High-strength fracking proppant and preparation method therefor

Abstract

The present invention relates to the field of oil and gas extraction technology, and specifically to a high-strength fracking proppant and a preparation method therefor. The preparation method for the high-strength fracking proppant comprises the following steps: evenly mixing dry residue of oil matrix cuttings and aluminum slag, and performing high-temperature calcination pretreatment, to obtain pretreated dry residue; crushing the pretreated dry residue, to obtain a dry powder; granulating the dry powder, to obtain green pellets; and sintering the green pellets, to obtain a high-strength fracking proppant. The high-strength fracking proppant has a particle size of 40-70 mesh, a crush rate of <9% at 86 Mpa, an acid solubility of <7%, and a sphericity of >0.9. The high-strength fracking proppant of the present invention is prepared from dry residue of oil matrix cuttings and aluminum slag, is capable of generating bubble-free barium feldspar, and improves its strength at small particle sizes.

Description

High-strength fracturing proppant and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas exploitation, in particular to a high-strength fracturing proppant and a preparation method thereof. BACKGROUND

[0002] Petroleum is an important strategic resource. The proven recoverable reserves, resource reserves and production of petroleum in China are significantly lower than the world average. Effective exploitation and increased production of oilfields become increasingly important. Hydraulic fracturing technology is the most commonly used measure for increasing production of oil wells. Proppant is an important component of hydraulic fracturing. The performance of proppant directly affects the level of production capacity of oil wells. With the continuous development of deep well tight oil layers, the bottom closure pressure of oil wells increases, and the strength requirement of proppant is also increasing.

[0003] At present, proppants used in oil and gas exploitation can be roughly divided into three categories: quartz sand proppant, artificial ceramic proppant and coated proppant. Quartz sand proppant has wide distribution and low price but low strength, is easy to crush and form cracks, and cannot be used in medium and high closure pressure fracturing layers. Artificial ceramic proppant is often made of bauxite and has the advantages of high strength and high flow conductivity. However, bauxite ceramic proppant has a high density, which increases the operation cost (such as higher performance and pumping conditions of fracturing fluid), and the supply and demand of bauxite resources is seriously imbalanced. Therefore, it is particularly important to reduce the use of bauxite. Coated proppant can better adapt to the complex environment at the bottom of the oil layer, has better acid resistance, strength and flow conductivity, but the coating increases the process cost and difficulty. TECHNICAL PROBLEM

[0004] In the prior art, Chinese patent CN117247282A discloses a microwave sintering oil-based rock residue ceramic proppant and a preparation method thereof, and specifically discloses that the proportions of the components of the ceramic proppant are as follows in terms of dry mass: oil-based rock residue: 40-60 parts, low-grade bauxite: 10-20 parts, waste aluminum ash: 30-40 parts, coal gangue: 5-10 parts, and wet metallurgical manganese slag: 10-15 parts. The main mineral components are barium feldspar, corundum and zirconia. In the present application, bauxite and waste aluminum ash are used, but only to enhance the strength of large-diameter proppants. In addition, the presence of carbonate ash in waste aluminum ash affects the strength of barium feldspar. TECHNICAL SOLUTION

[0005] The present application provides a high-strength fracturing proppant and a preparation method thereof. The high-strength fracturing proppant is prepared from oil-containing rock residue dry slag and aluminum slag, and can generate barium feldspar without air bubbles, thereby improving the strength of the proppant at small particle sizes.

[0006] A preparation method of a high-strength fracturing proppant, comprising the following steps:

[0007] 1) Pretreatment: taking oil-based cutting dry slag and aluminum slag, uniformly mixing, high-temperature calcination pretreatment, obtaining pretreated dry slag;

[0008] 2) Crushing: crushing the pretreated dry slag of step 1) pretreatment, obtaining dry powder;

[0009] 3) Granulation: granulating the dry powder of step 2) crushing, obtaining green balls;

[0010] 4) Sintering: sintering the green balls of step 3) granulation, obtaining high-strength fracturing proppant.

[0011] In one specific embodiment of the present application, step 1) pretreatment, the mass ratio of the oil-based cutting dry slag to the aluminum slag is 85-95:5-15.

[0012] In one specific embodiment of the present application, the chemical composition and content of the oil-based cutting dry slag are as follows: SiO2 30-45wt%, Al2O3 5-15wt%, CaO 10-15wt%, BaSO4 20-35wt%, MgO <3wt%, Fe2O3 <5%.

