A composition for ceramic proppant, ceramic proppant and a method of making and using the same

Abstract

The application relates to the technical field of petroleum fracturing proppant materials, and discloses a composition for ceramic proppant, ceramic proppant and a preparation method and application thereof. The composition contains tertiary bauxite, oil-based cuttings and clay in a mass ratio of 35-85:5-30:1; the content of Al2O3 in the tertiary bauxite is 55-65 wt%, and the content of SiO2 is 20-30 wt%; the content of Al2O3 in the oil-based cuttings is 5-15 wt%, and the content of SiO2 is 50-60 wt%. The application provides a ceramic proppant with low cost and low energy consumption, harmless resource utilization of solid waste and adaptability to medium and shallow oil and gas reservoirs.

Description

Technical Field

[0001] This invention relates to the field of oil fracturing proppant materials technology, specifically to a composition for ceramsite proppant, ceramsite proppant, its preparation method and application. Background Technology

[0002] Hydraulic fracturing is a core technology for enhancing oil and gas reservoir production. It involves injecting high-pressure fracturing fluid into the formation to create fractures, followed by the injection of proppant to open the fractures and ensure they remain open even after pump shutdown, providing a flow path for oil and gas. Due to its high strength and wear resistance, ceramic proppant is currently the mainstream propping material for fracturing operations in medium-deep oil and gas reservoirs.

[0003] Currently, the most commonly used ceramsite proppant is high-purity bauxite-based sintered ceramsite proppant, which is prepared by sintering primary bauxite at a high temperature of 1350~1450℃. It possesses characteristics such as high strength and resistance to breakage, and is widely used in hydraulic fracturing operations in medium-deep oil and gas reservoirs. However, this technology has the following significant drawbacks: (1) High raw material cost: High-purity first-grade bauxite resources are scarce and prices continue to rise, resulting in the cost of proppant raw materials accounting for more than 60%, which significantly increases the overall cost of oil and gas development.

[0004] (2) High energy consumption and carbon emissions: The high-temperature sintering process above 1350℃ has high energy consumption and the carbon emissions per unit product are about 1.2~1.5 t CO2 / t, which does not meet the current policy requirements for low-carbon production.

[0005] (3) High resource dependence: Over-reliance on bauxite mineral resources makes it susceptible to fluctuations in resource reserves, mining policies and international trade, resulting in poor supply chain stability.

[0006] (4) Poor performance adaptability: Shallow / shallow oil and gas reservoirs have low requirements for proppant strength (20~50MPa). Existing high-alumina bauxite proppants have serious performance redundancy, resulting in waste of resources and costs.

[0007] To address the aforementioned issues, the industry has attempted to utilize industrial solid waste such as oil-based rock cuttings to prepare proppant. Oil-based rock cuttings are typical solid waste generated during shale gas extraction, and their main component is aluminosilicate, providing a raw material basis for preparing ceramsite proppant.

[0008] However, in existing technologies, the application of oil-based rock chips often requires complex pretreatment processes and still requires the use of various expensive additives. At the same time, the sintering temperature is still maintained above 1300℃, which fails to effectively solve the problems of cost and energy consumption. Furthermore, the granulation process is inefficient, the raw material green body has poor strength, and the production loss is high.

[0009] Therefore, developing a low-cost, low-energy-consumption proppant suitable for shallow and medium-depth oil and gas reservoirs has become an urgent need for the industry. Summary of the Invention

[0010] The purpose of this invention is to overcome the problems of high raw material cost, high production energy consumption, and low solid waste utilization efficiency of existing ceramic proppant, and to provide a low-cost, low-energy-consumption ceramic proppant that enables harmless and resource-based utilization of solid waste and is suitable for shallow and medium-depth oil and gas reservoirs.

[0011] To achieve the above objectives, a first aspect of the present invention provides a composition for proppant in the form of ceramsite, the composition containing grade III bauxite, oil-based rock fragments and clay in a mass ratio of 35-85:5-30:1. The Al2O3 content in the grade III bauxite is 55-65 wt%, and the SiO2 content is 20-30 wt%. The oil-based rock cuttings contain 5-15 wt% Al2O3 and 50-60 wt% SiO2.

[0012] A second aspect of the present invention provides a method for preparing a ceramic proppant, the method comprising using the components of the ceramic proppant composition described in the first aspect, including: (1) In the presence of a wetting agent, a mixture containing grade III bauxite, oil-based rock fragments and clay is wet-granulated to obtain bio-balls; (2) The bio-balls are sieved to obtain ball material with an average particle diameter of 420-830µm; (3) The pellets are calcined to obtain the ceramic support agent; the calcination temperature is 1120-1280℃.

