Proppant having a glass-ceramic material

Proppant with glass-ceramic material

[0001] According to 35 U.SC § 119(e), this application claims the priority of the prior U.S. Provisional Patent Application No. 61/289,014 filed on December 22, 2009, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a proppant, a preparation method of the proppant and the use of the proppant. In the present invention, a glass-ceramic material is present in the proppant or a part thereof. The presence of the glass-ceramic material can provide one or more benefits, such as increased stiffness (or rigid modulus "MOR"), a desirable coefficient of thermal expansion, and/or other benefits.

[0003] Proppants are materials that are pumped into oil or gas wells at extreme pressures in a carrier solution (typically brine) during a hydrofracturing process. Once the pressure caused by pumping is removed, the proppant "supports" the fractures in the rock formation, thereby preventing the fractures from closing_oAs a result, the amount of formation surface area exposed to the well bore is increased, and the production rate is increased.

[0004] Ceramic proppants are widely used as supporting agents for maintaining gas permeability in oil and natural gas formations. High-strength ceramic proppants have been used in hydraulic fracturing of underground formations (earth) to improve the production of natural gas and/or petroleum. For wells drilled into the formation 10,000 feet or deeper, the proppant beads need to withstand a pressure of 10 kpsi or higher to effectively support the fractures produced by the hydraulic fracturing process. Currently, only proppants formed from high-strength materials (such as sintered bauxite and rock soil) have sufficient compressive and flexural strength for use in deep wells. However, these conventional high-strength materials are expensive due to the limited supply of raw materials, high requirements for purity, and the complexity of the manufacturing process. In addition, such high-strength materials have a high specific gravity exceeding 3.0, which is very undesirable for proppant applications. It is also a challenge to produce high-strength proppants with low specific gravity. In field applications, the difference in the specific gravity of the proppant and the carrier fluid hinders the transport capacity of the proppant in the well. Although light oxide materials (such as cordierite) have a low specific gravity, they have relatively weak flexural strength and stiffness.

Summary of the invention

[0005] The feature of the present invention is to provide a proppant having an improved coefficient of thermal expansion. Another feature of the present invention is to provide proppants capable of providing improved stiffness (rigid modulus).

[0006] Another feature of the present invention is to provide a proppant with better fracture resistance.

[0007] A further feature of the present invention is to provide a proppant that can have fewer discrete interfaces between the various layers that can form the proppant.

[0008] Additional features and advantages of the present invention will be partially explained in the following, and will be partially clear, or can be learned through the practice of the present invention. The purpose and other advantages of the present invention will be realized and achieved through the elements and combinations particularly pointed out in the appended claims.

[0009] In order to achieve these and other advantages, and in accordance with the purpose of the present invention, as embodied and generally described herein, the present invention relates to proppants with template spheres. The proppant optionally has a shell that can be sintered around the entire outer surface of the template ball. The optional shell may comprise glass-ceramic. The optional shell may include one or more layers, and may contain one or more metal oxides, ceramic materials or oxides thereof, and/or other suitable materials. The outer surface of the template ball may include or have a glass-ceramic material. In addition to the outer surface of the template ball with glass-ceramic material, or instead of the outer surface of the template ball with glass-ceramic material, a glass-ceramic-containing layer may exist outside the template ball

On the surface. The present invention further relates to a method of using one or more proppants of the present invention to prop up a subterranean stratum fracture (fraction), and the proppant may be included in a proppant formulation.

[0010] The present invention further relates to methods of preparing various proppants according to the present invention. For example, one method includes crystallizing at least the outer surface of the template material to form a glass-ceramic, and coating the ceramic material with an article containing a ceramic material or its oxide and/or one or more metal oxides and/or other materials. The template material is used to form a shell surrounding the template, and then the shell is hardened by, for example, sintering or calcining. Other methods are described further.

[0011] It should be understood that the foregoing general description and the following detailed description are only exemplary and illustrative, and are intended to provide further explanation of the claimed invention.

Description of the drawings

[0012] FIG. 1 is a graph showing the density of the glass-ceramic obtained from cenosphere powder according to the present invention as a function of Ti() 2 content. All samples were sintered at 1200C for 4h.

[0013] FIG. 2 shows the radial splitting tensile strength of the glass-ceramic obtained from hollow microspheres of the present invention as a function of Ti0₂Graph of content changes. All samples are sintered at 1200C for 4ho

[0014] FIG. 3 shows the ratio of the radial splitting tensile strength of the glass-ceramic obtained from hollow microspheres of the present invention as a function of Ti0₂Graph of content changes.

[0015] Figure 4 is a graph showing that 25% hollow microbeads (d5o=6um) and 75% cordierite in the absence of TiO2 (left) and with

Two SEMs of the fracture surface of the composite prepared with 7% Ti() 2 (right). The samples were sintered at 1260c for 6h.

Detailed ways

[0016] The present invention relates to a proppant, a method for preparing the proppant, and the use of the proppant, including using the proppant to assist bright mining.

[001 7] The present invention relates to the proppant in which the glass-ceramic or glass-ceramic material is present as a part of the proppant. When the proppant includes one or more components, one or more of the components may contain glass-ceramic. For example, the proppant may be a template sphere or core, and at least the outer surface of the template sphere or core may be or may include one or more glass-ceramics, or may be substantially composed of or composed of one or more glass -Ceramic composition.

[0018] Alternatively, the proppant may be the template ball having one or more layers on the template ball. At least one of these layers may comprise one or more glass-ceramics, or may consist essentially of or consist of one or more glass-ceramics. For example, the proppant may be a template sphere having a glass-ceramic-containing layer (which may optionally contain glass-ceramic), and the glass-ceramic-containing layer is in contact with at least the outer surface of the template sphere (direct contact or Contact with the layer located on the template ball). Alternatively, the proppant may be a template ball having an outer surface, wherein the outer surface of the template ball comprises glass-ceramic, and the proppant further has contact (direct contact or with the outer surface of the template ball). The layer located on the template ball contacts at least one layer), wherein the layer comprises glass-ceramic. The glass-ceramic-containing layer may at least partially diffuse into the outer surface of the template sphere.

[0019] The template ball (which may also be referred to as a core or a substrate) may be a solid ball or a hollow ball, or a ball with one or more voids, or a ball with porosity. It should be understood that the solid sphere used herein does not contain void space in the center, although porous materials will be suitable. A completely dense material is not a requirement for a solid ball. It should be understood that the hollow sphere used herein has at least one void space with a defined size and shape inside. The template sphere may have a void volume% of at least 30%. The template ball can be made of glass or a substantially glass-like material. For template balls, excellent

Choose to use hollow microspheres or similar hollow spheres like glass. The hollow microspheres can be commercially produced ceramic or glass hollow spheres, which are prepared as by-products in various industrial processes. For the purpose of the present invention, although the term "ball" is used, it should be understood that the "ball" may have an irregular shape (for example, non-spherical), and therefore, it may be a uniformly round spherical object, or it may be The sphericity and/or roundness are not so perfect, or may have other shapes. Alternatively, the template ball may have a Krumbein sphericity of at least about 0.3, for example a Krumbein sphericity of at least 0.4, at least 0.5, at least 0.6, or at least 0.7 , Such as from 0.3 to 0.9 or higher Crumbin sphericity. Alternatively, the template ball may alternatively or additionally have a roundness of at least about 0.1, for example a roundness of at least about 0.3, at least 0.4, at least 0.5, at least 0.7, such as a roundness from 0.1 to 0.9 or higher. degree. The entire proppant may be a single template ball, or may be a template ball with one or more layers on the template, and the proppant may have the same Crumbin sphericity and/or circle mentioned for the template. Degree value. The entire proppant may have a Crumbin sphericity of at least about 0.5 (e.g., at least 0.6, at least 0.7, at least 0.8, at least 0.9, such as from 0.5 to 0.9 or higher) and / Or the proppant may have at least about 0.4 (e.g. at least 0. 5. A roundness of at least 0.7, at least 0.8, for example from 0.4 to 0.9 or higher).

