# Patent

## Title
Petroleum fracturing proppant prepared from flyash and waste ceramic, and preparation method thereof

## Abstract

Provided is a petroleum fracturing proppant prepared from flyash and waste ceramics, the petroleum fracturing proppant being prepared from the following components: 40 wt. %-90 wt. % of main material, the main material being flyash and waste ceramics; 1 wt. %-40 wt. % of auxiliary material, the auxiliary material being potassium feldspar powder and manganese ore powder; and the sum of the main material and the auxiliary material is 100%. The present invention employs low-cost flyash and waste ceramics as raw material, and the petroleum fracturing proppant prepared under a low temperature has low apparent density and strong crushing resistance, and is also low cost and reduces energy consumption.

## Background
The present application claims priority of the patent application (No. 201310148377.7) entitled “petroleum fracturing proppant produced from flyash and waste ceramics and a method for preparing the same” filed with SIPO on Apr. 25, 2013, which is entirely incorporated into the present application by reference.
FIELD OF THE INVENTION
The present invention belongs to the technical field of petroleum fracturing proppant, and particularly relates to a petroleum fracturing proppant produced from flyash and waste ceramics and a method for preparing the same.
BACKGROUND OF THE INVENTION
Fracturing process is widely used in oil and gas production for increasing production of oil well, prolonging high-production life of oil well, and exploiting undeveloped resources. In order to prevent underground fracturing fracture from closure, to retain oil and gas passages and to maintain fracture conductivity capacity, it is necessary to fill the fractures with a proppant. Due to the difference in depth of oil reservoir and in oil viscosity, the requirements for properties of proppants, such as strength, apparent density and particle size, are different. The fracturing proppants are divided into high-density and high-strength proppants, medium-density and high-strength proppants and low-density and high-strength proppants according to bulk density thereof. In recent years, requirements for proppants with a super-low density have appeared. At present, the fracturing proppants on market commonly have a particle size of 16-30 mesh (1180-600 μm), 20-40 mesh (850-425 μm), 30-50 mesh (600-300 μm), 40-60 mesh (425-250 μm), 40-70 mesh (425-212 μm), etc. However, no matter what kind and what specification a petroleum fracturing proppant is, it should have a relatively low apparent density on the premise of having a sufficient crushing resistance, so as to decrease the fracturing cost, guarantee fracture filling saturation and increase production of oil well.
Currently, petroleum fracturing proppants are generally produced with bauxite as main raw material, and one or more metal oxides, such as manganese oxide, calcium oxide, iron oxide, magnesium oxide and zircon, as a mineralizer. Chinese patent No. 02112746.8 discloses a fracturing proppant prepared from, as main raw materials, 45%-55% by weight of sintered bauxite, 10%-30% by weight of kaolin, and 20%-35% weight of red mud produced in Yixing. The above raw materials are pulverized, mixed, pelletized, and sintered to give the fracturing proppant. Chinese patent No. 93111983.9 discloses a fracturing proppant prepared by sintering and pulverizing 70%-90% of sintered bauxite as a main raw material, adding an auxiliary material composed of a multi-component oxide and soft clay for co-milling, adding water or an organic solvent for grinding, then debonding, palletizing, sieving, sintering, polishing and sieving again. Chinese patent No. 02157202.X discloses a fracturing proppant prepared by sintering 90%-94% of high-grade born bauxite and 6%-10% of manganese oxide ore powders at a high temperature of 1330° C.-1350° C. Chinese patent No. 02157202.X discloses a formula widely used in proppant production industry at present, but the fracturing proppant provided by the patent is prepared from high-quality resources such as special-grade or first-grade bauxite and MnO2 or manganese ore with a content of more than 50% at a relatively high temperature. Thus, high energy consumption and high resource consumption in the preparation process limit further development of fracturing proppants.
SUMMARY OF THE INVENTION
In view of this, the technical problem to be solved by the present invention is to provide a petroleum fracturing proppant produced from flyash and waste ceramics and a method for preparing the same. In the present invention, low-cost flyash and waste ceramics are used as raw materials, and a petroleum fracturing proppant is prepared at a low temperature, which exhibits a low apparent density and a high crushing resistance. Moreover, the present invention is low in cost and reduces energy consumption.
The present invention provides a petroleum fracturing proppant produced from flyash and waste ceramics, characterized in that it is prepared from the following components:
40%-90% by weight of a main material that is composed of flyash and waste ceramics; and
1%-40% by weight of an auxiliary material that is composed of potash feldspar powder and manganese ore powder;
wherein sum of the main material and the auxiliary material is 100%.
Preferably, the waste ceramics are a low-aluminum waste ceramics.
Preferably, a mass ratio of the flyash to the waste ceramics is (4-6):(2-3).
Preferably, a mass ratio of the potash feldspar powder to the manganese ore powder is (2-5):1.
Preferably, MnO2 in the manganese ore powder accounts for 0-5% by weight of the petroleum fracturing proppant produced from flyash and waste ceramics.
The present invention further provides a method for preparing a petroleum fracturing proppant from flyash and waste ceramics, comprising the following steps:
A) mixing flyash, waster ceramics, potash feldspar powder and manganese ore powder to perform homogenization and refining treatment, and then sieving it after granulation so as to obtain a mixture; and
B) sintering the mixture to obtain the petroleum fracturing proppant produced from flyash and waste ceramics.
Preferably, the waste ceramics are a low-aluminum waste ceramics.
Preferably, the mixture has a particle size of 3350-106 μm.
Preferably, the step A) is particularly: mixing the flyash, the waster ceramics, the potash feldspar powder and the manganese ore powder, placing into a forced mixer to perform homogenization and refining treatment, and then sieving it after granulation so as to obtain a mixture.
Preferably, the sintering is performed for 4-8 h.
Compared to the prior art, by the present invention, a petroleum fracturing proppant produced from flyash and waste ceramics is prepared by using flyash, waste ceramics, potash feldspar powder and manganese ore powder as the raw materials. The present invention takes low-cost flyash and waste ceramics as the raw materials. During the preparation, flyash and Al2O3 in waste ceramics generate mullite, surplus SiO2 in the raw materials converts to low-apparent-density minerals such as tridymite, thereby reducing the apparent density of products. By using a composite mineralizer formed by K2O in the potash feldspar powder and MnO2 in the manganese ore powder, a liquid phase making up 30%-40% of the total volume of the raw materials is formed in the raw materials mixed at a high temperature. The formed liquid phase has a large surface tension and good wettability, which renders the materials denser and therefore enhances strength of the petroleum fracturing proppant. In addition, the liquid phase shows a high dissolving capacity to Al2O3 and SiO2 in the raw materials at 1100° C. When Al2O3 and SiO2 in the raw materials are dissolved to reach a certain concentration, they react with each other to form needle-like mullite which crystallizes out subsequently, and then dissolves and crystallizes continuously, so that mullitization changes from a solid-phase reaction to a liquid-phase reaction, thereby reaction speed is increased greatly and the temperature required by the reaction is lowered. While the mullite is liquefied, surplus SiO2 converts to double-end spear-shaped tridymite crystals due to the function of the mineralizer, thereby endowing the product with a high strength.
The result shows the petroleum fracturing proppant produced from flyash and waster ceramics that is provided according to the present invention has a bulk density of 1.50 g/cm3 or lower, an apparent density of 2.60 g/cm3 or lower, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
MODE OF CARRYING OUT THE INVENTION
The present invention provides a petroleum fracturing proppant produced from flyash and waste ceramics, characterized in that it is prepared from the following components:
80%-90% by weight of a main material that is composed of flyash and waste ceramics; and
10%-20% by weight of an auxiliary material that is composed of potash feldspar powder and manganese ore powder;
wherein sum of the main material and the auxiliary material is 100%.
The present invention uses flyash and waste ceramics as the main material of petroleum fracturing proppant. The type of the waste ceramics used in the present invention is not particularly restricted, and they are preferably low-aluminum waste ceramics. Low-aluminum waste ceramics and flyash are wasted in a large amount in industry, and are low in cost. Thus, reasonable utilization of low-aluminum waste ceramics and flyash has the significance of energy saving, environment protection, and resource saving. The flyash and waste ceramics make up preferably 40%-90%, more preferably, 50%-80%, and most preferably, 60%-70% by weight of the total amount of the raw materials. In addition, a mass ratio of the flyash to the waste ceramics is preferably (4-6):(2-3), and more preferably, (4.5-5.5):(2.2-2.8).
The present invention uses potash feldspar powder and manganese ore powder as an auxiliary material of the petroleum fracturing proppant, wherein the potash feldspar powder and manganese ore powder form a composite mineralizer with the potash feldspar powder serving as a primary mineralizer, and K2O in the potash feldspar powder plays the role of mineralization; the manganese ore powder serves as an auxiliary mineralizer and a colorant, and MnO2 in the manganese ore powder accounts for 0-5%, more preferably, 1%-4%, and most preferably, 2%-3% by weight of the petroleum fracturing proppant produced from flyash and waste ceramics. The manganese ore powder and potash feldspar powder are added in an amount of preferably 1%-40%, more preferably, 10%-30%, and most preferably, 15%-25% by weight of the total amount of the raw materials. In addition, a mass ratio of the potash feldspar powder to the manganese ore powder is preferably (2-5):1, more preferably, (2.5-4.5):1, and most preferably, (3-4):1.
By using a composite mineralizer formed of K2O in the potash feldspar powder and MnO2 in the manganese ore powder, a liquid phase making up 30%-40% of the total volume of the raw materials is formed in the raw materials mixed at high temperature in the present invention. The liquid phase formed has a large surface tension and good wettability, which renders the materials denser, and therefore enhances strength of the petroleum fracturing proppant.
The petroleum fracturing proppant provided in the present invention has a bulk density of 1.50 g/cm3 or lower, and an apparent density of 2.60 g/cm3 or lower. Preferably, the bulk density is 1.40 g/cm3 or lower, and the apparent density is 2.40 g/cm3 or lower.
The present invention further provides a method for preparing petroleum fracturing proppant produced from flyash and waste ceramics, comprising the following steps:
A) mixing flyash, waster ceramics, potash feldspar powder and manganese ore powder to perform homogenization and refining treatment, and then sieving it after granulation so as to obtain a mixture; and
B) sintering the mixture to obtain the petroleum fracturing proppant produced from flyash and waste ceramics.
In the present invention, flyash, waster ceramics, potash feldspar powder and manganese ore powder are firstly mixed to perform homogenization and refining treatment. The manner of homogenization and refining is not particularly restricted. The particular method comprises: placing flyash, waster ceramics, potash feldspar powder and manganese ore powder in a forced mixer to perform homogenization and refining treatment. In the present invention, the raw materials are homogenized and refined, which renders particle size of the raw materials to be distributed more uniformly and the chemical reaction to proceed more smoothly and thoroughly, so as to endow the obtained petroleum fracturing proppant with smaller crystal grains and enhanced strength.
Flyash and waste ceramics make up preferably 40%-90%, more preferably, 50%-80%, and most preferably 60%-70% by weight of the total amount of the raw materials. A mass ratio of the flyash to the waste ceramics is preferably (4-6):(2-3), and more preferably, (4.5-5.5):(2.2-2.8). The MnO2 in the manganese ore powder accounts for 0-5% by weight of the petroleum fracturing proppant produced from flyash and waste ceramics. The manganese ore powder and potash feldspar powder are added in an amount of preferably 1%-40%, more preferably, 10%-30%, and most preferably, 15%-25% by weight of the total amount of the raw materials. A mass ratio of the potash feldspar powder to the manganese ore powder is preferably (2-5):1, more preferably, (2.5-4.5):1, and most preferably, (3-4):1.
After flyash, waster ceramics, potash feldspar powder and manganese ore powder are placed in a forced mixer to perform homogenization and refining treatment, they are granulated and then sieved to give a mixture. The manners of granulation in the present invention are not particularly restricted, as long as they are known to those skilled in the art. In addition, there is no particular restriction to the manners of sieving in the present invention, as long as they are known to those skilled in the art. The mixture obtained after sieving has different specifications in particle size, preferably ranging from 3350 to 106 μm, more preferably, from 850 to 425 μm, from 600 to 300 μm, from 425 to 250 μm, from 425 to 212 μm, or from 212 to 106 μm. The waste ceramics used in the present invention are preferably low-aluminum waste ceramics.
In the present invention, the petroleum fracturing proppant produced from flyash and waste ceramics can be obtained by sintering the mixture. There is not particular restriction to the site for sintering in the present invention, and it is preferable to perform sintering in a rotary kiln. The temperature for sintering differs according to the specification of the rotary kiln and the raw materials used, but is preferably between 1100 and 1200° C., and more preferably, between 1110 and 1150° C. The time for sintering is preferably from 4 to 8 h, and more preferably, from 5 to 7 h.
After sintering is complete, the petroleum fracturing proppant produced from flyash and waste ceramics are obtained. The petroleum fracturing proppant produced from flyash and waste ceramics comprises, based on weight percentage, chemical components: Al2O3 40%-48%, SiO2 38%-45%, and K2O 2%-4%.
By the present invention, a petroleum fracturing proppant prepared from flyash and waste ceramics is prepared by using flyash, waste ceramics, potash feldspar powder and manganese ore powder as the raw materials. The present invention takes low-cost flyash and waste ceramics as the raw materials. During the preparation, flyash and Al2O3 in waste ceramics generate mullite, surplus SiO2 in the raw materials converts to low-apparent-density minerals such as tridymite, thereby reducing the apparent density of products. By using a composite mineralizer formed by K2O in the potash feldspar powder and MnO2 in the manganese ore powder, a liquid phase making up 30%-40% of the total volume of the raw materials is formed in the raw materials mixed at a high temperature. The formed liquid phase has a large surface tension and good wettability, which renders the materials denser and therefore enhances strength of the petroleum fracturing proppant. In addition, the liquid phase shows a high dissolving capacity to Al2O3 and SiO2 in the raw materials at 1100° C. When Al2O3 and SiO2 in the raw materials are dissolved to reach a certain concentration, they react with each other to form needle-like mullite which crystallizes out subsequently, and then dissolves and crystallizes continuously, so that mullitization changes from a solid-phase reaction to a liquid-phase reaction, thereby reaction speed is increased greatly and the temperature required by the reaction is lowered. While the mullite is liquefied, surplus SiO2 converts to double-end spear-shaped tridymite crystals due to the function of the mineralizer, thereby endowing the product with a high strength.
The result shows the petroleum fracturing proppant produced from flyash and waster ceramics that is provided in the present invention has a bulk density of 1.50 g/cm3 or lower, an apparent density of 2.60 g/cm3 or lower, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
For further understanding of the present invention, the petroleum fracturing proppant produced from flyash and waste ceramics that is provided in the present invention and its preparation method are explained in combination with the following examples, but the protection scope of the present invention is not limited by the following examples.


