Preparation method of variable-density petroleum fracturing propping agent

Abstract

The invention relates to the technical field of preparation of petroleum fracturing propping agents, and particularly provides a preparation method of a variable-density petroleum fracturing propping agent which comprises 5-10 parts of polyethylene glycol 400, 1-5 parts of polyethylene glycol 600, 5-15 parts of polyacrylamide, 1600-2200 parts of propping agent raw materials, 1-5 parts of a coupling agent, 80-100 parts of an adhesive and 10-30 parts of a curing agent. The preparation method comprises the following steps: step 1, preparing a solution A; step 2, preparing a carrying liquid B; step 3, treating the proppant raw materials; 4, the proppant raw materials are treated again; 5, preparing a sample C; and 6, mixing the sample C into the solution B to obtain a finished product. The prepared petroleum fracturing propping agent has a high suspension effect, is like a'swim ring 'in water, effectively reduces the settling time of the propping agent, improves the petroleum permeability, and further improves the oil yield.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum fracturing proppant preparation, and in particular to a method for preparing a variable-density petroleum fracturing proppant. Background Art

[0002] Oil fracturing proppants play a crucial role in the fracturing process. Currently, quartz sand and ceramsite are the most commonly used proppants, but they share a common disadvantage: high density. This makes the proppants easily settle when driven into formation fractures, making them unable to effectively support the fracture length during fracturing. This leads to lower permeability and reduced oil production. Currently, the market typically increases the viscosity of the fracturing fluid or replaces traditional ceramsite or quartz sand with low-density proppants. However, increasing the viscosity of the fracturing fluid also increases the difficulty and cost of construction, while using low-density proppants is costly and reduces strength. Therefore, the current problem remains unresolved. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing a variable density petroleum fracturing proppant, which is used to solve the problem of fast sedimentation rate of quartz sand or ceramsite as proppant in the prior art due to its high density.

[0004] To achieve the above-mentioned and other related purposes, the present invention provides a variable-density petroleum fracturing proppant, which comprises the following components, by weight: 5-10 parts of polyethylene glycol 400, 1-5 parts of polyethylene glycol 600, 5-15 parts of polyacrylamide, 1600-2200 parts of proppant raw material, 1-5 parts of coupling agent, 80-100 parts of adhesive, and 10-30 parts of curing agent.

[0005] In one embodiment of the present invention, the proppant raw material is quartz sand or ceramsite with a particle size of 20-100 mesh.

[0006] In one embodiment of the present invention, the coupling agent is any one of KH550, KH-560, KH-570, A151, A171, and A172.

[0007] In one embodiment of the present invention, the adhesive is made by mixing epoxy resin and a foaming agent (polymethylhydrogensiloxane).

[0008] In one embodiment of the present invention, the epoxy resin is selected from one or both of E51 and E44 types.

[0009] In one embodiment of the present invention, the mixing ratio of the foaming agent to the epoxy resin is 1-3:80-100.

[0010] In one embodiment of the present invention, the curing agent is any one of polyamide 650, T31, JH-1020, and JH-0112.

[0011] A method for preparing a variable-density petroleum fracturing proppant comprises the following steps:

[0012] Step 1: Place 5-10 parts of polyethylene glycol 400, 1-5 parts of polyethylene glycol 600, and 5-15 parts of polyacrylamide in a container and stir at 1000 rpm for 2 hours to obtain solution A.

