Composition for reducing bulk density of quartz sand and preparation process therefor

Abstract

A composition for reducing the bulk density of quartz sand and a preparation process therefor. The composition comprises the following components in parts by weight: 800-1200 parts of 40-70-mesh activated quartz sand, 8-10 parts of a modified epoxy resin, 30-50 parts of a powder, 1-3 parts of a curing agent and 0.5-1.5 parts of calcium stearate. In the composition for reducing the bulk density of quartz sand and the preparation process therefor, the quartz sand is subjected to a surface treatment, so artificial micro-nano protrusions are formed on the surface of the quartz sand and the bulk volume of the quartz sand is increased without affecting the sphericity, and thus the bulk density of the quartz sand is reduced. The bulk density of the treated quartz sand is reduced from 1.5 g / cm3 to 1.4 g / cm 3 or less, with a level of reduction exceeding 6%.

Description

A composition for reducing the bulk density of quartz sand and its preparation process Technical Field

[0001] The invention belongs to the technical field of quartz sand proppants, and particularly relates to a composition for reducing the bulk density of quartz sand and a preparation process thereof. Background Art

[0002] In existing fracturing systems, proppants are essential components. As the fracturing fluid enters the fracture, they prop up the crack and prevent it from closing. Currently, the main materials used in fracturing proppants include quartz sand, ceramsite, and coated sand, with quartz sand accounting for over 80% of the total fracturing proppant market. With the development of unconventional oil and gas fields, the use of quartz sand is increasing. Compared to ceramsite and coated sand, quartz sand has become the primary material for oil and gas field development due to its low price. Quartz sand is a natural product, and its bulk density is inherently difficult to change. However, bulk density directly affects the filling strength of the fracturing stimulation process and the height of the proppant in the fracture. The lower the bulk density, the greater the proppant filling height in the fracture. For the same sand loading strength, the effective fracture filling is higher, which is more beneficial for the stimulation of oil and gas wells. Therefore, it is necessary to develop quartz sand with a low bulk density.

[0003] Summary of the Invention

[0004] The purpose of the present invention is to provide a composition for reducing the bulk density of quartz sand and a preparation process thereof, so as to solve the problem that the bulk density of the above-mentioned natural product quartz sand is relatively high when used as a proppant.

[0005] To achieve the above objectives, the first aspect of the present invention provides a composition for reducing the bulk density of quartz sand, which comprises, by weight, 800-1200 parts of 40-70 mesh activated quartz sand, 8-10 parts of modified epoxy resin, 30-50 parts of powder, 1-3 parts of curing agent and 0.5-1.5 parts of calcium stearate.

[0006] Preferably, the powder is quartz sand powder or walnut shell powder, and the particle size of the powder is 400 mesh.

[0007] Preferably, the activated quartz sand is quartz sand surface-modified by a silane coupling agent.

[0008] Preferably, the modified epoxy resin is an organosilicon epoxy resin, which is prepared by reacting 1,4-butanediol, maleic anhydride, hydroxy silicone oil and an oxidant.

[0009] A second aspect of the present invention provides a process for preparing a composition for reducing the bulk density of quartz sand, comprising the following steps:

[0010] (1) preparing activated quartz sand and modified epoxy resin;

[0011] (2) heating activated quartz sand to 200-250° C., adding it to a stirred kettle and cooling it to 180-230° C., then adding modified epoxy resin and stirring for 15-30 seconds to obtain a mixture;

[0012] (3) Add powder to the mixture and stir for 15-30 seconds, add curing agent and stir for 30-60 seconds, add calcium stearate and stir for 15-30 seconds, remove from the pot, cool, and sieve to obtain a composition.

[0013] Preferably, the specific preparation method of activated quartz sand in step (1) is:

[0014] S1: adding a silane coupling agent to an ethanol aqueous solution and mixing them uniformly, wherein the volume ratio of anhydrous ethanol to water in the ethanol aqueous solution is 9:1, and adjusting the pH value to 3-4 with oxalic acid to obtain a coupling agent solution;

[0015] S2: The coupling agent solution is added into a high-speed heating mixer by atomization method, and the quartz sand reacts with it, so that the silane coupling agent and the quartz sand form a stable and strong covalent bond to obtain activated quartz sand.

[0016] Preferably, the reaction time in step S2 is 5-10 min and the temperature is 100-130°C.

[0017] Preferably, the specific preparation method of the modified epoxy resin in step (1) is:

[0018] a: Maleic anhydride and 1,4-butanediol undergo esterification reaction to obtain intermediate product A;

[0019] b: Add hydroxy silicone oil to the intermediate product A to carry out esterification reaction to obtain the intermediate product B;

[0020] c: The intermediate product B is subjected to epoxidation reaction with an oxidant to obtain a modified epoxy resin, namely, an organosilicon epoxy resin.

