A kind of quartz sand for fracturing and its preparation method

Abstract

The present invention discloses a quartz sand for fracturing and a preparation method thereof, relating to the technical field of quartz sand for fracturing. The quartz sand for fracturing comprises the following raw materials in parts by weight: 50 parts of quartz sand and 5-8 parts of an organosilicon-modified epoxy resin film-forming agent. In the present invention, a transparent colloidal solid is prepared by the reaction of PEG800 and 2,6-toluene diisocyanate, then the transparent colloidal solid reacts with bisphenol A epoxy resin to prepare an intermediate, and then reacts with aminopropylmethylpolysiloxane to prepare an organosilicon-modified epoxy resin film-forming agent. The quartz sand for fracturing prepared by the present invention has high sphericity, low density and high conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of quartz sand for fracturing, and specifically relates to a quartz sand for fracturing and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of the world economy and the rapid progress of science and technology, the demand for oil and natural gas remains high. The hydraulic fracturing technology is an important means to increase the production of oil and gas wells and has been widely used in the development of various oil and gas wells. During the hydraulic fracturing operation, the role of the proppant is crucial. The proppant is a key material for fracturing construction in the exploitation of low-permeability oil and gas wells and shale gas reservoirs, and it is a product with high added value characteristics. Its performance determines the success or failure of the hydraulic fracturing technology and also affects the service life of oil and gas wells. Quartz sand is a natural mineral with high hardness, good stability and wide distribution, mainly produced in river beaches, deserts or coastal areas. Quartz sand resources are rich, cheap, have a low density and are convenient to be pumped with the fracturing fluid, but its compressive strength is low, and the conductivity drops greatly after crushing. Therefore, it is particularly important to develop a proppant with high sphericity, low bulk density, low breakage rate and high conductivity.

[0003] Chinese invention patent with publication number CN112876118A discloses a quartz sand for fracturing and a preparation method thereof. The quartz sand for fracturing includes a quartz sand aggregate and a coating layer coated on the outer surface of the quartz sand aggregate. The coating layer is composed of the following raw materials: fly ash, coal gangue, clay, kaolin, silica powder, silane coupling agent, metal ore powder; the preparation method of the quartz sand for fracturing prepared by this invention is simple and has strong corrosion resistance, but its breakage rate and conductivity are poor. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a quartz sand for fracturing and a preparation method thereof.

[0005] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0006] A quartz sand for fracturing, the quartz sand for fracturing includes the following raw materials in parts by weight: 25-50 parts of quartz sand, 5 parts of modified epoxy resin film-forming agent.

[0007] The modified epoxy resin film-forming agent is prepared by the following method:

[0008] S1: Under nitrogen protection, DMF and 2,6-toluene diisocyanate are sequentially added to the reactor, stirred and dissolved, heated to 50-70 °C, then PEG800 is slowly added dropwise. After dropping, dibutyltin dilaurate as a catalyst is added, and the reaction is carried out for 4-6 h. After post-treatment, a transparent colloidal solid is obtained. The reaction equation is shown as follows:

[0009]

[0010] S2: Under nitrogen protection, acetone, the transparent gelatinous solid, and bisphenol A epoxy resin are successively added into the reactor, stirred and dissolved, heated to 80 - 100 °C, dibutyltin dilaurate as the catalyst is added, and after reacting for 6 - 8 h, post-treatment is carried out to obtain the intermediate. The reaction equation is schematically shown as follows:

[0011]

[0012] S3: DMF, the intermediate, and aminopropylmethylpolysiloxane are successively added into the reactor, stirred and dissolved, heated to 80 - 120 °C, reacted for 4 - 6 h, cooled to 60 - 80 °C, neutralized with triethylamine, and vacuum distilled to obtain the organosilicon-modified epoxy resin coating agent. The reaction equation is schematically shown as follows:

[0013]

[0014]

[0015] Among them, m, n, o, r, s, t, p, and q are natural numbers.

[0016] In the step S1, the feeding mass ratio of DMF, tolylene 2,6 - diisocyanate, PEG800, and dibutyltin dilaurate is 20:(8 - 10):(4 - 6):(0.01 - 0.03).

[0017] In the step S2, the feeding mass ratio of acetone, the transparent gelatinous solid, bisphenol A epoxy resin, and dibutyltin dilaurate is 50:(6 - 8):(10 - 12):(0.05 - 0.08).

[0018] In the step S3, the feeding mass ratio of DMF, the intermediate, and aminopropylmethylpolysiloxane is 50:(8 - 12):(10 - 15).