[0020] As mentioned, as an option, the proppant may have one or more layers on the template sphere. At least one of these layers may form a shell surrounding the entire outer surface of the template ball. The shell may be a continuous shell or a discontinuous shell. The shell may have a thickness from about 5 microns to 150 microns or more. The shell can be sintered. The shell may include ceramic. The shell may include glass-ceramic.

[0021] For the glass-ceramics present in the proppant, as described, the glass-ceramics may be present in one or more components (or parts) of the proppant. The glass-ceramic may be present on at least the outer surface of the template ball. For this option, the glass-ceramic may be present on the entire circumference or part of the outer surface of the template ball. The outer surface may include an exposed outermost surface. The presence of glass-ceramics may include the part below the exposed surface, such as the internal volume of the template ball or 0.1%-100% of the area, such as 1%-90%. 5%-80%, 10%-70 %, 15% - 60%, 20% - 50%, etc. Other materials can exist with glass-ceramics. The glass-ceramic may be uniformly or unevenly distributed in the outer surface and/or inner volume of the template ball. The glass-ceramic of the template ball may be in solid form. The glass-ceramic of the template ball can be porous or hollow.

[0022] The glass-ceramic may be uniformly present on the entire shell, or unevenly distributed in one or more parts of the shell. The glass-ceramic of the shell may be in solid form. The glass-ceramic of the shell can be porous or hollow.

[0023] The glass-ceramic of the shell may be the same as or different from the glass-ceramic of the template ball. For example, the glass-ceramic of the shell and the glass-ceramic of the template ball may have the same or different degrees of crystallinity, and/or the same or different compositions.

[0024] In the present invention, the glass-ceramic may account for about 0.5% by weight to about 100% by weight of the entire proppant, based on the total weight of the proppant. For example, the glass-ceramic may be present in an amount of about 5wt% to about 90wt% or higher, about 10wt% to about 75wt%, about 15wt% to about 50wt%, about 20wt% to about 30wt% or higher, all based on The total weight of the proppant.

[0025] As used herein, "glass-ceramic" refers to when glass or a substantially glass-like material is annealed at an elevated temperature to produce a substantially crystalline material with limited crystallinity or controlled crystallite size Any glass-ceramic formed at the time. As used herein, limited crystallinity should be understood as about 5% to about 100% by volume (for example, 10%-90%; 20%-80%; 30%-70%; 40%-60% by volume) crystallization degree. The crystallite size may be about 0.01 to 20 microns, for example, 0.1 to 5 microns. Preferably, the crystallite size is less than 1 micron. The glass-ceramic may be composed of aluminum oxide, silicon oxide, boron oxide, potassium oxide, zirconium oxide, magnesium oxide, calcium oxide, lithium oxide, phosphorous oxide, and/or titanium oxide, or any combination thereof.

[0026] The glass-ceramic may contain about 35% to about 55% by weight SiO.₂ ; About 18%-about 28% by weight Α1₂0₃ ;approximately

1%-about 15% by weight (for example, 1-5wt%) Ca0; about 7%-about 14% by weight MgO; about 0.5%-about 15% by weight Ti() 2 (for example, 0.5-5wt%); About 0.4%-about 3% by weight B₂0₃, And/or greater than 0% by weight and up to about 1% by weight P2O5, all based on the total weight of the glass-ceramic. The glass-ceramic may contain about 3% to about 5% by weight Li₂0 ; About 0% about 15% by weight Α1₂0₃ ; About 10%-about 45% by weight Si0₂ ; About 20%-about 50% by weight MgO; about 0.5%-about 5% by weight Ti0₂ ; About 15%-about 30% by weight of B2O3, and/or about 6%-about 20% by weight of ZnO, all based on the total weight of the glass-ceramic.

[0027] The template sphere may include aluminum oxide, silicon oxide, titanium oxide, iron oxide, magnesium oxide, calcium oxide, potassium oxide, and/or sodium oxide, and/or a mixture of any combination thereof.

[0028] The glass-ceramic may be completely or nearly completely crystalline, or may contain a glass component (for example, a phase) and a crystalline component (for example, a phase) containing crystallites. The glass-ceramic may have a degree of crystallinity of about 5% to about 100%, or about 15% to about 80%. For example, the glass-ceramic may have about 50%-80% crystallinity, about 60%-78% crystallinity, or about 70%-75% crystallinity, by volume. The crystallites may have random and/or directional orientation. Regarding the orientation of the crystals present in the glass-ceramic, the crystal orientation of the crystals in the glass-ceramic may be mainly random or may be mainly oriented in a specific orientation (for example, non-random). For example, the crystal orientation of the glass-ceramic may be predominantly random, for example based on the total orientation of the crystals present, at least 50% or more of the orientation being random. For example, for the percentage of random crystals based on the measured crystals, the random orientation may be at least 60%, at least 70%, at least 80%, at least 90%, For example, about 51%-99%, 60%-90%, 70%-95% or higher. X-ray diffraction ("XRD") can be used to determine the randomness of crystallites. Since glass-ceramics can have both crystalline and glass components, glass-ceramics can have some of the same properties as glass and/or crystalline ceramics. Therefore, glass-ceramic can provide an ideal gradient interface between the template ball and the ceramic shell (if present). Glass-ceramics are not affected by thermal shock. Moreover, the ratio of the glass to the resultant component of the glass-ceramic can be adjusted to match the coefficient of thermal expansion (CTE) of the shell or other materials with which it will be bonded or attached or contacted (for example, within 10%, within 5%, Within 1%, within 0.5%, within 0.1%) to prevent premature fracture caused by cyclic stress or thermal fatigue caused by temperature changes. For example, when the glass-ceramic has 70%-78% crystallinity, the two coefficients are balanced, so that the glass-ceramic as a whole has a thermal expansion coefficient mismatch that is very close to zero._o[0029] The present invention can provide proppants with improved stiffness and/or lower density. Unlike some proppants, which are composites with sharp interfaces (for example, layer interfaces) or composites with distinct linear interfaces between two dissimilar components, the proppants of the present invention can be either monolithic or monolithic. The structure, either has a gradient interface between the components of the complex, or a complex with a gradient in the properties of the complex. Therefore, the proppant of the present invention has little or no stress, and the stress is related to the proppant having a distinct linear interface between dissimilar materials. The stress or internal locked stress of the proppant can be measured by any suitable technique known in the art. For example, the stress of proppant can be determined by X-ray diffraction peak curve analysis. As known in the art, using X-ray diffraction, the broadening of the diffraction peak can indicate the stress in the material. The measurement technique of diffraction peak broadening is known in the art. Therefore, the proppant of the present invention is less susceptible to fracture than the conventional proppant.

[0030] The proppant may be a multi-phase system or a single-phase system. In a multiphase system (such as a two-phase system), the proppant may include a template sphere or core and a second phase that may be different or dissimilar to the template sphere or core. The second phase of the two-phase system can be applied to or encapsulate the supporting or templated first phase or serve as its shell, and/or infiltrate (e.g., partially to an optionally varying degree or gradient or completely Ground) said supporting or templated first phase, and/or reacting with said supporting or templated first phase. The template ball may at least partially include glass or a glass-containing ceramic material. The second phase can be a ceramic or glass-ceramic shell. The inventors have found that in order to achieve an improved

If the proppant is capable, the sharp interface between the shell of the proppant and the template ball should be avoided. For example, the sharp interface between the glass template ball and the ceramic shell can be avoided by crystallizing at least the outer surface of the template ball to form a glass-ceramic, providing a glass-ceramic layer and/or providing a shell between the interface (It is at least partially glass-ceramic). By providing glass-ceramic at least between the template ball and the shell, a sharp interface between two different materials can be avoided. In the proppant of the present invention, glass-ceramic can be used as a functionally graded material. In other words, glass-ceramics can tolerate a gradual transition in the ratio between the glass content and the ceramic content, and thereby tolerate a gradient in the properties of the composite. Moreover, glass-ceramics can have improved properties compared to glass. For example, by incorporating glass-ceramic in the template ball, the proppant can achieve increased stiffness, improved fracture toughness, low thermal expansion coefficient, high hardness, high Young's modulus, thermal stability, and/or high strength.