EXAMPLE 1
60 Kg of dedusted waste ash from HEBIWANHE power plant, 20 Kg of low-aluminum waste ceramics from XINZHONGYUAN ceramic plant in ceramic industrial zone in HEBI city, 15 Kg of potash feldspar powder and 5 Kg of manganese ore powder were mixed to perform homogenization and refining treatment in a forced mixer, subsequently granulated and sieved to obtain a mixture with a particle size ranging from 900 to 600 μm. The mixture was sintered at a temperature between 1100° C. and 1150° C. under atmospheric pressure in a 2.5 m×45 m rotary kiln for 4 h, then cooled and sieved to obtain 20-40 mesh (850-425 μm) petroleum fracturing proppant produced from flyash and waste ceramics.
The petroleum fracturing proppant produced from flyash and waste ceramics was determined to have a bulk density of 1.42 g/cm3, an apparent density of 2.47 g/cm3, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
EXAMPLE 2
50 Kg of dedusted waste ash from HEBIWANHE power plant, 30 Kg of low-aluminum waste ceramics from JINJISHAN ceramic plant in ceramic industrial zone in HEBI city, 15 Kg of potash feldspar powder and 5 Kg of manganese ore powder were mixed to perform homogenization and refining treatment in a forced mixer, subsequently granulated and sieved to obtain a mixture with a particle size ranging from 900 to 600 μm. The mixture was sintered at a temperature between 1100° C. and 1150° C. under atmospheric pressure in a 2.5 m×45 m rotary kiln for 4 h, then cooled and sieved to obtain 20-40 mesh (850-425 μm) petroleum fracturing proppant produced from flyash and waste ceramics.
The petroleum fracturing proppant produced from flyash and waste ceramics was determined to have a bulk density of 1.45 g/cm3, an apparent density of 2.50 g/cm3, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
EXAMPLE 3
60 Kg of dedusted waste ash from HEBIWANHE power plant, 20 Kg of low-aluminum waste ceramics from XINZHONGYUAN ceramic plant in ceramic industrial zone in HEBI city, 15 Kg of potash feldspar powder and 5 Kg of manganese ore powder were mixed to perform homogenization and refining treatment in a forced mixer, subsequently granulated and sieved to obtain a mixture with a particle size ranging from 710 to 425 μm. The mixture was sintered at a temperature between 1100° C. and 1150° C. under atmospheric pressure in a 2.5 m×45 m rotary kiln for 4 h, then cooled and sieved to obtain 30-50 mesh (600-300 μm) petroleum fracturing proppant produced from flyash and waste ceramics.
The petroleum fracturing proppant produced from flyash and waste ceramics was determined to have a bulk density of 1.45 g/cm3, an apparent density of 2.52 g/cm3, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
EXAMPLE 4
50 Kg of dedusted waste ash from HEBIWANHE power plant, 30 Kg of low-aluminum waste ceramics from JINJISHAN ceramic plant in ceramic industrial zone in HEBI city, 15 Kg of potash feldspar powder and 5 Kg of manganese ore powder were mixed to perform homogenization and refining treatment in a forced mixer, subsequently granulated and sieved to obtain a mixture with a particle size ranging from 710 to 425 μm. The mixture was sintered at a temperature between 1100° C. and 1150° C. under atmospheric pressure in a 2.5 m×45 m rotary kiln for 4 h, then cooled and sieved to obtain 30-50 mesh (600-300 μm) petroleum fracturing proppant produced from flyash and waste ceramics.
The petroleum fracturing proppant produced from flyash and waste ceramics was determined to have a bulk density of 1.48 g/cm3, an apparent density of 2.53 g/cm3, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
EXAMPLE 5
