Wear-resistant high-strength lightening admixture for drilling fluid, and preparation method therefor

Abstract

Disclosed in the present invention are a wear-resistant high-strength lightening admixture for a drilling fluid, and a preparation method therefor. The lightening admixture comprises the following components in percentages by mass (on the basis of all the components totaling 100%): 65-75% of silicon dioxide, 5-10% of aluminum oxide, 5-10% of diboron trioxide, 5-10% of an alkaline earth metal oxide, 5-10% of an alkali metal oxide, 0.2-3% of a rare-earth element, 0-2% of ferric oxide, 0-2% of manganese dioxide, 0-2% of zirconium oxide, 0-2% of zinc oxide, and 0.2-5% of other trace element materials. The preparation method comprises: crushing, grinding and granulating all the components to prepare precursor particles; and pre-treating the precursor particles, then subjecting same to high-temperature hollow-sphere formation, and then performing a surface treatment to prepare a wear-resistant high-strength lightening admixture for a drilling fluid. The product has the advantages of being environmentally friendly an obvious density reducing effect, lubricating and resistance-reducing functions, no loss of MWD signals, etc.; moreover, the problems of low compressive strength, proneness to breakage, poor wear resistance, etc., of existing low-density hollow glass bead lightening admixtures are solved.

Description

A wear-resistant high-strength lightening agent for drilling fluid and a preparation method thereof TECHNICAL FIELD

[0001] The present application belongs to the field of high-temperature-resistant additive materials for drilling fluid and cement slurry in the process of drilling and completion of oil and gas resources, and particularly relates to a wear-resistant high-strength lightening agent for drilling fluid and a preparation method thereof, which is mainly applied to the field of oil and gas resource exploitation and is particularly suitable for preparing low-density drilling fluid with a density of 0.8-1.0 g / cm 3 and low-density cement slurry for well cementation with a density of 0.90-1.45 g / cm 3 . BACKGROUND

[0002] Oil and gas resources are the foundation of the national industry and the guarantee of the people's livelihood. With the continuous exploitation of oil and gas resources, the proportion of unconventional oil and gas resources is increasing, and the exploitation difficulty is increasing.

[0003] Oil and gas reservoirs with a pressure coefficient less than 0.96 are low-pressure oil and gas reservoirs. According to statistics, the number of low-pressure oil and gas reservoirs accounts for 11.7% in the oil and gas fields of more than 160 countries in the world. There are also a large number of low-pressure oil and gas resources in the basins of Ordos, Sichuan, Songliao and Tarim. Such oil and gas resources are difficult to exploit, and the requirements for drilling fluid are high. Conventional drilling fluid with a density of ≥1.05 g / cm 3 is prone to drilling fluid loss and oil layer pollution during drilling and completion. In order to avoid the above problems and improve drilling efficiency, the density of drilling fluid for low-pressure oil and gas reservoirs is required to be ≤1.0 g / cm 3 .

[0004] Traditional low-density drilling fluid is mainly oil-based drilling fluid, aerated drilling fluid or foam drilling fluid. Among them, drilling fluid with a density of 0.85-1.00 g / cm 3 is mostly oil-based drilling fluid. Although this system drilling fluid has the advantages of good flowability, strong temperature resistance and low density, it also has unavoidable disadvantages such as serious environmental pollution, high cost and being not conducive to logging operations. Drilling fluid with a density lower than 0.85 g / cm 3 is mostly aerated drilling fluid or foam drilling fluid, which has the advantages of low density, wide adjustable range and good leak-off prevention ability. However, it has the disadvantages of compressibility of gas, serious attenuation of pulse signal, limitation of MWD technology, corrosion of drilling tools, complex hydraulic calculation and high friction coefficient, which limits its application range. Therefore, it is of great significance to study an environmentally friendly, low-density, temperature-resistant, incompressible and MWD technology suitable lightening agent for drilling fluid.

[0005] As a multifunctional reducer developed in recent years, hollow glass microspheres are widely used in cementing cement slurry due to their excellent properties such as hollow, lightweight, compression resistance, high strength, etc., which has effectively promoted the progress of cementing technology in China. In the early 21st century, relevant technical personnel also began to use hollow glass microspheres as a drilling fluid reducer to prepare low-density drilling fluid and conducted several field tests, which verified that the hollow glass microspheres as a reducer for preparing drilling fluid have the advantages of environmental friendliness, obvious density reduction effect, lubrication and drag reduction, no loss of MWD signal, etc. However, due to the large amount of crushing of hollow glass microspheres, the flowability is poor, the viscosity increases, and the cost increases, which makes it impossible to be used as a reducer for low-density drilling fluid system.

