A wear-resistant high-strength lightening agent for preparing a low-density drilling fluid

Abstract

The application discloses a wear-resistant high-strength lightening agent for preparing low-density drilling fluid, and the mass content of each component of raw material components is calculated according to 100%: 64-75% of silicon dioxide, 4.5-8% of aluminum oxide, 4.5-9% of boron oxide, 4.5-9% of calcium oxide and magnesium oxide, 5-9% of sodium oxide and potassium oxide, 0.2-2.2% of cerium oxide and lanthanum oxide, 0.3-1.5% of iron oxide and manganese dioxide, and 0.5-5% of other trace element materials. All components are crushed, ground and granulated to prepare precursor particles; the precursor particles are pretreated, high-temperature hollow spheroidized, and then surface treated to prepare the wear-resistant high-strength lightening agent for preparing low-density drilling fluid. The product has the advantages of environmental friendliness, obvious density reduction effect, lubrication and drag reduction, no loss of MWD signal, and the like, and solves the problems of low pressure strength, easy breakage and poor wear resistance of the existing low-density hollow glass microsphere lightening agent.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional material preparation for drilling fluid, and particularly relates to a wear-resistant high-strength lightening agent for preparing low-density drilling fluid, which is particularly suitable for preparing low-density drilling fluid with a density of 0.8-1.0 g / cm 3 . BACKGROUND

[0002] Low-density drilling fluid technology is one of the core technologies for the exploration and development of low-pressure and low-permeability depleted oil and gas reservoirs and underbalanced drilling, and is beneficial to leakage prevention, reservoir protection and speed increase. In common technologies, the environment is polluted by mixing oil, and the cost of air charging and foaming equipment is high. Adding a lightening agent is the simplest way, but the shell of glass hollow microbeads lightening agent is brittle and has a high breakage rate. This technology has not had a major breakthrough due to the lack of new high-performance lightening agents.

[0003] Traditional low-density drilling fluid is mostly oil-based drilling fluid, air-charged 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 of drilling fluid has the advantages of good flowability, strong temperature resistance and low density, it also has the unavoidable disadvantages of 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 air-charged drilling fluid or foam drilling fluid, which has the advantages of low density, wide adjustable range and good leakage prevention ability. However, because it uses gas as a lightening agent, the gas has the disadvantages of compressibility, serious pulse signal attenuation and limitation of the use of MWD technology, and also causes problems such as corrosion of drilling tools, complex hydraulic calculation and high friction coefficient, which limits its range of use. Therefore, it is of great significance to research a lightening agent for drilling fluid that is environmentally friendly, has low density, strong temperature resistance, is incompressible and suitable for MWD technology.

[0004] As a multifunctional reducer developed in recent years, hollow glass microspheres are widely used in cementing cement slurry due to their excellent characteristics such as hollow, light weight, 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 try to use hollow glass microspheres as a drilling fluid reducer to prepare low-density drilling fluid, and carried out several field tests, which verified that it has the advantages of environmental friendliness, obvious density reduction effect, lubrication and drag reduction, no loss of MWD signal, etc. as a reducer to prepare drilling fluid, such as Chinese patent application 202110626850.2 discloses a kind of hollow glass microspheres special for drilling fluid density reducer and its production method, including 50% to 70% by weight of silicon dioxide, 6% to 9% by weight of water glass, 17.5% to 26.8% by weight of sodium borate, 5.3% to 14.5% by weight of calcium carbonate and 0.12% to 1% by weight of magnesium nitrate. The technology overcomes the shortcomings of high breakage rate, high viscosity and high water loss of general hollow glass microspheres in ultra-low density drilling fluid applications, as well as high dosage and high maintenance and processing costs during use, and can effectively solve the problems of frequent maintenance and processing, high dosage, high water loss and thickening of drilling fluid for ultra-low density drilling fluid prepared with hollow glass microspheres as density reducer. However, due to the large amount of broken hollow glass microspheres, the fluidity is poor, the viscosity is increased, and the cost is increased, which makes it impossible to be used as a reducer for low-density drilling fluid system.

