Carbon sequestration ceramsite proppant as well as preparation method and application thereof

Abstract

The invention provides a carbon sequestration ceramsite proppant as well as a preparation method and application thereof. The carbon sequestration ceramsite proppant has a coated shell-core structure, the core is a waste FCC catalyst-based mother sphere prepared from a waste FCC catalyst, silica, a high-iron material, a fluxing agent and a first binder, and the shell is a carbon sequestration shell layer composed of a calcium-containing compound (specifically calcium hydroxide and / or calcium oxide) and a second binder. The film is a degradable film formed by a third binder, and the shell-core structure is wrapped by the film.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas field proppants, and particularly relates to a carbon-fixing ceramsite proppant, a preparation method thereof, and an application thereof. Background Art

[0002] In oil and gas field development processes, especially in the development of shale oil and gas and low-permeability oil and gas, the petroleum fracturing technology plays a very important role. In order to improve the oil and gas recovery rate and recovery speed of low-permeability oil and gas reservoirs and shale oil and gas reservoirs, oil and gas companies generally use fracturing proppants to improve the formation voids and void connectivity. A fracturing proppant is a support that keeps the rock fractures deep in the formation open after hydraulic fracturing. It has a certain roundness and sphericity, and the particle size can be selected. During use, the proppant is mixed into the fracturing fluid and injected into the deep rock fractures by high-pressure means to support the formation, so as to improve the oil (gas) conductivity and increase the oil and gas production. It is generally believed that the fracturing proppant is a key technical point for the success of the fracturing technology, and the use of high-quality fracturing proppants is important for oil and gas field exploitation.

[0003] The ceramsite proppant has better sphericity, anti-crushing ability and conductivity than quartz sand, and is widely used in deep oil and gas wells. However, the density of ceramsite is greater than that of quartz sand, which puts higher requirements on the pumping conditions and the performance of the fracturing fluid, increasing the construction difficulty. In contrast, low-density proppants are easy to carry, can greatly reduce the viscosity of the fracturing fluid, reduce the damage to the fracturing equipment, and effectively reduce the construction difficulty and oil production cost. Therefore, the development of low-density proppants has become the research direction of proppants. At present, most of the preparation technologies of ultra-low-density ceramsite proppants in China use bauxite as the main raw material, add a small amount of mineralizer, and are fired at high temperature in a rotary kiln. And finding cheap and effective raw materials to replace bauxite for producing low-density and high-strength ceramsite proppants has always been one of the pursuit goals in this field.

[0004] Fluid catalytic cracking technology (FCC) is the most important core technology in China's petroleum refining industry, and its development momentum is very rapid. And FCC catalysts are one of the most important raw materials in the industrial processes of petroleum products. Their annual usage is far greater than the consumption of other various types of refining catalysts, accounting for more than 86% of the catalyst usage in the petroleum refining industry. Although the prior art has utilized waste FCC catalysts as partial raw materials to prepare fracturing proppants and ceramsite, there are still the following problems: 1) The dosage of waste FCC catalysts is relatively low, and bauxite still needs to be added; 2) The strength of the ceramsite with a high addition amount of waste FCC catalysts is small, and it can only be used as filling sand for well repair in oil production and has no function of petroleum fracturing proppants. It can be seen that the harmless treatment of waste FCC catalysts is a significant challenge.

[0005] On the other hand, with the development of the Carbon capture, utilisation and storage (CCUS) business, the application of CO2 enhanced oil recovery and storage technology is increasing. During the process of using CO2 to recover shale oil, proppants are still required. How to keep CO2 underground after CO2 flooding has always been a research hotspot. Therefore, there is an urgent need to develop a proppant that can make full use of waste FCC catalysts, ensure high strength, low density, and have the function of CO2 solidification. Summary of the Invention

[0006] To solve the above problems, in a first aspect of the present invention, a carbon-fixing ceramsite proppant is provided, which has a coated core-shell structure; the core is a waste FCC catalyst-based mother ball; the shell is a carbon-fixing shell layer; the film is a degradable film; and the film wraps the core-shell structure.

[0007] According to a specific embodiment of the present invention, the waste FCC catalyst-based mother ball includes waste FCC catalyst, silica, high-iron material, flux, and a first binder; and / or

[0008] The carbon-fixing shell layer includes a calcium-containing compound and a second binder; and / or the degradable film includes a third binder;

[0009] Preferably, the calcium-containing compound is calcium oxide and / or calcium hydroxide.