[0031] With the present invention, various proppant sizes are possible. The size (eg, particle size) can vary from 10 microns to 10,000 microns. The particle size may be 50 micrometers to 2,000 micrometers or 100 micrometers to 2000 micrometers. The size (eg, particle size) of the template ball can also vary. The template ball may, for example, have a diameter of about 20 microns to about 1000 microns, such as 100 microns to 1000 microns.

[0032] The glass-ceramic in the proppant can be a material with strong mechanical properties and can withstand temperatures up to about 800C to 1500C. Glass-ceramics can withstand a temperature change of 100C in a period of 1 minute or less (for example, 60 seconds to 1 second, 10 seconds to 50 seconds). The glass-ceramic may have a density of about 1.0 to about 3.5 g/cm) 3, such as 1.5, 2.0, 2.52, or 2.5 g/cm³Density. The glass-ceramic may have a Young's modulus of about 50 to about 80 GPa, for example, a Young's modulus of 68, 66.9 or 70 GPa. The glass-ceramic may have a shear modulus of about 20 to about 50 GPa (at 25° C.), for example, a shear modulus of 25 GPa or 25.5 GPa (at 25° C.). The glass-ceramic may have a modulus of failure (at 25° C.) of about 50 to about 150 MPa, for example, a modulus of failure of 60 MPa, 70 MPa, 80 MPa or 100 MPa (at 25° C.). The glass-ceramic may have a compressive strength of about 300 MPa to about 500 MPa, for example, a compressive strength of 360 MPa. The glass-ceramic may have a fracture cut of about 1 to about 10 MPa.n)s, such as a fracture cut of 1.52, 1.53, or 1.54 MPa. The glass-ceramic may have a thermal conductivity of 1.45 to about 1.53 W/(m·K) or higher, for example, a thermal conductivity of 1.47 W/(m·K).

[0033] The proppant may have properties similar to those described for glass-ceramics. For example, the proppant may have at least one of the following properties: from about 1.5 to about 3.0 g/cm³Density of about 50-about 80GPa; Young's modulus of about 50-about 150MPa (at 25 °C), such as 90-110MPa, or 93-97MPa MOR (at 25c); about 20-about 50GPa shear Shear modulus (at 25 °C); about 300MPa-about 500MPa compressive strength; and / or about 1-about lOMPa. m^1/2The fracture cut, for example 1. 54-about 1. 55MPa. m^1/2The fracture cut. The proppant may have a specific gravity of about 1.0 to about 4.0. For example, the proppant may have about 3 or less (e.g., 0.5-3, 0.8-2.5, 0.9-2.3, 1-2, 1.1-1.8, 1.2-1.7, 0.8-2, etc. ). The proppant may have 0.1 X io^-6/k-13x io^-6/k (for example, 0.1 Righteousness io^-6/k-12x io^-6/k,o. 3 X 1O^-7K-5 X 10^-6/K,0. 5 X ΙΟ^-6/ κ- 1.0X10^-7K,0.75X10^-7Κ- 1.5Χ10^-7Κ) the coefficient of thermal expansion (CTE, in 25C-300C). The proppant may have a thermal conductivity of about 0.01W/(ni·K)-3.0W/(ni·K) (for example, 1.45W/(m · K)-about 1.47W/(m ·Κ)) .

[0034] The proppant of the present invention may have 1,000 psi-20,000 psi or higher (for example, 1,500 psi-10,000 psi, 3,000 psi-10,000 psi, 5,000 psi-10,000 psi, 9,000 psi- 12, OOOpsi) crushing strength. Other crush strengths below or above these ranges are possible.

[0035] The template ball may have a coefficient of thermal expansion (CTE, at 25C-300 °C) of about 0.1 to 10-6 to about 13 to 10 to 6, such as 0.1 X 1θ^-7κ-2Χ 10^-6/K or 1.2Χ 10^-6/K-1.7Χ 10^-6/K coefficient of thermal expansion (CTE, in 25C- 300C). The template ball may have a specific gravity of 0.01 to about 3. The template ball may have about 1 to about

100MPa MOR, such as 10-90MPa MOR_o

[0036] The amount of glass-ceramic present in the template ball may be about 0.1%-100% by weight of the template ball. For example, the amount of glass-ceramic present in the template ball can be about 1% to about 90%, about 10% to 80%, about 20% to 70%, about 30% to 60%, about 40% of the template ball. -50%, about 5%-75%, about 50%-70%, about 65%-85%, about 15%-65% or about 90%-99% by weight, of which all percentages are based on the weight of the template ball Percent by weight. If the glass-ceramic content is less than 100% by weight of the template ball, the remaining part of the template ball can be made of glass, or a mixture of glass and crystalline ceramic materials, and/or other materials (such as metals, metal oxides, etc.). The template ball may also include a crystal initiator_oCrystal initiators may include, but are not limited to, alkali metals (or their oxides), such as lithium, sodium, potassium, flail, armor and imitation, and transition metals or oxides of transition metals, such as titanium, titanium , Steel, Ming, Special Men, Iron, Diamond, Silver, Copper, Zinc, Button, Wrong, Saw, Key, De, Nail, Ming, Rake, Silver, Cadmium, 4 Go, Car Mesh, Bustard, Baht, Hungry, Ye, meal, gold, mercury, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Cn or any combination thereof. The amount of the crystal initiator present in the template sphere may be about 0.1%-25% by weight, for example, 0.1%-7%, 0.1%-5%, or 0.1%-3% by weight.

[0037] The glass as used herein may be any inorganic, non-metallic solid amorphous material, such as a material prepared by the action of heat and subsequent cooling. The glass can be any conventional glass, such as soda-lime glass, lead glass or borosilicate glass. The crystalline ceramic material used herein can be any inorganic, non-metallic solid crystalline material prepared by the action of heat and subsequent cooling. For example, the crystalline ceramic material may include, but is not limited to, rock soil, aluminum oxide, stabilized aluminum oxide, mullite, aluminum oxide toughened rock soil, spinel, aluminosilicate ( For example, mullite, cordierite), perovskite, perchlorate, silicon carbide, silicon nitride, titanium carbide, titanium nitride, aluminum oxide, silicon oxide, zirconium oxide, stabilized zirconium oxide, carbide Aluminum, aluminum nitride, aluminum carbide, aluminum nitride, iron carbide, aluminum oxynitride, aluminum oxynitride silicon, aluminum titanate, bustard carbide, bustard nitride, talc, etc., or any combination thereof.

[0038] The template ball may have at least a glass-ceramic outer surface. For example, at least 1%-100% of the radius from the outer surface of the template ball to the center of the ball (for example, 10%-90%, 20%-70%, 0.5%-5%, 1%-5 %, 2% - 10%. 1% - 20%>5% - 30%, 5% - 40%> 10% - 50%) can be glass-ceramic. The template ball may include aluminum oxide, silicon oxide, iron oxide, magnesium oxide, calcium oxide, potassium oxide, etc., or a mixture thereof. The glass-ceramic of the template ball may have a thickness of any amount (for example, 1 micrometer to about 150 micrometers or about 5 micrometers to about 120 micrometers). The glass-ceramic can be formed to have a substantially uniform thickness around the template ball. For example, the thickness of the glass-ceramic may be substantially uniform in thickness, where the thickness variation does not exceed 20% or more of the total thickness, or more preferably does not exceed 10% of the total thickness. The glass-ceramic may be discontinuous or continuous. For the purpose of the present invention, continuous means that the entire outer surface of the template ball is glass-ceramic. Preferably, at least the entire outer surface of the template ball is glass-ceramic. The outer surface may have a thickness of about 0.1 to about 1000 um.

