A high-strength ceramsite proppant and its preparation method

Abstract

The present invention discloses a high-strength ceramsite proppant and a preparation method thereof, relating to the technical field of petroleum proppants. The ceramsite proppant comprises the following raw materials in parts by weight: bauxite: 70-90 parts, purple clay: 30-40 parts, bentonite: 3-6 parts, water-based organic binder: 8-10 parts, magnesium oxide: 2-4 parts. The present invention prepares a water-based organic binder by reacting xanthan gum, acrylamide and vinylpyrrolidone. The high-strength ceramsite proppant prepared by the present invention has properties such as low density, high strength, low breakage rate and high sphericity.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum proppants, and particularly relates to a high-strength ceramsite proppant and a preparation method thereof. Background Art

[0002] With the rapid development of industrialization and the continuous growth of social economy, people's demand for fossil fuels such as petroleum and natural gas is increasing. There are many methods for oil extraction currently, but the most practical, efficient, and highest-efficiency method is hydraulic fracturing; proppants are an essential filling material when using hydraulic fracturing technology to extract oil. It can maintain the cracking state of the oil-producing fractures, ensure the smoothness of the oil production channel, and good proppants can increase the oil extraction volume. Currently, bauxite is the main raw material for artificial ceramsite fracturing proppants, and its raw material quality and mining conditions directly affect the development of the proppant industry. Developing ceramsite proppant products with low density, high strength, and high anti-breakage ability has become a major issue in the current ceramsite proppant industry.

[0003] Chinese Patent Invention No. CN101560381A discloses a ceramsite proppant and a preparation method thereof. The ceramsite proppant is composed of the following raw materials in parts by weight: bauxite: 93 - 99 parts, manganese tetroxide: 1 - 7 parts, water-based organic binder: 8 - 15 parts; the ceramsite proppant prepared in its optimal embodiment has a breakage rate of 4.30% at 86 MPa and a breakage rate of 3.9% at 69 MPa, with poor mechanical strength. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a high-strength ceramsite proppant and a preparation method thereof.

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

[0006] A high-strength ceramsite proppant, comprising the following raw materials in parts by weight:

[0007] Bauxite: 70 - 90 parts, purple clay: 30 - 40 parts, bentonite: 3 - 6 parts, water-based organic binder: 8 - 10 parts, magnesium oxide: 2 - 4 parts;

[0008] The water-based organic binder is prepared by copolymerizing xanthan gum, acrylamide, and vinyl pyrrolidone.

[0009] The water-based organic binder is prepared by the following method:

[0010] Under nitrogen protection, deionized water, xanthan gum, acrylamide, and vinylpyrrolidone were added to the reaction flask, stirred evenly, heated to 50 - 60 °C, and an ammonium persulfate solution was slowly added dropwise to the reaction flask over 0.5 - 1 h. After graft copolymerization for 1 - 2 h, an aqueous organic binder was obtained. The reaction equation is shown as follows:

[0011]

[0012] Among them, m and n are natural numbers, and XG represents xanthan gum.

[0013] The mass ratio of the deionized water, xanthan gum, acrylamide, vinylpyrrolidone, and ammonium persulfate solution for feeding is 50:(10 - 12):(2 - 4):(5 - 8):(0.5 - 1).

[0014] The concentration of the ammonium persulfate solution is 0.05 - 0.1 mol / L.

[0015] A preparation method of a high-strength ceramsite proppant includes the following steps:

[0016] S1: Bauxite, purple clay, magnesium oxide, and bentonite were weighed and put into a tubular ball mill for mixing to make them evenly mixed, obtaining a mixed material.

[0017] S2: The mixed material was sent to a rolling granulator, and the aqueous organic binder was sprayed onto the mixed material to make it bond to form dense green balls. The green balls were screened by a circular rolling screen and then dried in a tower drying cylinder to obtain semi-finished balls.