[0010] According to a specific embodiment of the present invention, in the waste FCC catalyst-based mother ball, the dosage of the waste FCC catalyst is 56 to 76 parts by mass, the dosage of the silica is 5 to 25 parts by mass, the dosage of the high-iron material is 8 to 20 parts by mass, the dosage of the flux is 1 to 5 parts by mass, and the dosage of the first binder is 0.1 to 0.5 parts by mass; and / or

[0011] In the carbon-fixing shell layer, the mass ratio of the calcium-containing compound to the second binder is 1:(1 to 1.5).

[0012] According to a preferred embodiment of the present invention, in the waste FCC catalyst-based mother ball, the dosage of the waste FCC catalyst is 56 to 76 parts by mass, the dosage of the silica is 5 to 15 parts by mass, the dosage of the high-iron material is 10 to 15 parts by mass, the dosage of the flux is 1 to 5 parts by mass, and the dosage of the first binder is 0.1 to 0.5 parts by mass.

[0013] According to a preferred embodiment of the present invention, in the waste FCC catalyst-based mother balls, the amount of the waste FCC catalyst is 56 to 70 parts by mass, the amount of the silica is 5 to 15 parts by mass, the amount of the high-iron material is 10 to 15 parts by mass, the amount of the flux is 1 to 5 parts by mass, and the amount of the first binder is 0.3 to 0.45 parts by mass; and / or

[0014] In the carbon-fixing shell layer, the ratio of the mass of the calcium-containing compound to the mass of the second binder is 1:(1 to 1.1).

[0015] According to a specific embodiment of the present invention, taking the mass of the waste FCC catalyst as 100%, the content of Al2O3 in the waste FCC catalyst is 45 to 53 wt%, and the content of SiO2 is 42 to 53 wt%; and / or

[0016] Taking the mass of the silica as 100%, the content of SiO2 in the silica is 85 to 95 wt%; and / or

[0017] Taking the mass of the high-iron material as 100%, the content of Fe2O3 in the high-iron material is 25 to 53 wt%;

[0018] Preferably, taking the mass of the silica as 100%, the content of SiO2 in the silica is 90 to 95 wt%;

[0019] Preferably, taking the mass of the waste FCC catalyst as 100%, the content of Al2O3 in the waste FCC catalyst is 49.5 to 52 wt%, and the content of SiO2 is 42 to 44.2 wt%; and / or

[0020] Taking the mass of the silica as 100%, the content of SiO2 in the silica is 92 to 94 wt%; and / or

[0021] Taking the mass of the high-iron material as 100%, the content of Fe2O3 in the high-iron material is 33 to 53 wt%.

[0022] According to a specific embodiment of the present invention, the high-iron material is bauxite and / or red mud; and / or

[0023] The flux includes dolomite and / or potassium feldspar; and / or

[0024] The first binder is at least one of polyvinyl alcohol, polyvinyl butyral, methyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, ethyl cellulose, and hydroxypropyl cellulose; and / or

[0025] The second binder is cement; and / or

[0026] The third binder is a polylactic acid-based binder;

[0027] Preferably, the first binder is polyvinyl alcohol and / or sodium carboxymethyl cellulose; and / or

[0028] The flux is a mixture of dolomite and potassium feldspar; and / or

[0029] In the flux, the mass ratio of dolomite to potassium feldspar is (1 to 3):1;

[0030] More preferably, the first binder is sodium carboxymethyl cellulose; and / or

[0031] In the flux, the mass ratio of dolomite to potassium feldspar is (1 to 2):1.

[0032] According to a specific embodiment of the present invention, the particle size range of the core is 40 to 70 mesh or 30 to 50 mesh;

[0033] and / or

[0034] The average thickness of the carbon sequestration shell layer is 118 to 130 μm; and / or the average thickness of the degradable film is 2 to 5 μm; and / or

[0035] The particle size range of the carbon sequestration ceramsite proppant is 40 to 70 mesh or 30 to 50 mesh;

[0036] Preferably, the particle size range of the core is 45 to 75 mesh or 35 to 60 mesh.

