High-strength ceramsite proppant and preparation method thereof

Abstract

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

Description

Technical Field

[0001] The invention relates to the technical field of petroleum proppants, and in particular 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 oil and natural gas is increasing. There are many ways to extract oil now, but the most practical, efficient and effective method is hydraulic fracturing; proppant is an indispensable filling material when using hydraulic fracturing technology to extract oil. It can maintain the cracking state of oil-producing cracks and ensure the smoothness of oil production channels. Good proppant can increase the amount of oil produced. At present, high-alumina bauxite is the main raw material of artificial ceramsite fracturing proppant. The quality of its raw materials and mining conditions directly affect the development of the proppant industry. The development of low-density, high-strength, and high-resistance ceramsite proppant products has become a major issue in the current ceramsite proppant industry.

[0003] The Chinese invention patent with publication number CN101560381A discloses a ceramsite proppant and a preparation method thereof. The ceramsite proppant is composed of the following raw materials in parts by weight: 93-99 parts of bauxite, 1-7 parts of manganese tetraoxide, and 8-15 parts of an aqueous organic binder. The ceramsite proppant prepared in its optimal embodiment has a crushing rate of 4.30% at 86 MPa and a crushing rate of 3.9% at 69 MPa, and has poor mechanical strength. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention aims to provide a high-strength ceramsite proppant and a preparation method thereof.

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

[0006] A high-strength ceramsite proppant comprises 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 aqueous organic binder is prepared by copolymerizing xanthan gum, acrylamide and vinyl pyrrolidone.

[0009] The aqueous organic binder is prepared by the following method:

[0010] Under nitrogen protection, deionized water, xanthan gum, acrylamide, and vinyl pyrrolidone were added to the reaction bottle, stirred and mixed, and the temperature was raised to 50-60°C. Ammonium persulfate solution was slowly added dropwise to the reaction bottle for 0.5-1h. The graft copolymerization reaction was carried out for 1-2h to obtain a water-based organic binder. 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, vinyl pyrrolidone and ammonium persulfate solution 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 method for preparing a high-strength ceramsite proppant comprises the following steps:

[0016] S1: Bauxite, purple clay, magnesium oxide and bentonite are mixed together in a tubular ball mill according to weight ratio to obtain a mixture;

[0017] S2: sending the mixture to a rolling granulator, spraying an aqueous organic binder on the mixture to make it bonded to form a dense green ball, screening the green ball with a circular rolling screen, and then drying it in a tower drying drum to obtain a semi-finished ball;

[0018] S3: The semi-finished balls are sintered in a rotary kiln at 1200-1400°C. The speed of the rotary kiln is controlled at 1-3r / min. After calcining in the rotary kiln for 1-2h, a crude product is obtained. The crude product is cooled to 40-50°C through a cooling drum, and then sieved with a double-layer sieve to obtain a 20-40 mesh product. After polishing and dust removal, the ceramsite proppant is obtained.

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

[0020] (1) The present invention prepares an aqueous organic binder with good bonding strength through the graft copolymerization reaction of xanthan gum, acrylamide and vinyl pyrrolidone, and combines the prepared aqueous binder with raw materials such as bauxite, so that the prepared spheres have higher roundness and smoothness, which is beneficial to improving the mechanical strength and flow conductivity of expanded clay.

[0021] (2) The aqueous organic binder prepared by the present invention contains a large amount of oxidative functional groups. After the addition of the organic binder, the hydrophilicity of the mineral powder surface is enhanced, which is conducive to ball formation. At the same time, the adhesion of the solution between the particles can be improved, thereby increasing the capillary force and viscosity between the particles, and greatly improving the strength of the raw balls. At the same time, the binder affects the capillary attraction and viscosity through its polarity. In addition, the developed and continuous network structure formed by the linear long-chain molecules in the binder solution can tightly connect and wrap the mineral powder particles, playing a relatively strong "bridge chain role". This role makes the mineral powder particles tightly aggregate together, thereby improving the strength of the raw balls. DETAILED DESCRIPTION

[0022] The invention will be further described below in conjunction with the embodiments, but the invention is not limited to these embodiments.