[0039] It should be understood that the degree of crystallinity in the glass-ceramic can vary between the various parts of the template ball. For example, the glass-ceramic forming the outer surface of the template sphere or the portion of the template sphere closest to the shell may have a greater degree of crystallinity than the glass-ceramic formed deeper in the template sphere and away from the shell. The crystallinity of the glass-ceramic starting from the outer surface of the template ball can be, for example, about 10%-100%, and then the glass-ceramic gradually decreases as it approaches the amorphous glass portion of the template ball, ending at about 1%- 100% crystallinity.

[0040] The template ball may be entirely glass-ceramic. The template sphere can be hollow microspheres formed of glass and ceramic, and has a glass-ceramic outer surface.

[0041] In a two-phase system, the second phase as one or more layers can be coated with a supporting or templated first phase, and/or infiltrated with a supporting or templated first phase, and/ Or react with a supportive or template first phase. First

The two phases or shells can be partly ceramic, partly glass-ceramic, entirely ceramic, or entirely glass-ceramic. The shell can be crystalline or amorphous. For example, the shell may include oxides, such as alumina known as clay. The shell may include silicon oxide, sodium oxide, potassium oxide, calcium oxide, zirconium oxide, aluminum oxide, lithium oxide, iron oxide, magnesium oxide, calcium oxide, uranium oxide, orbital oxide, bronze oxide, titanium dioxide, cordierite, Spar, spodumene, talc, silicate, substituted aluminosilicate clay, or any combination thereof. The shell may include metal oxides, metal carbides, metal nitrides, metal borides, metal silicides, or any combination thereof derived from any metal source and any combination thereof.

[0042] The shell may include a mixed metal oxide of aluminum called aluminate, silicate, or aluminosilicate such as mullite or cordierite. The shell may include amorphous silica. The aluminate or ceramic may contain magnesium, calcium, nitrate, titanium, indium, steel and/or silicon. The ceramic can be formed from nanoparticle precursors such as aluminoxane. Aluminoxanes can be chemically functionalized alumina particles with surface groups including those derived from carboxylic acids such as acetate, methoxyacetate, methoxyethoxyacetic acid Ester, methoxyethoxyethoxy acetate, lysine and stearate, etc. The shell may further include a crystal initiator, such as Ti0₂Or Li₂The amount of crystal initiator present in the shell can be about 0.1%-25%, for example 1% 15%. 3%-13wt%. 0.1%-7%. 0.1%-5% or 0.1% - 3% by weight, based on the weight of the shell.

[0043] The shell may include one or more layers (for example, two, three, four, five or more layers). The composition of each shell layer may be different from the composition of adjacent shell layers. For example, the amount of one or more components (if one or more are the same) in each shell layer can gradually increase or decrease between each layer. Additionally or alternatively, one or more components of one shell layer may be different from that of another shell layer.

[0044] The shell may have 0.1 X 10^-6/K-13Χ 10^-6/K thermal expansion coefficient (CTE, at 25300°C), such as 0.1 X 10^-6/Κ-12Χ10^-7Κ or 1. 2X10^-6/K-5Χ10^-6/Κ The coefficient of thermal expansion (CTE, at 25 °C-300 °C) ο

[0045] The proppant of the present invention may comprise a single particle or a plurality of particles, and may be solid, partially hollow, partially hollow and randomly distributed or completely hollow within the particles. The shape of the particles may be spherical, nearly spherical, polygonal, elliptical (or any combination thereof), or have other shapes suitable for the purpose of being a proppant. The proppant may also have a shape such as a rod shape, a column shape, a nail shape, a gear shape, a ring shape, a cylinder shape, or a peanut shape. The desired proppant shape can be achieved in any suitable way. For example, extrusion, granulation, fluidized bed coating, fluidized bed granulator, fluid spray dryer or granulator such as Eirich mixer can be used to achieve the desired proppant shape. The particles may have any aspect ratio (L/D), such as 2:1-1:2 (for example, 1. 2:1-1: 1.12, such as 1:1 or about 1:1).

[0046] The entire proppant can have any particle size. For example, the proppant may have a particle size of about 90 microns to about 2 mm, or about 90 microns to about 20,000 microns in diameter, or about 100 microns to about 2,000 microns in diameter, or about 200 microns to about 200 microns in diameter. About 1000 microns in diameter. Other particle sizes can be used. Further, the particle size as measured by the diameter of the particle may be higher than the numerical range provided herein, or lower than the numerical range provided herein.

[0047] In a single-phase system, the proppant may include a sphere, but does not include a second phase as a shell, which is different or dissimilar to the template sphere or core. The spheres in the single-phase system may have the same composition and size as the template spheres of the above-mentioned multi-phase system. Like the template ball of the multi-phase system, the ball of the single-phase system may have at least a glass-ceramic outer surface. The spheres of the single-phase system can be entirely glass-ceramic. Single-phase spheres can, for example, have a composition of 44%-48% SiO₂.14% 18%Α1₂0₃>5%-10%B₂0₃>8%-12% Altar 0 and 13%-18% MgO, all weight percentages are based on the total weight of the ball. For example, a single-phase system ball can have 46wt% SiO₂.16wt%Al₂0₃>7wt%B₂0₃> 10wt%K₂0 And 17wt% MgO based on the weight of the ball.

[0048] The proppant of the present invention can be used to prop up fractures in underground formations. The proppant can be suspended in the liquid phase or other

In the medium to facilitate the transport of the proppant down the well to the subterranean formation and be placed to allow the flux to flow out of the formation. The medium selected for pumping the proppant can be any desired medium capable of transporting the proppant to its desired location, including but not limited to gas and/or liquid, energized fluid, foam, water-like solution such as water, saline solution And/or synthetic solution. Any proppant of the present invention can have a crushing strength sufficient to be used as a proppant to prop up fractures in underground formations. For example, the crush strength may be 1,000 psi or greater, 3,000 psi or greater, greater than 4,000 psi, greater than 9,000 psi, or greater than 12,000 psi. A suitable range of crush strength may be about 3,000 psi. One is about 20,000 psi, or about 5,000 psi to about 20,000 psi, etc. In some applications, such as coal bed methane mining, a crush strength of less than 3,000 psi may be useful, for example, 500 psi-3,000 psi, or 1,500 psi-2,000 psi._o

[0049] The proppant can be suspended in a suitable gas, foam, energizing fluid, or liquid phase. A carrier material, such as a liquid phase, is generally a carrier material that allows the proppant to be delivered to the location of use, such as a well site or underground formation. For example, an underground formation may be an underground formation in which proppants are used to improve or promote the flow of natural gas or other raw materials from it. The invention also relates to a wellsite or underground formation containing one or more proppants of the invention.

[0050] The preparation of glass-ceramics may involve heat-treating the glass article at a temperature that allows the core to form in the glass and processing the glass article at a temperature that allows the crystallites of the desired phase to grow to a desired degree. In the present invention, the glass-ceramic crystal grains can be annealed by glass or substantially glass balls or template balls. Annealing causes the nucleation of one or more crystalline phases. Nucleation can be accelerated by seeding the glass with a crystal initiator, such as titanium dioxide and/or lithium oxide. When the desired level of crystallinity is reached, annealing is completed, and the crystallinity is typically 1%-100%, 15%-80%, 50%-80%, 60%-78% and 70%-75%, to Calculated as a weight percentage of the weight of the article (for example, template ball or layer).

[0051] As described above, the template ball may be formed of glass or a substantially glass-like material. The template sphere can be glass or a hollow sphere like glass. During the heating of the glass spheres or the sintering of the shell, the glass spheres can be partially or completely converted into glass-ceramics. By adjusting the temperature, crystal growth can occur, which itself is usually random. The temperature is adjusted by introducing a temperature gradient and the degree of cooling or heating and then cooling followed by heating to promote glass-ceramic formation or transformation. However, it is also possible to achieve an oriented crystal arrangement, which can further enhance the stiffness. During annealing, the grains nucleate, begin to grow, and eventually contain most of the material. High melting point compounds or crystal initiators, such as titanium dioxide or alkali metals or alkali metal oxides or other materials listed elsewhere in this article, can promote nucleation and/or act as catalysts. The nucleation temperature is the temperature at which crystals begin to form and grow in the glass. The nucleation temperature selected should be lower than the temperature at which the glass will be thermally deformed. Below its melting temperature, the crystal typically has a significantly lower thermal deformation than the corresponding glass. [0052] The crystal initiator may be in the form of a solid powder. The particle size of the powder can be changed by grinding. Alternatively, the crystal initiator may be in liquid form. Crystal initiators can be derived from precursors that are converted to oxides in liquid, solid, or gaseous form. For example, the precursor may include TiCl^LiCKTi ((^&)4 or Li (0H) ο The oxide is partially or completely converted into glass-ceramic.