[0018] S3: The semi-finished balls were sintered in a rotary kiln at 1200 - 1400 °C, the rotation speed of the rotary kiln was controlled at 1 - 3 r / min, and after calcination in the rotary kiln for 1 - 2 h, a crude product was obtained. The crude product was cooled to 40 - 50 °C by a cooling cylinder and then screened by a double-layer screen to obtain a 20 - 40 mesh product, and then polished and dust-removed to obtain the ceramsite proppant.

[0019] Due to the above technical solutions, the beneficial effects of the present invention include:

[0020] (1) The present invention prepared an aqueous organic binder with good bonding strength through the graft copolymerization reaction of xanthan gum, acrylamide, and vinylpyrrolidone. Combining the prepared aqueous binder with raw materials such as bauxite makes the prepared spheres have high roundness and smoothness, which is beneficial to improving the mechanical strength and conductivity of the ceramsite.

[0021] (2) The water-based organic binder prepared by the present invention contains a large number of oxidized functional groups. After adding the organic binder, the hydrophilicity of the mineral powder surface is enhanced, which is beneficial to pelletizing. At the same time, the bonding degree of the solution between particles can be improved, thereby increasing the capillary force energy and viscous action energy between particles, and greatly improving the green pellet strength. At the same time, the binder affects the capillary attraction and viscous force through its polarity. Moreover, in the binder solution, the developed and continuous network structure formed by linear long-chain molecules can tightly connect and wrap the mineral powder particles, playing a relatively firm "bridging chain effect". This effect tightly aggregates the mineral powder particles together, thereby improving the green pellet strength. Detailed implementation manners

[0022] The following is further illustrated with reference to embodiments, but the present invention is not limited to these embodiments.

[0023] Embodiment 1

[0024] Preparation of water-based organic binder:

[0025] Under nitrogen protection, add 500 g of deionized water, 100 g of xanthan gum, 20 g of acrylamide, and 50 g of vinyl pyrrolidone to the reaction flask, stir and mix evenly, and heat up to 50 °C. Slowly add 5 g of ammonium persulfate solution (0.05 mol / L) to the reaction flask dropwise over 0.5 h, carry out graft copolymerization reaction for 2 h, cool to room temperature after the reaction, and add 2 kg of deionized water and stir and mix evenly to obtain the water-based organic binder.

[0026] Embodiment 2

[0027] Preparation of water-based organic binder:

[0028] Under nitrogen protection, add 500 g of deionized water, 110 g of xanthan gum, 30 g of acrylamide, and 65 g of vinyl pyrrolidone to the reaction flask, stir and mix evenly, and heat up to 55 °C. Slowly add 8 g of ammonium persulfate solution (0.08 mol / L) to the reaction flask dropwise over 45 min, carry out graft copolymerization reaction for 1.5 h, cool to room temperature after the reaction, and add 2 kg of deionized water and stir and mix evenly to obtain the water-based organic binder.

[0029] Embodiment 3

[0030] Preparation of water-based organic binder:

[0031] Under nitrogen protection, add 500 g of deionized water, 120 g of xanthan gum, 40 g of acrylamide, and 80 g of vinyl pyrrolidone to the reaction flask, stir and mix evenly, and heat up to 60 °C. Slowly add 10 g of ammonium persulfate solution (0.1 mol / L) to the reaction flask dropwise over 1 h, carry out graft copolymerization reaction for 1 h, cool to room temperature after the reaction, and add 2 kg of deionized water and stir and mix evenly to obtain the water-based organic binder.

[0032] Example 4

[0033] Preparation of high-strength ceramsite proppant:

[0034] S1: 700g of bauxite, 300g of purple sand clay, 20g of magnesium oxide, and 30g of bentonite were weighed and put into a tubular ball mill for mixing until evenly mixed to obtain a mixed material;

[0035] S2: The mixed material was sent to a rotary granulator, and 80g of water-based organic binder (prepared in Example 1) was sprayed onto the mixed material to make it bond to form dense green balls. The green balls were screened by a circular vibrating screen and then dried in a tower dryer to obtain semi-finished balls;

[0036] S3: The semi-finished balls were sintered in a rotary kiln at 1200°C, and the rotation speed of the rotary kiln was controlled at 1r / min. After calcining in the rotary kiln for 2h, the crude product was obtained. The crude product was cooled to 40°C in a cooling cylinder, and then screened by a double-layer screen to obtain 20-40 mesh products, and then polished and dust-removed to obtain the ceramsite proppant.