[0013] Step 2: Add 5000 mL of distilled water to Liquid A and stir Liquid A in the distilled water with a stirring rod until it is completely dispersed to obtain a carrier liquid B with a viscosity of 30-60 mPa·s;

[0014] Step 3: Select 800-1000 parts of proppant raw material with a particle size of 20-100 mesh, wash it in an aqueous solution, take it out, and then soak it in an acidic solution for 2 hours. The temperature during the soaking process is controlled at 40°C. After soaking, take it out, wash it with distilled water until it is neutral, and dry it for later use;

[0015] Step 4: Take 1-5 parts of the coupling agent and place it into 1600-2200 parts of the proppant raw material treated in step 3, and perform surface treatment at 50-90°C for 4 hours. After the treatment is completed, take it out and dry it for later use;

[0016] Step 5: Mix 80-100 parts of adhesive with 1600-2200 parts of the proppant raw material processed in step 4, then add 16-22 parts of curing agent, and mix well to obtain sample C;

[0017] Step 6: Slowly add sample C into liquid B and stir at a speed of 300-500 r / min for 1-2 hours to obtain a variable density petroleum fracturing proppant product.

[0018] In one embodiment of the present invention, in step three, the acidic solution comprises hydrofluoric acid with a concentration of 0-3% and oxalic acid with a concentration of 3-8%.

[0019] In one embodiment of the present invention, in step 6, the volume density of the variable density petroleum fracturing proppant product is variable in the range of 0.7-1 g·cm -3 .

[0020] As described above, the method for preparing the variable density petroleum fracturing proppant of the present invention has the following beneficial effects:

[0021] The present invention uses polyethylene glycol 400, polyethylene glycol 600, polyacrylamide, proppant raw materials, coupling agents, adhesives, and curing agents as raw materials for product preparation. A circle of gas-containing "sleeping ring" resembling a "swimming ring" is formed on the outer surface of quartz sand or ceramsite. By adding a foaming agent, the proppant has a good suspension effect. Compared with the traditional method of using quartz sand and ceramic as proppant materials, this product can greatly prolong its sedimentation time during use; and the volume density of this product can be reduced to 1g / cm -3 The following greatly ensures the strength of the proppant product; by adjusting the adhesive component ratio, the volume density of this product is 0.7-1g / cm -3 The proppant can be varied within a certain range and the volume density can be adjusted according to actual application needs, with excellent application adaptability. The present invention also makes the proppant and the sand-carrying fluid compatible with each other, thus avoiding the adverse effects caused by the compatibility problems of the sand-carrying fluid brought about by different construction methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shown is an enlarged picture of Sample 1 prepared in Example 3.

[0023] Figure 2 Shown is an enlarged image of Sample 2 prepared in Example 3.

[0024] Figure 3 An enlarged picture of Sample 3 prepared in Example 3 is shown.

[0025] Figure 4 The following is a comparison of the sedimentation of the quartz sand in Example 4 and Sample 1 at 5 minutes.

[0026] Figure 5 The following is a comparison of the sedimentation of the quartz sand in Example 4 and Sample 2 at 5 minutes.

[0027] Figure 6 The following is a comparison of the sedimentation of the quartz sand in Example 4 and Sample 3 at 5 minutes.

[0028] Figure 7 Shown is the equipment used to determine the bulk density Pbulk in Example 4. DETAILED DESCRIPTION

[0029] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0030] See also Figures 1 to 7. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0031] Example 1. This embodiment provides a variable density petroleum fracturing proppant, which comprises the following components in parts by weight: 5-10 parts of polyethylene glycol 400, 1-5 parts of polyethylene glycol 600, 5-15 parts of polyacrylamide, 1600-2200 parts of proppant raw material, 1-5 parts of coupling agent, 80-100 parts of adhesive, and 10-30 parts of curing agent; the proppant raw material is quartz sand or ceramsite with a particle size of 20-100 mesh; the coupling agent is KH550, KH-560, KH-570, A1 51, any one of A171, and A172; the adhesive is made by mixing epoxy resin and foaming agent (polymethylhydrogensiloxane); the epoxy resin is selected from one or both of E51 and E44; the mixing ratio of the foaming agent to the epoxy resin is 1-3:80-100; the curing agent is selected from any one of polyamide 650, T31, JH-1020, and JH-0112, among which JH-1020 and JH-0112 are product models of Hangzhou Mojiafa New Materials Co., Ltd.