[0037] The second aspect of the present invention provides a method for preparing the carbon sequestration ceramsite proppant as described in the first aspect of the present invention, which includes the following steps:

[0038] 1) Mix the waste FCC catalyst, silica, high-iron material, flux and the first binder to obtain a first mixed powder;

[0039] 2) Granulate the first mixed powder to obtain green balls, and sinter them to obtain the waste FCC catalyst-based mother balls;

[0040] 3) Mix the calcium-containing compound and the second binder to obtain a second mixed powder;

[0041] 4) Wet the waste FCC catalyst-based mother balls and then adhere the second mixed powder, and perform the first curing to form the carbon sequestration shell layer on the surface of the waste FCC catalyst-based mother balls to obtain the mother balls with the carbon sequestration shell layer;

[0042] 5) Coat the mother balls with the solid carbon shell layer using the third binder and conduct the second curing to form the degradable film on the surface of the solid carbon shell layer, thereby obtaining the solid carbon ceramic proppant.

[0043] According to a specific embodiment of the present invention, in step 1), first grind the first mixed powder, and then perform step 2); and / or

[0044] In step 1), the average particle size of the first mixed powder is not less than 400 mesh; and / or

[0045] In step 2), the granulation is granulation with water addition; and / or the particle size range of the green balls is 40 to 70 mesh or 30 to 50 mesh; and / or

[0046] In step 5), the film coating process is to coat the solution of the third binder on the surface of the mother balls with the solid carbon shell layer, and then conduct the second curing; and / or

[0047] During the second curing process, the solvent in the third binder solution is evaporated, and the third binder remains on the surface of the solid carbon shell layer to form the degradable film;

[0048] Preferably, in step 2), the particle size range of the green balls is 40 to 70 mesh or 35 to 60 mesh;

[0049] Preferably, in step 5), in the solution of the third binder, the solvent is dichloromethane and methanol;

[0050] Preferably, the mass ratio of dichloromethane to methanol is (7 to 9):1; and / or in the solution of the third binder, the amount of the solvent is sufficient to dissolve the third binder to obtain a solution with fluidity;

[0051] Preferably, in step 2), the sintering is carried out in a rotary kiln; and / or

[0052] In step 5), the film coating and the second curing are carried out by a fluidized bed process.

[0053] According to a specific embodiment of the present invention, in step 2), the sintering conditions are to keep the temperature at 1200 °C for 0.5 h, and then keep the temperature at 1280 to 1350 °C for 0.8 to 2 h; and / or

[0054] In step 4), the first curing conditions are to air dry at room temperature (i.e., the ambient temperature without additional heating or cooling); and / or

[0055] In step 5), the temperature of the second curing is 100 to 105 °C;

[0056] Preferably, in step 2), the sintering conditions are to hold at 1200 °C for 0.5 h, and then hold at 1290 to 1300 °C for 1.8 to 2 h;

[0057] Preferably, in step 2), the sintering conditions are to heat up from room temperature to 200 °C, then heat up at a rate of 2 to 5 °C / min to 300 °C, then heat up to 1200 °C and hold for 0.5 h, and finally heat up to 1280 to 1350 °C and hold for 0.8 to 2 h.

[0058] The application of the carbon-fixing ceramsite proppant according to the first aspect of the present invention or the carbon-fixing ceramsite proppant prepared by the method according to the second aspect of the present invention in oil and gas field fracturing, especially in the post-fracturing of CO2 flooding in oil and gas fields.

[0059] The beneficial effects of the present invention:

[0060] Aiming at the problems of low content of waste FCC catalyst and low strength in the ceramsite proppant containing waste FCC catalyst prepared by the prior art, as well as the problem of CO2 solidification after CO2 flooding, the present invention provides a carbon-fixing ceramsite proppant, its preparation method and application. The carbon-fixing ceramsite proppant has a coated core-shell structure, wherein the core is a waste FCC catalyst-based mother ball prepared from waste FCC catalyst, silica, high-iron material, flux and a first binder, the shell is a carbon-fixing shell layer composed of a calcium-containing compound and a second binder, and the film is a degradable film formed by a third binder, and the film wraps the core-shell structure.

