A low-density ceramic proppant and method of making the same

Abstract

The application belongs to the field of oil and natural gas exploitation, and particularly relates to a low-density ceramic proppant and a preparation method thereof. The preparation method comprises the following steps: S1, high-temperature calcination of oil sludge dry residue for standby; S2, mixing of the high-temperature calcined oil sludge dry residue and titanium-containing blast furnace slag to obtain a mixture; S3, crushing and granulation of the mixture obtained in step S2, and then sintering in a rotary kiln, and then quenching in a cooling device to obtain the low-density ceramic proppant. The preparation method of the low-density ceramic proppant uses oil sludge dry residue and titanium-containing blast furnace slag as raw materials to prepare the low-density ceramic proppant without adding other materials, so that waste is reused, and the demand for bauxite resources for preparing the low-density ceramic proppant is reduced. In addition, the titanium-containing blast furnace slag is used to provide titanium as a condensation core for the formation of microcrystals, so that the crystallization time is shortened, and the sintering time required is greatly reduced, and the sintering cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of oil and natural gas extraction, and specifically relates to a low-density ceramic proppant and its preparation method. Background Technology

[0002] The raw material for commonly used artificial low-density ceramsite proppant is bauxite. The higher the alumina content, the greater the density and strength. With the rapid development of the ceramics industry, the reserves of high-quality bauxite with high alumina content are rapidly declining. Commonly used bauxite proppant is produced using the sintering method, with a sintering temperature of 1300-1600℃, which consumes a lot of energy.

[0003] With improvements in crude oil extraction technology, oil production has increased, but so has the amount of oil sludge generated. The dried residue obtained after oil sludge treatment is classified as general solid waste. Due to its high barium sulfate content, its use as a cement admixture is limited. Currently, the disposal of dried oil sludge mainly focuses on low-value-added uses such as road paving at well sites, cement admixture, and brick-making raw materials. This is essentially a last resort for industrial solid waste disposal, and the value of the dried oil sludge has not been realized. Titanium-containing blast furnace slag is a solid waste slag produced from the smelting of vanadium-titanium magnetite concentrate. Due to its high titanium content, the blast furnace slag has low activity and cannot be processed into slag powder like other blast furnace slags, thus it is largely stockpiled.

[0004] Therefore, how to utilize oil sludge and titanium-containing blast furnace slag has become an urgent problem to be solved. Summary of the Invention

[0005] The main objective of this invention is to provide a low-density ceramic proppant and its preparation method to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] The first aspect of this invention is to provide a method for preparing a low-density ceramsite proppant, the method comprising the following steps:

[0008] S1. Calcining the dried oil sludge at high temperature for later use;

[0009] S2. Mix the dry residue of oily sludge after high-temperature calcination with titanium-containing blast furnace slag to obtain a mixture;

[0010] S3. The mixture obtained in step S2 is crushed, granulated, sintered, and then rapidly cooled to obtain the low-density ceramic proppant.

[0011] Furthermore, the oil sludge dry residue comprises the following components by weight: 35-55 parts SiO2, 5-12 parts Al2O3, 15-25 parts CaO, 1-5 parts MgO, 3-8 parts Fe2O3, and 15-30 parts BaSO4; and the oil content in the oil sludge dry residue is ≤3‰ by weight.

[0012] Furthermore, the high-temperature calcination temperature is 950–1050°C, and the time is 20–60 min.

[0013] Furthermore, the titanium-containing blast furnace slag comprises the following components by weight: 15-25 parts SiO2, 8-12 parts Al2O3, 25-30 parts CaO, 5-10 parts MgO, 1-3 parts Fe2O3, and 15-25 parts TiO2.

[0014] Furthermore, in step S2, the mixing mass ratio of oily sludge dry residue to titanium-containing blast furnace slag is (9-9.5):(0.5-1).

[0015] Furthermore, the crushing in step S3 includes crushing the mixture of dry oil sludge and titanium-containing blast furnace slag to below 500 mesh, and the mass ratio of the residue obtained after crushing to the mixture is less than 5%.