[0019] The preparation method of the quartz sand for fracturing includes the following steps:

[0020] S1: Weigh quartz sand by weight, wash it 3 times with deionized water, wash it 1 time with absolute ethanol, and then wash it 1 time with petroleum ether, and dry it in an electrothermal blast drying oven at 80 - 100 °C for 4 - 6 h to obtain the precursor;

[0021] S2: Mix the organosilicon-modified epoxy resin coating agent and DMF evenly at room temperature to obtain a viscous modified epoxy resin coating agent;

[0022] S3: Add the precursor and the viscous modified epoxy resin film-forming agent into the reactor, stir at 100 - 120 °C for 4 - 6 h, and then dry at 105 - 115 °C for 10 - 12 h to obtain the quartz sand for fracturing.

[0023] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0024] (1) The present invention prepares a transparent colloidal solid by reacting PEG800 with tolylene 2,6 - diisocyanate, then reacts the transparent colloidal solid with bisphenol A epoxy resin to prepare an intermediate, and then reacts with aminopropylmethylpolysiloxane to prepare an organosilicon - modified epoxy resin film-forming agent.

[0025] (2) The organosilicon - modified epoxy resin film-forming agent prepared by the present invention contains a large number of oxidation functional groups. Among them, the epoxy and hydroxyl groups in the epoxy resin endow the resin with high reactivity, making the resin have strong cohesion and adhesion, and the benzene ring endows the resin with heat resistance and stiffness. On the other hand, the modification of epoxy resin by organosilicon makes the advantages of the two polymers complementary. Flexible Si - O bonds are introduced into the epoxy. The Si - O bonds can make the polymer chain segments rotate more easily, which can reduce the internal stress of the epoxy resin, thereby well improving the fracture toughness of the epoxy resin, and making the prepared quartz sand for fracturing have high mechanical strength and good diversion ability. Specific Embodiments

[0026] The following is further described in conjunction with embodiments, but the present invention is not limited to these embodiments.

[0027] Example 1

[0028] Preparation of organosilicon - modified epoxy resin film-forming agent:

[0029] S1: Under nitrogen protection, add 200 g of DMF and 80 g of tolylene 2,6 - diisocyanate into the reactor in sequence, stir to dissolve, heat up to 50 °C, then slowly dropwise add 40 g of PEG800 over 20 min. After dropping, add 0.1 g of catalyst dibutyltin dilaurate, react for 6 h, then add 500 ml of ice water for precipitation and filtration, and dry at 40 °C under vacuum for 12 h to obtain a transparent colloidal solid;

[0030] S2: Under nitrogen protection, add 500 g of acetone, 60 g of transparent colloidal solid, and 100 g of bisphenol A epoxy resin (E51) into the reactor in sequence, stir to dissolve, heat up to 80 °C, add 0.5 g of catalyst dibutyltin dilaurate, react for 8 h, and distill under reduced pressure at 50 °C for 6 h to obtain an intermediate;

[0031] S3: Add 500 g of DMF, 80 g of the intermediate, and 100 g of aminopropylmethylpolysiloxane into the reactor in sequence, stir to dissolve, heat up to 80 °C, react for 6 h, cool down to 60 °C, add 150 ml of triethylamine for neutralization, and carry out vacuum distillation at 60 °C for 6 h to obtain the organosilicon-modified epoxy resin coating agent.

[0032] Example 2

[0033] Preparation of organosilicon-modified epoxy resin coating agent:

[0034] S1: Under nitrogen protection, add 200 g of DMF and 90 g of 2,6-toluene diisocyanate into the reactor in sequence, stir to dissolve, heat up to 60 °C, then slowly dropwise add 50 g of PEG800 over 25 min. After dropping, add 0.2 g of the catalyst dibutyltin dilaurate, react for 5 h, then add 500 ml of ice water for precipitation and filtration, and carry out vacuum drying at 50 °C for 10 h to obtain a transparent gelatinous solid;

[0035] S2: Under nitrogen protection, add 500 g of acetone, 70 g of the transparent gelatinous solid, and 110 g of bisphenol A epoxy resin (E51) into the reactor in sequence, stir to dissolve, heat up to 90 °C, add 0.65 g of the catalyst dibutyltin dilaurate, react for 7 h, and carry out vacuum distillation at 60 °C for 5 h to obtain the intermediate;

[0036] S3: Add 500 g of DMF, 100 g of the intermediate, and 125 g of aminopropylmethylpolysiloxane into the reactor in sequence, stir to dissolve, heat up to 100 °C, react for 5 h, cool down to 70 °C, add 180 ml of triethylamine for neutralization, and carry out vacuum distillation at 70 °C for 5 h to obtain the organosilicon-modified epoxy resin coating agent.