[0013] A third aspect of the present invention provides a ceramic proppant prepared by the method described in the second aspect.

[0014] The fourth aspect of the present invention provides the application of the ceramic proppant described in the third aspect in the development of shallow to medium-depth oil and gas reservoirs.

[0015] The present invention has at least the following beneficial effects: 1) This invention uses inexpensive grade III bauxite to replace high-cost grade I bauxite, while also disposing of a large amount of oil-based rock debris industrial solid waste. The raw material cost is reduced by more than 30% compared to traditional high-alumina proppant, and the harmless and resource-based utilization of solid waste is achieved.

[0016] 2) By optimizing the raw material ratio, this invention achieves low-temperature roasting of 1120~1280℃. Compared with the traditional roasting temperature of 1350℃ or above, the production energy consumption is reduced by more than 20%, and the carbon emission per unit product is reduced by about 25%, which meets the requirements of low-carbon production.

[0017] 3) The bulk density of the ceramsite proppant provided by this invention is preferably as low as 1.1~1.3 g / cm³. 3 This is beneficial for pumping during fracturing operations; at the same time, under a stress of 52MPa, the breakage rate of the ceramic proppant is preferably less than 9%, which fully meets the requirements of the SY / T5108-2014 standard, adapts to the operational needs of shallow and medium-depth oil and gas reservoirs, and avoids performance redundancy and cost waste of high-performance proppant. Attached Figure Description

[0018] Figure 1 This is a flowchart of the preparation method of the ceramic proppant provided by the present invention; Figure 2 This is a scanning electron microscope image of the ceramic proppant provided in Example 1.

[0019] Explanation of reference numerals in the attached figures 1. Oil-based rock fragments; 2. Tertiary bauxite and clay; 3. Ball mill; 4. Deionized water; 5. Mixed materials; 6. High-intensity mixing granulator; 7. Feed balls; 8. Drying oven; 9. Muffle furnace; 10. Ceramsite proppant. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] As mentioned above, a first aspect of the present invention provides a composition for proppant in the form of ceramsite, the composition containing grade III bauxite, oil-based rock fragments and clay in a mass ratio of 35-85:5-30:1; The Al2O3 content in the grade III bauxite is 55-65 wt%, and the SiO2 content is 20-30 wt%. The oil-based rock cuttings contain 5-15 wt% Al2O3 and 50-60 wt% SiO2.

[0022] Preferably, the composition contains grade III bauxite, oil-based rock fragments, and clay in a mass ratio of 35-70:10-30:1. In this preferred embodiment, this proportion enhances the sintering synergy between the components, significantly improves the compressive strength of the ceramsite proppant, and reduces the breakage rate.

[0023] More preferably, the tertiary bauxite is tertiary bauxite clinker. Clinker refers to the finished product after raw materials have been calcined at high temperatures.

[0024] Preferably, the clay contains 15-25 wt% Al2O3 and 45-55 wt% SiO2.

[0025] More preferably, the clay is kaolinite.

[0026] As previously described, a second aspect of the present invention provides a method for preparing a ceramic proppant, the method comprising using the components of the composition of the ceramic proppant described in the first aspect, including: (1) In the presence of a wetting agent, a mixture containing grade III bauxite, oil-based rock fragments and clay is wet-granulated to obtain bio-balls; (2) The bio-balls are sieved to obtain ball material with an average particle diameter of 420-830µm; (3) The pellets are calcined to obtain the ceramic support agent; the calcination temperature is 1120-1280℃.

[0027] This invention enables the efficient utilization of oil-based rock debris solid waste, and at the same time, it can prepare ceramsite proppant through low-temperature calcination.

[0028] In a preferred embodiment, in step (1), before wet granulation, raw materials containing grade III bauxite, oil-based rock fragments and clay are added to a ball mill, grinding media are added for mixing and pulverization, and the mixed and pulverized raw materials are passed through a 300-mesh sieve with a residue of ≤3wt% on the sieve to obtain the mixture.

[0029] Preferably, in step (1), the conditions for mixing and pulverizing are controlled such that the average particle diameter of the mixture is less than 50µm, more preferably 10-40µm. In this preferred case, the particle size of the mixture is uniform and fine, which can make the green pellets obtained by wet granulation have better sphericity and smoother surface, thereby improving the density and anti-crushing performance of the ceramsite support after sintering.

[0030] Preferably, the grinding medium is alumina balls.

