Self-anti-swelling, self-drag-reduction and self-hydrolysis full-crack proppant and preparation method thereof

Abstract

The invention relates to the technical field of full-fracture proppants, and discloses a preparation method of a self-anti-swelling, self-drag-reduction and self-hydrolysis full-fracture proppant, which comprises the following steps: S1, obtaining special polymer powder: dissolving an acrylamide polymer in a mixed solution of methanol and water in a volume ratio of 2: 1, heating and refluxing, dropwise adding dodecylphenol, refluxing for 1 hour, and filtering to obtain the special polymer powder; (3-chloropropyl) triethoxysilane is added, a saturated sodium carbonate solution is dropwise added at a constant speed, heat preservation is conducted for 30 m < 1 > n, vacuum drying and smashing are conducted, and modified special polymer powder is obtained. According to the invention, high molecules with self-anti-swelling, self-drag-reduction and self-hydration capabilities are combined with solid particles to form a whole, a new fracturing propping agent system is formed, and clear water can be utilized to carry out fracturing operation, so that full-fracture support with self-drag-reduction, self-anti-swelling, self-hydrolysis, high-suspension and long-distance transportation is realized.

Description

Technical Field

[0001] The invention relates to the technical field of proppants, and in particular to a self-swelling-proof, self-drag-reducing and self-hydrolyzing full-fracture proppant and a preparation method thereof. Background Art

[0002] In the existing fracturing system, fracturing fluid and proppant are two independent systems. Fracturing fluid can suspend sand, carry sand, reduce friction and other functions to reduce construction pressure. During construction, debonding agent is often added to ensure that fracturing fluid can be hydrated and returned after carrying sand.

[0003] The disadvantages of this construction scheme are:

[0004] 1) The construction process requires independent preparation of fracturing fluid, which contains a series of additives such as drag reducer, anti-swelling agent, drainage agent, etc. The preparation process is complicated, costly, time-consuming and labor-intensive;

[0005] 2) Fracturing fluid and proppant are two independent systems. Fracturing fluid relies entirely on viscosity to carry sand. The viscosity of fracturing fluid tends to drop rapidly due to flow shear, resulting in low sand carrying efficiency and seriously affecting the laying radius. Studies have found that in the fracturing cracks of the reservoir, the proppant migration distance is much shorter than the designed half-crack length.

[0006] 3) During the hydraulic fracturing process, due to the rough outer surface of the solid proppant, there are rigid collisions between particles, particles and blastholes, and fracture walls, resulting in the fragments of the proppant after collision seriously affecting the conductivity of the fracture.

[0007] As mentioned above, the traditional fracturing system has obvious technical disadvantages. Summary of the invention

[0008] The purpose of the present invention is to solve the problems existing in the prior art and to propose a self-swelling-proof, self-drag-reducing and self-hydrolyzing full-fracture proppant and a preparation method thereof.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A method for preparing a self-swelling, self-drag-reducing and self-hydrolyzing full-fracture proppant comprises the following steps:

[0011] S1, obtain specialty polymer powder:

[0012] The acrylamide polymer was dissolved in a mixture of methanol and water in a volume ratio of 2:1, heated to reflux, dodecylphenol was added dropwise, refluxed for 1 hour, (3-chloropropyl) triethoxysilane was added, and then saturated sodium carbonate solution was added dropwise at a uniform rate, kept warm for 30 minutes, vacuum dried, and crushed to obtain a modified special polymer powder;

[0013] S2, preparation of full fracture proppant:

[0014] S201: Take quartz sand, pass it through a 20 / 40 mesh sieve, and set aside;

[0015] S202: heating to 140° C., adding the special polymer powder prepared in step S1 to the sandy inner core;

[0016] S203: adding clean water several times during the stirring process and monitoring the temperature of the mixture until the temperature of the mixture drops to 80 degrees Celsius;

[0017] S204: Continue stirring, drying, crushing, and screening to obtain full-fracture proppant.

[0018] Preferably, in step S1, the weight ratio of acrylamide polymer, mixed solution, dodecylphenol, (3-chloropropyl)triethoxysilane and saturated sodium carbonate solution is 5:500:0.2:0.5:10.

[0019] Preferably, in step S1, the saturated sodium carbonate solution is added dropwise at an amount of 1% per minute.

[0020] Preferably, in step S202, the added amount of the special polymer powder is 0.05-1.5wt% of the quartz sand.

[0021] Preferably, in step S1, the molecular weight of the acrylamide polymer is 1 million.

[0022] Preferably, in step S204, the particle size of the full-fracture proppant obtained after screening is in the range of 16-200 mesh.