[0037] Example 3

[0038] Preparation of organosilicon-modified epoxy resin coating agent:

[0039] S1: Under nitrogen protection, add 200 g of DMF and 100 g of 2,6-toluene diisocyanate into the reactor in sequence, stir to dissolve, heat up to 70 °C, then slowly dropwise add 60 g of PEG800 over 30 min. After dropping, add 0.3 g of the catalyst dibutyltin dilaurate, react for 4 h, then add 500 ml of ice water for precipitation and filtration, and carry out vacuum drying at 60 °C for 8 h to obtain a transparent gelatinous solid;

[0040] S2: Under nitrogen protection, add 500 g of acetone, 80 g of the transparent gelatinous solid, and 120 g of bisphenol A epoxy resin (E51) into the reactor in sequence, stir to dissolve, heat up to 100 °C, add 0.8 g of the catalyst dibutyltin dilaurate, react for 6 h, and carry out vacuum distillation at 70 °C for 4 h to obtain the intermediate;

[0041] S3: Add 500 g of DMF, 120 g of the intermediate, and 150 g of aminopropylmethyl polysiloxane into the reactor in sequence, stir to dissolve, heat up to 120 °C, react for 4 h, cool to 80 °C, add 200 ml of triethylamine for neutralization, and carry out vacuum distillation at 80 °C for 4 h to obtain the silicone-modified epoxy resin film coating agent.

[0042] Example 4

[0043] Preparation of proppant quartz sand:

[0044] S1: Weigh 500 g of quartz sand, wash it 3 times with deionized water (500 g of deionized water each time), wash it once with 500 g of absolute ethanol, and then wash it once with 300 g of petroleum ether, and dry it in an electric heating blast drying oven at 80 °C for 6 h to obtain the precursor.

[0045] S2: Mix 50 g of the silicone-modified epoxy resin film coating agent (prepared in Example 1) and 100 g of DMF evenly at room temperature to obtain a viscous silicone-modified epoxy resin film coating agent.

[0046] S3: Add 500 g of the precursor and 150 g of the viscous silicone-modified epoxy resin film coating agent into the reactor, stir at 100 °C for 6 h, and then dry at 105 °C for 12 h to obtain the proppant quartz sand.

[0047] Example 5

[0048] Preparation of proppant quartz sand:

[0049] S1: Weigh 500 g of quartz sand, wash it 3 times with deionized water (500 g of deionized water each time), wash it once with 500 g of absolute ethanol, and then wash it once with 300 g of petroleum ether, and dry it in an electric heating blast drying oven at 90 °C for 5 h to obtain the precursor.

[0050] S2: Mix 65 g of the silicone-modified epoxy resin film coating agent (prepared in Example 2) and 130 g of DMF evenly at room temperature to obtain a viscous silicone-modified epoxy resin film coating agent.

[0051] S3: Add 500 g of the precursor and 195 g of the viscous silicone-modified epoxy resin film coating agent into the reactor, stir at 110 °C for 5 h, and then dry at 110 °C for 11 h to obtain the proppant quartz sand.

[0052] Example 6

[0053] Preparation of proppant quartz sand:

[0054] S1: Weigh 500 g of quartz sand, wash it three times with deionized water (500 g of deionized water each time), wash it once with 500 g of absolute ethanol, then wash it once with 300 g of petroleum ether, and dry it in an electric blast drying oven at 100 °C for 4 h to obtain a precursor;

[0055] S2: Mix 80 g of the organosilicon-modified epoxy resin coating agent (prepared in Example 3) and 160 g of DMF evenly at room temperature to obtain a viscous organosilicon-modified epoxy resin coating agent;

[0056] S3: Add 500 g of the precursor and 240 g of the viscous organosilicon-modified epoxy resin coating agent to a reactor, stir at 120 °C for 4 h, and then dry at 115 °C for 10 h to obtain quartz sand for fracturing.

[0057] Comparative Example 1

[0058] The preparation method of quartz sand for fracturing is as follows: Weigh 500 g of quartz sand, wash it three times with deionized water (500 g of deionized water each time), wash it once with 500 g of absolute ethanol, then wash it once with 300 g of petroleum ether, and dry it in an electric blast drying oven at 90 °C for 5 h to obtain quartz sand for fracturing.