[0005] In addition, in order to develop an environmentally friendly, obvious density reduction effect, lubrication and drag reduction, MWD signal loss, stable drilling fluid performance, low cost reducer or low density drilling fluid system for low pressure oil and gas reservoir drilling and completion process, 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 drilling fluid density fluctuations, pulse signal weakening and other problems.

[0006] In view of the above technical problems, it is urgent to develop a safe and environmentally friendly, obvious density reduction effect, adjustable density, low cost wear-resistant high-strength reducer for preparing low-density drilling fluid. SUMMARY

[0007] The present application aims at the shortcomings of the conventional oil-based low-density drilling fluid, such as serious environmental pollution, high cost, and being not conducive to mud logging operation, and the shortcomings of the aerated drilling fluid or foam drilling fluid, such as compressibility, serious pulse signal attenuation, and limitation of the use of MWD technology, and the technical problems of corrosion of drilling tools, complex hydraulic calculation, high friction coefficient, and the problems of the existing low-density hollow glass microsphere reducing agent, such as low compressive strength, easy breakage, and poor wear resistance, and the problems of the high polymer microsphere, such as easy deformation, drilling fluid density fluctuation, and pulse signal attenuation, and provides a wear-resistant high-strength reducing agent for preparing a low-density drilling fluid. 3 The present application aims at the shortcomings of the conventional oil-based low-density drilling fluid, such as serious environmental pollution, high cost, and being not conducive to mud logging operation, and the shortcomings of the aerated drilling fluid or foam drilling fluid, such as compressibility, serious pulse signal attenuation, and limitation of the use of MWD technology, and the technical problems of corrosion of drilling tools, complex hydraulic calculation, high friction coefficient, and the problems of the existing low-density hollow glass microsphere reducing agent, such as low compressive strength, easy breakage, and poor wear resistance, and the problems of the high polymer microsphere, such as easy deformation, drilling fluid density fluctuation, and pulse signal attenuation, and provides a wear-resistant high-strength reducing agent for preparing a low-density drilling fluid. 3 The low-density cement slurry for well cementing has the advantages of environmental friendliness, obvious density reduction effect, lubrication and drag reduction, and no loss of MWD signal, and solves the technical problems of the existing low-density hollow glass microsphere reducing agent, such as low compressive strength, easy breakage, and poor wear resistance.

[0008] To achieve the above-mentioned purposes of the present application, the wear-resistant high-strength reducing agent for preparing a low-density drilling fluid is prepared from the following components, and when the sum of the raw material components is calculated as 100%, the mass content of each component is: 64-75% of silicon dioxide, 4.5-9% of aluminum oxide, 4.5-8% of boron oxide, 4.5-9% of calcium oxide + magnesium oxide, 5-9% of sodium oxide + potassium oxide, 0.2-2.2% of cerium oxide + lanthanum oxide, 0.3-1.5% of ferric oxide + manganese dioxide, and 0.5-5% of other trace element materials; and the following steps are used for preparation:

[0009] 1) Preparation of precursor particles

[0010] According to the formula composition, each raw material component is accurately weighed, all components are pre-mixed and treated, then crushed and ground to a certain particle size, then granulated to prepare precursor particles with a particle size D50 of 20-40 μm; and the precursor particle size D90 is controlled to be ≤60 μm through physical classification treatment.

[0011] The granulation treatment can use one or more of wet granulation, dry granulation, adhesive granulation, fluidized bed granulation, and dry granulation, to prepare precursor particles with a particle size D50 of 20-40 μm.

[0012] 2) Pretreatment of precursor particles

[0013] The precursor particles prepared in step 1) are subjected to drying treatment to reduce the water content to within 0.5%; 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, while improving the heat transfer efficiency of the particles.

