling response and its application. The gel material can automatically identify the lost circulation zone, adapt to the lost circulation channel, can quickly stagnate in the high-pressure brine layer, and has excellent lost circulation prevention and control effects.

[0006] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0007] One object of the present invention is to provide a gel material with simultaneous temperature and pH coupling response, and the gel material includes an acrylic acid ternary copolymer and an AM / NVP / DMDAAC copolymer.

[0008] As a preferred technical solution of the present invention, the mass fraction of the acrylic acid ternary copolymer in the gel material is 15 - 25%, such as 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24% or 25%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0009] Preferably, the mass fraction of the AM / NVP / DMDAAC copolymer in the gel material is 25-45%, such as 25%, 26%, 28%, 30%, 32%, 35%, 38%, 40%, 42% or 45%, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0010] As a preferred technical solution of the present invention, the gel material further includes water and / or bentonite slurry.

[0011] As a preferred technical solution of the present invention, the acrylic acid ternary copolymer is a ternary copolymer of acrylic acid monomer - acrylamide monomer - vinyl monomer.

[0012] As a preferred technical solution of the present invention, the mass ratio of acrylic acid monomer, acrylamide monomer and vinyl monomer in the acrylic acid ternary copolymer is 10-20:10-15:3-5, such as 10:15:3, 12:14:3.5, 15:13:4, 18:12:4.5 or 20:10:5, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0013] As a preferred technical solution of the present invention, the acrylic acid monomer includes any one or a combination of at least two of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate, isobornyl methacrylate, 2-ethylhexyl acrylate, sec-butyl acrylate or tert-butyl acrylate.

[0014] Preferably, the acrylamide monomer includes any one or a combination of at least two of N-(isobutoxy)methylacrylamide, isopropylacrylamide, N-isopropylacrylamide or N,N-dimethylaminopropylmethacrylamide.

[0015] Preferably, the vinyl monomer includes any one or a combination of at least two of styrene, acrylonitrile or vinyl acetate.

[0016] As a preferred technical solution of the present invention, the mass fraction of AM in the AM / NVP / DMDAAC copolymer is 10-35%, the mass fraction of NVP is 20.5-70%, and the balance is AM. Among them, the mass fraction of AM can be 10%, 15%, 20%, 25%, 30% or 35%, etc., and the mass fraction of NVP can be 20.5%, 22.5%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%, etc., but not limited to the listed values, and other unlisted values within the above ranges are equally applicable.

[0017] As a preferred technical solution of the present invention, the preparation method of the acrylic acid ternary copolymer includes:

[0018] Mix a chain transfer agent with a solvent, heat it, and then dropwise add monomers and an initiator solution. After the dropping is completed, carry out a reaction to obtain the acrylic acid ternary copolymer.

[0019] As a preferred technical solution of the present invention, the preparation method of the AM / NVP / DMDAAC copolymer includes:

[0020] Dissolve DMDAAC in water and adjust the pH to neutral;

[0021] After adding AM and NVP, heat and introduce a protective atmosphere, add an initiator to carry out a reaction to obtain the AM / NVP / DMDAAC copolymer.

[0022] The second object of the present invention is to provide an application of the temperature and pH simultaneously coupled responsive gel material provided by the first object, and the gel material is used for preventing and plugging leakage in fractured lost circulation.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] (1) The present invention provides a temperature and pH simultaneously coupled responsive gel material, and the gel material can automatically identify the lost circulation layer, that is, in a specific lost circulation layer, the pH range is about 7.4, and under the conditions of 70-90 °C, the volume of the gel material can rapidly expand greatly, and the leakage rate can be rapidly reduced.

[0025] (2) The present invention provides a temperature and pH simultaneously coupled responsive gel material, and the gel material is a high-strength and high-toughness fluid, which can adaptively deform to plug different-sized fractures and cavities;

[0026] (3) The present invention provides a temperature and pH simultaneously coupled responsive gel material, and the gel material can rapidly stagnate in a high-pressure brine layer, that is, under the conditions of high calcium and magnesium ion concentrations, a pH value of about 7.4, and a temperature of 70-90 °C, a strong phase change will occur, and the swelling degree change of the gel is the largest. Description of the Drawings

[0027] Figure 1 It is the macroscopic and microscopic morphology diagrams of the temperature and pH simultaneously coupled responsive gel material provided by the present invention;

[0028] Figure 2 It is the swelling multiple test diagram of the gel material in different salinity environments at the response temperature (150 °C) in the specific embodiment of the present invention.

[0029] The present invention will be further described in detail below. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. Detailed implementation manners

[0030] The technical solution of the present invention will be further described below through specific implementation manners.

[0031] A temperature and pH simultaneously coupled responsive gel material is provided in a specific implementation manner of the present invention. The gel material includes an acrylic acid ternary copolymer and an AM / NVP / DMDAAC copolymer.

[0032] In the present invention, the gel material contains an acrylic acid ternary copolymer and an AM / NVP / DMDAAC copolymer. By utilizing the sensitivity of these two substances to pH value, salinity, and calcium and magnesium ions, and the resulting huge volume differences in different environments, the disadvantages of conventional plugging materials, such as strong selectivity for leakage channels, ineffective in leakage zones, easily diluted in formation water, and insufficient anti-salt and anti-calcium performance, are solved. It can achieve the unique effect of identifying the leakage zone, displacing formation water, and stagnating in the leakage channel to achieve plugging, reaching the international leading level.

[0033] In a specific implementation manner of the present invention, the weight-average molecular weight of the acrylic acid ternary copolymer is 10,000 to 90,000, such as 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, or 90000, etc.; the weight-average molecular weight of the AM / NVP / DMDAAC copolymer is 5000 to 40000, such as 5000, 10000, 15000, 20000, 30000, or 40000, etc., but is not limited to the listed values. Other unlisted values within the above numerical ranges are equally applicable.

[0034] In a specific implementation manner of the present invention, the structural formulas of the three monomers in the AM / NVP / DMDAAC copolymer are as shown below.

[0035]

[0036] In a specific implementation manner of the present invention, in the preparation method of the acrylic acid ternary copolymer, the chain transfer agent used can be any one or a combination of at least two of sodium bisulfite, dodecyl mercaptan, or octadecyl mercaptan.

[0037] In a specific implementation manner of the present invention, the addition amount of the chain transfer agent can be 3 to 5% of the total mass of the reaction system, such as 3%, 3.5%, 4%, 4.5%, or 5%, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0038] In a specific embodiment of the present invention, in the preparation method of the acrylic acid ternary copolymer, the initiator used can be any one or a combination of at least two of 2,2'-azobisisobutyronitrile, benzoyl peroxide or azobisisoheptonitrile.

[0039] In a specific embodiment of the present invention, the addition amount of the initiator can be 0.05-0.1% of the total mass of the reaction system, such as 0.05%, 0.06%, 0.07%, 0.08%, 0.09% or 0.1%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0040] In a specific embodiment of the present invention, in the preparation method of the acrylic acid ternary copolymer, the heating temperature can be 50-70°C, such as 50°C, 55°C, 60°C, 65°C or 70°C, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0041] In a specific embodiment of the present invention, in the preparation method of the acrylic acid ternary copolymer, the monomer and the initiator solution can be an aqueous solution, and the dropping time can be 2-5 h, such as 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0042] In a specific embodiment of the present invention, in the preparation method of the acrylic acid ternary copolymer, the reaction time can be 2-5 h, such as 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0043] In a specific embodiment of the present invention, in the preparation method of the acrylic acid ternary copolymer, after the reaction, an alkali (such as sodium hydroxide solution) is added to adjust the pH to neutral (such as 7-7.5) to obtain a colorless viscous low molecular weight acrylic acid ternary copolymer solution.

[0044] In a specific embodiment of the present invention, in the preparation method of the AM / NVP / DMDAAC copolymer, sodium hydroxide can be used to adjust the pH of the DMDAAC aqueous solution to neutral (such as 6.5-7).

[0045] In a specific embodiment of the present invention, in the preparation method of the AM / NVP / DMDAAC copolymer, the heating temperature can be 45-60°C, the protective atmosphere can be nitrogen, and the introduction time is not less than 30 min.

[0046] In a specific embodiment of the present invention, in the preparation method of the AM / NVP / DMDAAC copolymer, the initiator can be any one of cyclohexanone peroxide, benzoyl peroxide, tert-butyl hydroperoxide, ammonium persulfate, potassium persulfate, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide or sodium bisulfate, or a combination of any two of the above initiators with a mass ratio of 1:1. The addition amount of the initiator can be 0.1-0.5% of the total mass of the reaction monomers.

[0047] In a specific embodiment of the present invention, in the preparation method of the AM / NVP / DMDAAC copolymer, the polymerization reaction time can be 10-15 h, such as 10 h, 11 h, 12 h, 13 h, 14 h or 15 h, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0048] In a specific embodiment of the present invention, in the preparation method of the AM / NVP / DMDAAC copolymer, after the reaction, a gel-like product is obtained. The gel-like product is precipitated and washed repeatedly with anhydrous ethanol, dried, and pulverized to obtain the AM / NVP / DMDAAC terpolymer.

[0049] To better illustrate the present invention and facilitate understanding of its technical solutions, the typical but non-limiting embodiments of the present invention are as follows:

[0050] Example 1

[0051] This example provides a temperature and pH simultaneously coupled responsive gel material, and its macroscopic and microscopic morphologies are as Figure 1 shown. The gel material includes 25% by total mass of an acrylic acid terpolymer, 25% by total mass of the AM / NVP / DMDAAC copolymer, and the balance is water.

[0052] The three monomers of the acrylic acid terpolymer are N-(isobutoxy)methylacrylamide, methyl acrylate and styrene respectively. The preparation method of the acrylic acid terpolymer includes:

[0053] In a 500 mL four-necked flask equipped with a stirrer, reflux condenser, thermometer and dropping funnel, a certain amount of deionized water is added, and then sodium bisulfite as a chain transfer agent (the dosage accounts for 4.5% of the system mass) is added and stirred to dissolve. The temperature is raised to 65 °C, and then an aqueous solution of the three monomers and an initiator is added dropwise. Among them, the mass fraction of methyl acrylate in the system is 10%, the mass fraction of N-(isobutoxy)methylacrylamide in the system is 10%, the mass fraction of styrene in the system is 3%, and the mass fraction of the initiator in the system is 0.06%. The dropping time is 3 h. After dropping, it is kept warm for 3 h and neutralized to pH 7-7.5 with a 30% by mass aqueous sodium hydroxide solution to obtain a colorless viscous and low molecular weight terpolymer solution.

[0054] The preparation method of the AM / NVP / DMDAAC copolymer includes:

[0055] Weigh each monomer according to the mass ratio (25% DMDAAC, 20.5% NVP, and the rest is AM).

[0056] Dissolve DMDAAC in an appropriate amount of water, and then neutralize it with an equimolar sodium hydroxide solution (20 wt%) to pH = 6.5 - 7.

[0057] Add AM and NVP, stir to dissolve them, and supplement water to control the monomer concentration at 15%.

[0058] Heat up to 60 °C, pass nitrogen for more than 30 min, and add tert-butyl hydroperoxide accounting for 0.3% of the total mass of the monomers.

[0059] React at a constant temperature for 12 h to obtain a gel-like product.

[0060] Precipitate the obtained gel-like product with absolute ethanol, wash it 3 times, dry it at 80 °C, and pulverize it to obtain the AM / NVP / DMDAAC terpolymer.

[0061] Example 2

[0062] This example provides a gel material with simultaneous temperature and pH coupling response. The gel material includes 20% by total mass of an acrylic acid terpolymer, 30% by total mass of the AM / NVP / DMDAAC copolymer, and the balance is water.

[0063] The three monomers of the acrylic acid terpolymer are N,N-dimethylaminopropyl methacrylamide, n-butyl methacrylate, and vinyl acetate. The preparation method of the acrylic acid terpolymer includes:

[0064] Acrylic acid terpolymer polymerization method: In a 500 mL four-necked flask equipped with a stirrer, reflux condenser, thermometer, and dropping funnel, add a certain amount of deionized water, then add a chain transfer agent (the dosage accounts for 4.5% of the system mass), stir to dissolve, heat up to 65 °C, and start dropping the monomer and initiator aqueous solution. Among them, the mass fraction of n-butyl methacrylate in the system is 15%, the mass fraction of N,N-dimethylaminopropyl methacrylamide in the system is 12%, the mass fraction of vinyl acetate in the system is 5%, the mass fraction of benzoyl peroxide in the system is 0.06%, the dropping time is 3 h, keep warm for 3 h after dropping, and neutralize it with a 30% sodium hydroxide aqueous solution to a pH value of 7 - 7.5 to obtain a colorless viscous, low molecular weight acrylic acid terpolymer solution.

[0065] The preparation method of the AM / NVP / DMDAAC copolymer is the same as that of Example 1 except that the mass fractions of the monomers are 15% of DMDAAC, 22.5% of NVP, and the rest is AM.

[0066] Example 3

[0067] This example provides a gel material with simultaneous temperature and pH coupling response. Except that the gel material includes 15% of acrylic acid ternary copolymer by total mass, 45% of AM / NVP / DMDAAC copolymer by total mass, and the balance is water, the other conditions are the same as those of Example 1.

[0068] The gel properties of the gel material provided in Example 1 were tested:

[0069] The swelling multiples of the gel material provided in Example 1 in solutions with different salinities were tested. The addition amount of the gel material was 0.5%. The test temperatures were 50 °C, 60 °C, 80 °C, 100 °C, and 120 °C respectively. The pH values of the solutions used for testing were 4, 6, 7, 9, and 10 respectively. Taking ordinary polymer gel particles as a comparison, the selected ordinary polymer gel particles were polyacrylamide with a molecular weight of 100,000.

[0070] The results are as Figure 1 shown. It can be seen from Figure 1 that the gel undergoes a strong phase change when the pH value is 7 and the temperature is 70 - 90 °C, and the swelling ratio becomes 1350 - 1560. When pH = 4 and temperature = 50 °C, pH = 6 and temperature = 60 °C, pH = 9 and temperature = 100 °C, pH = 4 and temperature = 50 °C, pH = 10 and temperature = 120 °C, the swelling ratio is 3 - 135, and the phase change amplitude is very small.

[0071] The swelling multiples of the gel material provided in Example 2 in solutions with different pH values at different temperatures were tested. The addition amount of the gel material was 0.3%. The test temperatures were 50 °C, 60 °C, 80 °C, 100 °C, and 120 °C respectively. The pH values of the solutions used for testing were 4, 6, 7, 9, and 10 respectively. Taking ordinary polymer gel particles as a comparison, the selected ordinary polymer gel particles were polyacrylamide with a molecular weight of 100,000.

[0072] The results are shown in Table 1. It can be seen from Table 1 that the gel undergoes a strong phase change when the pH value is 7 and the temperature is 80 °C. At other pH values such as 5 or 10, etc., the phase change degree is lower or there is no phase change when the temperature is 70 - 90 °C.

[0073] Table 1

[0074]

[0075] The applicant declares that the detailed structural features of the present invention are illustrated by the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

[0076] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0077] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, without contradiction, they can be combined in any appropriate way. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0078] In addition, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

1. A temperature and pH simultaneously coupled responsive gel material, characterized in that: The gel material includes acrylic terpolymer and AM / NVP / DMDAAC copolymer.

2. The gel material according to claim 1, characterized in that: The mass fraction of the acrylic terpolymer in the gel material is 15 to 25%; Preferably, the mass fraction of the AM / NVP / DMDAAC copolymer in the gel material is 25-45%.

3. The gel material according to claim 1, characterized in that: The gel material also includes water and / or bentonite slurry.

4. The gel material according to claim 1, characterized in that: The acrylic acid terpolymer is an acrylic acid monomer-acrylamide monomer-ethylene monomer terpolymer.

5. The gel material according to claim 6, characterized in that: The mass ratio of acrylic acid monomer, acrylamide monomer and vinyl monomer in the acrylic terpolymer is 10-20:10-15:3-5.

6. The gel material according to claim 4, characterized in that: The acrylic acid monomer includes any one or a combination of at least two of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate, isobornyl methacrylate, 2-ethylhexyl acrylate, sec-butyl acrylate or tert-butyl acrylate; Preferably, the acrylamide monomer includes any one or a combination of at least two of N-(isobutyloxy)methacrylamide, isopropylacrylamide, N-isopropylacrylamide or N,N-dimethylaminopropylmethacrylamide; Preferably, the vinyl monomer includes any one of styrene, acrylonitrile or vinyl acetate, or a combination of at least two of them.

7. The gel material according to claim 1, characterized in that: The mass fraction of AM in the AM / NVP / DMDAAC copolymer is 10-35%, the mass fraction of NVP is 20.5-70%, and the balance is AM.

8. The gel material according to claim 1, characterized in that: The preparation method of the acrylic terpolymer comprises: The chain transfer agent and the solvent are mixed, and after heating, the monomer and the initiator solution are added dropwise, and after the addition is completed, a reaction is carried out to obtain the acrylic terpolymer.

9. The gel material according to claim 1, characterized in that: The preparation method of the AM / NVP / DMDAAC copolymer comprises: Dissolve DMDAAC in water and adjust the pH to neutral; After adding AM and NVP, heating and introducing a protective atmosphere, an initiator is added to react to obtain the AM / NVP / DMDAAC copolymer.

10. An application of the temperature and pH simultaneously coupled response gel material according to any one of claims 1 to 9, characterized in that: The gel material is used for preventing and plugging leakage caused by fractures.

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