[0061] Compared with the prior art, the present invention has the following advantages:

[0062] (1) In the waste FCC catalyst-based mother ball, the waste FCC catalyst and silica can form mullite crystals during the sintering process, and the addition of high-iron material can provide Fe 3+ to replace Al in the mullite lattice 3+ , activate the lattice, promote the formation of mullite, and endow the carbon-fixing ceramsite proppant with sufficient strength;

[0063] (2) The second binder in the carbon-fixing shell layer is cement, so that the carbon-fixing shell layer has certain mechanical strength and reduces breakage during the injection process of the carbon-fixing ceramsite proppant; further, the degradable film has deformability, which can ensure that during the injection process of the carbon-fixing ceramsite proppant, formation plugging will not be caused by the leakage of debris generated by the inevitable small breakage of the carbon-fixing shell layer due to formation pressure; moreover, the presence of the degradable film can also reduce the density of the carbon-fixing ceramsite proppant, which is beneficial to injecting it deep into the formation, prolonging the formation closure time and enhancing the fracturing effect;

[0064] (3) After the carbon sequestration ceramsite proppant enters the formation, the degradable film hydrolyzes and ruptures, and the calcium-containing compound in the carbon sequestration shell reacts with the CO2 after CO2 flooding to form calcium carbonate on the surface of the spent FCC catalyst-based mother balls, realizing the solidification of CO2 while further enhancing the mechanical strength of the mother balls, which is beneficial to the stability and durability of the supporting effect of the carbon sequestration proppant. Moreover, since the calcium carbonate layer is formed only after entering the formation, it will not cause an increase in the density of the carbon sequestration ceramsite proppant during the injection process;

[0065] (4) The bulk density of the carbon sequestration ceramsite proppant provided by the present invention is less than 1.40 g / cm 3 , and the apparent density is not higher than 2.65 g / cm 3 , belonging to the ultra-low density ceramsite proppant, with the roundness and sphericity both above 0.8 and the turbidity below 50. The crushing rate of the 30 / 50 mesh product is less than 3% under a pressure of 52 MPa, and the crushing rate of the 40 / 70 mesh product is less than 3% under a pressure of 69 MPa, fully meeting the requirements of the enterprise standard "Technical Requirements for Ceramsite Proppants for Fracturing" of Sinopec Group Co., Ltd.;

[0066] (5) The carbon sequestration ceramsite proppant prepared by the present invention has low cost and good economic benefits. Specifically, the main raw material, the spent FCC catalyst, belongs to hazardous solid waste and has disposal fee income, with good economic benefits; among the auxiliary materials, silica and diaspore in the high-iron material are rich in reserves in China, with low prices and are easily available; the red mud in the high-iron material is a solid waste with a stockpile of tens of millions of tons, and the present invention also realizes the harmless utilization of red mud. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 is the process flow chart of the preparation of the carbon sequestration ceramsite proppant provided by the present invention;

[0068] Figure 2 is the structural schematic diagram of the carbon sequestration ceramsite proppant provided by the present invention;

[0069] Figure 3 is the internal crystal micrograph of the spent FCC catalyst-based mother balls in the carbon sequestration ceramsite proppant prepared in Example 1;

[0070] Figure 4 is the XRD pattern of the spent FCC catalyst-based mother balls in the carbon sequestration ceramsite proppant prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] The present invention will be further described below in conjunction with embodiments, but the embodiments of the present invention are only exemplary descriptions, and this implementation method does not constitute a limitation to the present invention under any circumstances.

[0072] Waste FCC catalyst (wherein, alumina content is 49.5%, silica content is 44.2%): purchased from Sinopec Catalyst Company;

[0073] Waste FCC catalyst (wherein, alumina content is 52%, silica content is 42%): purchased from Sinopec Qingdao Refining & Chemical Company;

[0074] Silica (wherein, silica content is 94%): purchased from Jingang New Materials Co., Ltd.;

[0075] Silica (wherein, silica content is 92%): purchased from Hebei Jiegui Mineral Products Co., Ltd.;

[0076] High-iron bauxite (wherein, alumina content is 42%, silica content is 17%, iron oxide content is 37%): purchased from Zhengzhou Gongyi Tiankai Mining Company;

[0077] High-iron bauxite (wherein, alumina content is 48%, silica content is 12%, iron oxide content is 33%): purchased from Zhengzhou Gongyi Tiankai Mining Company;

[0078] Red mud (wherein, alumina content is 17%, silica content is 6%, iron oxide content is 53%): purchased from Jingang New Materials Co., Ltd.;

[0079] Polylactic acid-based binder: product model is L-lactic acid polymer, purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0080] Hereinafter, room temperature refers to 25 °C; hereinafter, normal temperature refers to the ambient temperature without additional heating or cooling.