[0006] In order to solve the related problems existing in traditional low-density drilling fluid or reducer, technical personnel in the field have carried out a lot of technical research and innovation, hoping to develop an environmentally friendly, obvious density reduction effect, lubrication and drag reduction, no loss of MWD signal, stable drilling fluid performance, low-cost reducer or low-density drilling fluid system for use in the process of drilling and completion of low-pressure oil and gas reservoirs. For example, Chinese patent CN105086952B discloses a "drilling fluid reducer and its preparation method", the water-based drilling fluid reducer is a hollow glass microsphere coated with a polymer layer resistant to 90℃ temperature conditions, the hollow glass microspheres used only resist 28MPa pressure, and after being coated with a polymer layer, they only resist 40MPa pressure, and the drilling fluid prepared has a density >0.95g / cm 3 , poor applicability. Chinese patent CN115432921A (under review) discloses "a special hollow glass microsphere for drilling fluid density reducer and its production method", the reducer is a hollow glass microsphere, but it can only prepare a reducer with a density of 0.38-0.60g / cm 3 , the density adjustment range of drilling fluid is limited, and it does not provide a solution to the problems of drill tool wear and cement slurry flowability. Chinese patent CN103666407B discloses "drilling fluid and its preparation method", which uses lightweight high polymer hollow microspheres as a reducer, which is easy to pollute the environment; at the same time, due to its certain elasticity and deformability, it is easy to change under certain pressure conditions, causing problems such as drilling fluid density fluctuation, pulse signal weakening, etc.

[0007] In view of the above technical problems, the present application uses a material or mineral containing silicon, aluminum, boron, alkali metal oxide, alkaline earth metal oxide, rare earth element, iron, manganese, zirconium, zinc and other elements as the main raw material, granulates by physical or chemical method to form precursor particles, and hollows the particles by powder high-temperature spheroidization technology to prepare a wear-resistant high-strength lightening agent for drilling fluid. The lightening agent is modified by surface modification process and applied to low-density cement slurry and drilling fluid in the process of oil and gas resource exploitation, especially to low-density drilling fluid. The lightening agent has the advantages of safety and environmental protection, obvious density reduction effect, adjustable density, good stability under high temperature and high pressure, low lubricating drag and drill tool wear, improved mud cake quality and low filtration loss, good flowability, no loss of MWD signal and low cost.

[0008] SUMMARY

[0009] The present application aims at the unavoidable defects of traditional oil-based low-density drilling fluid, such as serious environmental pollution, high cost and adverse effects on logging operation, and the technical problems of aerated drilling fluid or foam drilling fluid, such as compressibility, serious attenuation of pulse signal, limitation of MWD technology, corrosion of drill tool, complex hydraulic calculation and high friction coefficient, and the problems of existing low-density hollow microsphere lightening agent, such as low compressive strength, easy breakage and poor wear resistance, and the deformation of high polymer microspheres, which causes density fluctuation of drilling fluid and attenuation of pulse signal. The present application provides a wear-resistant high-strength lightening agent for drilling fluid, which is used to prepare low-density drilling fluid with a density of 0.8-1.0 g / cm 3 and low-density cement slurry with a density of 0.90-1.45 g / cm 3 The low-density cement slurry has the advantages of environmental friendliness, obvious density reduction effect, lubricating drag, no loss of MWD signal and the like, and solves the technical problems of existing low-density hollow glass microsphere lightening agent, such as low compressive strength, easy breakage and poor wear resistance.

[0010] Another object of the present application is to provide a preparation method of the wear-resistant high-strength lightening agent for drilling fluid.

[0011] To achieve the above object, the wear-resistant high-strength lightening agent for drilling fluid is prepared from the following components, and the mass content of each component is calculated based on the sum of raw material components being 100%:

[0012] Silicon dioxide: 65-75%

[0013] Aluminum oxide: 5-10%

[0014] Boron trioxide: 5-10%

[0015] Alkaline earth metal oxide: 5-10%

[0016] Alkali metal oxide: 5-10%

[0017] Rare earth elements: 0.2-3%

[0018] Ferric oxide: 0-2%

[0019] Manganese dioxide: 0-2%

[0020] Zirconium oxide: 0-2%

[0021] Zinc oxide: 0-2%

[0022] Other trace element materials: 0.2-5%.

[0023] Further, the content of each compound in the alkaline earth metal oxide is, when the total content is calculated as 100%, calcium oxide 70-80%, magnesium oxide 10-25%, and strontium oxide 0-15%. This ratio makes full use of the difference in ion size of different alkaline earth metal oxides, and enhances the wear resistance of the glass after high-temperature hollow sphere formation.