[0023] A self-swelling-proof, self-drag-reducing and self-hydrolyzing full-fracture proppant is prepared by adopting the above preparation method.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention integrates a polymer with self-swelling prevention, self-drag reduction and self-hydration capabilities with solid particles to form a new fracturing proppant system, which can use clean water for fracturing operations to achieve full fracture support with self-drag reduction, self-swelling prevention, self-hydrolysis, and high suspension and long-distance transportation. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0027] Example 1

[0028] The preparation method of the proppant described in this embodiment is as follows:

[0029] (1) Dissolve 5g of acrylamide polymer (molecular weight of 1 million) in 500mL of a mixture of methanol and water in a volume ratio of 2:1, heat to reflux, drop 0.2g of dodecylphenol, reflux for 1h, then add 0.5g of (3-chloropropyl)triethoxysilane, then drop 10g of saturated sodium carbonate solution at a rate of 0.1g per minute, and keep warm for 30min. Vacuum dry and crush to obtain modified specialty polymer powder.

[0030] (2) Take 1 kg of quartz sand and pass it through a 20 / 40 mesh sieve for later use;

[0031] (3) Heat to 140°C and add 10 g of the special polymer powder prepared in (1) to the sandy inner core.

[0032] (4) During the stirring process, add clean water several times, 10 ml at a time, and monitor the mixing temperature. When the mixing temperature drops to 80 degrees Celsius, stop.

[0033] (5) Continue stirring, drying, crushing and screening to obtain full-fracture proppant.

[0034] Example 2

[0035] The preparation method of the proppant described in this embodiment is as follows:

[0036] (1) Dissolve 5g of acrylamide polymer (molecular weight of 1 million) in 500mL of a mixture of methanol and water in a volume ratio of 2:1, heat to reflux, drop 0.2g of dodecylphenol, reflux for 1h, then add 0.5g of (3-chloropropyl)triethoxysilane, then drop 10g of saturated sodium carbonate solution at a rate of 0.1g per minute, and keep warm for 30min. Vacuum dry and crush to obtain modified specialty polymer powder.

[0037] (2) Take 1 kg of quartz sand and pass it through a 20 / 40 mesh sieve for later use;

[0038] (3) Heat to 140°C and add 15 g of the special polymer powder prepared in (1) to the sandy inner core.

[0039] (4) During the stirring process, add clean water several times, 10 ml at a time, and monitor the mixing temperature. When the mixing temperature drops to 80 degrees Celsius, stop.

[0040] Example 3

[0041] The preparation method of the proppant described in this embodiment is as follows:

[0042] (1) Dissolve 5g of acrylamide polymer (molecular weight of 1 million) in 500mL of a mixture of methanol and water in a volume ratio of 2:1, heat to reflux, drop 0.2g of dodecylphenol, reflux for 1h, then add 0.5g of (3-chloropropyl)triethoxysilane, then drop 10g of saturated sodium carbonate solution at a rate of 0.1g per minute, and keep warm for 30min. Vacuum dry and crush to obtain modified specialty polymer powder.

[0043] (2) Take 1 kg of ceramsite and pass it through a 20 / 40 mesh sieve for later use;

[0044] (3) Heat to 140°C and add 15 g of the special polymer powder prepared in (1) to the sandy inner core.

[0045] (4) During the stirring process, add clean water several times, 10 ml at a time, and monitor the mixing temperature. When the mixing temperature drops to 80 degrees Celsius, stop.

[0046] Comparative Example 1

[0047] The clean water fracturing system described in this comparative example includes the following components:

[0048] Active water: 0.25g anionic polyacrylamide (3 million), 1g OP-10, 10g potassium chloride, 0.1g formaldehyde and 488.65g water.

[0049] Proppant: Ordinary expanded clay proppant.

[0050] The preparation method of the water-based fracturing fluid described in this comparative example is as follows:

[0051] (1) dissolving the above-mentioned specific amount of polyacrylamide in 488.65 g of water and mixing them evenly to obtain thickened water;

[0052] (2) dissolving the above-mentioned specific amount of OP-10 in the obtained thickened water and mixing evenly;

[0053] (3) Add 10 g of potassium chloride to the thickened water in step (2) and stir evenly;

[0054] (4) Add 0.1 g of formaldehyde to the thickened water in step (3) and stir evenly.

[0055] Comparative Example 2

[0056] The clean water fracturing system described in this comparative example includes the following components:

[0057] Active water: 0.25g anionic polyacrylamide (3 million), 1g OP-10, 10g potassium chloride, 0.1g formaldehyde and 488.65g water.

[0058] Proppant: Quartz sand.

[0059] The preparation method of the water-based fracturing fluid described in this comparative example is as follows:

[0060] (1) dissolving the above-mentioned specific amount of polyacrylamide in 488.65 g of water and mixing them evenly to obtain thickened water;

[0061] (2) dissolving the above-mentioned specific amount of OP-10 in the obtained thickened water and mixing evenly;

[0062] (3) Add 10 g of potassium chloride to the thickened water in step (2) and stir evenly;

[0063] (4) Add 0.1 g of formaldehyde to the thickened water in step (3) and stir evenly.