[0081] Example 1

[0082] 1) Weigh 70 tons of waste FCC catalyst (wherein, alumina content is 49.5%, silica content is 44.2%), 12 tons of high-iron bauxite (wherein, alumina content is 42%, silica content is 17%, iron oxide content is 37%), 15 tons of silica (wherein, silica content is 94%), 3 tons of flux (wherein the mass ratio of dolomite to potassium feldspar is 1:1), and then put them into a ball mill together with 0.3 tons of sodium carboxymethylcellulose for ball milling and air separation to obtain the first mixed powder with an average particle size of 400 mesh;

[0083] 2) Granulate the first mixed powder obtained in step 1) by adding water to form pellets, obtaining green pellets, then screen them with a 40 / 70 mesh sieve to obtain green pellets with a size of 40 to 70 mesh, convey them to a rotary kiln, heat from room temperature to 200 °C, then heat at a rate of 2.5 °C / min to 300 °C, then heat up to 1200 °C and hold for 0.5 h, finally heat up to 1290 °C and hold for 2 h, then enter a water-cooled kiln to cool to room temperature, and then classify and screen with a 45 / 75 mesh sieve to obtain waste FCC catalyst-based green pellets with a size of 45 to 75 mesh;

[0084] 3) While spraying water on the waste FCC catalyst-based green pellets with a size of 45 / 75 mesh obtained by screening, add a mixture of calcium hydroxide and a second binder cement (400 mesh fineness, mass ratio 1:1), and the pellets grow layer by layer in a dense manner. Hydrate and dry them in normal temperature water, and screen them with a 40 / 70 sieve to obtain green pellets with a carbon-fixing shell layer having a size of 40 to 70 mesh, and the average thickness of the carbon-fixing shell layer is 118 μm to 130 μm;

[0085] 4) The film coating of the green pellets with a carbon-fixing shell layer adopts a fluidized bed process. In the normal temperature film coating section, cover the green pellets with a carbon-fixing shell layer with a third binder solution (or called film coating liquid, where the solvent is a mixture of dichloromethane and methanol with a mass ratio of 9:1, and the solute is a polylactic acid-based binder, having a certain fluidity). Heat to 100 °C at a high temperature in the film forming section to complete the evaporation of the solvent in the third binder and the drying of the degradable film, and form a uniform, smooth and dense degradable film on the particle surface to obtain carbon-fixing ceramsite coated with a degradable film, and the average thickness of the degradable film is 2 μm to 5 μm;

[0086] 5) Screen the carbon-fixing ceramsite prepared above with a 40 / 70 sieve again to obtain a carbon-fixing ceramsite fracturing proppant with a size of 40 to 70 mesh, and its structure is as Figure 2 shown.

[0087] Example 2

[0088] 1) Weigh 56 tons of waste FCC catalyst (where the alumina content is 52%, and the silica content is 42%), 16 tons of high-iron bauxite (where the alumina content is 48%, the silica content is 12%, and the iron oxide content is 33%), 25 tons of silica (where the silica content is 92%), 3 tons of flux (where the mass ratio of dolomite to potassium feldspar is 2:1), and then put them into a ball mill together with 0.35 tons of sodium carboxymethylcellulose for ball milling and air separation to obtain a first mixed powder with an average particle size of 400 mesh;

[0089] 2) Granulate the first mixed powder obtained in step 1) by adding water to form pellets, obtaining green pellets, then screen them with a 35 / 60 mesh sieve to obtain 35-60 mesh green pellets, convey them to a rotary kiln, heat from room temperature to 200 °C, then heat at a rate of 5 °C / min to 300 °C, then heat up to 1200 °C and hold for 0.5 h, finally heat up to 1300 °C and hold for 1.8 h, then enter a water-cooled kiln to cool to room temperature, and then classify and screen with a 35 / 60 mesh sieve to obtain 35-60 mesh waste FCC catalyst-based mother pellets;

[0090] 3) While spraying water on the 35-60 mesh waste FCC catalyst-based mother pellets screened, add a mixture of calcium hydroxide and the second binder cement (400 mesh fineness, mass ratio 1:1.1), and the balls grow densely layer by layer, hydrate and dry in normal temperature water, and screen with a 30 / 50 sieve to obtain 30-50 mesh mother pellets with a carbon-fixing shell layer, and the average thickness of the carbon-fixing shell layer is 20 μm to 125 μm;