[0024] Further, the content of each compound in the alkali metal oxide is, when the total content is calculated as 100%, sodium oxide 70-80%, potassium oxide 10-25%, and lithium oxide 0-10%. This ratio makes full use of the mixed alkali effect and the difference in ion size of alkali metal ions, enhances the fluxing effect of alkali metal ions, and hinders ion migration in the glass by changing the microstructure of the glass after high-temperature hollow sphere formation, thereby improving the structural stability of the glass.

[0025] Further, the content of each compound in the rare earth elements is, when the total content is calculated as 100%, the total content of cerium oxide and lanthanum oxide 75-90%, yttrium oxide 0-10%, neodymium oxide 0-10%, and scandium oxide 0-10%. This ratio further prevents crystallization of the glass during high-temperature hollow sphere formation, and improves the thermal stability, hardness, and wear resistance of the glass.

[0026] Further, the other trace element materials are one or a mixture of two or more of tungsten oxide, vanadium oxide, and phosphorus pentoxide.

[0027] The total content of ferric oxide and manganese dioxide is not zero, which greatly improves the corrosion resistance and stability of the glass.

[0028] As a preferred embodiment of the present application, the other trace element materials are one or a mixture of two or more of tungsten oxide, vanadium oxide, and phosphorus pentoxide.

[0029] The above-mentioned formula of the present application uses materials or minerals containing silicon, aluminum, boron, alkali metal oxides, alkaline earth metal oxides, rare earth elements, iron, manganese, zirconium, zinc, and other elements as main raw materials, and the raw materials are widely available.

[0030] The application discloses a preparation method of a wear-resistant high-strength lightweight agent for a drilling fluid.

[0031] (1) Preparation of precursor particles

[0032] According to the formula, each raw material component is accurately weighed, all components are pre-mixed, and then broken and ground to a certain particle size, and then granulation treatment is performed to prepare precursor particles with a particle size D50 of 20-40 μm; through physical classification treatment, the particle size D90 of the precursor particles is controlled to be less than or equal to 60 μm, and particles exceeding the particle size range can be sorted out by physical classification, and the material is re-granulated.

[0033] The granulation treatment can adopt one or more of wet granulation, dry granulation, adhesive granulation, fluidized bed granulation, dry granulation and the like, to prepare precursor particles with a particle size D50 of 20-40 μm.

[0034] (2) Pretreatment of precursor particles

[0035] The precursor particles prepared in step (1) are dried to reduce the water content to less than or equal to 0.5%; and then the precursor particles are pretreated by physical or chemical methods to reduce the agglomeration between fine particles, improve the flowability, facilitate the subsequent process of conveying, and can be uniformly dispersed in the high-temperature vitrification process, and at the same time, the heat transfer efficiency of the particles is improved.

[0036] (3) High-temperature hollow spheroidization of precursor particles

[0037] After the precursor particles prepared in step (2) are fully mixed with the combustion-supporting gas, the material and the combustion-supporting gas are sent into a mixing chamber by pneumatic conveying to mix with fuel, and then the mixed precursor particles, combustion-supporting gas and fuel are introduced into a high-temperature vitrification furnace with a temperature of 1000-1450℃; the particles are melted into a glass melt under the action of surface tension, and at the same time, the high-temperature mixed gas is wrapped in the inside; after the glass melt passes through a high-temperature forming area, it is rapidly cooled to 400-600℃ within 2 minutes, and then slowly cooled to room temperature within 1-4 hours to form a wear-resistant high-strength lightweight agent with a density of 0.28-0.60 g / cm 3 , a particle size D50 of 20-40 μm, a particle size D90 of less than or equal to 60 μm, and a strength of 20-150 MPa;

[0038] (4) Surface treatment of the lightweight agent: a surface treatment agent is selected to perform surface treatment on the lightweight agent prepared in step (3) to obtain a lightweight agent with wide matrix adaptability and strong interfacial bonding force, and the density is 0.28-0.60 g / cm 3The drilling fluid wear-resistant high-strength lightening agent has a particle size D50 of 20-40 microns, a particle size D90 of less than or equal to 60 microns, and a strength of 20-150 MPa.

[0039] The physical method is to give the particles the same electric charge by using a corona charging machine or a Faraday charging machine, so that the particles repel each other and achieve good fluidity; the chemical method is to modify the surface of the precursor particles after drying by using a surface treatment agent, so as to avoid particle agglomeration and improve the fluidity.