[0016] Furthermore, in step S3, the roundness of the granulated particles is 0.9–1.0, the sphericity is 0.9–1.0, and the particle size is 70–140 mesh.

[0017] Furthermore, in step S3, the sintering temperature is 1100–1200℃ and the sintering time is 0.5–2h.

[0018] Furthermore, the preparation method of the low-density ceramsite proppant also includes a step of sieving the green pellets obtained after granulation according to different particle sizes. When the particle size of the green pellets is larger than a preset range, the green pellets are returned for granulation until the particle size reaches the preset range. When the particle size of the green pellets is smaller than the preset range, the green pellets are returned for crushing. The preset range of the green pellet particle size is 70 to 140 mesh.

[0019] A second aspect of the present invention is to provide a low-density ceramic proppant prepared by any of the above-described preparation methods, wherein the low-density ceramic proppant has a particle size of 70-140 mesh, a breakage rate of ≤6.5% under a closing pressure of 69 MPa, an acid solubility of less than 7%, and a sphericity greater than 0.8.

[0020] Compared with the prior art, the advantages of the present invention include:

[0021] (1) This invention provides a method for preparing low-density ceramsite proppant. The method uses dry oil sludge and titanium-containing blast furnace slag as raw materials to prepare low-density ceramsite proppant without adding other materials. This not only realizes waste recycling, but also reduces the demand for bauxite resources in the preparation of low-density ceramsite proppant, reduces production costs, and completes the resource utilization of two wastes, dry oil sludge and titanium-containing blast furnace slag. It can completely replace the traditional process of preparing low-density ceramsite proppant from bauxite, avoiding problems such as high cost and resource scarcity.

[0022] (2) The oil sludge dry residue used in this invention is composed of shale, with silicon dioxide as its main component. Its density is lower than that of bauxite, the raw material used in traditional proppant. The density of the oil sludge dry residue is 2.5–2.65 g / cm³. 3 The density of bauxite is 3.45 g / cm³. 3 The resulting low-density ceramic proppant has an even lower density.

[0023] (3) The present invention uses titanium-containing blast furnace slag to provide titanium as the condensation nucleus for the formation of microcrystals, which shortens the crystallization time and thus greatly reduces the time required for sintering and reduces the sintering cost. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] The first aspect of this invention is to provide a method for preparing a low-density ceramsite proppant, comprising the following steps:

[0026] S1. The oil sludge dry residue is subjected to high-temperature calcination pretreatment, wherein the temperature of the high-temperature calcination pretreatment is 950℃~1050℃ and the high-temperature calcination pretreatment time is 20~60min;

[0027] Preferably, the high-temperature calcination pretreatment temperature is 1000℃ and the high-temperature calcination pretreatment time is 30min.

[0028] S2. The dried oil sludge residue after high-temperature calcination is mixed with titanium-containing blast furnace slag to obtain a mixture. The mass ratio of the dried oil sludge residue to the titanium-containing blast furnace slag is (9-9.5):(0.5-1), preferably 9.5:0.5. Excessive or insufficient titanium-containing blast furnace slag content will affect the strength of the low-density ceramic proppant, causing a decrease in proppant strength. Simultaneously, if the titanium-containing blast furnace slag content is too low, the material may not be fully calcined in a short time, thus prolonging the sintering time and reducing preparation efficiency.

[0029] S3. The mixture obtained in step S2 is crushed and granulated, and the granulation time is 20 to 60 minutes, preferably 45 minutes.

[0030] After granulation, the material is sintered in a rotary kiln at a temperature of 1100–1200℃, preferably 1120–1160℃, for a time of 0.5–2 hours, preferably 1–1.5 hours. If the sintering time is too short, the heat transfer inside the green pellets will not reach the required temperature range, which will prevent the material from being fully burned and will reduce the strength of the low-density ceramic proppant.

[0031] Then it is transferred to a cooling device for rapid cooling to obtain the low-density ceramic proppant; the rapid cooling refers to cooling down to below 60°C.

[0032] The pulverization process includes pulverizing a mixture of dry oil sludge and titanium-containing blast furnace slag to below 500 mesh, with the mass ratio of the sieve residue to the mixture being less than 5%; the granulated pellets have a roundness of 0.9-1.0, a sphericity of 0.9-1.0, and a particle size of 70-140 mesh.