[0091] 4) The film coating of the mother pellets with a carbon-fixing shell layer adopts a fluidized bed process. In the normal temperature film coating section, cover the mother pellets with a carbon-fixing shell layer with a third binder solution (or called film coating solution, where the solvent is a mixture of dichloromethane and methanol with a mass ratio of 7:1, and the solute is a polylactic acid-based binder, having a certain fluidity). Heat to 102 °C at a high temperature in the film forming section to complete the evaporation of the solvent in the third binder and the drying of the degradable film, and form a uniform, smooth and dense degradable film on the particle surface to obtain carbon-fixing ceramsite coated with a degradable film, and the average thickness of the degradable film is 2 μm to 5 μm;

[0092] 5) Screen the carbon-fixing ceramsite prepared above with a 30 / 50 sieve again to obtain 30-50 mesh carbon-fixing ceramsite fracturing proppants, and its structure is as Figure 2 shown.

[0093] Example 3

[0094] 1) Weigh 68 tons of waste FCC catalyst (where the alumina content is 52%, and the silica content is 42%), 9 tons of red mud (where the alumina content is 17%, the silica content is 6%, and the iron oxide content is 53%), 20 tons of silica (where the silica content is 92%), 4 tons of flux (where the mass ratio of dolomite to potassium feldspar is 2:1), and then put them into a ball mill together with 0.45 tons of sodium carboxymethyl cellulose for ball milling and air separation to obtain a first mixed powder with an average particle size of 400 mesh;

[0095] 2) Granulate the first mixed powder obtained in step 1) by adding water to form pellets, obtaining green pellets, then screen them with a 40 / 70 mesh sieve to obtain green pellets with a size of 40 to 70 mesh, convey them to a rotary kiln, heat from room temperature to 200 °C, then heat at a rate of 2 °C / min to 300 °C, then heat up to 1200 °C and hold for 0.5 h, finally heat up to 1300 °C and hold for 1.8 hours, then enter a water-cooling kiln to cool to room temperature, and then classify and screen with a 45 / 75 mesh sieve to obtain waste FCC catalyst-based green pellets with a size of 45 to 75 mesh;

[0096] 3) While spraying water on the waste FCC catalyst-based green pellets with a size of 45 to 75 mesh obtained by screening, add a mixture of calcium hydroxide and the second binder cement (400 mesh fineness, mass ratio 1:1), and the pellets grow layer by layer densely. Hydrate and dry in normal temperature water, and screen with a 40 / 70 sieve to obtain green pellets with a carbon-fixing shell layer, and the average thickness of the carbon-fixing shell layer is 118 μm to 130 μm;

[0097] 4) The coating of the green pellets with a carbon-fixing shell layer adopts a fluidized bed process. In the normal temperature coating section, cover the green pellets with a carbon-fixing shell layer with a third binder solution (or called coating liquid, where the solvent is a mixture of dichloromethane and methanol with a mass ratio of 8:1, and the solute is a polylactic acid-based binder, with a certain fluidity). Heat to 105 °C in the film-forming section to form a film, complete the evaporation of the solvent in the third binder and the drying of the degradable film, and form a uniform, smooth and dense degradable film on the particle surface to obtain carbon-fixing ceramsite coated with a degradable film, and the average thickness of the degradable film is 2 μm to 5 μm;

[0098] 5) Screen the carbon-fixing ceramsite prepared above with a 40 / 70 sieve again to obtain a carbon-fixing ceramsite fracturing proppant with a size of 40 to 70 mesh, and its structure is as Figure 2 shown.

[0099] Test Example 1 - Structural Characterization of Waste FCC Catalyst-Based Green Pellets

[0100] ⅰ Observation of the internal crystal structure of the waste FCC catalyst-based green pellets in the carbon-fixing ceramsite proppants prepared in Examples 1 to 3

[0101] Here, the internal crystal micrographs of the waste FCC catalyst-based green pellets in the carbon-fixing ceramsite proppants prepared in Example 1 are taken as an example for detailed description. Figure 3 It is the internal crystal micrograph of the waste FCC catalyst-based green pellets in the carbon-fixing ceramsite proppants prepared in Example 1. From it, it can be seen that there are many needle-like crystals inside the waste FCC catalyst-based green pellets, which conform to the crystal morphological characteristics of mullite.