[0040] The surface treatment agent is any one or a mixture of two or more of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a zirconium aluminate coupling agent, a surfactant, an organosilicon, an unsaturated organic acid and an organic oligomer, an ultra-dispersant, a water-soluble polymer, and an inorganic surface modifier. The surface treatment agent needs to be customized according to the composition of the drilling fluid to improve the compatibility of the lightening agent with the drilling fluid, improve the interfacial bonding force of the lightening agent with the drilling fluid, and reduce the migration of metal ions.

[0041] In step (3), the combustion-supporting gas is hollow, oxygen, or a combination of the two, and the fuel is one or a combination of coal gas, natural gas, or petroleum gas.

[0042] In step (4), the surface treatment agent is any one or a mixture of two or more of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a zirconium aluminate coupling agent, a surfactant, an organosilicon, an unsaturated organic acid and an organic oligomer, an ultra-dispersant, a water-soluble polymer, and an inorganic surface modifier; the surface treatment method is to first use an inorganic surface modifier for surface treatment, and then use one or two of a surfactant, an unsaturated organic acid, a dispersant, and a water-soluble polymer for surface modification. This surface treatment mode improves the wear resistance and impact resistance of the lightening agent, further improves the interfacial bonding force of the lightening agent with the drilling fluid, and reduces the migration of metal ions.

[0043] The drilling fluid wear-resistant high-strength lightening agent prepared by the application is an aluminum-boron-silicate hollow glass microsphere treated by a surface treatment agent, has the advantages of low density, small particle size, high strength, wear resistance, good chemical stability, high mechanical strength, and high temperature resistance, and can be used to prepare a low-density drilling fluid with a density of 0.8-1.0 g / cm 3 and a low-density cement slurry with a density of 0.90-1.45 g / cm 3 The low-density cement slurry is particularly suitable for preparing a low-density drilling fluid. The prepared low-density drilling fluid has the advantages of environmental friendliness, obvious density reduction effect, lubrication and drag reduction, no loss of MWD signal, and solves the problems of low compressive strength, easy breakage, and poor wear resistance of existing low-density hollow glass microsphere lightening agents, and further promotes the progress of low-density drilling fluid technology.

[0044] Compared with the prior art, the drilling fluid wear-resistant high-strength lightening agent and the preparation method thereof have the following beneficial effects:

[0045] (1) The formula takes materials or minerals containing silicon, aluminum, boron, alkali metal oxides, alkaline earth metal oxides, rare earth elements, iron, manganese, zirconium, zinc and other elements as main raw materials, and the raw materials are widely sourced.

[0046] (2) Through formula optimization, the microspheres of the application are micro glass network structures with boron aluminum silicon skeletons, which improves the structural compactness and high temperature stability of the microspheres; the formula of the application fully utilizes the mixed alkali effect of alkali metal oxides, the size difference between the alkali metal ions and the alkaline earth metal ions, and through element introduction and formula design, the mechanical properties such as wear resistance, hardness and thermal stability are greatly improved; by changing the glass microstructure to hinder ion migration in the glass, the technical problems of poor wear resistance, low hardness and easy breakage during drilling of common hollow glass microspheres as lightening agents applied in drilling fluid are solved.

[0047] (3) The precursor particles after drying treatment are pretreated by physical or chemical methods, which avoids the agglomeration between the fine particles and significantly improves the flowability. Due to the small particle size and large specific surface area of the precursor particles, and the presence of a large amount of alkali metal, alkaline earth metal and boron-containing oxide components, the precursor particles are prone to absorb moisture in the air and form lumps. The application reduces the contact area and time of hydroxyl groups and other water-absorbing groups with water molecules in the form of surface coating, or gives the same surface charge to generate electrostatic repulsion, so that the particles have excellent flowability and dispersibility, and the particles are prevented from sticking together; compared with untreated particles, the processing amount of precursor particles per unit time during the high-temperature spheroidization process is greatly improved, and the industrialization time cost is saved.

[0048] (4) During the high-temperature spheroidization process of the precursor particles, the particles are prepared into micron-sized hollow glass microsphere particles with uniform composition, dense structure, wear resistance and high hardness. The low-density drilling fluid prepared by taking the hollow glass microsphere particles as a lightening agent has the advantages of safety and environmental protection, obvious effect of reducing density, adjustable density, good stability under high temperature and high pressure, low lubrication and drag reduction, low drilling tool wear, improved mud cake quality, reduced filtration loss, good flowability, no loss of MWD signal, and low cost.