[0037] Example 5

[0038] Preparation of high-strength ceramsite proppant:

[0039] S1: 800g of bauxite, 350g of purple sand clay, 30g of magnesium oxide, and 45g of bentonite were weighed and put into a tubular ball mill for mixing until evenly mixed to obtain a mixed material;

[0040] S2: The mixed material was sent to a rotary granulator, and 90g of water-based organic binder (prepared in Example 2) was sprayed onto the mixed material to make it bond to form dense green balls. The green balls were screened by a circular vibrating screen and then dried in a tower dryer to obtain semi-finished balls;

[0041] S3: The semi-finished balls were sintered in a rotary kiln at 1300°C, and the rotation speed of the rotary kiln was controlled at 2r / min. After calcining in the rotary kiln for 1.5h, the crude product was obtained. The crude product was cooled to 45°C in a cooling cylinder, and then screened by a double-layer screen to obtain 20-40 mesh products, and then polished and dust-removed to obtain the ceramsite proppant.

[0042] Example 6

[0043] Preparation of high-strength ceramsite proppant:

[0044] S1: 900g of bauxite, 400g of purple sand clay, 40g of magnesium oxide, and 60g of bentonite were weighed and put into a tubular ball mill for mixing until evenly mixed to obtain a mixed material;

[0045] S2: Feed the mixture to a rolling granulator, spray 100 g of the aqueous organic binder (prepared in Example 3) onto the mixture to make it bond and form dense green balls. Screen the green balls with a circular vibrating screen, and then dry them in a tower dryer to obtain semi-finished balls.

[0046] S3: Sinter the semi-finished balls in a rotary kiln at 1400 °C, control the rotation speed of the rotary kiln at 3 r / min, and obtain the crude product after calcining in the rotary kiln for 1 h. Cool the crude product to 50 °C in a cooling cylinder, and then screen it with a double-layer screen to obtain a product with a mesh size of 20 - 40. Then, perform polishing and dust removal treatments to obtain the ceramic proppant.

[0047] Comparative Example 1

[0048] The preparation method of the high-strength ceramic proppant is basically the same as that of Example 5, except that no aqueous organic binder is added to the components.

[0049] Comparative Example 2

[0050] The preparation method of the high-strength ceramic proppant is basically the same as that of Example 5, except that the aqueous organic binder is replaced with an aqueous solution of 14 g of acrylamide, 48 g of xanthan gum, and 28 g of vinylpyrrolidone.

[0051] Comparative Example 3

[0052] The preparation method of the high-strength ceramic proppant is basically the same as that of Example 5, except that the aqueous organic binder is replaced with 90 g of a 5 wt% aqueous solution of xanthan gum.

[0053] Comparative Example 4

[0054] The preparation method of the high-strength ceramic proppant is basically the same as that of Example 5, except that the aqueous organic binder is replaced with 90 g of a 5 wt% aqueous solution of polyvinylpyrrolidone (PVP K30).

[0055] Comparative Example 5

[0056] Adopt the raw material composition of Group 2 in Table 2 of the embodiment of the Chinese invention patent specification with the publication number of CN101560381A, and use the manufacturing process of the present application to make the ceramic proppant.

[0057] The bentonite used in the examples and comparative examples of the present application is of the type Bentone 38, produced by Dachang Huajia Huizheng Chemical (Shanghai) Co., Ltd.; xanthan gum is purchased from Shandong Fufeng Fermentation Co., Ltd.; bauxite is purchased from Gongyi Yuying Refractory Materials Co., Ltd. (the content of Al2O3 is 87.8 wt%); the purple clay is Xinjin purple clay (the sand content is 69.5 wt%, and the calcium carbonate content is 7.8 wt%).

[0058] The high-strength ceramsite proppants prepared in Examples 4-6 and Comparative Examples 1-5 of this application were tested for sphericity, bulk density, apparent density, and breakage rate. The test results are shown in Table 1.

