Method for preparing low-density high-strength petroleum fracturing propping agent from coal-based solid waste

Abstract

The invention discloses a method for preparing a low-density high-strength petroleum fracturing propping agent from coal-based solid waste. The propping agent is prepared from the following raw materials in parts by mass: 30-60 parts of low-grade bauxite, 30-60 parts of fly ash, 20-40 parts of coal gasification slag, 8-15 parts of bentonite and 2-5 parts of manganese powder. The petroleum fracturing propping agent is prepared by taking low-grade bauxite, fly ash, coal gasification slag and bentonite as main raw materials through a process of ball milling and mixing, balling by a round pot granulator and roasting by a muffle furnace. A ball milling process is adopted for mixing, so that the particle size and the mixing uniformity of mixed powder can be remarkably improved, and the compactness of green pellets is further improved; the bentonite is used as a binder, so that the molding rate of the ceramsite sand and the strength of the raw material can be improved, and meanwhile, the effect of adjusting the components of the raw material is also achieved. The volume density of the prepared low-density high-strength petroleum fracturing propping agent is 1.40-1.60 g / cm < 3 >, the sphericity is larger than 0.8, the breakage rate under the condition of 52 MPa is lower than 9%, and the requirements of the standard SY / T5108-2014 are met.

Description

Technical Field

[0001] The invention relates to a petroleum fracturing proppant and a preparation method thereof, and in particular to a method for preparing a low-density and high-strength petroleum fracturing proppant from coal-based solid waste. Background Art

[0002] Ceramic granule proppant is a kind of oil fracturing proppant. It is a high-strength, acid- and alkali-resistant spherical material. It plays a role in keeping the formation cracks open and improving the oil and gas conductivity during the hydraulic fracturing process. It is now widely used in the oil and gas extraction industry. The basic principle is to inject fracturing fluid containing a certain amount of proppant material into the oil and gas layer through the ground high-pressure pump system. When the hydraulic pressure is much higher than the rock crushing pressure, cracks will appear in the oil and gas layer. After the proppant enters the crack, it can make the crack continue to extend on the one hand, and on the other hand, it can keep the crack open, ensuring that when the fracturing is completed and the fracturing fluid is discharged from the wellbore, the oil and gas layer still has cracks of a certain length and width, improving its permeability and increasing production.

[0003] The production of traditional expanded clay proppants requires a large amount of bauxite. Although my country has abundant bauxite reserves, the application of bauxite is mainly high-quality bauxite with high aluminum content, which leads to a large demand for high-quality bauxite resources. However, as high-quality bauxite becomes increasingly scarce and its price continues to rise, in order to achieve sustainable development of resources and the environment, it is necessary to rationally allocate high-quality bauxite resources and find low-cost alternative raw materials to support the development of expanded clay proppant technology.

[0004] The coal-based solid waste fly ash and coal gasification slag contain a lot of Al2O3 and SiO2, which are consistent with the chemical composition of the raw materials of fracturing proppants and can partially replace bauxite to a certain extent. This property has become the basic condition for preparing fracturing proppants from coal-based solid waste. In addition, conventional ceramsite proppants have a large density, are prone to sedimentation during the fracturing process, and have poor conductivity. Since the aluminum content of fly ash is lower than that of bauxite, it can effectively reduce the density of the proppant after adding it, and it is laid more evenly in the cracks, effectively supporting the length of the cracks. Compared with landfilling coal-based solid waste, the use of fly ash and coal gasification slag to prepare fracturing proppants can reduce the consumption of natural minerals and the production cost of fracturing proppants, and it can also make use of coal-based solid waste as a resource, contributing to the promotion of waste-free city construction. Summary of the invention

[0005] The problem to be solved by the present invention is to provide a method for preparing a low-density and high-strength petroleum fracturing proppant by utilizing coal-based solid waste, and the method has a simple process and high production efficiency.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The method for preparing low-density and high-strength petroleum fracturing proppant using coal-based solid waste according to the present invention is characterized in that the following raw materials are included by mass percentage:

[0008]

[0009] Preferably, the Al2O3 content in the low-grade bauxite is 55.0-65.0%.

[0010] Preferably, the Al2O3 content in the fly ash is 30.0-45.0%, and the SiO2 content is 60-75%.

[0011] Preferably, the SiO2 content in the coal gasification slag is 60-75%, and the CaO content is 45-55%.

[0012] The method for preparing low-density and high-strength petroleum fracturing proppant using coal-based solid waste comprises the following steps:

[0013] (1) Weigh each component by mass percentage, mix the raw material: grinding medium in a weight ratio of 1:4-6, and dry grind in a ball mill until the raw material particle size reaches D50 = 8-12 μm and the fineness reaches 325 mesh sieve residue less than 5%.

[0014] (2) Adjust the inclination angle and speed of the round pot granulator, and use the material shovel to shake the mixed ball-milled raw materials from the middle of the round pot into the granulator; at the same time, aim the spray nozzle of the sprayer at the "material curtain" to spray and pelletize. After the raw material balls reach the target particle size, sieve them; continue to add the target raw balls on the sieve into the round pot granulator, and after rolling for a period of time, take them out and sieve them to obtain raw material balls.