[0013] In one specific embodiment of the present application, the chemical composition and content of the aluminum slag are as follows: Al2O3 70-85wt%, Na2O 5-15w%, NaCl 5-10w% and the balance <5wt%.

[0014] In one specific embodiment of the present application, step 1) pretreatment, the temperature of high-temperature calcination is 900-1000℃, and the time is 20-40min.

[0015] In one specific embodiment of the present application, step 2) crushing, the crushing is crushed to 500 mesh sieve residue ≤5%.

[0016] In one specific embodiment of the present application, step 3) granulation, the roundness of the green ball is 0.9-1.0, the sphericity is 0.9-1.0, and the particle size is 40-70 mesh.

[0017] In one specific embodiment of the present application, step 4) sintering, the sintering is carried out in a rotary kiln.

[0018] In one specific embodiment of the present application, step 4) sintering, the temperature of sintering is 1100-1180℃, and the time is 1-2h.

[0019] The high-strength fracturing proppant prepared by the preparation method has a particle size of 40-70 mesh, a crushing rate of <9% under 86Mpa, an acid solution degree of <7%, and a sphericity of >0.9.

[0020] In the application, the chemical reaction formula of the celsian generated in the sintering process is as follows:

[0021] 。

[0022] The high barium content in the oil-based dry cuttings slag and the high aluminum content in the aluminum slag can form celsian and further enhance the strength of the fracturing proppant. However, it is found through repeated experiments that the strength of the fracturing proppant prepared by directly sintering the oil-based dry cuttings slag and the aluminum slag is still poor. The inventors find that since the dry cuttings slag and the aluminum slag both contain carbonates, direct calcination will form carbon dioxide bubbles and celsian at the same time. The bubbles exist in the celsian grains and will affect the strength of the celsian grains. Therefore, the oil-based dry cuttings slag and the aluminum slag are mixed and then calcined at a temperature lower than the sintering temperature to decompose the carbonates and prevent the formation of celsian. After granulation, the mixture is sintered at the sintering temperature. As a result, the formed celsian does not contain carbon dioxide bubbles, the celsian grains are stable, and the high-strength fracturing proppant has better strength. Advantages

[0023] 1. In the preparation method of the high-strength fracturing proppant, the oil-based dry cuttings slag and the aluminum slag are mixed and then calcined at 900-1000℃ to decompose the carbonates, which is beneficial to the formation of celsian grains in the subsequent sintering process.

[0024] 2. In the preparation method of the high-strength fracturing proppant, the carbonates are decomposed by calcination, and there are no bubbles in the celsian grains in the sintering process, which ensures the strength of the celsian and significantly improves the strength of the small-particle-size high-strength fracturing proppant.

[0025] 3. The high-strength fracturing proppant prepared by the preparation method has a particle size of 40-70 mesh, a crushing rate of <9% under 86Mpa, an acid solution degree of <7%, and a sphericity of >0.9. BRIEF DESCRIPTION OF DRAWINGS

[0026] Fig. 1 is an XDR mineral phase diagram provided by the specific embodiment of the application;

[0027] Fig. 2 is a scanning electron microscope (SEM) image of the high-strength fracturing proppant provided by the embodiment of the application.

[0028] Fig. 3 is a performance test result diagram provided by the embodiment and the comparative example of the application. BEST MODE FOR CARRYING OUT THE INVENTION

[0029] The principles and features of the present application are described below in conjunction with the accompanying drawings, which are provided only for explanation of the present application and are not intended to limit the scope of the present application.

[0030] A preparation method of high-strength fracturing proppant, comprising the following steps:

[0031] 1) Pretreatment: uniformly mixing oil-based dry cuttings slag and aluminum slag, and performing high-temperature calcination pretreatment to obtain pretreated dry slag;

[0032] 2) Crushing: crushing the pretreated dry slag of step 1) to obtain dry powder;

[0033] 3) Granulation: granulating the dry powder of step 2) to obtain green balls;

[0034] 4) Sintering: sintering the green balls of step 3) to obtain high-strength fracturing proppant.

