RU2433966C1 - Glass composition and method of producing proppants therefrom - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to glass spheres used as proppants for propping oil and gas wells. The technical result of the invention is increase in strength of proppants and permeability of at high pressure in deep wells. A molten glass mass is obtained. The glass for producing proppant has the following composition, wt %: SiO₂ - 45-57; MgO - 26-36; Al₂O₃ - 3-6; (FeO+Fe₂O₃) - 5-11; CaO - 3-8; other components - less than 5. The molten glass mass is dispersed by a jet of water at pressure 200-1000 atm. The ratio of water consumption to molten glass consumption ranges from 0.8 to 4.0.

EFFECT: glass crystal spheres are formed as a result of dispersion by the jet of water.

5 cl, 2 ex, 2 tbl

Description

The invention relates to the composition of glass, as well as to methods for making glass spheres from it, used as proppants for wedging oil and gas wells.

Known glass composition for glass, containing, wt.% SiO ₂ - 67.1; Al ₂ O ₃ - 12.5; MgO - 5.6; Li ₂ O - 9.9; K ₂ O - 3.3; F - 2.7; B ₂ O ₃ - 1.0 (see FR patent No. 1159785, 1958).

The closest in technical essence is glass for glass, including SiO ₂ - 25-60; B ₂ O ₃ - 3-15; MgO - 4-25; Al ₂ O ₃ - 5-25; F - 4-20, R ₂ O, where as R ₂ O contains at least one oxide from the group K ₂ O - 2-15; Na ₂ O - 2-15; Li ₂ O - 2-7; Rb ₂ O - 2-20; Cs ₂ O - 2-20 (see the description of patent SU No. 631065 from 08/09/1971).

However, the known glass compositions for glass metals cannot be used for the manufacture of proppants, since the main task that these compositions solve is aimed at improving the dielectric properties and machinability. According to the international standard ISO 13053, the main proppant quality indicators are crush resistance, sphericity and roundness, which largely determine the proppant layer permeability in the well.

For economic reasons, proppants made of natural rounded quartz sand have become more widespread. However, the sphericity and roundness of the rounded sand, as a rule, does not exceed a value of 0.7 according to ISO 13053, and its use is limited to shallow wells due to the low crushing resistance. To increase permeability, natural sand is covered with a film of phenol-formaldehyde resin, which significantly increases their cost, but slightly increases permeability.

Known proppants, which are glass spheres (see US patent No. 3497008), which have high sphericity and roundness, smooth surface, but low mechanical strength. In addition, glass proppants have low resistance to clay acid (a mixture of hydrochloric and hydrofluoric acid), so their use in wells subjected to acid treatment is not possible.

The closest in technical essence to the claimed method of manufacturing proppant is a method of manufacturing proppant from glass spheres (see GB patent No. 1089213 of 01.11.1967), including the production of a melt of oxides in a rotary furnace, including in the form of glass powder with the formation of glass spheres, their cooling by air to a temperature of 480-675 ° C and their supply to the coolant - a solution of starch, glycol. Moreover, the resulting spheres have a strength of more than 700 kg / cm ² , a density of less than 2.6 g / cm ³ , a sphericity of 0.84, and resistance at a temperature of 1200 ° C and pH 3-11.

The disadvantages of glass-crystalline proppants include their insufficiently high strength, and therefore, permeability at high pressures, i.e. when fracturing in deep wells. This is due to the fact that in the known invention only the proppant production method is considered and the specific composition of the glass, aimed at increasing these indicators, is not considered.

The technical problem to be solved by the claimed invention is directed is to increase the yield of commercial proppant fractions, increase their strength and permeability at high pressures in deep wells.

The specified result is achieved by the fact that in the known glass composition for the manufacture of proppant, including SiO ₂ , MgO, Al ₂ O ₃ , it contains FeO + Fe ₂ O ₃ , CaO in the following ratio of components, wt.%:

SiO ₂ - 45-57

MgO - 26-36

Al ₂ O ₃ - 3-6

(FeO + Fe ