A self-crosslinking plant gum concentrated suspension system and a preparation method and application thereof

Abstract

The application discloses a self-crosslinking plant glue concentrated suspension system which is composed of the following substances: a thickening agent with a content of 0.5-5wt%; an emulsifier with a content of 0.2-2wt%; guar gum with a content of 20-60wt%; boron ore fine powder with a content of 5-25wt%; a penetrating agent with a content of 0.01-4wt%; and the rest is a dispersion medium. The application further discloses a preparation method of the self-crosslinking plant glue concentrated suspension system, and the steps are as follows: S1: adding a formula amount of the thickening agent into a formula amount of the dispersion medium, stirring for at least 1 hour, then adding a formula amount of the emulsifier into the mixture, and stirring for at least 10 minutes to obtain a suspension; S2: sequentially adding a formula amount of the guar gum, a formula amount of the boron ore fine powder and a formula amount of the penetrating agent into the suspension obtained in the step S1, and stirring for at least 30 minutes, so that the self-crosslinking plant glue concentrated suspension system is obtained.

Description

Technical Field

[0001] This invention relates to the field of downhole operations technology in oil and gas field exploration and development, specifically to a self-crosslinking plant gum concentrated suspension system, its preparation method, and its application. Background Technology

[0002] Guar gum has long been a commonly used thickener for fracturing fluids in conventional low-permeability oil and gas well fracturing. However, guar gum cannot dissolve and thicken in weakly alkaline water or water containing cross-linking agents. Before fracturing operations, a thickened fluid needs to be prepared with water, then adjusted to a weakly alkaline state with alkali, and finally the cross-linking agent is added during fracturing. This not only increases the operations of fluid preparation, transportation, and storage, but also requires the addition of bactericides because guar gum is prone to bacterial growth and spoilage in water. The pre-prepared fracturing fluid is stored in tanks, and after fracturing, the remaining fluid needs to be recovered and the tanks and pipelines need to be cleaned promptly.

[0003] In large-scale, high-volume fracturing of shale oil and gas wells, artificially synthesized modified polyacrylamide fracturing fluids are mainly used. Due to the difficulty in breaking down the gel, modified polyacrylamide fracturing fluids are easily adsorbed and retained in the pores of oil and gas reservoirs, resulting in a decrease in reservoir permeability. Moreover, the degradation products of modified polyacrylamide fracturing fluids can pollute groundwater and the environment.

[0004] If slickwater formulated with synthetic polymers is used for fracturing low-permeability oil and gas wells, it has disadvantages such as low viscosity, low sand-carrying capacity, and easy sand blockage in the high sand ratio stage.

[0005] Due to the inherent challenges of liquefying plant gums, there is currently limited literature on liquid plant gums both domestically and internationally. Xi'an Petroleum University and Turpan-Hami Oilfield have collaborated to develop a low-residue boron-crosslinked liquid guar gum fracturing fluid technology. This involves mixing guar gum and diesel fuel to create a suspension, followed by crosslinking with sodium tetraborate. However, this approach requires pre-mixing the solution before application, making continuous mixing impossible and hindering automated crosslinking.

[0006] Chinese invention patent application CN 116751329 A relates to a self-crosslinking emulsion-type fracturing fluid thickener and its preparation method. A self-crosslinking polymer was synthesized using N-hydroxymethylacrylamide, vinyl acetate, and hydroxyethyl acrylate, which can self-crosslink to form a stable three-dimensional network structure under high-temperature conditions. However, the above technical solution has the following shortcomings: it does not contain a crosslinking agent component, has low viscoelasticity and cannot be used for hooking, and is not a true crosslinking fracturing fluid.

[0007] Chinese invention patent application CN 111748332 A discloses a multifunctional online emulsified self-crosslinking fracturing fluid and its preparation method. The fracturing fluid is composed of the following components in parts by weight: 15-20 parts acrylamide, 0.3-0.6 parts sodium acrylate, 0.4-0.7 parts sodium salt, 24-26 parts N-hexadecylacrylamide, 38-45 parts water, 8-12 parts white oil, and 5-10 parts a composite emulsifier of TW, OP, and SP. However, the above technical solution has the following shortcomings: although the thickening ability is improved under the "like dissolves like" effect of the associating groups, it suffers from slow dissolution and thickening, and low resistance to temperature and shear. Summary of the Invention

[0008] Purpose of the invention: The technical problem to be solved by the present invention is that the powdered guar gum and liquid guar gum currently used both require pre-preparation of fracturing fluid and cannot achieve automatic cross-linking. The preparation and use process is cumbersome and not suitable for continuous mixing in shale oil and gas well fracturing. The invention provides a self-cross-linking plant gum concentrated suspension system and its preparation method and application.

[0009] The self-crosslinking plant gum concentrated suspension system of the present invention has the advantages of simple synthesis, rapid thickening, self-crosslinking capability, good adhesion, strong temperature and shear resistance, thorough gel breaking and water dissolution, and continuous mixing capability.

[0010] Technical solution: A self-crosslinking plant gum concentrated suspension system, comprising, by mass percentage, a thickener, an emulsifier, guar gum, fine boron ore powder, a penetrant, and a dispersion medium, wherein, based on the weight of the self-crosslinking plant gum concentrated suspension system:

[0011] The thickener content is 0.5–5 wt%.

[0012] The emulsifier content is 0.2–2 wt%.

[0013] The guar gum content is 20-60 wt%;

[0014] The content of the fine boron ore powder is 5-25 wt%;

[0015] The content of the penetrant is 0.01-4 wt%;

[0016] The remainder is the dispersion medium.

[0017] The preparation method of the above-mentioned self-crosslinking plant gum concentrated suspension system includes the following steps:

[0018] S1: Add the thickener of the formula amount to the dispersion medium of the formula amount, stir for at least 1 hour, then add the emulsifier of the formula amount to it, stir for at least 10 minutes to obtain a suspension;

[0019] S2: Add the prescribed amounts of guar gum, boron ore powder, and penetrant to the suspension obtained in step S1 in sequence, stir for at least 30 minutes, and after mixing evenly, obtain a self-crosslinking plant gum concentrated suspension system.

[0020] The self-crosslinking plant gum concentrate suspension system is prepared by any one of the methods described above.

[0021] The aforementioned self-crosslinking plant gum concentrated suspension system is used as a fracturing agent in the exploitation of low-permeability oil reservoirs.

[0022] The self-crosslinking plant gum concentrated suspension system of the present invention can effectively solve the above problems. It can be used not only for conventional fracturing but also for continuous mixed fracturing in shale oil (gas) wells. Compared with commonly used modified polyacrylamide self-crosslinking fracturing fluids, the guar gum raw material in the self-crosslinking plant gum concentrated suspension system of the present invention is a natural polymer with no molecular charge, strong resistance to salt and impurity interference, and can effectively overcome the above defects after crosslinking.

[0023] The main technical concept and innovation of this invention are as follows:

[0024] 1. By introducing a dispersion medium, thickener, and emulsifier to liquefy guar gum powder, the present invention can form a stable suspension that disperses rapidly when dissolved in water, avoiding the formation of fish eyes or clumps;

[0025] 2. By introducing a penetrant, the micropores inside the guar gum powder particles become strongly hydrophilic, enabling water molecules to spontaneously enter the interior of the guar gum powder and rapidly hydrate and thicken it.

[0026] 3. By introducing fine boron ore powder, which dissolves slowly in water without causing a significant increase in the pH value of the aqueous phase, this invention can function in water in the order of dispersion, thickening, cross-linking, and debinding.

[0027] Effects of the Invention: The self-crosslinking plant gum concentrated suspension system, its preparation method, and its application disclosed in this invention have the following beneficial effects and advantages:

[0028] (1) The self-crosslinking plant gum concentrated suspension system of the present invention has a simple synthesis process, the main raw materials are widely available, the cost is low and there is no environmental pollution.

[0029] (2) During the fracturing process, the self-crosslinking plant gum concentrated suspension system of the present invention can automatically crosslink to generate viscoelastic gel, which has a strong sand carrying capacity, effectively improves the sand ratio, and prevents sand desanding or sand blockage under complex formation conditions.

[0030] (3) The self-crosslinking plant gum concentrated suspension system of the present invention has strong high-temperature shear resistance, and the viscosity reduction rate after shearing is small. At 120°C, it has a viscosity reduction rate of 170 seconds.-1 After shearing for 120 minutes, the viscosity value remained above 110 mPa·s.

[0031] (4) The self-crosslinking plant gum concentrated suspension system of the present invention can achieve crosslinking under slightly alkaline conditions. The pH value of the broken gum solution is 6.1 to 7.3, which will not cause calcium and magnesium ions in the formation water to precipitate, prevent the decomposition or precipitation of the anti-swelling agent, and help protect the reservoir.

[0032] (5) The self-crosslinking plant gum concentrated suspension system of the present invention does not require the addition of pH adjuster during use, so it will not cause over-crosslinking or dehydration shrinkage after crosslinking.

[0033] (6) The self-crosslinking plant gum concentrated suspension system of the present invention does not require pre-mixing or the addition of bactericides, and can be used for continuous mixing to improve fracturing construction efficiency and shorten the construction cycle.

[0034] (7) The self-crosslinking plant gum concentrated suspension system of the present invention has strong salt resistance and can be used with high-mineralized formation water or brine; it has low requirements for water quality, and solid impurities, bacteria and reduction products have little impact on performance; it can be used with lake water, river water, sewage and the like. Attached Figure Description

[0035] Figure 1 This is a flowchart of a method for preparing a self-crosslinking plant gum concentrated suspension system disclosed in this invention. Detailed Implementation

[0036] The specific embodiments of the present invention are described in detail below.

[0037] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.

[0038] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0039] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0040] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0041] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0042] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.

[0043] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.

[0044] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.

[0045] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0046] A self-crosslinking plant gum concentrate suspension system, by mass percentage, comprises a thickener, an emulsifier, guar gum, fine boron ore powder, a penetrant, and a dispersion medium, wherein:

[0047] The thickener content is 0.5–5 wt%.

[0048] The emulsifier content is 0.2–2 wt%.

[0049] The guar gum content is 20-60 wt%;

[0050] The content of the fine boron ore powder is 5-25 wt%;

[0051] The content of the penetrant is 0.01-4 wt%;

[0052] The remainder is the dispersion medium.

[0053] Furthermore, the thickener content is 1-5 wt%.

[0054] The emulsifier content is 0.2–2 wt%.

[0055] The guar gum content is 30-50 wt%.

[0056] The content of the fine boron ore powder is 6-20 wt%.

[0057] The content of the penetrant is 0.01–2 wt%.

[0058] The remainder is the dispersion medium.

[0059] Furthermore, the thickener is one or more of organobentonite, polyamide wax, and fumed silica.

[0060] Further, the emulsifier is one or more of nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, sorbitan monostearate, sorbitan monooleate, and sorbitan monooleate polyoxyethylene ether.

[0061] Furthermore, the guar gum is one or both of instant guar gum or guar gum powder.

[0062] Furthermore, the instant guar gum powder is at least 240 mesh instant guar gum powder.

[0063] Furthermore, the boron ore fine powder is one or more of the following: borate fine powder, boromagnesia ore fine powder, and calcium borate fine powder.

[0064] Furthermore, the penetrant is a fatty alcohol polyoxyethylene ether with the molecular formula RO(CH2CH2O)nH, where R is a C5-C7 alkyl group and n = 5-7.

[0065] Further, the dispersion medium is one or more of the following: No. 3 white oil, No. 5 white oil, No. 7 white oil, No. 10 white oil, No. 15 white oil, No. 18 white oil, biodiesel, methyl oleate, ethylene glycol diacetate, polyethylene glycol 200, polyethylene glycol 300, and polyethylene glycol 400.

[0066] The preparation method of the above-mentioned self-crosslinking plant gum concentrated suspension system includes the following steps:

[0067] S1: Add the thickener of the formula amount to the dispersion medium of the formula amount, stir for at least 1 hour, then add the emulsifier of the formula amount to it, stir for at least 10 minutes to obtain a suspension;

[0068] S2: Add the prescribed amounts of guar gum, boron ore powder, and penetrant to the suspension obtained in step S1 in sequence, stir for at least 30 minutes, and after mixing evenly, obtain a self-crosslinking plant gum concentrated suspension system.

[0069] Furthermore, after the thickener is added to the dispersion medium, it is stirred at a speed of at least 9000 rpm, preferably 9000–11000 rpm, and / or

[0070] After the emulsifier is added to the dispersion medium, it is stirred at a speed of at least 6000 rpm, preferably 6000–8000 rpm, and / or

[0071] Guar gum, fine boron ore powder, and penetrant are added to the suspension in sequence and then stirred at a speed of at least 5000 rpm, preferably 5000-7000 rpm.

[0072] Furthermore, the boron ore fine powder in step S2 needs to be screened before use. It can only be used after passing the screening. The screening steps are as follows:

[0073] Step 1: Crush the boron ore into fine powder using a crusher, pass it through a 325-mesh sieve, and then dry it at 105℃ for 2-4 hours;

[0074] Step 2: Add 0.002 g of boron ore powder to 100 g of deionized water, stir at high speed for 5 minutes, and test with a pH meter. It can be used when the pH value is in the range of 6.5 to 8.58.

[0075] The self-crosslinking plant gum concentrate suspension system is prepared by any one of the methods described above.

[0076] The aforementioned self-crosslinking plant gum concentrated suspension system is used as a fracturing agent in the exploitation of low-permeability oil reservoirs.

[0077] In one embodiment

[0078] A self-crosslinking plant gum concentrate suspension system, by mass percentage, comprises a thickener, an emulsifier, guar gum, fine boron ore powder, a penetrant, and a dispersion medium, wherein:

[0079] The thickener content is 0.5 wt%;

[0080] The emulsifier content is 0.2 wt%;

[0081] The guar gum content is 60 wt%;

[0082] The boron ore fine powder content is 5 wt%;

[0083] The content of the penetrant is 0.01 wt%;

[0084] The remainder is the dispersion medium.

[0085] In another embodiment, the thickener content is 1 wt%, based on the weight of the self-crosslinking plant gum concentrate suspension system.

[0086] The emulsifier content is 0.2 wt%.

[0087] The guar gum content is 30 wt%.

[0088] The boron ore fine powder content is 6 wt%.

[0089] The content of the penetrant is 0.01 wt%.

[0090] The remainder is the dispersion medium.

[0091] Furthermore, the thickener is organic bentonite.

[0092] Furthermore, the emulsifier is nonylphenol polyoxyethylene ether.

[0093] Furthermore, the guar gum is instant guar gum.

[0094] Furthermore, the instant guar gum powder is 240 mesh instant guar gum powder.

[0095] Furthermore, the boron ore fine powder is hard borate fine powder.

[0096] Furthermore, the penetrant is a fatty alcohol polyoxyethylene ether with the molecular formula RO(CH2CH2O)nH, where R is n-pentyl and n = 5.

[0097] Furthermore, the dispersion medium is No. 3 white oil.

[0098] The preparation method of the above-mentioned self-crosslinking plant gum concentrated suspension system includes the following steps:

[0099] S1: Add the formula amount of thickener to the formula amount of dispersion medium, stir for 1 hour, then add the formula amount of emulsifier, stir for 10 minutes to obtain a suspension;

[0100] S2: Add the prescribed amounts of guar gum, boron ore powder, and penetrant to the suspension obtained in step S1 in sequence, stir for 30 minutes, and after mixing evenly, obtain a self-crosslinking plant gum concentrated suspension system.

[0101] Furthermore, the thickener is added to the dispersion medium and then stirred at a stirring speed of 9000 rpm and / or

[0102] After the emulsifier is added to the dispersion medium, it is stirred at a speed of 6000 rpm, and / or

[0103] Guar gum, fine boron ore powder, and penetrant were added to the suspension in sequence and then stirred at a speed of 5000 rpm.

[0104] Furthermore, the boron ore fine powder in step S2 needs to be screened before use. It can only be used after passing the screening. The screening steps are as follows:

[0105] Step 1: Crush the boron ore into fine powder using a crusher, pass it through a 325-mesh sieve, and then dry it at 105℃ for 2 hours;

[0106] Step 2: Add 0.002 g of boron ore powder to 100 g of deionized water, stir at high speed for 5 minutes, and test with a pH meter. It can be used when the pH value is in the range of 6.5 to 8.58.

[0107] The self-crosslinking plant gum concentrate suspension system is prepared by any one of the methods described above.

[0108] The aforementioned self-crosslinking plant gum concentrated suspension system is used as a fracturing agent in the exploitation of low-permeability oil reservoirs.

[0109] In another embodiment

[0110] A self-crosslinking plant gum concentrate suspension system, by mass percentage, comprises a thickener, an emulsifier, guar gum, fine boron ore powder, a penetrant, and a dispersion medium, wherein:

[0111] The thickener content is 5 wt%;

[0112] The emulsifier content is 2 wt%;

[0113] The guar gum content is 20 wt%.

[0114] The content of the fine boron ore powder is 25 wt%.

[0115] The content of the penetrant is 4 wt%;

[0116] The remainder is the dispersion medium.

[0117] In another embodiment, the thickener content is 5 wt%, based on the weight of the self-crosslinking plant gum concentrate suspension system.

[0118] The emulsifier content is 2 wt%.

[0119] The guar gum content is 50 wt%.

[0120] The boron ore fine powder content is 20 wt%.

[0121] The penetrant content is 2 wt%.

[0122] The remainder is the dispersion medium.

[0123] Furthermore, the thickener is a polyamide wax.

[0124] Furthermore, the emulsifier is octylphenol polyoxyethylene ether.

[0125] Furthermore, the guar gum is guar gum powder.

[0126] Furthermore, the instant guar gum powder is 300 mesh instant guar gum powder.

[0127] Furthermore, the boron ore fine powder is boron-magnesium ore fine powder.

[0128] Furthermore, the penetrant is a fatty alcohol polyoxyethylene ether with the molecular formula RO(CH2CH2O)nH, where R is n-heptyl and n = 7.

[0129] Furthermore, the dispersion medium is No. 5 white oil.

[0130] The preparation method of the above-mentioned self-crosslinking plant gum concentrated suspension system includes the following steps:

[0131] S1: Add the formula amount of thickener to the formula amount of dispersion medium, stir for 3 hours, then add the formula amount of emulsifier, stir for 60 minutes to obtain a suspension;

[0132] S2: Add the prescribed amounts of guar gum, boron ore powder, and penetrant to the suspension obtained in step S1 in sequence, stir for 90 minutes, and after mixing evenly, obtain a self-crosslinking plant gum concentrated suspension system.

[0133] Furthermore, the thickener is added to the dispersion medium and then stirred at a stirring speed of 11,000 rpm, and / or

[0134] After the emulsifier is added to the dispersion medium, it is stirred at a speed of 8000 rpm, and / or

[0135] Guar gum, fine boron ore powder, and penetrant were added to the suspension in sequence and then stirred at a speed of 7000 rpm.

[0136] Furthermore, the boron ore fine powder in step S2 needs to be screened before use. It can only be used after passing the screening. The screening steps are as follows:

[0137] Step 1: Crush the boron ore into fine powder using a crusher, pass it through a 325-mesh sieve, and then dry it at 105℃ for 4 hours;

[0138] Step 2: Add 0.002 g of boron ore powder to 100 g of deionized water, stir at high speed for 5 minutes, and test with a pH meter. It can be used when the pH value is in the range of 6.5 to 8.58.

[0139] The self-crosslinking plant gum concentrate suspension system is prepared by any one of the methods described above.

[0140] The aforementioned self-crosslinking plant gum concentrated suspension system is used as a fracturing agent in the exploitation of low-permeability oil reservoirs.

[0141] In yet another embodiment

[0142] A self-crosslinking plant gum concentrate suspension system, by mass percentage, comprises a thickener, an emulsifier, guar gum, fine boron ore powder, a penetrant, and a dispersion medium, wherein:

[0143] The thickener content is 3 wt%.

[0144] The emulsifier content is 1 wt%.

[0145] The guar gum content is 40 wt%.

[0146] The boron ore fine powder content is 10 wt%.

[0147] The penetrant content is 1 wt%.

[0148] The remainder is the dispersion medium.

[0149] Further, the thickener is fumed silica. In another embodiment, the thickener is a mixture of organobentonite, polyamide wax, and fumed silica in equal mass ratios.

[0150] Further, the emulsifier is sorbitan monostearate. In other embodiments, the emulsifier is sorbitan monooleate. In other embodiments, the emulsifier is sorbitan monooleate polyoxyethylene ether. In other embodiments, the emulsifier is a mixture of nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, sorbitan monostearate, sorbitan monooleate, and sorbitan monooleate polyoxyethylene ether in equal mass ratios.

[0151] Furthermore, the guar gum is a mixture of instant guar gum and guar gum powder in a mass ratio of 2:3.

[0152] Furthermore, the instant guar gum powder is 400 mesh instant guar gum powder.

[0153] Further, the boron ore fine powder is calcium borate fine powder. In other embodiments, the boron ore fine powder is a mixture of equimolar amounts of calcium borate fine powder, boromagnesia ore fine powder, and calcium borate fine powder.

[0154] Furthermore, the penetrant is a fatty alcohol polyoxyethylene ether with the molecular formula RO(CH2CH2O)nH, where R is n-hexyl and n = 6.

[0155] Further, the dispersion medium is No. 7 white oil. In other embodiments, the dispersion medium is No. 10 white oil. In other embodiments, the dispersion medium is No. 15 white oil. In other embodiments, the dispersion medium is No. 18 white oil. In other embodiments, the dispersion medium is biodiesel. In other embodiments, the dispersion medium is methyl oleate. In other embodiments, the dispersion medium is ethylene glycol diacetate. In other embodiments, the dispersion medium is polyethylene glycol 200. In other embodiments, the dispersion medium is polyethylene glycol 300. In other embodiments, the dispersion medium is polyethylene glycol 400. In other embodiments, the dispersion medium is a mixture of No. 3 white oil, No. 5 white oil, No. 7 white oil, No. 10 white oil, No. 15 white oil, No. 18 white oil, biodiesel, methyl oleate, ethylene glycol diacetate, polyethylene glycol 200, polyethylene glycol 300, and polyethylene glycol 400 in equal mass ratios.

[0156] The preparation method of the above-mentioned self-crosslinking plant gum concentrated suspension system includes the following steps:

[0157] S1: Add the formula amount of thickener to the formula amount of dispersion medium, stir for 2 hours, then add the formula amount of emulsifier, stir for 20 minutes to obtain a suspension;

[0158] S2: Add the prescribed amounts of guar gum, boron ore powder, and penetrant to the suspension obtained in step S1 in sequence, stir for 60 minutes, and after mixing evenly, obtain a self-crosslinking plant gum concentrated suspension system.

[0159] Furthermore, the thickener is added to the dispersion medium and then stirred at a speed of 10,000 rpm, and / or

[0160] After the emulsifier is added to the dispersion medium, it is stirred at a speed of at least 7000 rpm, and / or

[0161] Guar gum, fine boron ore powder, and penetrant were added to the suspension in sequence and then stirred at a speed of 6000 rpm.

[0162] Furthermore, the boron ore fine powder in step S2 needs to be screened before use. It can only be used after passing the screening. The screening steps are as follows:

[0163] Step 1: Crush the boron ore into fine powder using a crusher, pass it through a 325-mesh sieve, and then dry it at 105℃ for 3 hours;

[0164] Step 2: Add 0.002 g of boron ore powder to 100 g of deionized water, stir at high speed for 5 minutes, and test with a pH meter. It can be used when the pH value is in the range of 6.5 to 8.58.

[0165] The self-crosslinking plant gum concentrate suspension system is prepared by any one of the methods described above.

[0166] The aforementioned self-crosslinking plant gum concentrated suspension system is used as a fracturing agent in the exploitation of low-permeability oil reservoirs.

[0167] Example 1

[0168] The preparation method of the self-crosslinking plant gum concentrated suspension system is as follows:

[0169] (1) Further pulverize the instant guar gum powder and pass it through a 240-mesh sieve; pulverize the calcium borate and pass it through a 325-mesh sieve to obtain calcium borate fine powder.

[0170] (2) Add 200g of No. 5 white oil to a dry reactor, adjust the speed of the high-speed mixer to 9000 rpm, slowly add 6.4g of organic bentonite, and stir continuously for 60 minutes; adjust the speed of the high-speed mixer to 6000 rpm, add nonylphenol polyoxyethylene ether, and stir continuously for 10 minutes to obtain a suspension.

[0171] (3) Adjust the speed of the high-speed mixer to 5000 rpm, add 162 g of guar gum, 60 g of fine borosilicate powder and 2 ml of fatty alcohol polyoxyethylene ether to the suspension in sequence, stir for 30 minutes to obtain the cross-linked plant gum concentrated suspension system.

[0172] Furthermore, the fine powder of borosilicate needs to be screened before use. Only after passing the screening can it be used. The screening steps are as follows:

[0173] Step 1: Use a pulverizer to pulverize the calcium borate into fine powder, pass it through a 325-mesh sieve, and then dry it at 105℃ for 3 hours to obtain calcium borate fine powder;

[0174] Step 2: Add 0.002 g of fine borosilicate powder to 100 g of deionized water, stir at high speed for 5 minutes, and test with a pH meter. The pH value is 7.8, which is acceptable.

[0175] Example 2

[0176] The preparation method of the self-crosslinking plant gum concentrated suspension system is as follows:

[0177] (1) Further pulverize the instant guar gum powder and pass it through a 240-mesh sieve; pulverize the calcium borate and pass it through a 325-mesh sieve to obtain calcium borate fine powder.

[0178] (2) Add 200g of biodiesel to a dry reactor, adjust the speed of the high-speed mixer to 10000 rpm, slowly add 6.9g of polyamide wax, and stir continuously for 60 minutes; adjust the speed of the high-speed mixer to 8000 rpm, add octylphenol polyoxyethylene ether, and stir continuously for 10 minutes to obtain a suspension.

[0179] (3) Adjust the speed of the high-speed mixer to 7000 rpm, add 162 g of guar gum, 60 g of fine borosilicate powder and 2 ml of fatty alcohol polyoxyethylene ether to the suspension in sequence, stir for 30 minutes to obtain the cross-linked plant gum concentrated suspension system.

[0180] Furthermore, the fine powder of borosilicate needs to be screened before use. Only after passing the screening can it be used. The screening steps are as follows:

[0181] Step 1: Use a pulverizer to pulverize the calcium borate into fine powder, pass it through a 325-mesh sieve, and then dry it at 105℃ for 3 hours to obtain calcium borate fine powder;

[0182] Step 2: Add 0.002 g of fine borosilicate powder to 100 g of deionized water, stir at high speed for 5 minutes, and test with a pH meter. The pH value is 7.8, which is acceptable.

[0183] Example 3

[0184] The preparation method of the self-crosslinking plant gum concentrated suspension system is as follows:

[0185] (1) Further pulverize guar collagen powder and pass it through a 240-mesh sieve; pulverize boron magnesium ore and pass it through a 325-mesh sieve to obtain fine boron magnesium ore powder;

[0186] (2) Add 200g of methyl oleate to a dry reactor, adjust the speed of the high-speed mixer to 10500 rpm, slowly add 5.4g of organic bentonite, and stir continuously for 60 minutes; adjust the speed of the high-speed mixer to 7000 rpm, add dehydrated sorbitan monooleate polyoxyethylene ether, and stir continuously for 10 minutes to obtain a suspension.

[0187] (3) Adjust the speed of the high-speed mixer to 6000 rpm, add 162 g of guar collagen powder, 60 g of boron magnesium ore fine powder and 2 ml of fatty alcohol polyoxyethylene ether to the suspension in sequence, stir for 30 minutes to obtain the cross-linked plant gum concentrated suspension system.

[0188] Furthermore, the fine boron-magnesium ore powder needs to be screened before use. Only after passing the screening can it be used. The screening steps are as follows:

[0189] Step 1: Use a pulverizer to pulverize the boron-magnesium ore into fine powder, pass it through a 325-mesh sieve, and then dry it at 105℃ for 3 hours to obtain fine boron-magnesium ore powder;

[0190] Step 2: Add 0.002 g of fine boron-magnesium ore powder to 100 g of deionized water, stir at high speed for 5 minutes, and test with a pH meter. The pH value is 7.2, which is acceptable.

[0191] Example 4

[0192] The preparation method of the self-crosslinking plant gum concentrated suspension system is as follows:

[0193] (1) Further pulverize guar collagen powder and pass it through a 240-mesh sieve; pulverize boron magnesium ore and pass it through a 325-mesh sieve to obtain fine boron magnesium ore powder;

[0194] (2) Add 200g of polyethylene glycol 200 to a dry reactor, adjust the speed of the high-speed mixer to 10000 rpm, slowly add 5.2g of fumed silica, and stir continuously for 60 minutes; adjust the speed of the high-speed mixer to 6000 rpm, add dehydrated sorbitan monooleate polyoxyethylene ether, and stir continuously for 10 minutes to obtain a suspension.

[0195] (3) Adjust the speed of the high-speed mixer to 5000 rpm, add 162 g of guar collagen powder, 60 g of boron magnesium ore fine powder and 2 ml of fatty alcohol polyoxyethylene ether to the suspension in sequence, stir for 30 minutes to obtain the cross-linked plant gum concentrated suspension system.

[0196] Furthermore, the fine boron-magnesium ore powder needs to be screened before use. Only after passing the screening can it be used. The screening steps are as follows:

[0197] Step 1: Use a crusher to crush the boron-magnesium ore into fine powder, pass it through a 325-mesh sieve, and then dry the fine boron-magnesium ore powder at 105℃ for 3 hours;

[0198] Step 2: Add 0.002 g of fine boron-magnesium ore powder to 100 g of deionized water, stir at high speed for 5 minutes, and test with a pH meter. The pH value is 7.2, which is acceptable.

[0199] Performance testing

[0200] Test Example 1: Apparent Viscosity Test

[0201] Experimental method: Take 394g of tap water and add 6.0mL of the self-crosslinking plant gum concentrated suspension system prepared in Examples 1-4 of this invention at a stirring speed of 700 rpm. Stop stirring after 30 seconds and immediately measure the 100s using a six-speed rotational viscometer. -1 The apparent viscosity is as follows.

[0202] A comparative experiment was conducted using the self-crosslinking high-carrying-propeller fracturing fluid from Shengli Petrochemical Co., Ltd.

[0203] The results of the apparent viscosity test are shown in Table 1.

[0204] Table 1. Apparent viscosity test results (unit: mPa·s)

[0205] Time (S) 30 90 180 300 420 600 Example 1 9.0 16.5 27 40.5 57.0 81 Example 2 9.0 15.0 25.5 39.0 55.5 79.5 Example 3 7.5 13.5 25.5 39.0 54.0 78.0 Example 4 9.0 16.5 27 40.5 57.0 79.5 Comparative Example 6.0 12.0 23.5 36.0 43.5 48.0

[0206] As shown in Table 1, the self-crosslinking plant gum concentrated suspension systems prepared in Examples 1-4 of this invention, at a usage concentration of 1.5%, all exhibited an apparent viscosity of 7.5 mPa·s or higher after 30 seconds and an apparent viscosity of 78 mPa·s or higher after 600 seconds, with the highest reaching 81 mPa·s. In contrast, the apparent viscosities of the self-crosslinking high-proppant-carrying fracturing fluid from Shengli Petrochemical Co., Ltd., used as a comparative example, were 6.0 mPa·s and 48.0 mPa·s, respectively. The self-crosslinking plant gum concentrated suspension system of this invention is significantly superior to the comparative example.

[0207] Test Example 2: Temperature and Shear Resistance Test

[0208] Experimental method: Take 197g of tap water and add 3.0mL of the self-crosslinking plant gum concentrated suspension system of the present invention (Examples 1-4) at a stirring speed of 700 rpm. Stop stirring when the stirring time reaches 300 seconds. Test the temperature at 120℃ and 170 seconds using a Harker MARS III high temperature and high pressure rheometer. -1 The apparent viscosity after continuous shearing for 120 min was taken as the viscosity after high-temperature shearing.

[0209] A comparative example was prepared using self-crosslinking high-proppant-carrying fracturing fluid from Shengli Petrochemical Co., Ltd. The results are shown in Table 2.

[0210] Test Example 3: Hanging Test

[0211] Experimental method: Take 197g of tap water and add 3.0mL of the self-crosslinking plant gum concentrated suspension system prepared in Examples 1-4 of this invention while stirring at 700 rpm. Stop stirring after 300 seconds and place in a constant temperature water bath at 90℃. Stir with a glass rod and observe the adhesion. At the same time, measure the internal temperature of the fracturing fluid with a thermometer as the crosslinking temperature.

[0212] A comparative experiment was conducted using the self-crosslinking high-carrying-propeller fracturing fluid from Shengli Petrochemical Co., Ltd.

[0213] The results are shown in Table 2.

[0214] Test Example 4: Adhesive Destruction Test

[0215] Experimental method: Take 197g of tap water, and add 0.06g of ammonium persulfate and 3.0mL of the self-crosslinking plant gum concentrated suspension system prepared in Examples 1-4 of this invention sequentially while stirring at 700 rpm. Stop stirring after 300 seconds, pour into a wide-mouth bottle, seal it, and place it in a constant temperature water bath at 90℃. After 6 hours, remove it and test the viscosity and pH value of the broken gum solution using a glass capillary viscometer.

[0216] A comparative example was the self-crosslinking high-carrying-propeller fracturing fluid from Shengli Petrochemical Co., Ltd.

[0217] The results are shown in Table 2.

[0218] Table 2 Results of shear resistance, crosslinking and debonding performance tests

[0219]

[0220] As can be seen from Table 2, the self-crosslinking plant gum concentrated suspension system prepared in Examples 1-4 of the present invention has a maximum viscosity of 114 mPa·s after high-temperature shearing, while the comparative example has a viscosity of only 36 mPa·s. The self-crosslinking plant gum concentrated suspension system of the present invention is significantly better than the comparative example.

[0221] As can be seen from Table 2, the self-crosslinking plant gum concentrated suspension systems prepared in Examples 1-4 of the present invention can all be picked up at a crosslinking temperature of 52-58°C, while the comparative examples cannot be picked up.

[0222] As can be seen from Table 2, the self-crosslinking plant gum concentrated suspension system prepared in Examples 1-4 of the present invention has a liquid viscosity of no more than 2.0 mPa·s, indicating complete dissolution and water dissolution. In contrast, the comparative example has a viscosity of 5.8 mPa·s, indicating incomplete dissolution and water dissolution.

[0223] Test Example 5: On-site Water Reinjection Test

[0224] The reinjected water at a certain Shengli joint station had a chloride content of 4621 mg / L, a temperature of 42℃, a mineralization of 9830 mg / L, and a calcium + magnesium ion content of 305 mg / L.

[0225] The test was conducted using reinjected water, following the test methods described in Test Examples 1-4.

[0226] A comparative example was the self-crosslinking high-carrying-propeller fracturing fluid from Shengli Petrochemical Co., Ltd.

[0227] The test results are shown in Table 3.

[0228] Table 3 Results of Reinjection Water Test

[0229]

[0230] As shown in Table 3, the self-crosslinking plant gum concentrate suspension systems prepared in Examples 1-4 of this invention can all effectively thicken, crosslink, and exhibit good adhesion, with a viscosity of less than 3.6 mPa·s after dissolution. In contrast, the control sample exhibits poor thickening performance, fails to crosslink or exhibit good adhesion, and produces flocculent material after dissolution. This is significantly lower than the self-crosslinking plant gum concentrate suspension system of this invention.

[0231] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A self-crosslinking plant gum concentrated suspension system, characterized in that, The product, by mass percentage, comprises thickener, emulsifier, guar gum, fine boron ore powder, penetrant, and dispersion medium, based on the weight of the self-crosslinking plant gum concentrated suspension system, wherein: The thickener content is 0.5-5 wt%; The emulsifier content is 0.2–2 wt%. The guar gum content is 20-60 wt%; The content of the fine boron ore powder is 5-25 wt%; The content of the penetrant is 0.01-4 wt%; The remainder is the dispersion medium.

2. The self-crosslinking plant gum concentrated suspension system as described in claim 1, characterized in that, The thickener content is 1-5 wt%. The emulsifier content is 0.2–2 wt%. The guar gum content is 30-50 wt%. The content of the fine boron ore powder is 6-20 wt%. The content of the penetrant is 0.01–2 wt%. The remainder is the dispersion medium.

3. The self-crosslinking plant gum concentrated suspension system as described in claim 1 or 2, characterized in that, The thickener is one or more of organobentonite, polyamide wax, and fumed silica, and / or The emulsifier is one or more of nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, sorbitan monostearate, sorbitan monooleate, and sorbitan monooleate polyoxyethylene ether, and / or The guar gum is one or both of instant guar gum or guar gum powder.

4. The self-crosslinking plant gum concentrated suspension system as described in claim 3, characterized in that, The instant guar gum powder is at least 240 mesh instant guar gum powder.

5. A self-crosslinking plant gum concentrated suspension system as described in claim 1 or 2, characterized in that, The boron ore fine powder is one or more of the following: borate fine powder, boromagnesia ore fine powder, and calcium borate fine powder, and / or The penetrant is a fatty alcohol polyoxyethylene ether with the molecular formula RO(CH2CH2O)nH, where R is a C5-C7 alkyl group, n = 5-7, and / or The dispersion medium is one or more of the following: No. 3 white oil, No. 5 white oil, No. 7 white oil, No. 10 white oil, No. 15 white oil, No. 18 white oil, biodiesel, methyl oleate, ethylene glycol diacetate, polyethylene glycol 200, polyethylene glycol 300, and polyethylene glycol 400.

6. The method for preparing the self-crosslinking plant gum concentrated suspension system according to any one of claims 1-5, characterized in that, The steps are as follows: S1: Add the thickener of the formula amount to the dispersion medium of the formula amount, stir for at least 1 hour, then add the emulsifier of the formula amount to it, stir for at least 10 minutes to obtain a suspension; S2: Add the prescribed amounts of guar gum, boron ore powder, and penetrant to the suspension obtained in step S1 in sequence, stir for at least 30 minutes, and after mixing evenly, obtain a self-crosslinking plant gum concentrated suspension system.

7. The method for preparing the self-crosslinking plant gum concentrated suspension system as described in claim 6, characterized in that, The thickener is added to the dispersion medium and then stirred at a speed of at least 9000 rpm, preferably 9000–11000 rpm, and / or After the emulsifier is added to the dispersion medium, it is stirred at a speed of at least 6000 rpm, preferably 6000–8000 rpm, and / or Guar gum, fine boron ore powder, and penetrant are added to the suspension in sequence and then stirred at a speed of at least 5000 rpm, preferably 5000-7000 rpm.

8. The method for preparing the self-crosslinking plant gum concentrated suspension system as described in claim 6, characterized in that, The boron ore powder in step S2 needs to be screened before use. It can only be used after passing the screening. The screening steps are as follows: Step 1: Crush the boron ore into fine powder using a crusher, pass it through a 325-mesh sieve, and then dry it at 105℃ for 2-4 hours; Step 2: Add 0.002 g of boron ore powder to 100 g of deionized water, stir at high speed for 5 minutes, and test with a pH meter. It can be used when the pH value is in the range of 6.5 to 8.

58.

9. A self-crosslinking plant gum concentrated suspension system, characterized in that, Prepared by any of the methods described above.

10. The application of the self-crosslinking plant gum concentrated suspension system according to any one of claims 1-5 and 9 as a fracturing agent in the exploitation of low-permeability oil reservoirs.

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