[0023] Example 1

[0024] Preparation of water-based organic binder:

[0025] Under nitrogen protection, add 500g of deionized water, 100g of xanthan gum, 20g of acrylamide, and 50g of vinylpyrrolidone to the reaction bottle, stir to mix, and heat to 50°C; slowly add 5g of ammonium persulfate solution (0.05mol / L) to the reaction bottle, add for 0.5h, and graft copolymerize for 2h. After the reaction is completed, cool to room temperature, add 2kg of deionized water, stir to mix, and obtain an aqueous organic binder.

[0026] Example 2

[0027] Preparation of water-based organic binder:

[0028] Under nitrogen protection, add 500g of deionized water, 110g of xanthan gum, 30g of acrylamide, and 65g of vinylpyrrolidone to the reaction bottle, stir to mix, and heat to 55°C; slowly add 8g of ammonium persulfate solution (0.08mol / L) to the reaction bottle, add for 45min, and graft copolymerize for 1.5h. After the reaction is completed, cool to room temperature, add 2kg of deionized water, stir to mix, and obtain an aqueous organic binder.

[0029] Example 3

[0030] Preparation of water-based organic binder:

[0031] Under nitrogen protection, add 500g of deionized water, 120g of xanthan gum, 40g of acrylamide, and 80g of vinylpyrrolidone to the reaction bottle, stir to mix, and heat to 60°C; slowly add 10g of ammonium persulfate solution (0.1mol / L) to the reaction bottle, add for 1h, and carry out graft copolymerization for 1h. After the reaction is completed, cool to room temperature, add 2kg of deionized water, stir to mix, and obtain an aqueous organic binder.

[0032] Example 4

[0033] Preparation of high-strength ceramsite proppant:

[0034] S1: 700g of bauxite, 300g of purple clay, 20g of magnesium oxide, and 30g of bentonite were mixed in a tubular ball mill according to weight ratio to obtain a mixture;

[0035] S2: The mixture is sent to a rolling granulator, 80 g of an aqueous organic binder (prepared in Example 1) is sprayed on the mixture to form a dense green ball, the green ball is sieved with a circular rolling screen, and then dried in a tower drying drum to obtain a semi-finished ball;

[0036] S3: The semi-finished balls are sintered in a rotary kiln at 1200°C. The speed of the rotary kiln is controlled at 1r / min. After calcining in the rotary kiln for 2 hours, a crude product is obtained. The crude product is cooled to 40°C through a cooling drum, and then sieved with a double-layer sieve to obtain a 20-40 mesh product. After polishing and dust removal, the expanded clay proppant is obtained.

[0037] Example 5

[0038] Preparation of high-strength ceramsite proppant:

[0039] S1: 800g of bauxite, 350g of purple clay, 30g of magnesium oxide, and 45g of bentonite were put into a tubular ball mill according to the weight ratio and mixed to obtain a mixture;

[0040] S2: The mixture is sent to a rolling granulator, 90 g of an aqueous organic binder (prepared in Example 2) is sprayed on the mixture to form a dense green ball, the green ball is sieved with a circular rolling screen, and then dried in a tower drying drum to obtain a semi-finished ball;

[0041] S3: The semi-finished balls are sintered in a rotary kiln at 1300°C. The speed of the rotary kiln is controlled at 2r / min. After calcining in the rotary kiln for 1.5 hours, a crude product is obtained. The crude product is cooled to 45°C through a cooling drum, and then sieved with a double-layer sieve to obtain a 20-40 mesh product. After polishing and dust removal, the expanded clay proppant is obtained.