[0049] (5) One or more of the inorganic surface modifiers is preferably used in the surface treatment process of the lightening agent, which further improves the wear resistance and impact resistance of the lightening agent; further, after treatment with the inorganic surface modifier, one or more of the surfactants, unsaturated organic acids, dispersants, water-soluble polymers and other modifiers is used for surface modification, which improves the interfacial adhesion between the lightening agent and the drilling fluid, further improves the wear resistance and impact resistance of the lightening agent, and reduces the migration of metal ions. DETAILED DESCRIPTION

[0050] In order to describe the present application, a drilling fluid wear-resistant high-strength lightweight additive and a preparation method thereof are further described in detail below in combination with examples. However, the present application is not limited to the examples.

[0051] Example 1

[0052] The specific implementation process is as follows:

[0053] (1) Preparation of precursor particles: the raw materials are weighed according to the formula 1 in Table 1 and pre-mixed, the pre-mixed materials are broken and ground by a ball mill, the particle size distribution D 90 of the broken and ground raw materials is 4.8 μm, the mixture is granulated by a dry granulator to obtain precursor particles with a particle size D 50 of 36 μm, and the precursor particles with a particle size D 90 of 58 μm are returned to the breaking and grinding section for repeated use.

[0054] (2) Pretreatment of precursor particles: the precursor particles prepared in step (1) are placed in a drying machine and dried at a temperature of 80°C to obtain precursor particles with a water content of 0.32%, and a corona charging machine is used to give the same electric charge to the surface of the precursor particles so that the particles repel each other and achieve good fluidity.

[0055] (3) High-temperature hollow spheroidization of precursor particles: air is used as a combustion-supporting gas, the precursor particles prepared in step (2) are mixed with the air, and then the mixture is mixed with natural gas in a mixing chamber by means of pneumatic conveying, the mixed precursor particles, air and fuel are introduced into a high-temperature vitrification furnace with a temperature of 1150°C, the particles are melted into a glass melt under the action of surface tension, and the glass melt forms a spherical shape while wrapping the high-temperature mixed gas in the inside, after passing through the high-temperature forming zone, the glass melt is rapidly cooled to 400-600°C for 30-60 s, and then slowly cooled to room temperature for 1.0-1.5 h to form a wear-resistant high-strength lightweight additive with a density of 0.28 g / cm 3 , a particle size D50 of 36 μm, a particle size D90 of 58 μm and a strength of 20 MPa.

[0056] (4) Surface treatment of the lightweight additive: a commercially available vinyl silane coupling agent is selected, the vinyl silane coupling agent with a mass of 0.3% of the mass of the lightweight additive is weighed as a surface modifier, the lightweight additive prepared in step (3) is modified by wet method to coat a layer of vinyl silane coupling agent on the surface, and after drying at a temperature of 105°C by using a drying device, a wear-resistant high-strength lightweight additive with a density of 0.28 g / cm 3The drilling fluid wear-resistant high-strength light-weighting agent has a particle size D50 of 36 μm, a particle size D90 of 58 μm and a strength of 20 MPa.

[0057] Example 2

[0058] The specific implementation process is as follows:

[0059] (1) Preparation of precursor particles: the raw materials are weighed according to the formulation 2 in Table 1 and pre-mixed, the pre-mixed materials are broken and ground by using a ball mill, the particle size distribution D 90 of the broken and ground raw materials is 4.1 μm; the mixture is granulated by using a wet granulator to obtain precursor particles with a particle size D 50 of 32 μm; the precursor particles are prepared by physical classification treatment, the particle size D 90 of the precursor particles is 54 μm, and the remaining large-particle precursor particles are returned to the breaking and grinding section for repeated use.

[0060] (2) Pretreatment of precursor particles: the precursor particles prepared in step (1) are placed in a drying machine and dried at a temperature of 70 ℃ to obtain precursor particles with a water content of 0.28%; the precursor particles are surface treated by using an epoxy silane to obtain precursor particles with good fluidity.

[0061] (3) High-temperature hollow spheroidization of precursor particles: 80% air and 20% oxygen are used as combustion-supporting gas, the precursor particles prepared in step (2) are mixed with the combustion-supporting gas, the mixed materials are mixed with coal gas in a mixing chamber by using pneumatic conveying, the mixed precursor particles, air and fuel are introduced into a high-temperature vitrification furnace with a temperature of 1250 ℃; the particles are melted into glass melt, the glass melt forms a spherical shape under the action of surface tension, and the high-temperature mixed gas is wrapped in the interior of the glass melt; after the glass melt passes through the high-temperature forming zone, it is rapidly cooled to a temperature of 400-600 ℃ for 50-80 s, and then slowly cooled to room temperature for 1.5-2.0 h to obtain a wear-resistant high-strength light-weighting agent with a density of 0.38 g / cm 3 , a particle size D50 of 32 μm, a particle size D90 of 54 μm and a strength of 40 MPa.