[0014] 3) High-temperature hollow spheroidization of precursor particles

[0015] 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 the mixing chamber by pneumatic conveying to mix with the fuel. The mixed precursor particles, combustion-supporting gas and fuel are passed 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 the high-temperature mixed gas is wrapped inside; the glass melt passes through the high-temperature forming zone and is rapidly cooled to 400-600℃ within 2 min, and then slowly cooled to room temperature within 1-4 h, forming 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 ≤60 μm, and a strength of 20-150 MPa;

[0016] 4) Surface treatment of the lightweight agent: the lightweight agent prepared in step 3) is subjected to surface treatment with a selected surface treatment agent, to obtain a wear-resistant high-strength lightweight agent with wide matrix adaptability and strong interfacial bonding force, which is used for preparing low-density drilling fluid.

[0017] Research shows that when the sum of the raw material components is calculated as 100%, the mass content of each component is preferably: silicon dioxide 65-74%, aluminum oxide 6-8%, boron oxide 5-7%, calcium oxide + magnesium oxide 5-9%, sodium oxide + potassium oxide 5-9%, cerium oxide + lanthanum oxide 0.2-2.1%, iron trioxide + manganese dioxide 0.3-1.2%, and other trace element materials 0.5-5%. Among them, the addition of iron trioxide and manganese dioxide greatly improves the corrosion resistance and stability of the glass.

[0018] The research also shows that the ratio of calcium oxide to magnesium oxide in the calcium oxide + magnesium oxide component is preferably between 3:1 and 7:1, which takes full advantage of the difference in ion size of different alkaline earth metal oxides, enhances the wear resistance of the glass after high-temperature hollow sphere formation, and is conducive to improving the wear resistance, hardness, and thermal stability of the final product; in the sodium oxide + potassium oxide component, the ratio of sodium oxide to potassium oxide is preferably in the range of 3:1 to 7:1, which takes full advantage of the mixed alkali effect and the difference in ion size, 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.

[0019] The experiment found that the mass content of cerium oxide is preferably 0.1-0.8% of the raw material components, and the mass content of lanthanum oxide is preferably 0.1-1% of the sum of the raw material components, which further prevents crystallization of the glass during high-temperature hollow sphere formation, while improving the thermal stability, hardness, and wear resistance of the glass.

[0020] Further, the other trace element material is one or a mixture of two or more of yttrium oxide, neodymium oxide, scandium oxide, zirconium oxide, zinc oxide, tungsten oxide, vanadium oxide, and phosphorus pentoxide, wherein at least one of tungsten oxide, vanadium oxide, and phosphorus pentoxide is added.

[0021] The physical method is to use a corona charging machine or a Van de Graaff generator to impart the same charge to the surface of the particles, achieving mutual repulsion and thus good flowability; the chemical method is to use a surface treatment agent to modify the surface of the dried precursor particles, avoiding particle agglomeration and improving their flowability.

[0022] Further, 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 weight reducer with the drilling fluid and the interfacial bonding force between them, while reducing the migration of metal ions.

[0023] Further, 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.

[0024] Further, 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; and the surface treatment method is to first perform surface treatment with the inorganic surface modifier, and then perform surface modification with one or a mixture of two or more of a surfactant, an unsaturated organic acid, a dispersant, and a water-soluble polymer. With this surface treatment mode, the abrasion resistance and impact resistance of the weighting reducer are improved, and the interfacial bonding force between the weighting reducer and the drilling fluid is further improved, and the migration of metal ions is reduced.

[0025] The prepared high-strength and abrasion-resistant weighting reducer for preparing a low-density drilling fluid 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, abrasion resistance, good chemical stability, high mechanical strength, high temperature resistance, and the like, and is particularly suitable for preparing a low-density drilling fluid with a density of 0.8-1.0 g / cm 3 . The prepared low-density drilling fluid has the advantages of environmental friendliness, obvious density reduction effect, lubrication and drag reduction, and no loss of MWD signal, and solves the problems of low compressive strength, easy breakage, and poor abrasion resistance of the existing low-density hollow glass microsphere weighting reducer, and further promotes the progress of low-density drilling fluid technology. 3 The prepared low-density drilling fluid has the advantages of environmental friendliness, obvious density reduction effect, lubrication and drag reduction, and no loss of MWD signal, and solves the problems of low compressive strength, easy breakage, and poor abrasion resistance of the existing low-density hollow glass microsphere weighting reducer, and further promotes the progress of low-density drilling fluid technology.