[0102] After observation, there are also many needle-like crystals inside the waste FCC catalyst-based green pellets prepared in Examples 2 and 3, which conform to the crystal morphological characteristics of mullite.

[0103] ⅱ Use an X-ray diffractometer to measure the XRD patterns of the spent FCC catalyst-based mother balls in the carbon-fixing ceramsite proppants prepared in Examples 1 to 3.

[0104] Here, the XRD pattern of the spent FCC catalyst-based mother ball in the carbon-fixing ceramsite proppant prepared in Example 1 will be described in detail. Figure 4 It is the XRD pattern of the spent FCC catalyst-based mother ball in the carbon-fixing ceramsite proppant prepared in Example 1. The diffraction peaks therein are almost completely consistent with those of the mullite standard spectrum, further confirming that the main crystal inside the spent FCC catalyst-based mother ball in the carbon-fixing ceramsite proppant prepared in Example 1 is mullite crystal.

[0105] After measurement, the diffraction peaks in the XRD patterns of the spent FCC catalyst-based mother balls in the carbon-fixing ceramsite proppants prepared in Examples 2 and 3 are almost completely consistent with those of the mullite standard spectrum. Further, it can also be determined that the main crystal inside the spent FCC catalyst-based mother balls in the carbon-fixing ceramsite proppants prepared in Examples 2 and 3 is mullite crystal.

[0106] Test Example 2 - Performance determination of the spent FCC catalyst-based mother ball

[0107] According to the methods specified in the standards of Q / SH15000104 - 2016 and Q / SH31400072 - 2015, perform performance determination on the spent FCC catalyst-based mother balls prepared in Examples 1 to 3. The specific results are shown in Table 1.

[0108] Table 1. Performance of the spent FCC catalyst-based mother ball

[0109]

[0110] The data in Table 1 show that for the spent FCC catalyst-based mother balls in the carbon-fixing ceramsite proppants prepared in Examples 1 to 3: in terms of density, both the bulk density and the apparent density are relatively low. The bulk density is about 1.4 g / cm 3 and the apparent density is about 2.6 g / cm 3 , laying a foundation for achieving the low density of the carbon-fixing ceramsite proppant; in terms of geometric homogeneity, both the roundness and the sphericity are above 0.9, with high geometric homogeneity, which is conducive to achieving the geometric homogeneity of the carbon-fixing ceramsite proppant; in terms of turbidity, the turbidity is all below 50; in terms of crushing rate, the crushing rate is all about 6%, with a relatively low crushing rate and high strength, which is conducive to achieving the high strength of the carbon-fixing ceramsite proppant.

[0111] Test Example 3 - Performance determination of the carbon-fixing ceramsite proppant

[0112] According to the methods specified in the standards of Q / SH15000104-2016 and Q / SH31400072-2015, the performance of the carbon-fixing ceramsite proppants prepared in Examples 1 to 3 was determined. The specific results are shown in Table 2.

[0113] Table 2. Performance of Carbon-fixing Ceramsite Proppants

[0114]

[0115] The data in Table 2 show that for the carbon-fixing ceramsite proppants prepared in Examples 1 to 3: in terms of density, both the bulk density and the apparent density are relatively low, with the bulk density less than 1.4 g / cm 3 and the apparent density less than or equal to 2.65 g / cm 3 , belonging to ultra-low density ceramsite proppants; in terms of geometric homogeneity, both the roundness and sphericity are above 0.8, with high geometric homogeneity; in terms of turbidity, the turbidity is all below 50; in terms of breakage rate, the breakage rate is all less than 3%, with a relatively low breakage rate and high strength.

[0116] Although the present invention has been described with reference to specific embodiments, those skilled in the art should understand that various changes can be made without departing from the true spirit and scope of the present invention. In addition, various changes can be made to the subject matter, spirit, and scope of the present invention to adapt to specific situations, materials, material compositions, and methods. All such changes are included within the scope of the claims of the present invention.

Claims

1. A carbon-fixing ceramsite proppant, which has a coated shell-core structure; the core is a waste FCC catalyst-based mother ball; the shell is a carbon-fixing shell layer; the film is a degradable film; and the film wraps the shell-core structure.