[0032] Example 2: This example provides a method for preparing a variable density petroleum fracturing proppant, comprising the following steps:

[0033] Step 1: Place 5-10 parts of polyethylene glycol 400, 1-5 parts of polyethylene glycol 600, and 5-15 parts of polyacrylamide in a container and stir at 1000 rpm for 2 hours to obtain solution A.

[0034] Step 2: Add 5000 mL of distilled water to Liquid A and stir Liquid A in the distilled water with a stirring rod until it is completely dispersed to obtain a carrier liquid B with a viscosity of 30-60 mPa·s;

[0035] Step 3: Select 1600-2200 parts of proppant raw material with a particle size of 20-100 mesh, wash it in an aqueous solution, remove it, and then soak it in an acidic solution for 2 hours. The temperature during the soaking process is controlled at 40°C. After soaking, remove it, wash it with distilled water until neutral, and dry it for later use; the acidic solution contains hydrofluoric acid with a concentration of 0-3% and oxalic acid with a concentration of 3-8%;

[0036] Step 4: Take 1-5 parts of the coupling agent and place it into 1600-2200 parts of the proppant raw material treated in step 3, and perform surface treatment at 50-90°C for 4 hours. After the treatment is completed, take it out and dry it for later use;

[0037] Step 5: Mix 80-100 parts of adhesive with 1600-2200 parts of the proppant raw material processed in step 4, then add 10-30 parts of curing agent, and mix well to obtain sample C;

[0038] Step 6: Slowly add sample C to liquid B and stir at a speed of 300-500 r / min for 1-2 hours to obtain a variable density petroleum fracturing proppant product; the variable density petroleum fracturing proppant product has a variable range of volume density of 0.7-1 g·cm -3 .

[0039] The present invention uses polyethylene glycol 400, polyethylene glycol 600, polyacrylamide, proppant raw materials, coupling agents, adhesives, and curing agents as raw materials for product preparation. A circle of gas-containing "sleeping ring" resembling a "swimming ring" is formed on the outer surface of quartz sand or ceramsite. By adding a foaming agent, the proppant has a good suspension effect. Compared with the traditional method of using quartz sand and ceramic as proppant materials, this product can greatly prolong its sedimentation time during use; and the volume density of this product can be reduced to 1g / cm -3 The following greatly ensures the strength of the proppant product; since the adhesive is made of epoxy resin and foaming agent mixed in proportion, the foaming agent is polymethyl hydrogen siloxane, and the different ratios of foaming agent and epoxy resin affect the density of the finished product, by adjusting the adhesive component ratio, the volume density of this product is 0.7-1g / cm 3 The invention also makes the proppant and the sand-carrying fluid compatible with each other, thus avoiding the adverse effects caused by the compatibility problem of the sand-carrying fluid caused by different construction methods.

[0040] Example 3: This example uses the method for preparing the variable density petroleum fracturing proppant provided in Example 2 to prepare petroleum fracturing proppant samples 1, 2, and 3, respectively. The specific components are shown in Table 1:

[0041]

[0042] Table 1

[0043] See also Figure 1-3 , Figure 1-3 This is an enlarged picture of the finished products of oil fracturing proppant samples 1, 2, and 3. As can be seen from the picture, there is a circle of "sleeve" containing gas around the oil fracturing proppant samples 1, 2, and 3, which is shaped like a "swimming ring" and gives the proppant a suspension effect.

[0044] Example 4. This example provides a test method for testing the crushed material, bulk density, and static suspension time of quartz sand used in the prior art and Samples 1, 2, and 3 prepared in Example 3. The crushing rate and bulk density determination methods of this test method are performed in accordance with the standard "SY / T 5108-2014 Test Method for Proppant Performance for Hydraulic Fracturing and Gravel Packing Operations". Specific test data are shown in Table 2:

[0045]

[0046] Table 2

[0047] As shown in Table 2, the crushing rate of the petroleum fracturing proppant samples 1, 2 and 3 prepared by the present invention can be controlled below 20 under the condition of 35 MPa, and the bulk density can reach less than 1 g / cm 3 , under the condition of 40mpa·s, the static suspension time is not less than 15min. Compared with the solution using quartz sand in traditional technology, it has good application performance.