[0026] Compared with the prior art, the high-strength and abrasion-resistant weighting reducer for preparing a low-density drilling fluid has the following beneficial effects:

[0027] (1) The formula uses materials or minerals containing silicon, aluminum, boron, alkali metal oxides (sodium oxide + potassium oxide), alkaline earth metal oxides (calcium oxide + magnesium oxide), rare earth elements (cerium oxide + lanthanum oxide), iron, manganese, zirconium, zinc, and other elements as main raw materials, and the raw materials are widely available.

[0028] (2) Through formula optimization, the microspheres of the application have a boron-aluminum-silicon skeleton micro glass network structure, 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 abrasion resistance, hardness, and thermal stability are greatly improved; by changing the glass microstructure, the ion migration in the glass is hindered, and the technical problems of poor abrasion resistance, low hardness, and easy breakage during drilling when the common hollow glass microspheres are used as a weighting reducer in drilling fluid are solved.

[0029] (3) The precursor particles after drying treatment are pretreated by physical or chemical methods, so as to avoid agglomeration between the fine particles, and the flowability is significantly improved. Due to the small particle size, large specific surface area and the like of the precursor particles, and the fact that the precursor particles contain a large amount of alkali metals, alkaline earth metals and boron oxide and the like, the precursor particles are extremely easy to absorb moisture in the air and to be agglomerated. The present application reduces the area and time of contact between the hydroxyl groups and the like and water molecules in the form of surface coating, or gives the same surface charge to the precursor particles, so as to generate an electric repulsive force, so that the precursor particles have excellent flowability and dispersibility, and the agglomeration between the particles is avoided. Compared with the untreated particles, the processing amount of the precursor particles per unit time in the high-temperature spheroidization process is greatly improved, and the industrial time cost is saved.

[0030] (4) In 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 hollow glass microsphere particles are used as a lightweight agent to prepare a low-density drilling fluid, which has the advantages of safety and environmental protection, obvious density reduction effect, adjustable density, good stability at high temperature and high pressure, low lubrication resistance and drill tool wear, improved mud cake quality and low filtration loss, good flowability, no loss of MWD signal, and low cost.

[0031] (5) One or more of the inorganic surface modifiers is preferably used in the surface treatment process of the lightweight agent, so as to further improve the wear resistance and impact resistance of the lightweight agent. Further, after the inorganic surface modifier treatment, one or more of the surfactants, unsaturated organic acids, dispersants, water-soluble polymers and the like is used for surface modification, so as to improve the interfacial adhesion between the lightweight agent and the drilling fluid, further improve the wear resistance and impact resistance of the lightweight agent, and reduce the migration of metal ions. DETAILED DESCRIPTION

[0032] In order to describe the present application, a wear-resistant high-strength lightweight agent for preparing a low-density drilling fluid is further described in detail in combination with examples. However, the present application is not limited to the examples.

[0033] Example 1

[0034] The specific implementation process is as follows:

[0035] (1) Preparation of the precursor particles: the raw materials are weighed according to the formula 1 in Table 1 and are premixed, the premixed materials are broken and ground by a ball mill, the particle size distribution D 90 of the broken and ground raw materials is 5 μm, the mixed materials are granulated by a dry granulator, and the precursor particles with a particle size D 50 of 37 μm are prepared, the precursor particles with a particle size D 90 of 59 μm are prepared through physical classification treatment, and the remaining large precursor particles are returned to the breaking and grinding section for repeated use.

[0036] (2) Precursor particle pretreatment: 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 0.35%; the same electric charge is given to the surface of the precursor particles by using a corona charging machine, so that the particles repel each other and achieve good fluidity.