[0031] In a preferred embodiment, the mass ratio of the grinding media to the raw materials is 1-3:1.

[0032] Preferably, in step (1), the mass ratio of the mixture to the wetting agent is 1:0.15-0.20.

[0033] Preferably, in step (1), the rotation speed of the wet granulation is 20-30 rpm and the time is 25-35 min.

[0034] The present invention does not have any special requirements for the method of sieving the bio-balls, as long as the average particle diameter of the balls meets the above requirements. For example, the following method is used for sieving: the bio-balls are sieved through a 20-40 mesh screen to obtain the balls.

[0035] It should be noted that in this invention, the sieving refers to sieving using a Chinese standard sieve and collecting the material that passes through the sieve.

[0036] Preferably, in step (3), a drying process is performed before the roasting process, and the drying conditions include: a temperature of 100-105℃ and a time of 2-3h.

[0037] Preferably, the calcination time is 30-90 minutes. Under this preferred condition, it can ensure that the high-strength crystalline phases such as mullite inside the ceramsite support develop fully and uniformly, while avoiding abnormal grain growth and loose structure caused by over-firing, thereby further improving the density and compressive strength of the product.

[0038] In a preferred embodiment, the temperature is raised to the calcination temperature before the calcination process, with a heating rate of 3-8°C / min.

[0039] In some embodiments, the steps for preparing the ceramsite proppant include seven processes: batching and weighing, ball milling and mixing, high-intensity mixing and granulation, sieving and particle selection, drying and dehydration, calcination, and finished product processing.

[0040] like Figure 1 As shown, according to a specific embodiment, the method for preparing the ceramsite proppant includes: (1) Add grade III bauxite, oil-based rock chips and clay into a ball mill and mix and crush them using alumina balls as the grinding medium to obtain a mixture. The mixture and deionized water are added to a high-intensity mixer and granulator for wet granulation to obtain bio-balls; (2) Take out the bio-balls and sieve them through a standard sieve to obtain the target particle size; (3) The material balls are placed in a blower oven for drying to obtain a semi-finished blank; the semi-finished blank is placed in a muffle furnace for calcination and then naturally cooled to obtain the ceramic support.

[0041] As previously described, a third aspect of the present invention provides a ceramic proppant prepared by the method described in the second aspect.

[0042] Preferably, the bulk density of the ceramsite proppant is ≤1.4 g / cm³. 3 Roundness ≥ 0.8, sphericity ≥ 0.8.

[0043] Preferably, the breakage rate of the ceramsite proppant is ≤9% under a stress condition of 52MPa.

[0044] In this invention, "the breakage rate of the ceramsite proppant under a stress of 52 MPa" refers to the percentage of ceramsite particles crushed under a high pressure of 52 MPa. A smaller value indicates higher strength and less brittleness.

[0045] In this invention, roundness refers to the sharpness of the edges of the proppant particles and the difference between the overall outline and an ideal sphere.

[0046] In this invention, sphericity refers to the three-dimensional shape characteristics of the proppant used for fracturing, which is used to quantify the degree to which its particles approximate an ideal sphere in space.

[0047] As previously stated, the fourth aspect of the present invention provides the application of the ceramic proppant described in the third aspect in the development of shallow to medium-depth oil and gas reservoirs.

[0048] The present invention will be described in detail below through embodiments. Unless otherwise specified, all instruments and materials used in the following embodiments are commercially available products.

[0049] In the following examples, unless otherwise specified, room temperature / normal temperature refers to 25±2℃.

[0050] In the following examples, “serving” means “parts by weight”, where each part by weight represents 100g.

[0051] Grade 1 bauxite: purchased from Henan Yima Aluminum Co., Ltd., grade YM-1.

[0052] Grade III bauxite-I: clinker, purchased from Yangquan bauxite mine in Shanxi Province, grade YQ-3.

[0053] Grade III bauxite-DI: clinker, purchased from Yangquan bauxite mine in Shanxi Province, grade YQ-2.

[0054] Oil-based rock cuttings-I: from the shale gas extraction site in Karamay Oilfield, Xinjiang.

[0055] Oil-based cuttings-DI: from the drilling site of the Zhundong Oilfield in Xinjiang.

[0056] Clay: Kaolin, purchased from Suzhou Kaolin Co., Ltd., grade SZ-GL.

[0057] Manganese powder: manganese dioxide, with an average particle diameter of 20 μm, purchased from Sinopharm Chemical Reagent Co., Ltd., grade AR analytical grade.