[0062] (4) Surface treatment of light-weighting agent: commercially available zirconium aluminate is selected as a surface modifier, 0.3% zirconium aluminate of the light-weighting agent is weighed, the light-weighting agent prepared in step (3) is modified by wet method, and the light-weighting agent is dried at a temperature of 110 ℃ by using a drying device to obtain a wear-resistant high-strength light-weighting agent for drilling fluid with a density of 0.38 g / cm 3 , a particle size D50 of 32 μm, a particle size D90 of 54 μm and a strength of 40 MPa.

[0063] Example 3

[0064] The specific implementation process is as follows:

[0065] (1) Preparation of precursor particles: the raw materials are weighed according to the formulation 3 in Table 1 and pre-mixed, the pre-mixed materials are broken and ground by a ball mill, the particle size distribution D 90 of the broken and ground raw materials is 3.5 μm, the mixture is granulated by dry granulation to obtain precursor particles with a particle size D 50 of 25 μm, and the precursor particles are physically classified to obtain precursor particles with a particle size D 90 of 50 μm, and the remaining large-particle precursor particles are returned to the breaking and grinding section for repeated use.

[0066] (2) Pretreatment of precursor particles: the precursor particles prepared in step (1) are placed in a drying machine and dried at a temperature of 90°C to obtain precursor particles with a water content of 0.20%, and the precursor particles are surface treated with triisopropyl aluminate to obtain precursor particles with good fluidity.

[0067] (3) High-temperature hollow spheroidization of precursor particles: 60% air and 40% oxygen are used as combustion-supporting gas, the precursor particles prepared in step (2) are mixed with the combustion-supporting gas, the mixed materials are mixed with petroleum gas in a mixing chamber by pneumatic conveying, the mixed precursor particles, air and fuel are introduced into a high-temperature sintering furnace with a temperature of 1350°C, the particles are melted into glass melt under the action of surface tension to form spherical shape, and the high-temperature mixed gas is wrapped in the interior of the particles; after the glass melt passes through the high-temperature forming zone, it is rapidly cooled to 400-600°C for 20-40 s and then slowly cooled to room temperature for 0.5-1.0 h to form a wear-resistant high-strength lightweight agent with a density of 0.47 g / cm 3 , a particle size D50 of 25 μm, a particle size D90 of 50 μm and a strength of 60 MPa.

[0068] (4) Surface treatment of lightweight agent: commercially available triisopropyl aluminate is selected as a surface modifier, 0.5% triisopropyl aluminate by mass of the lightweight agent is weighed, the lightweight agent prepared in step (3) is wet modified, and the modified lightweight agent is dried at 135°C by using a drying device; then the lightweight agent is surface treated with 0.2% polymethacrylic acid by mass of the lightweight agent, and the surface treated lightweight agent is dried at 110°C, finally obtaining a wear-resistant high-strength lightweight agent for drilling fluid with a density of 0.47 g / cm 3 , a particle size D50 of 28 μm, a particle size D90 of 50 μm and a strength of 60 MPa.

[0069] Example 4

[0070] The specific implementation process is as follows:

[0071] (1) Preparation of precursor particles: the raw materials were weighed according to the formulation 4 in Table 1 and pre-mixed, the pre-mixed materials were broken and ground by a ball mill, the particle size distribution D 90 was 2.5 μm; the mixture was granulated by dry granulation to obtain precursor particles with a particle size D 50 of 25 μm; the precursor particles were subjected to physical classification to obtain precursor particles with a particle size D 90 of 45 μm, and the remaining large-particle precursor particles were returned to the breaking and grinding section for repeated use.

[0072] (2) Pretreatment of precursor particles: the precursor particles prepared in step (1) were placed in a dryer and subjected to drying treatment at a temperature of 110°C to obtain precursor particles with a water content of 0.18%; the precursor particles were subjected to surface treatment with polycaprolactone diol to obtain precursor particles with good flowability.

[0073] (3) High-temperature hollow spheroidization of precursor particles: 40% air and 60% oxygen were used as combustion-supporting gas, and the precursor particles prepared in step (2) were mixed with the gas, and then the mixture was mixed with petroleum gas in a mixing chamber by means of pneumatic conveying, and the mixed precursor particles, air and fuel were introduced into a high-temperature sintering furnace with a temperature of 1450°C; the particles were melted into glass melt under the action of surface tension to form spherical shape, and the high-temperature mixed gas was wrapped in the interior; after passing through the high-temperature forming zone, the glass melt was rapidly cooled to 400-600°C for 20-40 s, and then slowly cooled to room temperature for 1.0-2.0 h to form a wear-resistant high-strength lightweight agent with a density of 0.55 g / cm 3 , a particle size D50 of 25 μm, a particle size D90 of 45 μm and a strength of 103 MPa.