[0053] As previously mentioned, the shell may be formed of silica, clay, and/or other ceramics such as cordierite and mullite. The silica may be, for example, amorphous silica. Crystal initiators can be used to promote the conversion of the amorphous silica or soil into oxides.

[0054] Before or after the template sphere has achieved the desired degree of crystallinity, a shell may be applied to the template sphere. In other words, once the template ball is at least partially composed of glass-ceramic, the shell can be formed on the template ball. Alternatively, the shell coating may be applied to the surface of the glass template sphere before the crystallization of the template sphere. The template ball can be coated and sintered with a shell coating. During the heat treatment of the composite shell and the template sphere, any glass material in the shell and the glass in the template sphere can be partially or completely converted into glass-ceramic.

[0055] The shell may be formed of ceramics (such as cordierite and/or mullite), and/or with a crystal initiator (such as NO? or ΙΛ0). The crystal initiator may be added to the coating slurry as a solid powder, or as a liquid, solid or gas precursor converted into an oxide. If a solid powder is used, the size of the powder particles can be controlled by grinding. The precursor may be, for example, TiCjLiC^'Ti (Shen 24) 4 and/or Li (OH). The template ball may be coated with a ceramic shell coating and sintered. The sintered ceramic grain size may be less than 1 micrometer, for example, 0.1-0.8 micrometer or 0.2-0.5 micrometer. [0056] The shell may be formed of amorphous silica and/or soil. The amorphous silica and/or clay is a glass-ceramic precursor, and the precursor can be converted into an oxide when a crystal initiator is added. The oxide, once obtained, can be fully or at least partially converted into glass-ceramic.

[0057] The shell may be formed of glass-ceramic precursors and other ceramics such as cordierite or mullite. The composite of the glass-ceramic precursor and the ceramic material in the shell can be heat treated together with the template ball. Upon heating, the glass material in the template sphere and shell can be completely or at least partially converted into glass-ceramic.

[0058] The shell may be prepared from one or more different coating slurries to form one or more shell layers on the template ball. The at least one coating slurry may include a ceramic material, such as cordierite or mullite. The crystal initiator can be added to the coating slurry. If multiple shells are desired, the sprayer can be programmed to spray at least two different coating slurries alternately onto the template. After coating the template ball with at least two different coating slurries, the proppant can be heated to achieve a layered shell structure. During heating, the top shell is exposed to more heat than the shell and template balls below. Thus, the small glass ceramic particles that can be formed in the top shell layer can fuse together and result in a dense top layer.

[0059] The substrate or template, preferably before the optional second phase or optional coating or optional shell, can be treated in one or more ways to remove or reduce the substrate Or defects on the surface of the template. These defects can be convex or concave or both. This can be particularly beneficial when the template or substrate is an inorganic material. The removal or reduction of these flaws (especially those that limit strength) may allow the second phase or coating or shell to provide a more enhanced substrate or template and overall proppant reinforcement. The flaws may include, but are not limited to, peaks, protrusions, ridges, pits, and other flaws, which may include surface undulations, which are significantly different from the overall surface texture or surface smoothness of the substrate or template. A defect in a material system can be considered as anything that negatively affects the apparent strength of the material system. The defects themselves can be physical and/or chemical. Physical defects may include things such as protrusions, bumps, scratches, grooves, holes, pits, faults, and/or defects in the crystal structure of the material. Chemical defects may include phases that prevent solid-state bonding, such as grain boundary phases, changes in crystal structure through atomic substitution, and the like. By removing or reducing these imperfections in the surface of the substrate or template, the sharp protrusions or peaks or ridges can be removed or reduced, and a "smooth and more spherical" surface can be produced, which can allow a second phase or The coating or shell more effectively provides strength to the entire proppant. Save The removal or reduction of defects on the surface of the substrate or template can be quantitatively displayed in one or more ways. For example, aspect ratio (AR) test and/or comparable radius of curvature (RC) can be used_O

[0060] For the purpose of the present invention, the AR may be 5 or less, such as 0.1-5, or 0.2-5, or 0.5-5, or 0.1-4, or 0.1 -3, or 0.1-2, or 0.8-1, or 0.1-1. 8, or 0.1-1.5, or 0.5-1.3, or 0.7-1.2, and other ranges . Preferably, the AR is about 1.

[0061] The RC may typically be 0.5 μm to 100 μm, and the upper limit of the radius of curvature is the radius of the template.

[0062] For the heat treatment of crystallizing glass to form glass-ceramics, various devices and methods that provide a temperature sufficient to allow crystallization to occur can be used. These devices and/or methods include, but are not limited to, static bed furnaces, dynamic bed furnaces (for example, rotary tube furnaces), fluidized bed furnaces, direct injection of high-temperature flames (for example, oxidizing flames), and use included in vertical installations The gas flame in the combustion tube and/or the injection high-temperature plasma flame. The template ball can be heated enough to make all or part of

Any temperature for the crystallization of the template ball, for example, heating to about 300°C- 1,300°C or 500°C- 1, The temperature of 500C. The heat treatment may be performed for any time sufficient to crystallize all or part of the template spheres. For example, the heat treatment may be performed for a time of, for example, 10 minutes to 50 hours or more, for example, for a time of 2 hours to 10 hours. During the heat treatment, pressure can be used to control the template structure or the physical properties of the template. For example, a pressure lower than 0. latm-10 atm or greater can be used, such as a pressure of latm-5 atm. When the local pressure is reduced to a value lower than the ambient pressure, this can cause expansion of the template and subsequent decrease in the density of the template. When the local pressure rises above the ambient pressure, this can cause the template to shrink to a smaller overall diameter, thereby increasing the density of the template. Thus, the technology provides the ability to "dial in" or control the specific density of the proppant material. Moreover, a decrease or increase in pressure can improve the morphology of the template, especially when the template is maintained at or very close to the glass transition temperature of the template material. The local pressure can be changed by using various pressure control devices and technologies (for example, a sealed ceramic tube surrounded by a heating element and containing a template material), wherein the ceramic tube is connected to a pressure source or a radiator (sink) ο can be used Pressurized fluid to achieve the desired partial pressure, such as air, nitrogen, inert gas such as fermented gas, or any gas. Before the heat treatment, as described elsewhere herein, a crystal initiator is optionally included to promote the crystallization of the glass.

[0063] The heat treatment may also be performed in an alternative atmosphere other than the air atmosphere to cause the formation of a new phase, for example, heat treatment in a nitriding atmosphere to form nitrides, or heat treatment in a carbonized atmosphere to form carbides. Examples of such an atmosphere include inert gas, carbon monoxide, nitrogen, nitrogen monoxide, nitrogen dioxide, dinitrogen pentoxide, anhydrous ammonia, and the like.

[0064] The properties of the template or substrate can be changed by the effect of pressure and/or temperature. The change in pressure under the application of thermal energy can be used to change the specific gravity of the template material.

[0065] The template and/or the shell (or one or more layers containing the shell) may be surface-modified, such as adding silicon oxide, sodium oxide, potassium oxide, calcium oxide, zirconium oxide, aluminum oxide , Lithium oxide, iron oxide, cordierite, spinel, spodumene, talc, silicate, aluminosilicate materials, aluminum-containing materials, silicon-containing materials, aluminum-silicon-containing materials, substituted aluminosilicates Clay or any combination of them.