[0058] The composition results of primary bauxite, tertiary bauxite-I, tertiary bauxite-DI, oil-based rock fragments-I, oil-based rock fragments-DI, and clay are shown in Table 1.

[0059] Table 1

[0060] Example 1 (1) Weigh out grade III bauxite, oil-based rock chips, and clay; add the above raw materials to a ball mill, use alumina balls (average particle diameter of 10-20 mm) as the grinding medium, the mass ratio of grinding medium to raw materials is 2:1, pass the dry-ground raw materials through a 300-mesh sieve, the residue on the sieve is 3wt%, and obtain a mixture. Add the obtained mixture to a high-intensity mixing granulator, and add deionized water (i.e. wetting agent). Start the granulator and wet granulate at 25 rpm for 30 minutes. (2) In order to avoid the presence of large particles, the bio-balls were further screened through a standard sieve to obtain ball material with an average particle diameter of 420-830µm; (3) Place the raw pellets into a forced-air drying oven and dry them at 105℃ for 2 hours to remove free moisture from the raw pellets and obtain a semi-finished green body. Place the semi-finished green body into a muffle furnace and heat it to 1200℃ at a rate of 5℃ / min for 60 minutes. Then cool it naturally to room temperature to obtain the ceramic proppant.

[0061] The specific types / amounts of raw materials or process parameters in this embodiment are shown in Table 2.

[0062] Examples 2-5 The same method as in Example 1 was used, except that the types / amounts of raw materials or process parameters were different, as shown in Table 2.

[0063] Table 2

[0064] Comparative Example 1 The existing traditional methods for preparing high-alumina proppant are employed, specifically: Weigh 98 parts of first-grade bauxite and 2 parts of manganese powder. Add the above raw materials to a ball mill. After dry grinding, pass the raw materials through a 300-mesh sieve. The residue on the sieve is ≤3wt% to obtain a mixture with a D50 of 25µm. Deionized water was added as a wetting agent, and the mass ratio of the mixture to the wetting agent was 1:0.18. The mixture was wet granulated at 25 rpm for 12 min to obtain raw material balls with an average particle diameter of 420-830 μm. Ceramsite proppant was obtained by calcination at 1400℃ for 90 minutes.

[0065] Comparative Example 2 The method is similar to that in Example 1, except that Grade I bauxite is replaced with an equal part by weight of Grade DI bauxite. The remaining steps are the same as in Example 1, to obtain the ceramic proppant.

[0066] Comparative Example 3 The method is similar to that in Example 1, except that oil-based rock cuttings-I are replaced with an equal part by weight of oil-based rock cuttings-DI; The remaining steps are the same as in Example 1, to obtain the ceramic proppant.

[0067] Comparative Example 4 Following a method similar to Example 1, except that the mass ratio of grade III bauxite, oil-based rock cuttings, and clay is 30:19:1, specifically, Weigh 60 parts of grade III bauxite-I, 38 parts of oil-based rock fragments-I, and 2 parts of clay. The remaining steps are the same as in Example 1 to obtain ceramsite proppant.

[0068] To verify the technical effect of the present invention, performance tests were conducted on the embodiments and comparative examples. All performance tests were carried out in accordance with SY / T5108-2014 "Performance Test Method for Proppants Used in Hydraulic Fracturing and Gravel Backfilling Operations". The test results are shown in Table 3.

[0069] Table 3

[0070] As can be seen from the results in Table 3, this invention provides a low-cost, low-energy-consumption ceramic proppant that enables the harmless and resource-based utilization of solid waste and is suitable for shallow and medium-depth oil and gas reservoirs. At the same time, it realizes the efficient utilization of oil-based rock cuttings solid waste and has good application prospects.

[0071] The bulk density of the ceramsite proppant provided in Example 1 is 1.20 g / cm³. 3 The breakage rate under 52MPa stress conditions was 8.2%, the roundness was 0.8, and the sphericity was 0.8, which fully met the standard requirements.

[0072] The breakage rate of the ceramsite proppant in Examples 1-5 is ≤9%, and the roundness and sphericity are ≥0.8, which fully meet the industry standard requirements.

[0073] Among them, the bulk density of Examples 1-3 was as low as 1.18-1.20 g / cm³. 3 Compared with traditional high-alumina proppant (Comparative Example 1), it reduces pumping costs by more than 17%, significantly reducing pumping costs and eliminating performance redundancy.

[0074] The performance of Examples 4 and 5 also met the standards, proving that the process parameters of the present invention have a wide range and good stability.