[0074] (4) Surface treatment of lightweight agent: a commercially available monoalkoxy titanate was selected as a surface modifier, 0.8% of the mass of the lightweight agent was weighed, and the lightweight agent prepared in step (3) was subjected to wet modification, and then dried at 140°C by using a drying device; subsequently, 0.3% of the mass of the lightweight agent was weighed as sodium dodecylbenzenesulfonate, and the lightweight agent was subjected to surface treatment, and then dried at 100°C, to finally obtain a wear-resistant high-strength lightweight agent for drilling fluid with a density of 0.55 g / cm 3 , a particle size D50 of 25 μm, a particle size D90 of 45 μm and a strength of 103 MPa.

[0075] Example 5

[0076] The specific implementation process is as follows:

[0077] (1) Preparation of precursor particles: the raw materials were weighed according to the formulation 5 in Table 1 and pre-mixed, the pre-mixed materials were broken and ground by a ball mill, the particle size distribution D50 of the broken and ground raw materials was 1.8 μm, the mixture was granulated by a wet granulation method, and the precursor particles with a particle size D50 of 16 μm were prepared. 90 The particle size distribution D50 of the broken and ground raw materials was 1.8 μm; the mixture was granulated by a wet granulation method, and the precursor particles with a particle size D 50 50 of 16 μm were prepared; the precursor particles were prepared by physical classification treatment, and the particle size D50 of the precursor particles was 35 μm. 90 The remaining large precursor particles were returned to the breaking and grinding section for repeated use.

[0078] (2) Pretreatment of precursor particles: the precursor particles prepared in step (1) were placed in a drying machine and dried at a temperature of 110°C to obtain precursor particles with a water content of 0.18%; the precursor particles were surface treated with sodium lauryl polyoxyethylene ether sulfate to obtain precursor particles with good flowability.

[0079] (3) High-temperature hollow spheroidization of precursor particles: oxygen was used as a combustion-supporting gas, the precursor particles prepared in step (2) were mixed with oxygen, the mixed materials were mixed with natural gas in a mixing chamber by pneumatic conveying, the mixed precursor particles, air and fuel were introduced into a high-temperature vitrification furnace with a temperature of 1450°C; the particles were melted into a glass melt, and under the action of surface tension, the particles formed a spherical shape, and the high-temperature mixed gas was wrapped inside; after passing through the high-temperature forming zone, the glass melt was rapidly cooled to 400-600°C for 20-40 s, and then slowly cooled to room temperature for 1.0-2.0 h, to form a wear-resistant high-strength lightweight agent with a density of 0.60 g / cm 3 , a particle size D50 of 16 μm, a particle size D90 of 35 μm and a strength of 150 MPa.

[0080] (4) Surface treatment of lightweight agent: commercially available 80% monoalkoxy titanate and 30% aluminate coupling agent were selected as a composite surface modifier, 0.5% of the composite surface modifier based on the mass of the lightweight agent was weighed, the lightweight agent prepared in step (3) was dry modified, and the modified lightweight agent was dried at 140°C by using a drying device; then, 0.4% of a mixed treatment agent (60% dodecylbenzenesulfonic acid sodium and 40% lauryl polyoxyethylene ether sulfate) based on the mass of the lightweight agent was used for surface treatment of the lightweight agent, and the treated lightweight agent was dried at 100°C, to finally obtain a drilling fluid wear-resistant high-strength lightweight agent with a density of 0.60 g / cm 3 , a particle size D50 of 16 μm, a particle size D90 of 35 μm and a strength of 150 MPa.

[0081] Table 1: mass fraction of each component in examples 1-5 Table 1: mass fraction of each component in examples 1-5 Table 1: mass fraction of each component in examples 1-5

[0082] The upper and lower limits of the values of each raw material and process parameter, and the interval values can realize the present application, and are not listed one by one here.

Claims

1. A wear-resistant and high-strength lightener for drilling fluid, characterized in that It is prepared by processing the following components. When the sum of the raw material components is calculated as 100%, the mass content of each component is: Silicon dioxide: 65-75% Aluminum oxide: 5-10% Boron trioxide: 5-10% Alkaline earth metal oxides: 5-10% Alkali metal oxides: 5-10% Rare earth elements: 0.2-3% Ferric oxide: 0-2% Manganese dioxide: 0-2% Zirconia: 0-2% Zinc oxide: 0-2% Other trace element materials: 0.2~5%.