[0037] (3) High-temperature hollow spheroidization of precursor particles: after the precursor particles prepared in step (2) are mixed with air as a combustion-supporting gas, the mixed material is mixed with natural 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 1150°C; the particles melt into a glass melt under the action of surface tension, forming a spherical shape, and the high-temperature mixed gas is wrapped inside; after passing through the high-temperature forming zone, the glass melt is rapidly cooled to 400-600°C for 30-60s, and then slowly cooled to room temperature for 1.0-1.5h, forming a wear-resistant high-strength lightweight agent with a density of 0.28g / cm 3 , a particle size D50 of 35μm, a particle size D90 of 56μm, and a strength of 23MPa.

[0038] (4) Surface treatment of the lightweight agent: a commercially available vinyl silane coupling agent is selected, and 0.3% of the mass of the lightweight agent is weighed as a surface modifier; the lightweight agent prepared in step (3) is modified by wet modification to coat a layer of vinyl silane coupling agent on the surface; after drying at 105°C using a drying device, a wear-resistant high-strength lightweight agent for preparing low-density drilling fluid is obtained, with a density of 0.28g / cm 3 , a particle size D50 of 35μm, a particle size D90 of 56μm, and a strength of 23MPa.

[0039] Example 2

[0040] The specific implementation process is as follows:

[0041] (1) Preparation of precursor particles: the raw materials are weighed according to the formulation 2 in Table 1 and pre-mixed; the pre-mixed material is broken and ground by using a ball mill, and the particle size distribution D 90 of the broken and ground raw materials is 4.0μm; the mixed material is granulated by using a wet granulator to obtain precursor particles with a particle size D 50 of 31μm; the precursor particle with a particle size D 90 of 54μm is prepared by physical classification treatment, and the remaining large particle precursor particles are returned to the breaking and grinding section for repeated use.

[0042] (2) Precursor particle pretreatment: the precursor particles prepared in step (1) are placed in a drying machine and dried at a temperature of 70°C to obtain precursor particles with a water content of 0.31%; the precursor particles are surface treated with epoxy silane to obtain precursor particles with good fluidity.

[0043] (3) High-temperature hollow spheroidization of precursor particles: 80% air and 20% oxygen are used as combustion-supporting gas, and the precursor particles prepared in step (2) are mixed with the gas by pneumatic conveying, and then the mixed material and coal gas are mixed in a mixing chamber; the mixed precursor particles, air and fuel are introduced into a high-temperature vitrification furnace with a temperature of 1250°C; the particles are melted into a glass melt under the action of surface tension, and the high-temperature mixed gas is wrapped inside; after passing through the high-temperature forming zone, the glass melt is rapidly cooled to 400-600°C for 50-80s, and then slowly cooled to room temperature for 1.5-2.0h to form a wear-resistant high-strength lightweight agent with a density of 0.36g / cm 3 , a particle size D50 of 31μm, a particle size D90 of 52μm, and a strength of 45MPa.

[0044] (4) Surface treatment of lightweight agent: commercially available zirconium aluminate is selected as a surface modifier, and 0.3% zirconium aluminate by mass of the lightweight agent is weighed and used to modify the lightweight agent prepared in step (3) by wet method; after drying at 110°C using a drying device, a wear-resistant high-strength lightweight agent for preparing low-density drilling fluid is obtained, which has a density of 0.36g / cm 3 , a particle size D50 of 31μm, a particle size D90 of 52μm, and a strength of 45MPa.

[0045] Example 3

[0046] The specific implementation process is as follows:

[0047] (1) Preparation of precursor particles: the raw materials are weighed according to the formulation 3 in Table 1 and pre-mixed, and the pre-mixed material is broken and ground by a ball mill; the particle size distribution D 90 of the broken and ground raw material is 3.2μm; the mixed material is granulated by dry granulation to obtain precursor particles with a particle size D 50 of 26μm; after physical classification treatment, the precursor particles with a particle size D 90 of 48μm are obtained, and the remaining large-particle precursor particles are returned to the breaking and grinding section for repeated use.

[0048] (2) Precursor particle pretreatment: 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 0.22%; the precursor particles are surface treated with triisopropyl aluminate to obtain precursor particles with good fluidity.