[0075] Comparing the examples and Comparative Example 1, it can be seen that the present invention uses oil-based rock cuttings in conjunction with grade III bauxite as the main raw material to prepare fracturing proppant, replacing the traditional high-cost grade I bauxite raw material system. The fracturing proppant prepared by the present invention has performance that is basically the same as that of traditional fracturing proppant made from pure grade I bauxite in terms of bulk density, apparent density, fragmentation rate, roundness, sphericity, temperature and acid corrosion resistance, and comprehensive performance for downhole pressure bearing and conductivity. At the same time, it significantly reduces the raw material procurement cost and the overall production cost, realizes the resource utilization of industrial solid waste and the low-cost mass production of products, and has both economic value and environmental benefits.

[0076] In contrast, Comparative Examples 2-4, due to their lower raw material grade or the fact that the ratio of grade III bauxite, oil-based rock fragments, and clay did not meet the requirement of 35-85:5-30:1, all had a breakage rate exceeding 12.8%, which failed to meet the usage requirements. This fully verified the key role of the raw material system and ratio in this invention.

[0077] For the ceramic proppant of the present invention, excessively high calcination temperature cannot improve product performance, but instead increases energy consumption. Therefore, the present invention controls the calcination temperature at 1120~1280℃, which significantly reduces production energy consumption compared to the traditional calcination temperature of 1350℃ or above.

[0078] The ceramsite proppant prepared in Example 1 was subjected to scanning electron microscopy, and the results are as follows: Figure 2 As shown. From Figure 2 As shown in a, b, c, and d, the ceramic proppant particles have uniformly distributed micropores inside, which is the core reason for the product's low bulk density. The low-density ceramic proppant is more conducive to pumping during fracturing operations and reduces the pump pressure during construction. At the same time, the grain boundaries inside the particles are tightly bonded, and the mullite whiskers are intertwined to form a stable three-dimensional network structure. This structure gives the ceramic proppant excellent compressive strength, enabling the product to still meet the fragmentation rate requirements at 52 MPa while maintaining low density, making it suitable for fracturing operations in shallow and medium-depth oil and gas reservoirs.

[0079] In summary, the ceramsite proppant provided by this invention can be widely used in fracturing and production enhancement operations of unconventional oil and gas reservoirs such as shale oil and tight oil and gas, to support fractures and maintain long-term conductivity, while realizing the resource utilization of solid waste and cost reduction and efficiency improvement.

[0080] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composition for use as a proppant in ceramic aggregates, characterized in that, The composition contains grade III bauxite, oil-based rock fragments, and clay in a mass ratio of 35-85:5-30:

1. The Al2O3 content in the grade III bauxite is 55-65 wt%, and the SiO2 content is 20-30 wt%. The oil-based rock cuttings contain 5-15 wt% Al2O3 and 50-60 wt% SiO2.

2. The composition according to claim 1, characterized in that, The composition contains grade III bauxite, oil-based rock fragments, and clay in a mass ratio of 35-70:10-30:

1.

3. The composition according to claim 1, characterized in that, The clay contains 15-25 wt% Al2O3 and 45-55 wt% SiO2.

4. A method for preparing ceramsite proppant, characterized in that, This method utilizes the components of the ceramic proppant composition according to any one of claims 1-3 for preparation, comprising: (1) In the presence of a wetting agent, a mixture containing grade III bauxite, oil-based rock fragments and clay is wet-granulated to obtain bio-balls; (2) The bio-balls are sieved to obtain ball material with an average particle diameter of 420-830µm; (3) The pellets are calcined to obtain the ceramic support agent; the calcination temperature is 1120-1280℃.

5. The method according to claim 4, characterized in that, In step (1), the average particle diameter of the mixture is less than 50µm.

6. The method according to claim 4, characterized in that, In step (1), the mass ratio of the mixture to the wetting agent is 1:0.15-0.

20.

7. The method according to claim 4, characterized in that, In step (3), a drying process is performed before the roasting process. The drying process conditions include: a temperature of 100-105℃ and a time of 2-3h. And / or, the roasting time is 30-90 min.

8. Ceramsite proppant prepared by the method according to any one of claims 4-7.

9. The ceramsite proppant according to claim 8, characterized in that, The ceramic proppant has a bulk density of ≤ 1.4 g / cm 3 , a roundness of ≥ 0.8, and a sphericity of ≥ 0.8; And / or, the breakage rate of the ceramsite proppant is ≤9% under a stress condition of 52MPa.

10. The application of the ceramic proppant as described in claim 8 or 9 in the development of shallow to medium-depth oil and gas reservoirs.

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