2. The carbon-fixing ceramsite proppant according to claim 1, wherein The waste FCC catalyst-based mother ball includes waste FCC catalyst, silica, high-iron material, flux, and a first binder; and / or The carbon-fixing shell layer includes a calcium-containing compound and a second binder; and / or the degradable film includes a third binder; Preferably, the calcium-containing compound is calcium oxide and / or calcium hydroxide.

3. The carbon sequestration ceramsite proppant according to claim 2, wherein In the waste FCC catalyst-based mother ball, the dosage of the waste FCC catalyst is 56 to 76 parts by mass, the dosage of the silica is 5 to 25 parts by mass, the dosage of the high-iron material is 8 to 20 parts by mass, the dosage of the flux is 1 to 5 parts by mass, and the dosage of the first binder is 0.1 to 0.5 parts by mass; and / or In the carbon-fixing shell layer, the ratio of the mass of the calcium-containing compound to the mass of the second binder is 1:(1 to 1.5).

4. The carbon sequestration ceramsite proppant according to claim 2 or 3, wherein Taking the mass of the waste FCC catalyst as 100%, the content of Al2O3 in the waste FCC catalyst is 45 to 53 wt%, and the content of SiO2 is 42 to 53 wt%; and / or Taking the mass of the silica as 100%, the content of SiO2 in the silica is 85 to 95 wt%; and / or Taking the mass of the high-iron material as 100%, the content of Fe2O3 in the high-iron material is 25 to 53 wt%.

5. The carbon sequestration ceramsite proppant according to any one of claims 2 to 4, characterized in that, The high-iron material is bauxite and / or red mud; and / or the flux includes dolomite and / or potassium feldspar; and / or The first binder is at least one of polyvinyl alcohol, polyvinyl butyral, methyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, ethyl cellulose, and hydroxypropyl cellulose; and / or The second binder is cement; and / or The third binder is a polylactic acid-based binder.

6. The carbon-fixing ceramsite proppant according to any one of claims 1 to 5, characterized in that, The particle size range of the core is 40 to 70 mesh or 30 to 50 mesh; and / or The average thickness of the carbon-fixing shell layer is 118 μm to 130 μm; and / or the average thickness of the degradable film is 2 to 5 μm; and / or The particle size range of the carbon-fixing ceramsite proppant is 40 to 70 mesh or 30 to 50 mesh.

7. A method for preparing the carbon-fixing ceramsite proppant according to any one of claims 1 to 6, which includes the following steps: 1) Mix the waste FCC catalyst, silica, high-iron material, flux, and first binder to obtain a first mixed powder; 2) Granulate the first mixed powder to obtain blank balls, and sinter to obtain the waste FCC catalyst-based mother ball; 3) Mix the calcium-containing compound and the second binder to obtain a second mixed powder; 4) Wet the waste FCC catalyst-based mother ball and adhere the second mixed powder, and perform first curing to form the carbon-fixing shell layer on the surface of the waste FCC catalyst-based mother ball to obtain a mother ball with the carbon-fixing shell layer; 5) Coat the mother ball with the carbon-fixing shell layer using the third binder, and perform second curing to form the degradable film on the surface of the carbon-fixing shell layer to obtain the carbon-fixing ceramsite proppant.

8. The method according to claim 7, wherein In step 1), the average particle size of the first mixed powder is not less than 400 mesh; and / or In step 2), the granulation is carried out by adding water; and / or the particle size range of the green balls is 40 to 70 mesh or 30 to 50 mesh; and / or In step 5), the film coating process is to coat the solution of the third binder on the surface of the mother balls with the carbon-fixing shell layer, and then carry out the second curing.

9. The method according to claim 8, wherein In step 2), the sintering conditions are to keep the temperature at 1200 °C for 0.5 h, and then keep the temperature at 1280 to 1350 °C for 0.8 to 2 h; and / or In step 4), the first curing condition is to dry at room temperature; and / or In step 5), the temperature of the second curing is 100 to 105 °C.

10. Application of the carbon-fixing ceramsite proppant according to any one of claims 1 to 6 or the carbon-fixing ceramsite proppant prepared by the method according to any one of claims 7 to 9 in oil and gas field fracturing, especially in post-fracturing of CO2 flooding in oil and gas fields.

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