60 Kg of dedusted waste ash from HEBIWANHE power plant, 20 Kg of low-aluminum waste ceramics from XINZHONGYUAN ceramic plant in ceramic industrial zone in HEBI city, 15 Kg of potash feldspar powder and 5 Kg of manganese ore powder were mixed to perform homogenization and refining treatment in a forced mixer, subsequently granulated and sieved to obtain a mixture with a particle size ranging from 500 to 425 The mixture was sintered at a temperature between 1100° C. and 1150° C. under atmospheric pressure in a 2.5 m×45 m rotary kiln for 4 h, then cooled and sieved to obtain 40-60 mesh (425-250 μm) petroleum fracturing proppant produced from flyash and waste ceramics.
The petroleum fracturing proppant produced from flyash and waste ceramics was determined to have a bulk density of 1.47 g/cm3, an apparent density of 2.53 g/cm3, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
EXAMPLE 6
50 Kg of dedusted waste ash from HEBIWANHE power plant, 30 Kg of low-aluminum waste ceramics from JINJISHAN ceramic plant in ceramic industrial zone in HEBI city, 15 Kg of potash feldspar powder and 5 Kg of manganese ore powder were mixed to perform homogenization and refining treatment in a forced mixer, subsequently granulated and sieved to obtain a mixture with a particle size ranging from 500 to 425 μm. The mixture was sintered at a temperature between 1100° C. and 1150° C. under atmospheric pressure in a 2.5 m×45 m rotary kiln for 4 h, then cooled and sieved to obtain 40-60 mesh (425-250 μm) petroleum fracturing proppant produced from flyash and waste ceramics.
The petroleum fracturing proppant produced from flyash and waste ceramics was determined to have a bulk density of 1.49 g/cm3, an apparent density of 2.55 g/cm3, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
EXAMPLE 7
60 Kg of dedusted waste ash from HEBIWANHE power plant, 20 Kg of low-aluminum waste ceramics from XINZHONGYUAN ceramic plant in ceramic industrial zone in HEBI city, 15 Kg of potash feldspar powder and 5 Kg of manganese ore powder were mixed to perform homogenization and refining treatment in a forced mixer, subsequently granulated and sieved to obtain a mixture with a particle size ranging from 500 to 355 μm. The mixture was sintered at a temperature between 1100° C. and 1150° C. under atmospheric pressure in a 2.5 m×45 m rotary kiln for 4 h, then cooled and sieved to obtain 40-70 mesh (425-212 μm) petroleum fracturing proppant produced from flyash and waste ceramics.
The petroleum fracturing proppant produced from flyash and waste ceramics was determined to have a bulk density of 1.49 g/cm3, an apparent density of 2.56 g/cm3, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
EXAMPLE 8
50 Kg of dedusted waste ash from HEBIWANHE power plant, 30 Kg of low-aluminum waste ceramics from JINJISHAN ceramic plant in ceramic industrial zone in HEBI city, 15 Kg of potash feldspar powder and 5 Kg of manganese ore powder were mixed to perform homogenization and refining treatment in a forced mixer, subsequently granulated and sieved to obtain a mixture with a particle size ranging from 500 to 355 μm. The mixture was sintered at a temperature between 1100° C. and 1150° C. under atmospheric pressure in a 2.5 m×45 m rotary kiln for 4 h, then cooled and sieved to obtain 40-70 mesh (425-212 μm) petroleum fracturing proppant produced from flyash and waste ceramics.
The petroleum fracturing proppant produced from flyash and waste ceramics was determined to have a bulk density of 1.49 g/cm3, an apparent density of 2.56 g/cm3, and a crush rate of 8% or lower under a closure pressure of 86 MPa.
The above is merely preferable embodiments of the present invention. It should be noted that a number of improvements and modifications may be made by those skilled in the art without deviation from the principle of the present invention, and these improvements and modifications should be regarded as falling within the protection scope covered by the present invention.