[0015] (3) The raw material balls obtained in step (2) are placed in an oven and dried at 60-80° C. to obtain a semi-finished green body.

[0016] (4) The semi-finished green body obtained in step (3) is sent to a muffle furnace for roasting at a temperature of 1100 to 1300° C. for a holding time of 30 to 90 min, and is naturally cooled to obtain a ceramsite sand product.

[0017] Preferably, during the ball milling mixing process in step (1), the weight ratio of raw material to ball is designed to be mixed raw material: grinding medium = 1:4-6; after ball milling, the particle size reaches D50 = 8-12 μm, and the fineness reaches 325 mesh sieve residue less than 5%.

[0018] Preferably, in step (2), the inclination angle and speed of the round pot granulator are adjusted, and the mixed ball-milled raw materials are shaken from the middle of the round pot into the granulator by a shovel. The inclination angle of the granulator is in the range of 35-50°, and the speed of the granulator is 40-50 r / min.

[0019] Preferably, in step (2), the spray nozzle of the sprayer is aimed at the "material curtain" to spray and pelletize, and after the raw material balls reach the target particle size, they are sieved, and the sieve is a 20-40-60-80 mesh combination sieve, and the raw material balls are taken under the 20 mesh sieve and on the 80 mesh sieve.

[0020] Preferably, in step (2), the target raw balls on the sieve are continuously added into the round pot granulator, and after rolling for a period of time, taken out and sieved to obtain raw balls, the rolling time is 2-5 minutes, the sieve is a 20-40-60-80 mesh combination sieve, and the raw balls under the 20 mesh sieve and on the 80 mesh sieve are taken as the target raw balls.

[0021] Preferably, in step (3), the raw material balls are placed in an oven and dried at 60-80° C. to obtain a semi-finished green body.

[0022] Preferably, the calcination temperature in step (4) is 1100-1300° C., and the holding time is 30-90 min.

[0023] Beneficial effects:

[0024] 1. The low-density and high-strength petroleum fracturing proppant prepared by the present invention has a volume density of 1.40 to 1.60 g / cm 3 , sphericity>0.8, and the breakage rate is less than 9% under 52MPa conditions.

[0025] 2. The present invention uses coal-based solid waste fly ash and coal gasification slag as main raw materials and adopts a lower sintering temperature range, which can reduce the production cost of the proppant and provide a new way for the resource recycling of fly ash.

[0026] 3. The present invention obtains uniformly mixed raw materials with smaller particle sizes through the ball milling mixing process, which is beneficial to improving the sphericity and strength of the proppant. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope photo of ceramsite sand. Figure 2 It is the effect of roasting temperature on bulk density and breakage rate. DETAILED DESCRIPTION

[0028] The present invention is described in further detail below.

[0029] Example 1

[0030] The ceramsite proppant comprises the following components in mass fractions: 45% of low-grade bauxite, 30% of fly ash, 15% of coal gasification slag, 10% of bentonite, and 3% of externally mixed manganese dioxide.

[0031] The preparation of ceramsite proppant includes the following steps:

[0032] (1) Weigh each component by mass percentage, mix the raw material: grinding medium in a weight ratio of 1:4, and ball mill for 20 minutes. The fineness is 325 mesh and the residue is 3.5%.

[0033] (2) Adjust the inclination angle and speed of the round pot granulator to 45° and 45 r / min respectively, and add the raw materials obtained in step (1) to the granulator from the middle of the round pot by shaking; at the same time, aim the spray nozzle of the sprayer at the "material curtain" to spray and pelletize, and sieve the raw material balls after they reach the target particle size. The target raw balls on the sieve are continuously added to the round pot granulator, and after rolling for 3 minutes, they are taken out and sieved to obtain raw material balls.

[0034] (3) The raw material balls obtained in step (2) are placed in an oven and dried at 80° C. to obtain a semi-finished green body.

[0035] (4) The semi-finished green body obtained in step (3) is sent to a muffle furnace for roasting at a temperature of 1150° C. for a holding time of 90 min, and is naturally cooled to obtain a ceramsite sand product.

[0036] Example 2

[0037] The ceramsite proppant comprises the following components in mass fractions: 45% of low-grade bauxite, 30% of fly ash, 15% of coal gasification slag, 10% of bentonite, and 3% of externally mixed manganese dioxide.

[0038] The preparation of ceramsite proppant includes the following steps:

[0039] (4) Weigh each component by mass percentage, with the weight ratio of mixed raw material: grinding medium = 1:5, and ball mill for 20 minutes. The fineness is 325 mesh and the residue is 3.5%.

[0040] (5) Adjust the inclination angle and speed of the round pot granulator to 43° and 48 r / min respectively, and add the raw material obtained in step (1) to the granulator from the middle of the round pot by shaking; at the same time, aim the spray nozzle of the sprayer at the "material curtain" to spray and pelletize, and sieve the raw material balls after they reach the target particle size. The target raw balls on the sieve are continuously added to the round pot granulator, and after rolling for 2 minutes, they are taken out and sieved to obtain raw material balls.