2. The wear-resistant and high-strength lightening agent for drilling fluid according to claim 1, characterized in that: The content of each compound in the alkaline earth metal oxide when the total content is calculated as 100% is: calcium oxide 70-80%, magnesium oxide 10-25%, and strontium oxide 0-15%.

3. The wear-resistant and high-strength lightening agent for drilling fluid according to claim 1, characterized in that: The content of the alkali metal oxide when the total content of each compound is calculated as 100% is: sodium oxide 70-80%, potassium oxide 10-25%, lithium oxide 0-10%.

4. The wear-resistant and high-strength lightening agent for drilling fluid according to claim 1, characterized in that: The total content of each compound in the rare earth element is 100%, and the total content of cerium oxide and lanthanum oxide is 75-90%, yttrium oxide is 0-10%, neodymium oxide is 0-10%, and scandium oxide is 0-10%.

5. The wear-resistant and high-strength lightening agent for drilling fluid according to claim 1, characterized in that: The other trace element materials are one or a mixture of two or more of tungsten oxide, vanadium oxide and phosphorus pentoxide.

6. The method for preparing a wear-resistant and high-strength lightening agent for drilling fluid according to claim 1, 2, 3, 4 or 5, characterized in that Use the following steps to implement: (1) Preparation of precursor particles Accurately weigh each raw material component according to the formula composition, premix all the components, crush and grind them to a certain particle size, and then granulate them to prepare precursor particles with a particle size D50 of 20 to 40 μm; after physical classification, control the particle size D90 of the precursor particles to ≤ 60 μm; (2) Precursor particle pretreatment The precursor particles prepared in step (1) are dried to reduce their moisture content to less than 0.5%; the precursor particles are then pretreated using physical or chemical methods to reduce agglomeration between fine particles and improve their fluidity; (3) High-temperature hollow spheroidization of precursor particles After the precursor particles prepared in step (2) are fully mixed with the combustion-supporting gas, the materials and the combustion-supporting gas are transported into a mixing chamber by pneumatic conveying to be mixed with the fuel. The mixed precursor particles, combustion-supporting gas and fuel are introduced into a high-temperature vitrification furnace at a temperature of 1000-1450°C; the particles are melted into a glass melt at high temperature and formed into a spherical shape under the action of surface tension, while the high-temperature mixed gas is wrapped inside the glass melt; after the glass melt passes through the high-temperature forming zone, it is rapidly cooled to 400-600°C within 2 minutes, and then slowly cooled to room temperature over 1-4 hours to form a density of 0.28-0.60 g / cm 3 , wear-resistant high-strength lightener with particle size D50 of 20-40μm, particle size D90≤60μm, and strength of 20-150MPa; (4) Surface treatment of lightening agent: Select a surface treatment agent and perform surface treatment on the lightening agent prepared in step (3) to obtain a lightening agent with a density of 0.28 to 0.60 g / cm 3 Wear-resistant and high-strength reducing agent for drilling fluid with particle size D50 of 20-40μm, particle size D90≤60μm and strength of 20-150MPa.

7. The method for preparing a wear-resistant and high-strength lightening agent for drilling fluid according to claim 6, characterized in that: The physical method is to use a corona generator or a paradigm generator device to give the particles the same charge on the surface, achieving a mutual repulsion effect, thereby achieving good fluidity; the chemical method is to use a surface treatment agent to modify the surface of the dried precursor particles to avoid particle agglomeration and improve their fluidity.

8. The method for preparing a wear-resistant and high-strength lightening agent for drilling fluid according to claim 6, wherein: The surface treatment agent is any one of silane coupling agent, titanate coupling agent, aluminate coupling agent, zirconium aluminate coupling agent, surfactant, organosilicon, unsaturated organic acid and organic oligomer, hyperdispersant, water-soluble polymer, inorganic surface modifier or a mixture of two or more thereof.

9. The method for preparing a wear-resistant and high-strength lightening agent for drilling fluid according to claim 6, wherein: In step (3), the combustion-supporting gas is hollow, oxygen or a combination of the two, and the fuel is one or more combinations of coal gas, natural gas or petroleum gas.

10. The method for preparing a wear-resistant and high-strength lightening agent for drilling fluid according to claim 6, characterized in that: In step (4), the surface treatment agent is any one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a zirconium aluminate coupling agent, a surfactant, an organosilicon, an unsaturated organic acid and an organic oligomer, a hyperdispersant, a water-soluble polymer, and an inorganic surface modifier, or a mixture of two or more thereof; the surface treatment method is: firstly performing surface treatment with an inorganic surface modifier, and then performing surface modification with one of a surfactant, an unsaturated organic acid, a dispersant, and a water-soluble polymer, or a mixture of two or more thereof.

Images