[0059] Comparative Example 2

[0060] The preparation method of quartz sand for fracturing is basically the same as that of Example 5, except that the organosilicon-modified epoxy resin coating agent (prepared in Example 2) is replaced with an equal weight of the intermediate prepared in Step S2 of Example 2.

[0061] Comparative Example 3

[0062] The preparation method of quartz sand for fracturing is basically the same as that of Example 5, except that the organosilicon-modified epoxy resin coating agent (prepared in Example 2) is replaced with an equal weight of aminopropylmethylpolysiloxane.

[0063] Comparative Example 4

[0064] The preparation method of quartz sand for fracturing is as follows:

[0065] S1: Weigh 500 g of quartz sand, wash it three times with deionized water (500 g of deionized water each time), wash it once with 500 g of absolute ethanol, then wash it once with 300 g of petroleum ether, and dry it in an electric blast drying oven at 90 °C for 5 h to obtain a precursor;

[0066] S2: Mix 29 g of the intermediate (prepared in Step S2 of Example 2), 36 g of aminopropylmethylpolysiloxane and 130 g of DMF evenly at room temperature to obtain a coating agent;

[0067] S3: Add 500 g of the precursor and 195 g of the film-forming agent into the reactor, stir at 110 °C for 5 h, and then dry at 110 °C for 11 h to obtain the quartz sand for fracturing.

[0068] Comparative Example 5

[0069] The preparation method of the quartz sand for fracturing is as follows:

[0070] S1: Weigh 500 g of quartz sand, wash it 3 times with deionized water (500 g of deionized water is used each time), wash it once with 500 g of absolute ethanol, and then wash it once with 300 g of petroleum ether, and dry it in an electric blast drying oven at 90 °C for 5 h to obtain the precursor;

[0071] S2: Mix 15 g of the transparent gel-like solid (prepared in step S1 of Example 2), 23 g of bisphenol A epoxy resin (E51), 27 g of aminopropylmethyl polysiloxane, and 130 g of DMF evenly at room temperature to obtain the film-forming agent;

[0072] S3: Add 500 g of the precursor and 195 g of the film-forming agent into the reactor, stir at 110 °C for 5 h, and then dry at 110 °C for 11 h to obtain the quartz sand for fracturing.

[0073] Comparative Example 6

[0074] The preparation method of the quartz sand for fracturing is basically the same as that of Example 5, the difference is that the organosilicon-modified epoxy resin film-forming agent (prepared in Example 2) in step S2 is replaced with the film material prepared in step (1) of Example 3 in the publication number CN117625171A with the same weight.

[0075] Comparative Example 7

[0076] A kind of quartz sand for fracturing prepared by using the raw material composition and process in Example 2 of the Chinese invention patent specification with the publication number CN112876118A.

[0077] The epoxy resin models used in the examples and comparative examples of this application are E51, purchased from Hunan Baling Petrochemical Company; the quartz sand specification is 140 mesh, purchased from Inner Mongolia Changfan Quartz Sand Co., Ltd.; aminopropylmethyl polysiloxane is purchased from Gelest 6-7Psil in the United States, where p = 6-7 and q = 93-94.

[0078] Perform sphericity, bulk density, breakage rate, and conductivity performance tests on the quartz sand for fracturing prepared in Examples 4-6 and Comparative Examples 1-7 of this application, and the test results are shown in Table 1.

[0079] The sphericity, bulk density and breakage rate of the quartz sand for fracturing are determined and calculated with reference to SY / T5108-2014 "Test Methods for Proppant Performance in Hydraulic Fracturing and Gravel Packing Operations", and the conductivity is determined and calculated with reference to SY / T6302-2019 "Test Method for Conductivity of Fracturing Proppants".

[0080] Table 1

[0081]

[0082]

[0083] It can be seen from Table 1 that the quartz sand for fracturing prepared in Examples 4-6 of this application has excellent sphericity, bulk density, breakage rate and conductivity.

[0084] Comparative Example 1 is a comparative example prepared without adding the organosilicon-modified epoxy resin coating agent. It can be seen from the data in Table 1 that at 69 MPa, its breakage rate is 4.96% and the conductivity is 27.21 μm 2 ·cm.

[0085] The organosilicon-modified epoxy resin coating agent added in Comparative Example 2 is the intermediate prepared in Step S2 of Example 2. It can be seen from Table 1 that at 69 MPa, its breakage rate is 4.58% and the conductivity is 30.45 μm 2 ·cm.