[0035] The present application is based on the high barium content in the oil-based dry cuttings slag and the high aluminum content in the aluminum slag to form celsian and thus enhance the strength of the fracturing proppant. However, through repeated experiments and research, it is found that the strength of the fracturing proppant prepared by directly sintering the oil-containing dry cuttings slag and the aluminum slag is still poor. The inventors have found that since the dry cuttings slag and the aluminum slag both contain carbonates, direct calcination will form carbon dioxide bubbles and celsian at the same time. The bubbles exist in the grains of celsian, which will affect the strength of the celsian grains. In view of this, the oil-containing dry cuttings slag and the aluminum slag are mixed, then calcined (calcination temperature < sintering temperature) to promote the decomposition of carbonates and prevent the formation of celsian, and then sintered at the sintering temperature after granulation. Thus, the formed celsian does not have carbon dioxide bubbles, the grains of celsian are stable, and the high-strength fracturing proppant has better strength. Embodiments of the present application

[0036] In some examples, in step 1) pretreatment, the mass ratio of the oil-based dry cuttings slag to the aluminum slag is 85-95:5-15.

[0037] In some examples, the chemical composition and content of the oil-based dry cuttings slag are as follows: SiO2 30-45wt%, Al2O3 5-15wt%, CaO 10-15wt%, BaSO4 20-35wt%, MgO <3wt%, and Fe2O3 <5%.

[0038] In some examples, the chemical composition and content of the aluminum slag are as follows: Al2O3 70-85wt%, Na2O 5-15w%, NaCl 5-10w%, and the balance ≤5wt%.

[0039] In some examples, in step 1), the high-temperature calcination is performed at a temperature of 900-1000℃ for 20-40 min.

[0040] In some examples, in step 2), the crushing is performed to a 500-mesh residue of <5%.

[0041] In some examples, in step 3), the spheroidization is performed to obtain a roundness of 0.9-1.0 and a sphericity of 0.9-1.0, and a particle size of 40-70 mesh.

[0042] In some examples, in step 4), the sintering is performed in a rotary kiln.

[0043] In some examples, in step 4), the sintering is performed at a temperature of 1100-1180℃ for 1-2 h.

[0044] The high-strength fracturing proppant prepared by the preparation method has a particle size of 40-70 mesh, a crushing rate of <9% at 86 MPa, an acid solution degree of <7%, and a roundness of >0.9.

[0045] In the present application, the chemical reaction formula of the celsian generated in the sintering process is as follows:

[0046] 。

[0047] The specific embodiments of the present application are further described below in conjunction with the examples, and the present application is not limited in the scope of the described examples.

[0048] In the following examples and comparative examples, the oil-based rock debris dry residue is a dry residue obtained by removing oil and water from organic rock debris generated during the extraction process by heat treatment, and the oil content and water content are both <3 ‰. Example 1

[0049] The present embodiment provides a preparation method of high-strength fracturing proppant, which comprises the following steps:

[0050] 1. Take oil-based rock debris dry residue and aluminum slag in a mass ratio of 90:10, mix uniformly, and calcine at 1000℃ for 30 min to obtain pretreated dry residue;

[0051] 2. Grind the pretreated dry residue to a 500-mesh residue of 4.2% to obtain dry powder;

[0052] 3. Granulate the dry powder to obtain a green ball with a particle size of 40-70 mesh;

[0053] 4. The green ball is placed in a rotary kiln, sintered at 1100-1180 °C for 1 h (temperature fluctuation exists during sintering, the range of temperature fluctuation during 1 h sintering is recorded here), removed, and quenched in a coolant to ≤60 °C to obtain 40-70 mesh high-strength fracturing proppant. Example 2

[0054] The difference between this example and Example 1 is that the sintering temperature is 1140-1180 °C. Example 3

[0055] The difference between this example and Example 1 is that the sintering temperature is 1100-1140 °C and the time is 2 h. Example 4

[0056] The difference between this example and Example 2 is that the mass ratio of oil-based dry cuttings slag to aluminum slag is 85:15. Example 5

[0057] The difference between this example and Example 3 is that the mass ratio of oil-based dry cuttings slag to aluminum slag is 95:5.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 3 is that the mass ratio of oil-based dry cuttings slag to aluminum slag is 97:3.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 2 is that the mass ratio of oil-based dry cuttings slag to aluminum slag is 80:20 and the sintering time is 2 h.

[0062] Comparative Example 3

[0063] The difference between this comparative example and Example 1 is that the sintering temperature is 1050-1100 °C and the sintering time is 2 h.

[0064] Comparative Example 4

[0065] The difference between this comparative example and Example 1 is that the sintering temperature is 1190-1230 °C and the sintering time is 0.5 h.