[0064] In order to verify the effect of the full-fracture proppant prepared by the present invention, the following performance tests are now carried out:

[0065] Sedimentation velocity determination:

[0066] Use a 0.5m plexiglass tube, fill it with 45cm high active water and proppant with a sand ratio of 20%, shake it well and test the sedimentation rate of the proppant;

[0067] Drag reduction rate, anti-swelling rate and surface tension of debonding liquid:

[0068] Measured using "SY / T 6376-2008 General Technical Conditions for Fracturing Fluids";

[0069] Self-breaking performance:

[0070] 1) Take 100g of clean water and add 30g of the sample of the embodiment, stir for 1min, then put it into a water bath at 60℃ for 4h, and then test the liquid viscosity;

[0071] 2) Take the comparative liquid, put it into a water bath at 60℃ for 4 hours, and then test the viscosity of the liquid.

[0072] The test results are shown in the following table:

[0073] Table 1 Settling velocity of proppant

[0074]

[0075] Table 2 Drag reduction rate of proppant

[0076]

[0077] Table 3 Anti-swelling rate of proppant

[0078]

[0079] Table 4 Surface tension of proppant breaking solution

[0080]

[0081] Table 5 Breaking viscosity of proppant

[0082]

[0083] It can be seen from the above results that the present invention has excellent sand carrying capacity and friction reduction capacity. Compared with the preparation method of a full-fracture proppant in the existing patent (Announcement No. CN 113755154 A), the present invention adds dodecylphenol on the basis of the existing technology, introduces dodecyl hydrophobic groups on the molecular chain through reaction, so that its water-soluble polymer can form a hydrophobic association effect in water, and achieves a gelling effect at a lower concentration, thereby increasing the low sand ratio suspension of the proppant, the construction friction reduction performance, and the better gel breaking and drainage performance. The specific principle is:

[0084] 1) Add dodecylphenol to introduce dodecyl hydrophobic chains into the polyacrylamide molecular chain through reaction. The presence of this hydrophobic chain allows the modified polymer to form hydrophobic associations in aqueous solution, that is, the dodecyl groups in the molecular chain form associated micelles, which play a weak cross-linking role at a certain concentration (CMC), increase the viscosity of the aqueous solution, and thus hinder the sedimentation of quartz sand;

[0085] 2) After gel breaking, the dodecyl group will be decomposed into anionic dodecyl surfactant, which will reduce the surface tension of the gel breaking liquid and play a role in assisting drainage.

[0086] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a self-swelling, self-drag-reducing, self-hydrolyzing full-fracture proppant, characterized in that: The following steps are involved: S1, obtain specialty polymer powder: The acrylamide polymer was dissolved in a mixture of methanol and water in a volume ratio of 2:1, heated to reflux, dodecylphenol was added dropwise, refluxed for 1 hour, (3-chloropropyl) triethoxysilane was added, and then saturated sodium carbonate solution was added dropwise at a uniform rate, kept warm for 30 minutes, vacuum dried, and crushed to obtain a modified special polymer powder; S2, preparation of full fracture proppant: S201: Take quartz sand, pass it through a 20 / 40 mesh sieve, and set aside; S202: heating to 140° C., adding the special polymer powder prepared in step S1 to the sandy inner core; S203: adding clean water several times during the stirring process and monitoring the temperature of the mixture until the temperature of the mixture drops to 80 degrees Celsius; S204: Continue stirring, drying, crushing, and screening to obtain full-fracture proppant.

2. The method for preparing a self-swelling, self-drag-reducing, self-hydrolyzing full-fracture proppant according to claim 1, characterized in that: In the step S1, the weight ratio of acrylamide polymer, mixed solution, dodecylphenol, (3-chloropropyl)triethoxysilane, and saturated sodium carbonate solution is 5:500:0.2:0.5:

10.

3. The method for preparing a self-swelling-proof, self-drag-reducing and self-hydrolyzing full-fracture proppant according to claim 2, characterized in that: In the step S1, the saturated sodium carbonate solution is added dropwise at a rate of 1% per minute.

4. The method for preparing a self-swelling-proof, self-drag-reducing and self-hydrolyzing full-fracture proppant according to claim 2, characterized in that: In the step S202, the added amount of the special polymer powder is 0.05-1.5wt% of the quartz sand.

5. The method for preparing a self-swelling-proof, self-drag-reducing and self-hydrolyzing full-fracture proppant according to claim 1, characterized in that: In step S203, the addition of clean water is to cool the sand to 80 degrees Celsius.

6. The method for preparing a self-swelling-proof, self-drag-reducing, self-hydrolyzing full-fracture proppant according to claim 1, characterized in that: In the step S1, the molecular weight of the acrylamide polymer is 1 million.

7. The method for preparing a self-swelling-proof, self-drag-reducing and self-hydrolyzing full-fracture proppant according to claim 1, characterized in that: In the step S204, the particle size of the full-fracture proppant obtained after screening is in the range of 16-200 mesh.

8. A self-swelling-proof, self-drag-reducing and self-hydrolyzing full-fracture proppant, prepared by the preparation method according to any one of claims 1 to 7.

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