[0049] (3) High-temperature hollow spheroidization of precursor particles: 60% air and 40% oxygen are used as combustion-supporting gas, and the precursor particles prepared in step (2) are mixed with the combustion-supporting gas; the mixed material and petroleum gas are mixed in a mixing chamber by means of 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 melt into a glass melt under the action of surface tension, and form a spherical shape with the high-temperature mixed gas wrapped inside; after passing through the high-temperature forming zone, the glass melt is rapidly cooled to 400-600°C for 20-40 seconds, and then slowly cooled to room temperature for 0.5-1.0 hours to form a wear-resistant high-strength lightweight agent with a density of 0.45 g / cm 3 , a particle size D50 of 26 μm, a particle size D90 of 51 μm, and a strength of 62 MPa.

[0050] (4) Surface treatment of the lightweight agent: commercially available triisopropyl aluminate is selected as a surface modifier, and 0.5% triisopropyl aluminate by mass of the lightweight agent is weighed and used to modify the lightweight agent prepared in step (3) by wet method; the modified lightweight agent is dried at 135°C by using a drying device; then the lightweight agent is surface treated with 0.2% poly-methyl methacrylate by mass of the lightweight agent, and dried at 110°C; finally, a wear-resistant high-strength lightweight agent for preparing low-density drilling fluid is prepared, which has a density of 0.45 g / cm 3 , a particle size D50 of 26 μm, a particle size D90 of 51 μm, and a strength of 62 MPa.

[0051] Example 4

[0052] The specific implementation process is as follows:

[0053] (1) Preparation of precursor particles: the raw materials are weighed and pre-mixed according to the formula 4 in Table 1, and the pre-mixed material is broken and ground by using a ball mill; the particle size distribution D 90 of the broken and ground raw material is 2.5 μm; the mixed material is granulated by using dry granulation to obtain precursor particles with a particle size D 50 of 25 μm; the precursor particles are physically classified to obtain precursor particles with a particle size D 90 of 43 μm, and the remaining large precursor particles are returned to the breaking and grinding section for repeated use.

[0054] (2) Precursor particle pretreatment: the precursor particles prepared in step (1) are placed in a drying machine and dried at a temperature of 110°C to obtain precursor particles with a water content of 0.2%; the precursor particles are surface treated with polycaprolactone diol to obtain precursor particles with good fluidity.

[0055] (3) High-temperature hollow spheroidization of precursor particles: 40% air and 60% oxygen are used as combustion-supporting gas, and the precursor particles prepared in step (2) are mixed with the combustion-supporting gas; the mixed material and petroleum gas are mixed in a mixing chamber by means of pneumatic conveying; the mixed precursor particles, air and fuel are introduced into a high-temperature sintering furnace with a temperature of 1450°C; the particles melt into a glass melt under the action of surface tension, and form a spherical shape with the high-temperature mixed gas wrapped inside; after passing through the high-temperature forming zone, the glass melt is rapidly cooled to a temperature of 400-600°C for 20-40 seconds, and then slowly cooled to room temperature for 1.0-2.0 hours to obtain a wear-resistant high-strength lightweight agent with a density of 0.53 g / cm 3 , a particle size D50 of 23 μm, a particle size D90 of 41 μm, and a strength of 101 MPa.

[0056] (4) Surface treatment of the lightweight agent: commercially available monoalkoxy titanate is selected as a surface modifier, and 0.8% of the mass of the lightweight agent is used to modify the lightweight agent prepared in step (3) by wet method; the modified lightweight agent is dried at a temperature of 140°C by using a drying device; then the lightweight agent is surface treated with 0.3% of the mass of the lightweight agent of sodium dodecyl benzene sulfonate, and dried at a temperature of 100°C; finally, a wear-resistant high-strength lightweight agent for preparing low-density drilling fluid is obtained, which has a density of 0.53 g / cm 3 , a particle size D50 of 23 μm, a particle size D90 of 41 μm, and a strength of 101 MPa.