[0066] Comparative Example 5

[0067] The difference between this comparative example and Example 1 is that no calcination treatment is performed.

[0068] The XDR mineral phase results of the high-strength fracturing proppants of Examples 1-4 and Comparative Example 1 are shown in FIG. 1.

[0069] In the attached drawing 1, S1 represents Example 1, S3 represents Example 2, C3 represents Example 3, T1 represents Comparative Example 1, and C4 represents Example 4.

[0070] The scanning electron microscope result of the high-strength fracturing proppant of Example 1 is shown in FIG. 2.

[0071] In the attached drawing 2, the main component elements of P4 and P7 are O, Si, Al and Ba.

[0072] The performance result statistics of the crushing rate, acid solubility, roundness and sphericity of the high-strength fracturing proppants of Examples 1-5 and Comparative Examples 1-5 are shown in FIG. 3.

[0073] As can be seen from the experimental results of FIG. 3, compared with Comparative Examples 1-5, the crushing rate of the high-strength fracturing proppants of Examples 1-5 under the closed pressure of 86 MPa meets the requirement of the crushing rate < 9% in SY / T 5108-2014 “Performance Test Method for Proppants for Hydraulic Fracturing and Gravel Packing Operations”, which indicates that the oil-based dry cuttings and aluminum slag can be used to obtain high-strength fracturing proppants at a better mass ratio and a better sintering temperature. Industrial applicability

[0074] The present application is based on the high barium content in the oil-based dry cuttings and the high aluminum content in the aluminum slag to form celsian and thus to enhance the strength of the fracturing proppant. However, it is found through repeated experiments and researches that the strength of the fracturing proppant prepared by directly sintering the oil-based dry cuttings and the aluminum slag is still poor. The inventors find that since the oil-based dry cuttings and the aluminum slag both contain carbonates, direct calcination will form carbon dioxide bubbles and celsian at the same time, and the bubbles exist in the grains of the celsian, which will affect the strength of the celsian grains. In view of this, the oil-based dry cuttings and the aluminum slag are mixed and then calcined (calcination temperature < sintering temperature) to promote the decomposition of the carbonates and prevent the formation of celsian, and then sintered at the sintering temperature after granulation, so that the celsian formed does not contain carbon dioxide bubbles, and thus the grains of the celsian are stable and the high-strength fracturing proppant obtained has better strength.

Claims

1. A method of making a high-strength frac proppant, characterized by, The method comprises the following steps: 1) Pretreatment: uniformly mixing oil-based dry cuttings slag and aluminum slag, and performing high-temperature calcination pretreatment to obtain pretreated dry slag; 2) Crushing: crushing the pretreated dry slag of step 1) to obtain dry powder; 3) Granulation: granulating the dry powder of step 2) to obtain green balls; 4) Sintering: sintering the green balls of step 3) to obtain high-strength fracturing proppant.

2. The method of claim 1, wherein: In step 1), the mass ratio of the oil-based dry cuttings slag to the aluminum slag is 85-95:5-15.

3. The production method according to claim 1 or 2, characterized by: The chemical composition and content of the oil-based dry cuttings slag are as follows: SiO2 30-45wt%, Al2O3 5-15wt%, CaO 10-15wt%, BaSO4 20-35wt%, MgO <3wt%, and Fe2O3 <5%.

4. The method of claim 1, wherein: The chemical composition and content of the aluminum slag are as follows: Al2O3 70-85wt%, Na2O 5-15wt%, NaCl 5-10wt%, and the balance ≤5wt%.

5. The method of claim 1, wherein: In step 1), the high-temperature calcination is performed at a temperature of 900-1000℃ for 20-40min.

6. The method of claim 1, wherein: In step 2), the crushing is performed to a 500-mesh sieve residue of <5%.

7. The method of claim 1, wherein: In step 3), the green balls have a roundness of 0.9-1.0, a sphericity of 0.9-1.0, and a particle size of 40-70 mesh.

8. The method of claim 1, wherein: In step 4), the sintering is performed in a rotary kiln.

9. The method of claim 1, wherein: In step 4), the sintering is performed at a temperature of 1100-1180℃ for 1-2h.

10. The high-strength proppant produced by the method of any one of claims 1-9, wherein the high-strength proppant has a crush strength of at least 30,000 psi. The high-strength fracturing proppant has a particle size of 40-70 mesh, a crushing rate of <9% under 86Mpa, an acid solution degree of <7%, and a roundness of >0.9.

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