[0066] The shell may be surface-modified, for example, by adding one or more inorganic materials or phases, or attaching (eg chemically attaching or bonding) one or more chemical groups, such as hydrophilic groups Or a hydrophobic group. The chemical group may be a surfactant, polymer, ionic group, ionizable group, acid group, salt, surface active agent, etc. Surface modification can improve the surface morphology of the proppant, especially after the proppant is a sintered proppant. The inorganic materials or phases used for surface modification may include glassy materials, such as silicon oxide, which are alone or added with sodium, potassium, calcium, aluminum, aluminum, lithium, iron oxides, or any combination thereof. The amount of silicon oxide can be about 70% by weight to about 99% by weight, for example, about 85% by weight to about 95% by weight, and the added one or more other oxides, such as sodium oxide, etc., can be about 1% by weight to about 15% by weight, for example About 2wt%-about 10wt%_oThe surface modification of the shell may include applying one or more organic materials (for example, aliphatic compounds, ionic compounds, surfactants, aromatic compounds, polymeric compounds) or applying an organic phase. The organic material or chemical group may be bonded or adsorbed or absorbed or attached to the surface of the shell. The organic material or organic phase can change the proppant's tendency to interact with the aqueous solution, thereby making the proppant hydrophobic, hydrophilic or water-neutral. The surface modification of the shell may include the use of a substance that is effectively activated by the temperature increase of the proppant to produce a modification of the proppant transport fluid (for example, used to transport the proppant through the gel rupture of the subterranean area). The surface treatment that can be performed after the sintering of the proppant can have the ability to improve one or more chemical and/or mechanical properties, such as enhanced transport capacity.

[0067] The template or substrate and/or shell can be modified by a variety of techniques, such as surface modification. For example, the surface of the template or substrate may be modified by one or more heat treatments before forming a shell on the template. Another form of surface treatment can be

To chemically modify the surface of the template, for example, by glazing, applying an adhesive coating, or chemical etching. The chemical modification can improve the performance of the template surface and/or stabilize the template surface. Remove residual impurities, clean the surface, reduce the distribution of residual stains before coating, increase the micro-roughness of the surface to improve the bonding strength of the coating or remove and/or improve the shape of the protrusions. Moreover, modification can be achieved by preferentially removing one or more constituent phases on the template. For example, a lotion with caustic soda can dissolve gravel from the template.

[0068] The present invention includes the following aspects/embodiments/features in any order and/or any combination:

[0069] 1. A proppant comprising a template ball and a continuous sintered shell surrounding the entire outer surface of the template ball, the template ball having a Crumbin sphericity of at least about 0.3 and at least about 0.1 The proppant has a Crumbin sphericity of at least about 0.5 and a roundness of at least about 0.4, wherein at least the outer surface of the template ball includes the outer surface of the template ball Contacting glass-ceramic or glass-ceramic containing layer.

[0070] 2. The proppant of any preceding or following embodiment/feature/aspect, wherein the template ball is a solid ball.

[0071] 3. The proppant of any preceding or following embodiment/feature/aspect, wherein the template ball is a hollow ball.

4. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant comprises a continuous sintered shell surrounding the entire outer surface of the template ball or the glass-ceramic-containing layer, and The shell includes a ceramic material or oxide thereof.

[0073] 5. The proppant of any preceding or following embodiment/feature/aspect, wherein the template sphere is entirely glass-ceramic.

[0074] 6. The proppant of any preceding or following embodiment/feature/aspect, wherein the template sphere is a hollow microbead.

[0075] 7. The proppant of any preceding or following embodiment/feature/aspect, wherein the template sphere comprises ceramic and/or glass.

[0076] 8. The proppant of any preceding or following embodiment/feature/aspect, wherein the template sphere comprises glass.

[0077] 9. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant comprises the glass-ceramic-containing layer in contact with the template ball, and the glass-ceramic-containing layer Contains glass-ceramic that at least partially diffuses into the outer surface of the template sphere.

[0078] 10. The proppant of any preceding or following embodiment/feature/aspect, wherein the outer surface has about

0. Ιμπι a thickness of about 1000 m.

[0079] 1L of the proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic has a degree of crystallinity of about 1% to about 100%.

[0080] 12. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic has a degree of crystallinity of about 60% to about 80%.

[0081] 13. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic comprises crystallites having random orientation.

[0082] 14. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic comprises crystallites with non-random orientation.

[0083] 15. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic can withstand temperatures up to about 800C-1,500°C.

[0084] 16. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant has at least one of the following properties:

[0085] a) The template ball has a small coefficient of thermal expansion (CTE, at 25C-300°C) of 0.1X1 (T7κ-13 = 10-6); and/or

[0086] b) The shell has a coefficient of thermal expansion (CTE, at 25°C-300°C) of 0.1 X 10-VK-13X ΙΟ^/Κ. [0087] 17. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant has about

3 or less specific gravity; and/or about 0.1Χ10~⁶/Κ -about 13X10-⁶/K coefficient of thermal expansion (CTE, at 25C-300°C); and/or about 0.01W/m · K-about 3. OW/m · K thermal conductivity.

[0088] 18. The proppant of any preceding or following embodiment/feature/aspect, the proppant having a specific gravity of about 0.7 approximately4.0.

[0089] 19. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic has at least one of the following properties: about 1.5-about 3.5 g/cm³Density; Young's modulus of about 50 to about 80GPa; and/or MOR of about 50 to about 150MPa.

[0090] 20. The proppant of any preceding or following embodiment/feature/aspect, wherein the template ball has a MOR of about 1 to about 100 MPa_o

[0091] 21. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic has at least one of the following properties:

[0092] a) Shear modulus of about 20 to about 50 GPa (at 25° C.);

[0093] b) A modulus of failure of about 50 to about 150 MPa (at 25° C.);

[0094] c) A compressive strength of about 300 MPa to about 500 MPa;

[0095] d) about 1-about lOMPa. m^1/2Rupture cut; or

[0096] e) Thermal conductivity of about 0.01 to about 3W/(m·K).

[0097] 22. The proppant of any preceding or following embodiment/feature/aspect, wherein the shell has a thickness of about

A continuous shell of 0.1 to 1000 microns, and the template sphere has a specific gravity of about 0.01 to about 3, and the proppant has a crushing strength of about 1,000 psi or greater, and the template sphere has at least 30% void volume

[0098] 23. The proppant of any preceding or following embodiment/feature/aspect, wherein the template sphere has a sphericity of at least about 0.6, and a continuous sintered shell surrounds the entire outer surface of the template sphere, wherein the continuous shell has A substantially uniform thickness, and wherein the proppant has a crushing strength of about 1,500 psi or greater, and the template ball has a void volume of at least 30%

24. The proppant of any preceding or following embodiment/feature/aspect, wherein the template ball comprises a mixture of aluminum oxide, silicon oxide, titanium oxide, iron oxide, magnesium oxide, calcium oxide, potassium oxide, and sodium oxide .

[0100] 25. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic of the template ball comprises aluminum oxide, silicon oxide, boron oxide, potassium oxide, zirconium oxide, magnesium oxide, oxide Calcium, titanium oxide or any combination of them.

[0101] 26. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic of the template ball contains about 10% to about 55% by weight SiO.₂ ; About 0%-about 28% by weight Α1₂0₃ ; About 1%-about 5% by weight CaO; about 7%-about 50% by weight MgO; about 0.5%-about 25% by weight Ti0₂ ; About 0.4% - about 30% by weight B₂0₃, And greater than 0% and up to about 5% by weight P₂0₅,Based on the weight of the glass-ceramic.

[0102] 27. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic of the template sphere contains about 3% to about 10% by weight Li₂0 ; About 0%-about 28% by weight Α1₂0₃ ; About 10%-about 55% by weight Si0₂ ;About 7%-about 50% by weight MgO; about 0.5%-about 25% by weight Ti0₂ ; About 0.4%-about 30% by weight Β?. ?,with

About 6% to about 20% by weight of ZnO, based on the weight of the glass-ceramic.