[0033] S4. The method for preparing low-density ceramic proppant by co-processing multiple solid wastes further includes a step of sieving the green pellets obtained after granulation according to different particle sizes. When the particle size of the green pellets is larger than a preset range, the green pellets are returned for granulation to the preset range. When the particle size of the green pellets is smaller than the preset range, the green pellets are transported back for crushing. The preset range of the green pellet particle size is 70 to 140 mesh. Only when the particle size is within the preset range will the green pellets continue to be sintered.

[0034] The method described in this invention uses dry oil sludge and titanium-containing blast furnace slag as raw materials to prepare low-density ceramsite proppant without adding other materials. This not only achieves waste recycling but also reduces the demand for bauxite resources in the preparation of low-density ceramsite proppant.

[0035] The sintering mechanism in this embodiment is as follows: During sintering, as the calcination temperature rises, according to the principle of the lowest eutectic point, the melting point of the mixture of oil sludge dry residue and titanium-containing blast furnace slag will be lower than the melting point of each component. The low-melting-point substances begin to melt. Silica and barium sulfate melt first, then iron oxide begins to melt, and finally magnesium oxide and calcium oxide melt. Due to the fast flow mass transfer rate, the liquid phase sintering densification rate is high, resulting in particle rearrangement and pore filling. Then the liquid phase (silica and calcium oxide) is evenly dispersed, and the voids between glassy particles are significantly reduced. As the temperature continues to rise, microcrystals grow between the glass particles, and the densification degree of the glass particles continuously increases. The microcrystals formed by silica and calcium oxide further grow to form a microcrystalline interwoven structure, so that the particle structure densification degree reaches the highest level and the compressive strength is high.

[0036] The oily sludge dry residue comprises the following components in parts by weight: 35-55 parts SiO2, 5-12 parts Al2O3, 15-25 parts CaO, 1-5 parts MgO, 3-8 parts Fe2O3, and 15-30 parts BaSO4; and the oil content in the oily sludge dry residue is ≤3‰ by mass.

[0037] Preferably, the dried oil sludge comprises the following components in parts by weight: 37.59 parts SiO2, 5.97 parts Al2O3, 18.34 parts CaO, 1.75 parts MgO, 3.68 parts Fe2O3, and 20.56 parts BaSO4; and the oil content in the dried oil sludge is ≤3‰ by mass.

[0038] The titanium-containing blast furnace slag comprises the following components in parts by weight: 15-25 parts SiO2, 8-12 parts Al2O3, 25-30 parts CaO, 5-10 parts MgO, 1-3 parts Fe2O3, and 15-25 parts TiO2.

[0039] Preferably, the titanium-containing blast furnace slag comprises the following components in parts by weight: 23.9 parts SiO2, 10.1 parts Al2O3, 27.1 parts CaO, 7.45 parts MgO, 1.47 parts Fe2O3, and 19.48 parts TiO2.

[0040] A second aspect of the present invention is to provide a low-density ceramic proppant prepared by any of the above methods, wherein the low-density ceramic proppant has a particle size of 70-140 mesh, a breakage rate of ≤6.5% under a closing pressure of 69MPa, an acid solubility of less than 7%, and a sphericity greater than 0.8.

[0041] Example

[0042] The present invention will be described in detail below with reference to specific embodiments to facilitate understanding of the technical solution of the present invention.

[0043] Example 1

[0044] 1. The main components of the dry oil sludge are SiO2, Al2O3, CaO, MgO, Fe2O3 and BaSO4; the oil content in the dry oil sludge is less than or equal to 3‰, and the content of its main components is shown in Table 1.

[0045] Table 1. Components and percentage content of dry oil sludge.

[0046] Element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO MgO <![CDATA[Fe2O3]]> <![CDATA[BaSO4]]> content / % 37.59 5.97 18.34 1.75 3.68 20.56

[0047] The main components of titanium-containing blast furnace slag are shown in Table 2 below. The main purpose of adding titanium-containing blast furnace slag is to utilize the titanium within it as a nucleus for microcrystal formation; therefore, the amount added is 5% to 10% of the total weight of the raw materials.