[0048] See also Figure 4-Figure 6 , Figure 4-Figure 6 This is a comparison of the settlement of quartz sand and sample 1, sample 2, and sample 3 at 5 minutes. Figure 4 The left side of the middle is quartz sand, and the right side is sample 1; Figure 5 The left side in the middle is quartz sand, and the right side is sample 2; Figure 6 The left side in the middle is quartz sand, and the right side is sample 3.

[0049] Specifically, according to the standard "SY / T 5108-2014 Test Method for Proppant Performance for Hydraulic Fracturing and Gravel Packing Operations", the first test method for proppant breakage rate is as follows:

[0050] 11.1 Purpose

[0051] The breakage rate test determines the amount of proppant that breaks under given stress conditions.

[0052] 11.2 Description

[0053] This test is used to determine and compare the resistance of proppants to breakage. The test is conducted on samples that have been screened so that all particles are within a specified particle size range. The amount of proppant material that breaks at various pressures is measured. The test results should indicate the pressure level at which a significant amount of proppant breaks, i.e., the maximum pressure the proppant material can withstand.

[0054] 11.3 Equipment and Materials

[0055] 11.3.1 A hydraulic press shall provide a pressure of 103 MPa. The press shall be equipped with a pressure plate that can remain parallel when pressurizing the crushing chamber. The hydraulic press shall be calibrated at least once a year and after each overhaul to ensure that the pressure measurement accuracy is within 5%. Alternatively, an independent, calibrated load measuring device shall be used when pressurizing the crushing chamber. The test pressure shall never exceed 5% of the established value. An automatic loading press is highly recommended.

[0056] 11.3.2 Crushing chamber, or corresponding equipment. The piston shall be 88.9 mm long, 50.8 mm in diameter, and have a Rockwell hardness of 43 HRC or higher (60 HRC preferred). Regular inspection of the inner diameter will indicate when the piston should be replaced. The crushing chamber must be replaced when the inner diameter at the lower portion exceeds 3.25% of the design size (a 10% increase in cross-sectional area).

[0057] 11.3.3 Test sieves (GB / T 6003.1-2012 series), pans and lids.

[0058] 11.3.4 Balance, used to weigh the proppant sample and the proppant retained on each sieve, with an accuracy of 0.1 g or better.

[0059] 11.3.5 Vibrating screen.

[0060] 11.3.6 Timer.

[0061] 11.3.7 Sample divider.

[0062] 11.3.8 Metal beakers or weighing dishes. Plastic, glass, or paper containers that are prone to generating static electricity should be avoided.

[0063] 11.4 Sample Preparation

[0064] 11.4.1 Use a sample divider to reduce the sample to 80 g to 120 g.

[0065] 11.4.2 Select the mesh size of the top and bottom sieves appropriate for the proppant sample size. Prepare the sieve stack and place it in the sieve shaker.

[0066] 11.4.3 Pour the sample obtained after splitting into the top sieve and cover it with the lid.

[0067] 11.4.4 Place the sieve assembly in a vibrating sieve machine and vibrate for 10 minutes.

[0068] 11.4.5 Remove the group sieve from the sieve vibrator and discard all the sample remaining in the top sieve and bottom pan. Only the sample in the bottom sieve should be retained for the crushing rate test.

[0069] 11.5 Proppant Breakage Rate Test Method

[0070] 11.5.1 Determine the exact mass m of the proppant for the breakage rate experiment as follows: p .

[0071] 11.5.1.1 Determine the uncompacted bulk density of the proppant sample used in the experiment in 10.3.