[0086] The organosilicon-modified epoxy resin coating agent added in Comparative Example 3 is aminopropylmethylpolysiloxane. It can be seen from Table 1 that at 69 MPa, its breakage rate is 4.21% and the conductivity is 31.68 μm 2 ·cm.

[0087] The organosilicon-modified epoxy resin coating agent added in Comparative Example 4 is 29 g of the intermediate prepared in Step S2 of Example 2 and 36 g of aminopropylmethylpolysiloxane. It can be seen from Table 1 that at 69 MPa, its breakage rate is 3.45% and the conductivity is 35.23 μm 2 ·cm.

[0088] The organosilicon-modified epoxy resin coating agent added in Comparative Example 5 is 15 g of a transparent colloidal solid (prepared in Step S1 of Example 2), 23 g of bisphenol A epoxy resin (E51) and 27 g of aminopropylmethylpolysiloxane. It can be seen from Table 1 that at 69 MPa, its breakage rate is 3.56% and the conductivity is 34.84 μm 2 ·cm.

[0089] Comparative Example 6 is a double-hydrophobic modified quartz sand proppant made from the raw material composition and manufacturing process in Table 2 of the embodiment of the Chinese invention patent specification of CN115851254A. As can be seen from Table 1, its breakage rate is 3.89% at 69 MPa, and its conductivity is 34.32 μm 2 ·cm.

[0090] Comparative Example 7 is a kind of quartz sand for fracturing made from the raw material composition and manufacturing process in Example 2 of the Chinese invention patent specification with the publication number of CN112876118A. As can be seen from Table 1, its breakage rate is 10.32% at 69 MPa, and its conductivity is 15.25 μm 2 ·cm.

[0091] The above are only the preferred embodiments of the present invention and are not used to limit the present invention; however, for those of ordinary skill in the art, within the scope not departing from the technical solution of the present invention, any equivalent changes such as slight modifications, refinements, and evolutions made using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A quartz sand for fracturing, characterized in that, The quartz sand for fracturing comprises the following raw materials in parts by weight: 50 parts of quartz sand, and 5 - 8 parts of organosilicon - modified epoxy resin film - forming agent; The organosilicon - modified epoxy resin film - forming agent is prepared by the following method: S1: Under nitrogen protection, DMF and 2,6 - tolylene diisocyanate are successively added into a reactor, stirred and dissolved, heated to 50 - 70 °C, then PEG800 is slowly added dropwise. After the addition is completed, dibutyltin dilaurate as a catalyst is added, and the reaction is carried out for 4 - 6 h. After post - treatment, a transparent colloidal solid is obtained; S2: Under nitrogen protection, acetone, the transparent colloidal solid, and bisphenol A epoxy resin are successively added into a reactor, stirred and dissolved, heated to 80 - 100 °C, dibutyltin dilaurate as a catalyst is added, and the reaction is carried out for 6 - 8 h. After post - treatment, an intermediate is obtained; S3: DMF, the intermediate, and aminopropylmethylpolysiloxane are successively added into a reactor, stirred and dissolved, heated to 80 - 120 °C, the reaction is carried out for 4 - 6 h, cooled to 60 - 80 °C, triethylamine is added for neutralization, and then vacuum distillation is carried out to obtain the organosilicon - modified epoxy resin film - forming agent; In step S1, the feeding mass ratio of DMF, 2,6 - tolylene diisocyanate, PEG800, and dibutyltin dilaurate is 20:(8 - 10):(4 - 6):(0.01 - 0.03); In step S2, the feeding mass ratio of acetone, the transparent colloidal solid, bisphenol A epoxy resin, and dibutyltin dilaurate is 50:(6 - 8):(10 - 12):(0.05 - 0.08); In step S3, the feeding mass ratio of DMF, the intermediate, and aminopropylmethylpolysiloxane is 50:(8 - 12):(10 - 15).

2. The preparation method of the quartz sand for fracturing according to claim 1, characterized in that, It includes the following steps: S1: Weigh quartz sand by weight parts, wash it 3 times with deionized water, wash it 1 time with absolute ethanol, and then wash it 1 time with petroleum ether, and dry it in an electro - thermal blast drying oven at 80 - 100 °C for 4 - 6 h to obtain a precursor; S2: Mix the organosilicon - modified epoxy resin film - forming agent and DMF evenly at room temperature to obtain a viscous modified epoxy resin film - forming agent; S3: Add the precursor and the viscous modified epoxy resin film - forming agent into a reactor, stir at 100 - 120 °C for 4 - 6 h, and then dry at 105 - 115 °C for 10 - 12 h to obtain the quartz sand for fracturing.

Images