[0021] Preferably, in step a, the molar ratio of maleic anhydride to 1,4-butanediol is 2:1, the reaction temperature is 70° C., the catalyst is aluminum chloride, and the reaction time is 2 h;

[0022] In step b, the molar ratio of intermediate product A to hydroxy silicone oil is 1:2, the reaction temperature is 70°C, the catalyst is concentrated sulfuric acid, and the reaction time is 6 hours;

[0023] In step c, the molar ratio of the intermediate product B and the oxidant is 1:2, the oxidant is m-chloroperoxybenzoic acid, and the oxidant is slowly added dropwise to the intermediate product B cooled to room temperature, and then the temperature is raised to 30° C. and reacted at the reaction temperature for 3 hours, and the modified epoxy resin is obtained by distillation under reduced pressure.

[0024] A third aspect of the present invention provides a use of a composition for reducing the bulk density of quartz sand in preparing a proppant.

[0025] Therefore, the present invention adopts a composition for reducing the bulk density of quartz sand and a preparation process thereof of the above structure, which has the following beneficial effects:

[0026] By surface treating the quartz sand, artificial micro-nano protrusions are formed on the surface of the quartz sand, which increases the volume of the quartz sand without affecting the sphericity, thereby reducing its bulk density. After treatment, the bulk density of the quartz sand increases from 1.5g / cm 3 Reduced to 1.4g / cm 3 Below, the reduction is more than 6%.

[0027] The technical solution of the present invention is further described in detail below through examples. DETAILED DESCRIPTION

[0028] The present invention will be further described below. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the present invention is not limited to this embodiment.

[0029] Example 1

[0030] The preparation method of activated quartz sand is:

[0031] S1: adding a silane coupling agent to an ethanol aqueous solution and mixing them uniformly, wherein the volume ratio of anhydrous ethanol to water in the ethanol aqueous solution is 9:1, and adjusting the pH value to 3-4 with oxalic acid to obtain a coupling agent solution;

[0032] S2: The coupling agent solution is added to a high-speed heating mixer by atomization method, and the quartz sand reacts with it. The reaction time is 8 minutes and the temperature is 120°C, so that the silane coupling agent and the quartz sand form a stable and strong covalent bond to obtain activated quartz sand.

[0033] Example 2

[0034] The preparation method of modified epoxy resin is:

[0035] a: Maleic anhydride and 1,4-butanediol are subjected to esterification reaction to obtain intermediate product A. The molar ratio of maleic anhydride to 1,4-butanediol is 2:1, the reaction temperature is 70°C, the catalyst is aluminum chloride, and the reaction time is 2 hours;

[0036] b: Add hydroxy silicone oil to intermediate product A for esterification to obtain intermediate product B. The molar ratio of intermediate product A to hydroxy silicone oil is 1:2. The reaction temperature is 70°C. The catalyst is concentrated sulfuric acid. The reaction time is 6 hours.

[0037] c: The intermediate product B and the oxidant are subjected to an epoxidation reaction, the molar ratio of the intermediate product B to the oxidant is 1:2, the oxidant is m-chloroperoxybenzoic acid, the oxidant is slowly added dropwise to the intermediate product B cooled to room temperature, the temperature is raised to 30°C, and the reaction is carried out at this reaction temperature for 3 hours, and the modified epoxy resin, i.e., silicone epoxy resin, is obtained by distillation under reduced pressure.

[0038] Example 3

[0039] A process for preparing a composition for reducing the bulk density of quartz sand comprises the following steps:

[0040] 1 kg of activated quartz sand (60 mesh) was heated to 250° C., added to a stirred tank and cooled to 230° C., followed by the addition of 10 g of a modified epoxy resin and stirring for 15 seconds. 40 g of quartz sand powder (400 mesh) was added and stirred for 15 seconds. 2 g of the corresponding curing agent T-31 was added and stirred for 30 seconds. 1 g of calcium stearate was added and stirred for 15 seconds. The mixture was removed from the pot, cooled, and sieved to obtain a composition. The preparation methods of the activated quartz sand and the modified epoxy resin were the same as those in Examples 1 and 2.

[0041] Example 4

[0042] A process for preparing a composition for reducing the bulk density of quartz sand comprises the following steps:

[0043] 1 kg of activated quartz sand (60 mesh) was heated to 200° C., added to a stirred tank and cooled to 180° C., then 10 g of modified epoxy resin was added and stirred for 20 seconds, 20 g of walnut shell powder (400 mesh) was added and stirred for 15 seconds, 2 g of the corresponding curing agent T-31 was added and stirred for 30 seconds, 1 g of calcium stearate was added and stirred for 15 seconds, the mixture was removed from the pot, cooled, and sieved to obtain a composition. The preparation methods of the activated quartz sand and modified epoxy resin were the same as those in Examples 1 and 2.

[0044] Comparative Example 1

[0045] The difference from Example 3 is that the quartz sand is not activated.