[0048] Table 2. Components and percentage content of titanium-containing blast furnace slag

[0049]

[0050] 2. Specific steps:

[0051] (1) The oil sludge dry residue is pretreated by high-temperature calcination to remove volatile substances and avoid the decomposition of carbonates during subsequent sintering, which would generate pores and adversely affect the strength. The pretreatment temperature is 1000℃ and the holding time is 30 minutes.

[0052] (2) 9.5 parts of pretreated oil sludge dry residue and 0.5 parts of titanium-containing blast furnace slag are crushed to 4.7% residue on a 500-mesh sieve by a dry micro powder mill. Crushing is also a mixing process.

[0053] (3) The crushed dry residue is granulated for 45 minutes. The roundness and sphericity of the granulated green pellets are 0.9-1.0. Green pellets with different particle size requirements are obtained by sieving. Green pellets larger than 70 mesh are returned to the mill for further grinding and reuse, and green pellets smaller than 140 mesh are returned to the granulator for granulation and reuse, forming a closed-loop cycle.

[0054] (4) Place green pellets with a particle size range of 70 to 140 mesh into a rotary kiln for sintering at a temperature of 1150°C for 1.5 hours.

[0055] (5) Cool the product to below 60°C in a cooler to obtain the low-density ceramic proppant product.

[0056] (6) The ceramsite proppant (70-140 mesh) prepared according to the performance test method of proppant for hydraulic fracturing and gravel packing operations (SY / T 5108-2014) was subjected to fracturing at a closing pressure of 69 MPa. The measured breakage rate of the finished proppant was 6.5% (a breakage rate of less than 9% is considered qualified), acid solubility was less than 7%, sphericity was greater than 0.8, and density was 1.48 g / cm³. 3 .

[0057] Example 2

[0058] The low-density ceramsite proppant was prepared in a manner similar to that in Example 1, except that the pretreatment temperature was 1050°C and the temperature was maintained for 20 minutes.

[0059] The ceramsite proppant (70-140 mesh) prepared according to the performance test method for proppants used in hydraulic fracturing and gravel packing operations (SY / T 5108-2014) was subjected to fracturing at a closure pressure of 69 MPa. The results showed that the fragmentation rate of the finished proppant was 6.8%, the sphericity was greater than 0.8, and the density was 1.51 g / cm³. 3

[0060] Example 3

[0061] The low-density ceramsite proppant was prepared in a manner similar to that in Example 1, except that the pretreatment temperature was 950°C and the temperature was maintained for 60 minutes. Nine parts of the pretreated oil sludge dry residue and one part of titanium-containing blast furnace slag were pulverized in a dry micro powder mill until the residue was 4.7% on a 500-mesh sieve.

[0062] The ceramsite proppant (70-140 mesh) prepared according to the performance test method of proppant for hydraulic fracturing and gravel filling operations (SY / T 5108-2014) was subjected to fracturing at a closing pressure of 69 MPa. The brokenness rate of the finished proppant was 8.1%, and the roundness and sphericity were greater than 0.8.

[0063] Comparative Example

[0064] Comparative Example 1

[0065] The low-density ceramsite proppant was prepared in a manner similar to that in Example 1, except that the pretreatment temperature was 900℃ and the holding time was 30 min. 9.5 parts of the pretreated oil sludge dry residue and 0.5 parts of titanium-containing blast furnace slag were pulverized using a dry micronizer until a residue of 6.7% was obtained on a 500-mesh sieve.

[0066] The ceramsite proppant (70-140 mesh) prepared according to the performance test method for proppants used in hydraulic fracturing and gravel packing operations (SY / T 5108-2014) was subjected to fracturing at a closure pressure of 69 MPa. The results showed that the fragmentation rate of the finished proppant was 10.5%, the sphericity was greater than 0.8, and the density was 1.66 g / cm³. 3 .