[0072] 11.5.1.2 The mass of the 850 / 425 μm proppant sample used in the experiment was spread on the piston surface at a laying concentration equivalent to 19.6 g / cm. The average uncompacted bulk density of 850 / 425 μm quartz sand is 1.60 g / cm. Therefore, the volume of 850 / 425 μm quartz sand required per square meter of crushing chamber piston area is 1.22 cm' (1.96 / 1.60). In a crushing chamber with an inner diameter of φ50.8 mm, 24.7 cm is required. Proppants of different bulk densities require different amounts. The sample mass for other proppant crushing experiments with different bulk densities also varies, and their mass m (approximately 0.1 g) is calculated according to formula (7).

[0073] mp=24.7ρbulk··········(7)

[0074] Where:

[0075] mp—sample mass, in grams (g);

[0076] ρbulk—bulk density, in grams per cubic centimeter (g / cm 3 ).

[0077] 11.5.2 Use a sample divider to reduce the sieved sample to the calculated mass, which shall not exceed 5 g.

[0078] 11.5.3 Weigh the sample mass m p .

[0079] 11.5.4 Pour the weighed sample into the crushing chamber. The proppant surface in the crushing chamber should be as flat as possible. To ensure a level surface for the proppant sample, pour the proppant into the crushing chamber smoothly. If the sieved and weighed sample is poured out of the crushing chamber, start over at step 11.5.2.

[0080] 11.5.5 Insert the piston into the crushing chamber containing the weighed proppant sample without applying any external force except gravity.

[0081] 11.5.6 Rotate the piston 180° clockwise once without applying any pressure to ensure that the proppant sample placement surface is flush.

[0082] 11.5.7 Carefully lift the crushing chamber and place it directly into the press, aligning it directly under the press's centering plate. Do not shake or jolt the crushing chamber, as this may cause the proppant pack to sink, resulting in changes in particle pack morphology or particle rearrangement when pressurized.

[0083] 11.5.10 Pressurize the piston of the crushing chamber at a steady rate (see 11.5.8) for 1 minute. The time to reach the rated pressure should be within 5% of the time at this loading rate. If the pressure exceeds ±2.5% of the rated pressure, the test should be stopped and restarted with a new sample. The use of an automatic loading press is strongly recommended.

[0084] 11.5.11 Maintain this pressure for 2 minutes.

[0085] 11.5.12 After unloading the pressure, remove the crushing chamber from the press.

[0086] 11.5.13 Carefully pour the sample into the same set of sieves used in step 11.4.2, scraping the sample from the bottom of the crushing chamber to ensure that all the sample is poured out.

[0087] 11.5.14 Place the sieve assembly into the vibrating sieve machine and vibrate for 10 minutes.

[0088] 11.5.15 Carefully weigh the mass m of the crushed material in the pan and record it to an accuracy of 0.1 g.

[0089] 11.5.16 Calculate the crushing rate m'pan of the crushed sample according to formula (9) and submit the test results based on the crushing rate of the crushed sample. For the proppant crushing test, prepare three samples according to 11.4 and conduct three tests under the same crushing stress. The average value is used as the result.

[0090]

[0091] Where:

[0092] m′pitn —Proppant breakage rate, expressed as a percentage;

[0093] m pan —The mass of particles produced in the experiment, in grams (g);

[0094] m χ —Mass of the proppant in grams (g).

[0095] 2. The bulk density test method is as follows:

[0096] 10.3.1 Equipment and Materials

[0097] Determine the bulk density P bulk See the equipment Figure 7 , Figure 7 The following is explained:

[0098] 1--spring, diameter p9.525mm;

[0099] 2--Rubber ball valve, diameter p30.48mm;

[0100] 3--Bracket diameter, p4.8mm, welded to the base;

[0101] 4--cylinder, inner diameter 38.1mm;

[0102] 5--3 hole positioning, diameter p139.7mm;

[0103] 10.3.1.1 Funnel stand: It consists of a 304.8mm x 304.8mm metal base and a 304.8mm high tripod. The upper part of the tripod is a horizontal circular platform with a diameter of φ203.2mm, which forms the support part of the funnel and can be replaced, adjusted or fixed in place with screws.