[0057] Example 5

[0058] The specific implementation process is as follows:

[0059] (1) Preparation of precursor particles: the raw materials are weighed according to the formula 5 in Table 1 and pre-mixed, and the pre-mixed material is broken and ground by using a ball mill; the particle size distribution D 90 of the broken and ground raw material is 1.9 μm; the mixed material is granulated by using a wet granulation method to obtain precursor particles with a particle size D 50 of 18 μm; the precursor particles are physically classified to obtain precursor particles with a particle size D 90 of 36 μm, and the remaining large precursor particles are returned to the breaking and grinding section for repeated use.

[0060] (2) Pretreatment of precursor particles: The precursor particles obtained in step (1) are placed in a dryer and dried at 110° C. to obtain precursor particles with a moisture content of 0.17%; the precursor particles are surface treated with sodium lauryl polyoxyethylene ether sulfate to obtain precursor particles with good fluidity.

[0061] (3) High-temperature hollow spheroidization of precursor particles: Oxygen is used as a combustion-supporting gas, and after being fully mixed with the precursor particles prepared in step (2), the mixed material is mixed with natural gas in a mixing chamber by pneumatic conveying. The mixed precursor particles, air and fuel are introduced into a high-temperature vitrification furnace at a temperature of 1450°C; the particles are melted into glass melt at high temperature, and form a spherical shape under the action of surface tension, while the high-temperature mixed gas is wrapped inside; after the glass melt passes through the high-temperature forming zone, it is rapidly cooled to 400-600°C after 20-40 seconds, and then slowly cooled to room temperature after 1.0-2.0 hours, forming a glass melt with a density of 0.58 g / cm 3 , a wear-resistant and high-strength lightener with a particle size D50 of 15μm, a particle size D90 of 33μm, and a strength of 152MPa.

[0062] (4) Surface treatment of lightening agent: 80% monoalkoxy titanate and 30% aluminate coupling agent available on the market were selected as composite surface modifiers, 0.5% of the weight of the lightening agent by weight of the composite surface modifier was weighed, and the lightening agent prepared in step (3) was subjected to dry modification, and dried at 140°C using a drying device; then, the lightening agent was surface treated with a mixed treatment agent of sodium dodecylbenzene sulfonate and sodium lauryl polyoxyethylene ether sulfate (60% sodium dodecylbenzene sulfonate and 40% sodium lauryl polyoxyethylene ether sulfate) at a weight of 0.4% by weight of the lightening agent, and dried at 100°C to obtain a material with a density of 0.58 g / cm 3 A wear-resistant and high-strength lightener for preparing low-density drilling fluid with a particle size D50 of 15μm, a particle size D90 of 33μm, and a strength of 152MPa.

[0063] The process steps of Example 6 are the same as those of Example 3. The performance of the wear-resistant and high-strength lightener finally prepared for preparing low-density drilling fluid is: density of 0.46 g / cm 3 , particle size D50 is 25μm, particle size D90 is 50μm, and strength is 60MPa.

[0064] The process steps of Example 7 are the same as those of Example 4. The performance of the wear-resistant and high-strength lightener finally prepared for preparing low-density drilling fluid is: density of 0.55g / cm 3 , particle size D50 is 25μm, particle size D90 is 42μm, and strength is 95MPa.

[0065] The process steps of example 8 are the same as example 5. The final prepared wear-resistant high-strength lightening agent for preparing low-density drilling fluid has the performance of density 0.55 g / cm 3 , particle size D50 16 μm, particle size D90 35 μm, and strength 158 MPa.

[0066] Table 1 mass fraction of each component of examples 1-8

[0067]

[0068]

[0069] The upper and lower limit values and interval values of each raw material and process parameter involved in the present application can all realize the present application, and are not listed one by one here.

[0070] Industrial test verification shows that the present application 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, granulates by physical or chemical methods to form precursor particles, and makes them hollow through powder high-temperature spheroidization technology to prepare a wear-resistant high-strength lightening agent for preparing low-density drilling fluid, and modifies it through surface modification process, and applies it to low-density cement slurry and drilling fluid in the process of oil and gas resource exploitation, especially to low-density drilling fluid, which has the advantages of safety and environmental protection, obvious effect of reducing density, adjustable density, good stability under high temperature and high pressure, lubrication and drag reduction, low drilling tool wear, improved mud cake quality and reduced filtration loss, good flowability, no loss of MWD signal, low cost, etc.

