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

Abstract

The present invention discloses a composition for reducing the bulk density of quartz sand and a preparation process thereof. 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 in parts by weight. The present invention adopts a composition for reducing the bulk density of quartz sand of the above structure and a preparation process thereof. By surface treating the quartz sand, artificial micro-nano protrusions are formed on the surface of the quartz sand, and the accumulated volume of the quartz sand is increased without affecting the sphericity, thereby reducing its bulk density. The bulk density of the quartz sand after treatment is increased from 1.5g / cm 3 Reduced to 1.4g / cm 3 Below, the reduction is more than 6%.

Description

Technical Field

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

[0002] In the existing fracturing system, proppant is an indispensable component. It supports the cracks as the fracturing fluid enters the cracks to prevent the cracks from closing. At present, the materials used for fracturing proppants mainly include quartz sand, ceramsite and coated sand, among which quartz sand accounts for more than 80% of the entire fracturing proppant market. With the development of unconventional oil and gas fields, the amount of quartz sand is increasing. Compared with ceramsite and coated sand, quartz sand has become the main material for oil and gas field development due to its low price. Quartz sand is a natural product. Its bulk density is its inherent property and it is difficult to change. However, the bulk density directly affects the filling strength of fracturing transformation and the filling height of proppant in the cracks. The smaller the bulk density, the greater the filling height of proppant in the cracks. Under the same sand adding strength, the higher the effective filling of the cracks, the more conducive to the transformation effect of oil and gas wells. For this reason, it is necessary to develop a quartz sand with low bulk density. Summary of the invention

[0003] 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.

[0004] To achieve the above-mentioned object, the first aspect of the present invention provides a composition for reducing the bulk density of quartz sand, which 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 in parts by weight.

[0005] Preferably, the powder is quartz sand powder or walnut shell powder, and the particle size of the powder is 400 meshes.

[0006] Preferably, the activated quartz sand is quartz sand surface-modified by a silane coupling agent.

[0007] Preferably, the modified epoxy resin is an organosilicon epoxy resin, and the organosilicon epoxy resin is prepared by the reaction of 1,4-butanediol, maleic anhydride, hydroxy silicone oil and an oxidant.

[0008] The second aspect of the present invention provides a preparation process of a composition for reducing the bulk density of quartz sand, comprising the following steps:

[0009] (1) Preparation of activated quartz sand and modified epoxy resin;

[0010] (2) heating the activated quartz sand to 200-250°C, adding it into a stirring kettle and cooling it to 180-230°C, then adding the modified epoxy resin and stirring for 15-30 seconds to obtain a mixture;

[0011] (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.

[0012] Preferably, the specific preparation method of activated quartz sand in step (1) is:

[0013] 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;

[0014] 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.

[0015] Preferably, the reaction time in step S2 is 5-10 min and the temperature is 100-130°C.

[0016] Preferably, the specific preparation method of the modified epoxy resin in step (1) is:

[0017] a: Maleic anhydride and 1,4-butanediol undergo esterification reaction to obtain intermediate product A;

[0018] b: Add hydroxy silicone oil to the intermediate product A for esterification reaction to obtain the intermediate product B;

[0019] c: The intermediate product B is subjected to epoxidation reaction with an oxidant to obtain a modified epoxy resin, namely, a silicone epoxy resin.

[0020] 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;

[0021] 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;

[0022] 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.

[0023] A third aspect of the present invention provides an application of a composition for reducing the bulk density of quartz sand in preparing a proppant.

[0024] 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:

[0025] 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 volume density. After treatment, the volume density of the quartz sand increases from 1.5g / cm 3 Reduced to 1.4g / cm 3 Below, the reduction is more than 6%.