[0046] Comparative Example 2

[0047] The difference from Example 3 is that the epoxy resin is not modified but directly purchased, and the epoxy resin is bisphenol A epoxy resin.

[0048] Comparative Example 3

[0049] The difference from Example 3 is that quartz sand and epoxy resin are directly used.

[0050] Comparative Example 4

[0051] The difference from Example 3 is that the particle size of the quartz sand powder is 60 mesh.

[0052] Comparative Example 5

[0053] The difference from Example 3 is that the particle size of the quartz sand powder is 1000 mesh.

[0054] Examples 3-4 and Comparative Examples 1-5 were tested using a bulk density meter. The test results are shown in the table below.

[0055] Table 1 Bulk density test results of Examples 3-4 and Comparative Examples 1-5

[0056] Therefore, the present invention adopts a composition for reducing the bulk density of quartz sand and its preparation process of the above structure, and the bulk density of the quartz sand after the treatment is reduced from 1.5g / cm 3 Reduced to 1.4g / cm 3 Below, the reduction is more than 6%.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A composition for reducing the bulk density of quartz sand, characterized in that: The composition comprises 800-1200 parts of 40-70 mesh activated quartz sand, 8-10 parts of modified epoxy resin, 30-50 parts of powder, 1-3 parts of curing agent and 0.5-1.5 parts of calcium stearate according to weight parts.

2. A composition for reducing the bulk density of quartz sand according to claim 1, characterized in that: The powder is quartz sand powder or walnut shell powder, and the particle size of the powder is 400 meshes.

3. A composition for reducing the bulk density of quartz sand according to claim 1, characterized in that: Activated quartz sand is quartz sand whose surface is modified by silane coupling agent.

4. A composition for reducing the bulk density of quartz sand according to claim 1, characterized in that: The modified epoxy resin is an organic silicon epoxy resin, and the organic silicon epoxy resin is prepared by the reaction of 1,4-butanediol, maleic anhydride, hydroxy silicone oil and an oxidant.

5. A process for preparing a composition for reducing the bulk density of quartz sand according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) preparing activated quartz sand and modified epoxy resin; (2) heating activated quartz sand to 200-250° C., adding it into a stirring kettle and cooling it to 180-230° C., then adding modified epoxy resin and stirring for 15-30 seconds to obtain a mixture; (3) Add powder to the mixture and stir for 15-30 seconds, add curing agent and stir for 30-60 seconds, add calcium stearate and stir for 15-30 seconds, remove from the pot, cool, and sieve to obtain a composite.

6. The process for preparing a composition for reducing the bulk density of quartz sand according to claim 5, characterized in that: The specific preparation method of activated quartz sand in step (1) is: S1: adding a silane coupling agent to an ethanol aqueous solution and mixing them evenly, wherein the volume ratio of anhydrous ethanol to water in the ethanol aqueous solution is 9:1, and adjusting the pH value to 3-4 with oxalic acid to obtain a coupling agent solution; S2: Add the coupling agent solution into a high-speed heating mixer by atomization, and the quartz sand reacts with the coupling agent so that the silane coupling agent and the quartz sand form a stable and strong covalent bond to obtain activated quartz sand.

7. The process for preparing a composition for reducing the bulk density of quartz sand according to claim 6, characterized in that: The reaction time in step S2 is 5-10 min and the temperature is 100-130°C 8. The process for preparing a composition for reducing the bulk density of quartz sand according to claim 5, characterized in that: The specific preparation method of the modified epoxy resin in step (1) is: a: Maleic anhydride and 1,4-butanediol undergo esterification reaction to obtain intermediate product A; b: Add hydroxy silicone oil to the intermediate product A for esterification reaction to obtain the intermediate product B; c: The intermediate product B is subjected to epoxidation reaction with an oxidant to obtain a modified epoxy resin, namely, a silicone epoxy resin.

9. The process for preparing a composition for reducing the bulk density of quartz sand according to claim 8, characterized in that: In step a, the molar ratio of maleic anhydride to 1,4-butanediol is 2:1, the reaction temperature is 70°C, the catalyst is aluminum chloride, and the reaction time is 2h; In step b, the molar ratio of intermediate product A to hydroxy silicone oil is 1:2, the reaction temperature is 70°C, the catalyst is concentrated sulfuric acid, and the reaction time is 6 hours; In step c, the molar ratio of the intermediate product B to the oxidant is 1:2, the oxidant is m-chloroperoxybenzoic acid, the oxidant is slowly added dropwise to the intermediate product B cooled to room temperature, the temperature is raised to 30° C., and the reaction is carried out at the reaction temperature for 3 hours, and the modified epoxy resin is obtained by distillation under reduced pressure.

10. Use of a composition for reducing the bulk density of quartz sand according to any one of claims 1 to 4 in preparing a proppant.

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