[0059] The sphericity, bulk density, apparent density, and breakage rate of the ceramsite proppants were determined and calculated with reference to SY / T5108-2014 "Test Methods for Proppant Performance in Hydraulic Fracturing and Gravel Packing Operations". The Xpert MPD Pro X-ray diffractometer was used to perform phase analysis on the samples, and the JSM-6360LV scanning electron microscope was used to observe the structure of the ceramsite proppants.

[0060] Table 1

[0061]

[0062]

[0063] It can be seen from Table 1 that the high-strength ceramsite proppants prepared in Examples 4-6 of this application have excellent sphericity, bulk density, apparent density, and breakage rate.

[0064] Comparative Example 1 is a comparative example of a high-strength ceramsite proppant prepared without adding an aqueous organic binder. It can be seen from the data in Table 1 that its breakage rate is 5.1% at 69 MPa.

[0065] The aqueous organic binder added in Comparative Example 2 is an aqueous solution of acrylamide, xanthan gum, and vinyl pyrrolidone. It can be seen from Table 1 that its breakage rate is 4.2% at 69 MPa.

[0066] The aqueous organic binder added in Comparative Example 3 is an aqueous solution of xanthan gum. It can be seen from Table 1 that its breakage rate is 4.6% at 69 MPa.

[0067] The aqueous organic binder added in Comparative Example 4 is a 0.5% aqueous solution of polyvinyl pyrrolidone. It can be seen from Table 1 that its breakage rate is 4.0% at 69 MPa.

[0068] Comparative Example 5 is a ceramsite proppant prepared using the optimal raw material composition of the Chinese invention patent with the publication number CN101560381A and the manufacturing process of this application. It can be seen from Table 1 that its breakage rate is 3.9% at 69 MPa.

[0069] 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, without departing from the technical solution of the present invention, any minor changes, modifications, and equivalent variations made using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any changes, modifications, and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A high-strength ceramsite proppant, characterized in that, It comprises raw materials in the following parts by weight: Bauxite: 70 - 90 parts, purple sand clay: 30 - 40 parts, bentonite: 3 - 6 parts, water-based organic binder: 8 - 10 parts, magnesium oxide: 2 - 4 parts; The water-based organic binder is prepared by the following method: Under nitrogen protection, deionized water, xanthan gum, acrylamide, and vinylpyrrolidone are added to a reaction flask, stirred and mixed evenly, heated to 50 - 60 °C, and an ammonium persulfate solution is slowly added dropwise to the reaction flask over 0.5 - 1 h, followed by a graft copolymerization reaction for 1 - 2 h to obtain the water-based organic binder; The mass ratio of the deionized water, xanthan gum, acrylamide, vinylpyrrolidone, and ammonium persulfate solution for feeding is 50:(10 - 12):(2 - 4):(5 - 8):(0.5 - 1).

2. The high-strength ceramsite proppant according to claim 1, wherein The concentration of the ammonium persulfate solution is 0.05 - 0.1 mol / L.

3. The preparation method of the high-strength ceramsite proppant according to any one of claims 1-2, characterized in that, It comprises the following steps: S1: The bauxite, purple sand clay, magnesium oxide, and bentonite are weighed and put into a tubular ball mill for mixing to make them evenly mixed, obtaining a mixed material; S2: The mixed material is sent to a rotary granulator, and the water-based organic binder is sprayed onto the mixed material to make it bond to form dense green balls. The green balls are screened by a circular vibrating screen and then dried in a tower dryer to obtain semi-finished balls; S3: The semi-finished balls are sintered in a rotary kiln at 1200 - 1400 °C, the rotational speed of the rotary kiln is controlled at 1 - 3 r / min, and after calcination in the rotary kiln for 1 - 2 h, a crude product is obtained. The crude product is cooled to 40 - 50 °C by a cooling cylinder, then screened by a double-layer screen to obtain a 20 - 40 mesh product, and then polished and dust-removed to obtain the ceramic proppant.

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