[0067] Comparative Example 2

[0068] The low-density ceramsite proppant was prepared in a manner similar to that in Example 1, except that the pretreatment temperature was 1000℃ and the holding time was 40 min; and 9 parts of the pretreated oil sludge dry residue and 1 part of titanium-containing blast furnace slag were pulverized by a dry micronizer.

[0069] The ceramsite proppant (70-140 mesh) prepared according to the test method of SY / T 5108-2014 for the performance test of proppants for hydraulic fracturing and gravel packing operations was subjected to fracturing at a closing pressure of 69 MPa, and the breakage rate of the finished proppant product was measured to be 9.6%.

[0070] Comparative Example 3

[0071] The low-density ceramsite proppant was prepared in a manner similar to that in Example 1, except that the pretreatment temperature was 1000℃ and the holding time was 40 min; 9.7 parts of the pretreated oil sludge dry residue and 0.3 parts of titanium-containing blast furnace slag were pulverized by a dry micronizer.

[0072] The ceramsite proppant (70-140 mesh) prepared according to the test method of SY / T 5108-2014 for the performance test of proppants for hydraulic fracturing and gravel filling operations was subjected to fracturing at a closing pressure of 69 MPa, and the breakage rate of the finished proppant product was measured to be 18.5%.

[0073] Comparative Example 4

[0074] The low-density ceramsite proppant was prepared in a manner similar to that in Example 1, except that: the pretreatment temperature was 1000℃ and the holding time was 40 min; 9.7 parts of the pretreated oil sludge dry residue and 0.3 parts of titanium-containing blast furnace slag were pulverized by a dry micronizer; and the granulated green pellets were sintered in a rotary kiln at a temperature of 1150℃ for 2.5 hours.

[0075] The ceramsite proppant (70-140 mesh) prepared according to the test method of SY / T 5108-2014 for the performance test of proppants for hydraulic fracturing and gravel packing operations was subjected to fracturing at a closing pressure of 69 MPa, and the breakage rate of the finished proppant product was measured to be 8.1%.

[0076] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of making a low density ceramic proppant, characterized by , comprising the following steps: S1, high temperature calcination of oil sludge dry residue, standby; S2, the oil sludge dry residue after high temperature calcination and titanium containing blast furnace slag are mixed to obtain a mixture; S3, the mixture obtained in step S2 is crushed, granulated, then sintered, and then quenched to prepare the low density ceramsite proppant, The mixing mass ratio of oil sludge dry residue and titanium containing blast furnace slag in step S2 is (9-9.5):(0.5-1).

2. The method for preparing the low-density ceramsite proppant according to claim 1, characterized in that... , the 3. The method for preparing the low-density ceramsite proppant according to claim 1, characterized in that... : the temperature of high temperature calcination is 950-1050℃, and the time is 20-60min.

4. The method for preparing the low-density ceramsite proppant according to claim 1, characterized in that... : the crushing in step S3 includes crushing the mixture of oil sludge dry residue and titanium containing blast furnace slag to 500 mesh or less, and the mass ratio of the obtained residue to the mixture after crushing is less than 5%.

5. The method for preparing the low-density ceramsite proppant according to claim 1, characterized in that... : the roundness of the granules after granulation in step S3 is 0.9-1.0, the sphericity is 0.9-1.0, and the particle size is 70-140 mesh.

6. The method of claim 1, wherein the low density ceramic proppant is prepared by the steps of : the sintering temperature in step S3 is 1100-1200℃, and the sintering time is 0.5-2h.

7. The method for preparing the low-density ceramsite proppant according to claim 1, characterized in that... : in step S3, it further includes the step of screening the green balls obtained after granulation according to the particle size, when the particle size of the green balls is greater than the preset range, the green balls are returned to granulation until the particle size reaches the preset range, and when the particle size of the green balls is less than the preset range, the green balls are returned to crushing; the preset range of the particle size of the green balls is 70-140 mesh.

8. A low density ceramic proppant produced by the method of any one of claims 1-7, characterized by : the particle size of the low density ceramsite proppant is 70-140 mesh, the breakage rate under closed pressure of 69MPa is ≤6.5%, the acid solubility is less than 7%, and the roundness and sphericity are greater than 0.8.

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