Claims

1. A wear-resistant and high-strength reducing agent for preparing low-density drilling fluid, characterized in that The invention is processed and prepared from the following components. When the sum of the raw material components is calculated as 100%, the mass content of each component is as follows: silicon dioxide 64-75%, aluminum oxide 4.5-8%, boron trioxide 4.5-9%, calcium oxide + magnesium oxide 4.5-9%, sodium oxide + potassium oxide 5-9%, cerium oxide + lanthanum oxide 0.2-2.2%, iron oxide + manganese dioxide 0.3-1.5%, and other trace elements 0.8-5%. The invention is prepared by the following steps: 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 20-40μm; after physical classification, control the particle size D90 of the precursor particles to ≤60μm; 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 pneumatically conveyed into a mixing chamber 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. At the same time, the high-temperature mixed gas is wrapped inside the glass melt. After passing through the high-temperature forming zone, the glass melt 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 and high-strength lightener with a particle size D50 of 20~40μm, a particle size D90≤60μm, and a strength of 20~150MPa; 4) Surface treatment of the lightening agent: Select a surface treatment agent and perform surface treatment on the lightening agent prepared in step 3) using the surface treatment agent to obtain a wear-resistant and high-strength lightening agent for preparing low-density drilling fluid with wide matrix adaptability and strong interfacial bonding strength; 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, a hyperdispersant, a water-soluble polymer, and an inorganic surface modifier; the surface treatment method is: first perform surface treatment with an inorganic surface modifier, and then perform surface modification with one or a mixture of two or more of a surfactant, an unsaturated organic acid, a dispersant, and a water-soluble polymer.

2. A wear-resistant and high-strength lightening agent for preparing low-density drilling fluid according to claim 1, characterized in that When the sum of the raw material components is calculated as 100%, the mass content of each component is: silicon dioxide 65~74%, aluminum oxide 6~8%, boron trioxide 5~7%, calcium oxide + magnesium oxide 5~9%, sodium oxide + potassium oxide 5~9%, cerium oxide + lanthanum oxide 0.2~2.1%, iron oxide + manganese dioxide 0.3~1.2%, and other trace element materials 0.5~5%.

3. The wear-resistant and high-strength lightening agent for preparing low-density drilling fluid according to claim 1, characterized in that: In the calcium oxide + magnesium oxide component, the ratio of calcium oxide to magnesium oxide is 3:1 to 7:

1.

4. The wear-resistant and high-strength lightening agent for preparing low-density drilling fluid according to claim 1, characterized in that: In the sodium oxide + potassium oxide component, the ratio of sodium oxide to potassium oxide is 3:1 to 7:

1.

5. The wear-resistant and high-strength lightening agent for preparing low-density drilling fluid according to claim 1, characterized in that: When the sum of the raw material components is calculated as 100%, the mass content of cerium oxide is 0.1-0.8%, and the mass content of lanthanum oxide is 0.1-1%.

6. The wear-resistant and high-strength lightening agent for preparing low-density drilling fluid according to claim 1, characterized in that: The other trace element materials are one or a mixture of two or more of yttrium oxide, neodymium oxide, scandium oxide, zirconium oxide, zinc oxide, tungsten oxide, vanadium oxide, and phosphorus pentoxide, wherein at least one of tungsten oxide, vanadium oxide, and phosphorus pentoxide is added.

7. The wear-resistant and high-strength lightening agent for preparing low-density drilling fluid according to claim 1, 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 wear-resistant and high-strength lightening agent for preparing low-density drilling fluid according to claim 7, characterized in that: 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 wear-resistant and high-strength lightening agent for preparing low-density drilling fluid according to claim 1, characterized in that: In step 3), the combustion-supporting gas is air, oxygen or a combination of the two, and the fuel is one or more combinations of coal gas, natural gas or petroleum gas.

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