[0042] Example 6

[0043] Preparation of high-strength ceramsite proppant:

[0044] S1: 900 g of bauxite, 400 g of purple clay, 40 g of magnesium oxide, and 60 g of bentonite were mixed together in a tubular ball mill according to a weight ratio to obtain a mixture;

[0045] S2: The mixture is sent to a rolling granulator, 100 g of an aqueous organic binder (prepared in Example 3) is sprayed on the mixture to form a dense green ball, the green ball is sieved with a circular rolling screen, and then dried in a tower drying drum to obtain a semi-finished ball;

[0046] S3: The semi-finished balls are sintered in a rotary kiln at 1400°C. The speed of the rotary kiln is controlled at 3r / min. After calcining in the rotary kiln for 1 hour, a crude product is obtained. The crude product is cooled to 50°C through a cooling drum, and then sieved with a double-layer sieve to obtain a 20-40 mesh product. After polishing and dust removal, the expanded clay proppant is obtained.

[0047] Comparative Example 1

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

[0049] Comparative Example 2

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

[0051] Comparative Example 3

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

[0053] Comparative Example 4

[0054] The preparation method of the high-strength ceramsite proppant is substantially 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 polyvinyl pyrrolidone (PVP K30).

[0055] Comparative Example 5

[0056] The ceramsite proppant was prepared by using the raw material composition of Group 2 in Example Table 2 of the Chinese invention patent specification with publication number CN101560381A and the production process of the present application.

[0057] The bentonite used in the examples and comparative examples of the present application is of model Bentone 38, produced by Dachanghua Jiahui Zhengxing 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 87.8wt%); and the purple clay is Xinjin purple clay (sand content 69.5wt%, calcium carbonate content 7.8wt%).

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

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

[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 the present application have excellent sphericity, bulk density, apparent density and crushing rate.

[0064] Comparative Example 1 is a comparative example of a high-strength ceramsite proppant prepared without adding an aqueous organic binder. From the data in Table 1, it can be seen that the crushing 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 vinylpyrrolidone. As can be seen from Table 1, the crushing rate is 4.2% at 69 MPa.

[0066] The aqueous organic binder added in Comparative Example 3 is a xanthan gum aqueous solution. As can be seen from Table 1, its crushing 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. As can be seen from Table 1, its crushing rate is 4.0% at 69 MPa.

[0068] Comparative Example 5 is a ceramsite proppant produced by using the optimal raw material composition of the Chinese invention patent with publication number CN101560381A and the production process of the present application. As can be seen from Table 1, its crushing rate is 3.9% at 69 MPa.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. However, any equivalent changes, modifications and evolutions made by ordinary technicians in the field without departing from the scope of the technical solution of the present invention by 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 are still within the protection scope of the technical solution of the present invention.

Claims

1. A high-strength ceramsite proppant, characterized in that: The invention 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 aqueous organic binder is prepared by the following method: Under nitrogen protection, deionized water, xanthan gum, acrylamide and vinyl pyrrolidone were added to the reaction bottle, stirred and mixed, and the temperature was raised to 50-60° C. Ammonium persulfate solution was slowly added dropwise to the reaction bottle for 0.5-1 h, and the graft copolymerization reaction was carried out for 1-2 h to obtain a water-based organic binder.

2. A high-strength ceramsite proppant according to claim 1, characterized in that: The mass ratio of the deionized water, xanthan gum, acrylamide, vinyl pyrrolidone and ammonium persulfate solution is 50:(10-12):(2-4):(5-8):(0.5-1).

3. A high-strength ceramsite proppant according to claim 1, characterized in that: The concentration of the ammonium persulfate solution is 0.05-0.1 mol / L.

4. A method for preparing a high-strength ceramsite proppant according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: Bauxite, purple clay, magnesium oxide and bentonite are mixed together in a tubular ball mill according to weight ratio to obtain a mixture; S2: sending the mixture to a rolling granulator, spraying an aqueous organic binder on the mixture to make it bonded to form a dense green ball, screening the green ball with a circular rolling screen, and then drying it in a tower drying drum to obtain a semi-finished ball; S3: The semi-finished balls are sintered in a rotary kiln at 1200-1400°C. The speed of the rotary kiln is controlled at 1-3r / min. After calcining in the rotary kiln for 1-2h, a crude product is obtained. The crude product is cooled to 40-50°C through a cooling drum, and then sieved with a double-layer sieve to obtain a 20-40 mesh product. After polishing and dust removal, the ceramsite proppant is obtained.

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