[0103] 28. The proppant of any preceding or following embodiment/feature/aspect, wherein the shell comprises aluminum oxide, silicon oxide, boron oxide, potassium oxide, zirconium oxide, magnesium oxide, calcium oxide, lithium oxide, sodium oxide , Iron oxide, phosphorus oxide and/or titanium oxide or any combination thereof.

[0104] 29. The proppant of any preceding or following embodiment/feature/aspect, wherein the shell comprises silicon oxide, sodium oxide, potassium oxide, calcium oxide, aluminum oxide, aluminum oxide, lithium oxide, iron oxide, cordierite , Spinel, spodumene, talc, silicate, substituted aluminosilicate clay, or any combination thereof.

[0105] 30. The proppant of any preceding or following embodiment/feature/aspect, wherein the shell comprises two or more layers, wherein one of the layers comprises the ceramic material or oxide thereof.

[0106] 31. The proppant of any preceding or following embodiment/feature/aspect, wherein the shell comprises cordierite.

[0107] 32. The proppant of any preceding or following embodiment/feature/aspect, wherein the shell comprises magnesium oxide, calcium oxide, uranium oxide, orbital oxide, bronze oxide, titanium dioxide, or any combination thereof.

[0108] 33. The proppant of any preceding or following embodiment/feature/aspect, wherein the shell comprises a metal derived from a silicon source, a titanium source, a bustard source, an aluminum source, a boron source, or any combination thereof Oxide, metal carbide, metal nitride, metal boride, metal silicide, or any combination thereof.

[0109] 34. The proppant of any preceding or following embodiment/feature/aspect, wherein the shell is surface modified by applying at least one organic material to the shell.

[0110] 35. The proppant of any preceding or following embodiment/feature/aspect, wherein the continuous sintered shell comprises glass-ceramic.

[0111] 36. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic of the continuous sintered shell is different from the glass-ceramic of the template ball.

[0112] 37. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic of the continuous sintered shell is the same as the glass-ceramic of the template ball.

[0113] 38. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic is uniformly distributed in a continuous sintered shell and/or template sphere.

[0114] 39. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic is unevenly distributed in the continuous sintered shell and/or template sphere.

[0115] 40. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant size is from about 90 microns to about 2,000 microns.

[0116] 41. The proppant of any preceding or following embodiment/feature/aspect, wherein the template ball has about

20 microns to about 1,000 microns in size.

[0117] 42. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic microitem size is about 0.1 to about 0.5 microns.

[0118] 43. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic microitem size is less than 1 micron.

[0119] 44. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant is rod-shaped, cylindrical, nail-shaped, gear-shaped, ring-shaped, cylindrical, polygonal, or peanut-shaped.

[0120] 45. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant comprises a shape with an aspect ratio of 1.

5Gram [0121] 46. A proppant comprising a ball having a Crumbin sphericity of at least about 0.3 and a roundness of at least about 0.1, the proppant having at least about 0.5GramRumbin sphericity and a roundness of at least about 0.4, wherein at least the outer surface of the ball comprises a glass-ceramic or glass-ceramic-containing layer in contact with the outer surface of the ball.

[0122] 47. The proppant of any preceding or following embodiment/feature/aspect, wherein the ball comprises ceramic and/or glass.

[0123] 48. The support of any preceding or following embodiment/feature/aspect, wherein the entire ball is glass-ceramic.

[0124] 49. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant comprises the glass-ceramic-containing layer in contact with the template ball, and the glass-ceramic-containing layer Contains glass-ceramic that at least partially diffuses into the outer surface of the template sphere.

[0125] 50. The proppant of any preceding or following embodiment/feature/aspect, wherein the outer surface has about

0. 1-Thickness of about 1000 um.

[0126] 51. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic comprises about 1% to about 100% crystallinity.

[0127] 52. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic comprises about 10% to about 100% crystallinity.

[0128] 53. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic comprises crystallites having random orientation.

[0129] 54. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic comprises crystallites having non-random orientation.

[0130] 55. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic can withstand temperatures up to about 800C-1,500°C.

[0131] 56. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant has at least one of the following properties: the template ball has from about 0.1 to 10 to 6 to about 13 to 10 6 Small thermal expansion coefficient (CTE, at 25°C- 300°C) o

[0132] 57. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant has a specific gravity of about 3 or less; and about 0.01 W/(m·K) to about 3.0 W/(m· K) Thermal conductivity.

[0133] 58. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant has at least one of the following properties: from about 1.5 to about 3.0 g/cm³Density; and/or Young's modulus of about 50 to about 80GPa; and/or MOR of about 50 to about 150MPa_o

[0134] 59. The proppant of any preceding or following embodiment/feature/aspect, wherein the template sphere has a MOR of about-about 100 MPa.

60. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant has at least one of the following properties; a shear modulus of about 20 to about 50 GPa (at 25° C.); about 50 -About 150MPa modulus of failure (at 25 °C); about 300MPa-about 500MPa compressive strength; about 1-about lOMPa. m^1/2The fracture cut; about 0.01-about 3W/ (m · K) thermal conductivity.

[0136] 61. The proppant of any preceding or following embodiment/feature/aspect, wherein the template sphere has about

The specific gravity is 0.01 to about 3, and the proppant has a crushing strength of about 20 kpsi or more, and the template ball has a void volume% of at least 30%.

[0137] 62. The proppant of any preceding or following embodiment/feature/aspect, wherein the template ball has a sphericity of at least about 0.6, and a continuous sintered shell surrounds the entire outer surface of the template ball, wherein the continuous The shell has a substantially uniform thickness, and wherein the proppant has a crush strength of about 1,500 psi or greater, and the template sphere has a void volume% of at least 30%.

[0138] 63. The proppant of any preceding or following embodiment/feature/aspect, wherein the proppant comprises about

10%-about 55% by weight Si0₂ ; About 0%-about 28% by weight Α1₂0₃ ; About 1%-about 5% by weight CaO; about 7%-about 50% by weight MgO; about 0.5%-about 25% by weight Ti0₂ ; About 0.4% - about 30% by weight B₂0₃, And greater than 0% and up to about 5% by weight P₂0₅,Based on the weight of glass-ceramic.

[0139] 64. The proppant of any preceding or following embodiment/feature/aspect, wherein the ball is a solid ball.

[0140] 65. The proppant of any preceding or following embodiment/feature/aspect, wherein the ball is a hollow ball.

[0141] 66. A method of forming a proppant, comprising providing a template ball containing glass; optionally hardening the template ball; crystallizing at least the outer surface of the template ball by heat treatment to form an outer surface containing glass-ceramic And optionally providing a shell surrounding the entire outer surface of the template ball; and sintering the shell to form a continuous sintered shell.

[0142] 67. The method of any preceding or following embodiment/feature/aspect, wherein the heat treatment comprises heating the template ball to a temperature of about 500°C to about 1,500°C.

[0143] 68. The method of any preceding or following embodiment/feature/aspect, further comprising applying a composition comprising an alkaline earth metal or a transition metal oxide on the template sphere before the template sphere is subjected to a heat treatment.

[0144] 69. The method of any preceding or following embodiment/feature/aspect, further comprising performing the heat treatment in the presence of at least one crystal initiator.

[0145] 70. The method of any preceding or following embodiment/feature/aspect, wherein the proppant is formed into a rod shape, a column shape, a nail shape, a gear shape, a ring shape, a cylindrical shape, a polygonal shape, or a peanut shape.

[0146] 71. The method of any preceding or following embodiment/feature/aspect, wherein the proppant shape is achieved by extrusion or fluidized bed coating, or granulation, or granulation.

[0147] 72. The method of any preceding or following embodiment/feature/aspect, wherein the proppant shape is achieved by using a fluidized bed granulator, a fluid spray dryer, or a granulator.

[0148] 73. A proppant comprising a template ball and a continuous sintered shell surrounding the entire outer surface of the template ball, the template ball having a Crumbin sphericity of at least about 0.3 and a sphericity of at least about 0.1 Roundness, the proppant has a Crumbin sphericity of at least about 0.5 and a roundness of at least about 0.4, wherein at least the continuous sintered shell comprises glass-ceramic.