## Claims

1. A petroleum fracturing proppant produced from flyash and waste ceramics, characterized in that it is prepared from the following components:
40%-90% by weight of a main material that is composed of flyash and waste ceramics;
1%-40% by weight of an auxiliary material that is composed of potash feldspar powder and manganese ore powder;
wherein sum of the main material and the auxiliary material is 100%.

2. The petroleum fracturing proppant according to claim 1, characterized in that a mass ratio of the flyash to the waste ceramics is (4-6):(2-3).

3. The petroleum fracturing proppant according to claim 1, characterized in that a mass ratio of the potash feldspar powder to the manganese ore powder is (2-5):1.

4. The petroleum fracturing proppant according to claim 1, characterized in that MnO2 in the manganese ore powder accounts for 0-5% by weight of the petroleum fracturing proppant produced from flyash and waste ceramics.

5. A method for preparing a petroleum fracturing proppant produced from flyash and waste ceramics, comprising the following steps:
A) mixing flyash, waste ceramics, potash feldspar powder and manganese ore powder to perform homogenization and refining treatment, and then sieving it after granulation so as to obtain a mixture; and
B) sintering the mixture to obtain the petroleum fracturing proppant produced from flyash and waste ceramics.

6. The preparation method according to claim 5, characterized in that the mixture has a particle size ranging from 3350 to 106 μm.

7. The preparation method according to claim 5, characterized in that the step A) is particularly: mixing the flyash, the waste ceramics, the potash feldspar powder and the manganese ore powder, placing into a forced mixer to perform homogenization and refining treatment, and then sieving it after granulation so as to obtain a mixture.

8. The preparation method according to claim 5, characterized in that the sintering is performed for 4-8 h.