[0041] (6) The raw material balls obtained in step (2) are placed in an oven and dried at 80° C. to obtain a semi-finished green body.

[0042] (4) The semi-finished green body obtained in step (3) is sent to a muffle furnace for roasting at a temperature of 1250° C. for a holding time of 60 min, and is naturally cooled to obtain a ceramsite sand product.

[0043] Comparative Example 1

[0044] The formula and basic steps are the same as those of Example 1, except that the calcination temperature in step (4) is 1200°C.

[0045] Comparative Example 2

[0046] The formula and basic steps are the same as those of Example 1, except that the calcination temperature in step (4) is 1300°C.

[0047] The ceramsite fracturing proppants prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were tested for bulk density and crushing rate in accordance with the test standard SY / T 5108-2014. The experimental results are shown in the following table.

[0048]

[0049]

[0050] From the data in the above table, it can be seen that the bulk density of the ceramsite proppant prepared by the method provided by the present invention is less than 1.60 g / cm 3 The compressive strength grade is 52MPa, which belongs to low-density ceramsite proppant. From the data of the examples and comparative examples in the table, it can be seen that the roasting temperature has a great influence on the performance of the proppant. As the roasting temperature increases, the bulk density increases and the crushing rate decreases.

Claims

1. A method for preparing low-density and high-strength petroleum fracturing proppants from coal-based solid waste, characterized in that: Contains the following raw materials by mass percentage: Among them, Al2O3 is mainly introduced from the main materials of low-grade bauxite and fly ash, SiO2 is mainly introduced from the main materials of fly ash and coal gasification slag, and CaO is mainly introduced from the main materials of coal gasification slag. The method for preparing low-density and high-strength petroleum fracturing proppant from coal-based solid waste has the following specific process steps: (1) Weigh each component by mass percentage, mix the raw material: grinding medium in a weight ratio of 1:4-6, and dry grind in a ball mill until the raw material particle size reaches D50 = 8-12 μm and the fineness reaches 325 mesh sieve residue less than 5%. (2) Adjust the inclination angle and speed of the round pot granulator, and use the material shovel to shake the mixed ball-milled raw materials from the middle of the round pot into the granulator; at the same time, aim the spray nozzle of the sprayer at the "material curtain" to spray and pelletize. After the raw material balls reach the target particle size, sieve them for screening; continue to add the target raw balls on the sieve into the round pot granulator, and after rolling for a period of time, take them out and sieve them to obtain raw material balls. (3) The raw material balls obtained in step (2) are placed in an oven and dried at 60-80° C. to obtain a semi-finished green body. (4) The semi-finished green body obtained in step (3) is sent to a muffle furnace for roasting at a temperature of 1100 to 1300° C. for a holding time of 30 to 90 min, and is naturally cooled to obtain a ceramsite sand product.

2. The low-density and high-strength petroleum fracturing proppant according to claim 1, characterized in that: The Al2O3 content in the low-grade bauxite is 55.0-65.0%.

3. The low-density and high-strength petroleum fracturing proppant according to claim 1, characterized in that: The Al2O3 content in the fly ash is 30.0-45.0%, and the SiO2 content is 60-75%.

4. The low-density and high-strength petroleum fracturing proppant according to claim 1, characterized in that: The SiO2 content in the coal gasification slag is 60-75%, and the CaO content is 45-55%.

5. The low-density and high-strength petroleum fracturing proppant according to claim 1, characterized in that: During the ball milling mixing process in step (1), the weight ratio of raw materials to balls is designed to be mixed raw materials: grinding media = 1:4-6; after ball milling, the particle size reaches D50 = 8-12 μm, and the fineness reaches 325 mesh sieve residue less than 5%.

6. The low-density and high-strength petroleum fracturing proppant according to claim 1, characterized in that: As described in step (2), the inclination angle and speed of the round pot granulator are adjusted, and the mixed ball-milled raw materials are shaken from the middle of the round pot into the granulator by a material shovel; at the same time, the spray nozzle of the sprayer is aimed at the "material curtain" to spray and pelletize, and after the raw material balls reach the target particle size, they are sieved and screened; the target raw balls on the sieve are continuously added to the round pot granulator, and after rolling for a period of time, they are taken out and sieved to obtain raw material balls.

7. The low-density and high-strength petroleum fracturing proppant according to claim 1, characterized in that: In step (3), the raw material balls obtained in step (2) are placed in an oven and dried at 60-80° C. to obtain a semi-finished green body.

8. The low-density and high-strength petroleum fracturing proppant according to claim 1, characterized in that: In step (4), the semi-finished green body obtained in step (3) is sent into a muffle furnace for roasting at a temperature of 1100 to 1300° C. for a holding time of 30 to 90 minutes, and then naturally cooled to obtain a ceramsite sand product.

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