[0149] 74. The proppant of any of the preceding or following embodiments/features/aspects, wherein the template sphere comprises a glassy glass.

[0150] 75. The proppant of any preceding or following embodiment/feature/aspect, wherein the template sphere and/or the glass-ceramic in the shell is in solid form.

[0151] 76. The proppant of any preceding or following embodiment/feature/aspect, wherein the glass-ceramic in the template sphere and/or shell is in a hollow or porous form.

[0152] The present invention may include any combination of the above and/or below these various features or embodiments as set forth in sentences and/or paragraphs. Any combination of features disclosed herein is considered a part of the present invention, and it is intended that there is no limitation on the features that can be combined.

[0153] The present invention is further illustrated by the following examples, which are intended to exemplify the present invention.

[0154] Examples

Example 1

[0156] The proppant according to the present invention can be prepared by coating conventional glass hollow microbeads with an alkali metal. The alkali metal can be dip-coated, spin-coated and sprayed onto the hollow glass beads. Alternatively, the hollow microbeads can be doped with transition metal oxides. Once the hollow microspheres are coated or doped as described, they are heat treated to crystallize. The hollow microbeads are heated to a temperature of 500C to 1,000C for a period of time, which is sufficient to make at least the outer surface of the hollow microbeads agglomerate. The amount of time the hollow microspheres are heated can vary depending on the degree of crystallinity desired. The hollow microbeads can be heated, for example, for a period of about 30 minutes to 12 hours or 2 hours to 10 hours. If it is desired that the hollow microbeads crystallize completely, the hollow microbeads should be heated from a few tenths of an hour to several hours, for example, 0.1-10 hours or more.

[0157] Once the desired crystallinity is achieved, the hollow microbeads can be coated with a ceramic shell, such as cordierite. The cordierite can be granulated or granulated by a granulator to achieve particles with a diameter of about 200 microns or more. The formed cordierite particles are then dried and used to coat hollow microbeads with at least a glass-ceramic outer layer. Then the hollow microspheres are sintered. Sintering can be performed in a conventional manner known in the art. For example, the coated hollow microbeads can be fired at a temperature of about 1,200°C to about 1,450°C, preferably 1,250°C to 1,420°C, to form a sintered cordierite proppant.

Example 2

[0159] Table 1

[0160] Chemical composition of two hollow microbead samples used for glass-ceramic synthesis (wt%)

[0161]

SiO₂ A1₂O₃ Fe₂O₃ MgO CaO Na₂OK₂O TiO₂ P₂O₅ MnO

62.05 23.40 5.89 149 L52 LI8 2.61 098 021 0.06

5929................................................. ....26.12 3Q2 1.3 3.62 2/3 L25 0.61 0.06 0.02

[0162] The above two hollow microbead samples were each reduced to a powder with an average particle size of about 6 μm. Then, round pellets (balls) were prepared from each powder, some of the powder mixtures having different levels of Ti() 2 added as shown in FIG. 1. The round pellets were then sintered at 1200C for 4 hours. The results are shown in Figures 1-3 and Table 2. As shown, the addition of Ti()2 is very effective in strength improvement. Figure 1 shows the density change with NO? content. As can be seen in Figures 2 and 3, the strength of the sample increases sharply with the overall increase in Tig content, but there is a valley at 13wt% NO2. The maximum strength is observed at 13wt% Ti()2. The increase in strength is more than doubled. It is believed that the increase in strength is due to the transition from glass to glass-ceramic.

[0163] Table 2

[0164] From the data shown in FIG. 2, for the sample sintered at 1200C for 4 hours, the resultant hollow microspheres formed by the glass-ceramic compared to the control sample (0%Ti0₂) Strength improvement

[0165]

<td>TiO₂wt%</td><td>Strength, psi</td><td>standard deviation</td><td>Net increase,%</td>

<td>0</td><td>1774</td><td>352</td><td>0</td>

<td>2</td><td>2433</td><td>206</td><td>37</td>

<td>5</td><td>3623</td><td>310</td><td>104</td>

<td>7</td><td>4447</td><td>808</td><td>151</td>

<td>9</td><td>3119</td><td>754</td><td>76</td>

<td>11</td><td>5070</td><td>331</td><td>186</td>

<td>13</td><td>2744</td><td>503</td><td>55</td>

<td>17</td><td>3717</td><td>840</td><td>110</td>

<td>20</td><td>4076</td><td>1148</td><td>130</td>

<td>23</td><td>4018</td><td>459</td><td>126</td>

Example 3

[0167] In this example, the first hollow bead powder and cordierite in Table 1 were used to prepare additional proppants. Specifically, the mixture (before considering the amount of NOZ present) consisted of 25 wt% hollow microbead powder and 75 wt% cordierite, and the mixture was formed into balls, added 702 as shown, and sintered at 1260c for 6 hours. The density and intensity data of the samples are shown in Table 3. The splitting strength of the composite varies with Ti0₂The content increases and gradually increases, and at 7wt%Ti0₂Reaches the maximum value. The amount of Ti()2 is based on the total weight of pellets or balls. In the Ti0₂The strength at the level is greater than without any Ti0₂Twice the sample (compared to the control sample, a net increase of 108% in strength). The increase in strength is mainly attributed to the formation of glass-ceramic in the hollow microsphere powder. With Ti0₂As the content increases, the strength of these 1260c sintered composite samples increases, then reaches the maximum point and then decreases, although the density keeps increasing. This is because when Ti()2 reaches a certain level, the further increase will only reduce the relative content of hollow microsphere powder. This again shows the glass-ceramic contribution from the hollow microspheres in the composite. Without 7wt%Ti0₂With 7wt% Ti0₂The microstructure of 25%: 75% hollow bead-cordierite matrix composite is shown in Figure 4. It can be seen that it has 7wt% Ti0₂The sample is better than without Ti0₂The sample is more dense.

[0168] Table 3

[0169] The density and radial splitting strength of glass-ceramic in a matrix of 25% hollow microspheres-75% cordierite. All samples were sintered at 1260c for 6 hours.

[0170]

<td>Ti0₂</td><td>density</td><td>strength</td><td>Specific strength</td><td>Net increase in strength</td><td>Net increase in specific strength</td>

<td>(wt. %)</td><td>(g/cm³)</td><td>(psi)</td><td>(psi)</td><td>(%)</td><td>(%)</td>

<td>0</td><td>2. 19</td><td>3229</td><td>1474</td><td>0</td><td>0</td>

<td>2. 5</td><td>2. 31</td><td>5063</td><td>2192</td><td>57</td><td>49</td>

<td>5</td><td>2. 39</td><td>5011</td><td>2097</td><td>55</td><td>42</td>

<td>7</td><td>2. 45</td><td>6716</td><td>2741</td><td>108</td><td>86</td>

<td>11</td><td>2. 50</td><td>5565</td><td>2226</td><td>72</td><td>51</td>

<td>13</td><td>2. 53</td><td>4841</td><td>1913</td><td>50</td><td>30</td>

[0171] The applicant specifically incorporates the entire contents of all cited references into the present disclosure. Further, when equivalents, concentrations or other values or parameters are given in the form of ranges, preferred ranges, or lists of preferred upper limits and preferred lower limits, this should be understood as specifically disclosing any upper limit or range of any pair. All ranges formed by the preferred value and the lower limit of any range or preferred value, regardless of whether each range is separately disclosed. Where numerical ranges are stated herein, unless otherwise stated, the ranges are intended to include their endpoints and all integers and fractions within the range. It is not intended to limit the scope of the present invention to the specific values stated when the scope is defined.

[0172] From the opinions of the present invention and the practice of the present invention disclosed herein, other embodiments of the present invention will be obvious to those skilled in the art. It is intended that the present and embodiments are only considered exemplary, and the true scope and spirit of the present invention are given by the following claims and their equivalents.