[0026] The technical solution of the present invention is further described in detail below through embodiments. DETAILED DESCRIPTION

[0027] 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 a specific operation process, but the present invention is not limited to this embodiment. Example 1

[0028] The preparation method of activated quartz sand is:

[0029] 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;

[0030] S2: Add the coupling agent solution into a high-speed heating mixer by atomization method, and react with the quartz sand. 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. Example 2

[0031] The preparation method of modified epoxy resin is:

[0032] 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 2h;

[0033] b: Add hydroxy silicone oil to the intermediate product A for esterification to obtain the intermediate product B, the molar ratio of the intermediate product A to the 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;

[0034] c: The intermediate product B and the oxidant are subjected to epoxidation reaction, the molar ratio of the intermediate product B and the oxidant is 1:2, the oxidant is meta-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, i.e., silicone epoxy resin, is obtained by distillation under reduced pressure. Example 3

[0035] A preparation process of a composition for reducing the bulk density of quartz sand comprises the following steps:

[0036] 1 kg of activated quartz sand (60 mesh) was heated to 250°C, added to a stirred kettle and cooled to 230°C, then 10 g of modified epoxy resin was added, stirred for 15 seconds, 40 g of quartz sand powder (400 mesh) was added, stirred for 15 seconds, 2 g of corresponding curing agent T-31 was added, stirred for 30 seconds, 1 g of calcium stearate was added, stirred for 15 seconds, removed from the kettle, cooled, and sieved to obtain a composition. The preparation methods of activated quartz sand and modified epoxy resin are the same as those in Examples 1 and 2. Example 4

[0037] A preparation process of a composition for reducing the bulk density of quartz sand comprises the following steps:

[0038] 1 kg of activated quartz sand (60 mesh) was heated to 200°C, added to a stirred kettle and cooled to 180°C, then 10 g of modified epoxy resin was added, stirred for 20 seconds, 20 g of walnut shell powder (400 mesh) was added, stirred for 15 seconds, 2 g of corresponding curing agent T-31 was added, stirred for 30 seconds, 1 g of calcium stearate was added, stirred for 15 seconds, removed from the kettle, cooled, and sieved to obtain a composition. The preparation methods of activated quartz sand and modified epoxy resin are the same as those in Examples 1 and 2.

[0039] Comparative Example 1

[0040] The difference from Example 3 is that the quartz sand is not activated.

[0041] Comparative Example 2

[0042] 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.

[0043] Comparative Example 3

[0044] The difference from Example 3 is that quartz sand and epoxy resin are directly used.

[0045] Comparative Example 4

[0046] The difference from Example 3 is that the particle size of the quartz sand powder is 60 mesh.

[0047] Comparative Example 5

[0048] The difference from Example 3 is that the particle size of the quartz sand powder is 1000 mesh.

[0049] Examples 3-4 and Comparative Examples 1-5 were tested using a bulk density meter. The test results are shown in the table below.

[0050]

[0051] 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%.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. 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 solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A process for preparing a composition for reducing the bulk density of quartz sand, 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) adding powder to the mixture and stirring for 15-30 seconds, adding curing agent and stirring for 30-60 seconds, adding calcium stearate and stirring for 15-30 seconds, removing from the pot, cooling, and sieving to obtain a composition; The surface of the quartz sand in the composition has micro-nano protrusions; 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 in parts by weight; Activated quartz sand is quartz sand surface-modified by silane coupling agent; The specific preparation method of activated quartz sand 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: adding 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; The modified epoxy resin is an organic silicon epoxy resin, and the organic silicon epoxy resin is formed by the reaction of 1,4-butanediol, maleic anhydride, hydroxy silicone oil and an oxidant; The specific preparation method of modified epoxy resin 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.

2. The preparation process of 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. The preparation process of a composition for reducing the bulk density of quartz sand according to claim 1, characterized in that: The reaction time in step S2 is 5-10 min, and the temperature is 100-130°C.

4. The preparation process of a composition for reducing the bulk density of quartz sand according to claim 1, 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.

5. Use of a composition obtained by the preparation process according to any one of claims 1 to 4 in the preparation of a proppant.

Images