[0104] 10.3.1.2 There is a shut-off valve at the funnel outlet. It is a φ34.9mm rubber ball connected to the funnel by two coil springs. The strength of the springs can form a strong seal. The dimensions of the funnel are as follows:

[0105] a) Top diameter (inside): 114.3 mm ± 0.4 mm.

[0106] b) Bottom diameter (inside): 12.7mm+0.4mm.

[0107] c) Height of slope section: 76.2mm±0.4mm.

[0108] d) Height of parallel section: 12.7mm+0.4mm.

[0109] 10.3.1.3 Brass cylinder: Capacity approximately 100 cm3. Calibrate the cylinder capacity with water as described in 10.3.2. The cylinder should be made of No. 17 brass seamless tubing. Its dimensions are as follows:

[0110] a) Internal diameter: gp38.9mm.

[0111] b) Height: 88.9mm+0.4mm.

[0112] c) Base thickness: 12.7mm+0.4mm.

[0113] d) The bottom surface of the base should be recessed, and the cylinder should be centered with a peg on the main plate, just below the outflow of the funnel.

[0114] NOTE 1: The inside diameter of the brass cylinder should be within the tolerances specified for standard high-grade commercial tubing.

[0115] Note 2: Other unimportant dimensions of the equipment may be adjusted according to the user's convenience.

[0116] 10.3.2 Calibration of brass cylinders

[0117] 10.3.2.1 Cover the dry empty brass cylinder with a flat glass plate and weigh its mass, which is recorded as mf. + RP.

[0118] 10.3.2.2 Add water to the cylinder and slide the glass plate so that it contacts the upper edge of the cylinder and the water surface stops at the flat edge of the brass cylinder.

[0119] 10.3.2.3 Hold the glass plate firmly in place, wipe off any excess water, and then weigh the total mass mf+RP+1.

[0120] 10.3.2.4 Calculate the volume V of the cylinder according to formula (3) Cyl .

[0121] V Cyl =m W / 0.9971··············(3)

[0122] m W =mf+RP+1-mf+RP

[0123] Where:

[0124] V Cyl --The volume of the cylinder in cubic centimeters (cm);

[0125] m W --Net mass of water in grams (g);

[0126] The density of water is 0.9971. The temperature of the test liquid must not be lower than 18°C nor higher than 28°C.

[0127] 10.3.3 Bulk density test method

[0128] 10.3.3.1 Weigh the mass of the dry empty cylinder in grams (g), recorded as mf.

[0129] 10.3.3.2 The temperature of the test sample is between 18°C and 28°C. Place the proppant sample in a 150 mL beaker.

[0130] 10.3.3.3 Close the outlet of the funnel, center the brass cylinder just below the outlet of the funnel, and pour the sample from the beaker into the funnel.

[0131] 10.3.3.4 Open the rubber ball valve at the bottom of the funnel to allow the proppant to flow into the brass cylinder.

[0132] 10.3.3.5 After all the proppant in the funnel has flowed out, use a ruler to push smoothly along the edge of the cylinder so that the proppant is flush with the surface of the brass cylinder mouth.

[0133] 10.3.3.6 Weigh the mass of the cylinder filled with proppant in grams (g), recorded as mf + p.

[0134] 10.3.3.7 Calculate the bulk density Pbalk according to formula (4).

[0135]

[0136] mp=mf-p-mi

[0137] Where:

[0138] Pbalk - bulk density, in grams per cubic centimeter (g / cm);

[0139] M p --Net mass of the proppant in grams (g).

[0140] The static suspension time is measured as follows:

[0141] Select liquid B with a viscosity of 40 mPa·s, add an appropriate amount of proppant to it, with the proppant accounting for 30%, mix well, pour into a measuring cylinder, and wait for the proppant to settle to its own volume. The time taken is recorded as the static suspension time.

[0142] In summary, the petroleum fracturing proppant prepared by the present invention has a high suspension effect, which is like wearing a "swimming ring" in water, effectively reducing the sedimentation time of the proppant, effectively supporting the crack length during the fracturing construction process, increasing the oil permeability, and thus increasing the oil production; and this product reduces the density to 1g / cm 3 The overall strength of the product is good, which effectively improves the support strength during the oil fracturing construction process. By adjusting the adhesive component ratio, the volume density of this product is 0.7-1g / cm 3 The volume density can be adjusted according to the actual application needs, and the present invention has excellent application adaptability. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial utilization value.

[0143] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A variable density petroleum fracturing proppant, characterized in that: The composition comprises the following components in parts by weight: 5-10 parts of polyethylene glycol 400, 1-5 parts of polyethylene glycol 600, 5-15 parts of polyacrylamide, 1600-2200 parts of proppant raw materials, 1-5 parts of coupling agent, 80-100 parts of adhesive, and 10-30 parts of curing agent.

2. The variable density petroleum fracturing proppant according to claim 1, characterized in that: The proppant raw material is quartz sand or ceramsite with a particle size of 20-100 mesh.

3. The variable density petroleum fracturing proppant according to claim 1, characterized in that: The coupling agent is selected from any one of KH550, KH-560, KH-570, A151, A171, and A172.

4. The variable density petroleum fracturing proppant according to claim 1, characterized in that: The adhesive is prepared by mixing epoxy resin and foaming agent (polymethyl hydrogen siloxane).

5. The variable density petroleum fracturing proppant according to claim 4, characterized in that: The epoxy resin is selected from one or both of E51 and E44 types.

6. The variable density petroleum fracturing proppant according to claim 5, characterized in that: The mixing ratio of the foaming agent to the epoxy resin is 1-3:80-100.

7. The variable density petroleum fracturing proppant according to claim 1, characterized in that: The curing agent is selected from any one of polyamide 650, T31, JH-1020, and JH-0112.

8. A method for preparing a variable density petroleum fracturing proppant, characterized in that: The steps include: Step 1: Place 5-10 parts of polyethylene glycol 400, 1-5 parts of polyethylene glycol 600, and 5-15 parts of polyacrylamide in a container and stir at 1000 rpm for 2 hours to obtain solution A. Step 2: Add 5000 mL of distilled water to Liquid A and stir Liquid A in the distilled water with a stirring rod until it is completely dispersed to obtain a carrier liquid B with a viscosity of 30-60 mPa·s; Step 3: Select 1600-2200 parts of proppant raw material with a particle size of 20-100 mesh, wash it in an aqueous solution, take it out, and then soak it in an acidic solution for 2 hours. The temperature during the soaking process is controlled at 40°C. After soaking, take it out, wash it with distilled water until it is neutral, and dry it for later use; Step 4: Take 1-5 parts of the coupling agent and place it into 1600-2200 parts of the proppant raw material treated in step 3, and perform surface treatment at 50-90°C for 4 hours. After the treatment is completed, take it out and dry it for later use; Step 5: Mix 80-100 parts of adhesive with 1600-2200 parts of the proppant raw material processed in step 4, then add 16-22 parts of curing agent, and mix well to obtain sample C; Step 6: Slowly add sample C into liquid B and stir at a speed of 300-500 r / min for 1-2 hours to obtain a variable density petroleum fracturing proppant product.

9. The method for preparing a variable density petroleum fracturing proppant according to claim 8, characterized in that: In step three, the acidic solution contains hydrofluoric acid with a concentration of 0-3% and oxalic acid with a concentration of 3-8%.

10. The method for preparing a variable density petroleum fracturing proppant according to claim 8, characterized in that: In step 6, the volume density of the variable density petroleum fracturing proppant product is variable in the range of 0.7-1 g·cm -3 .

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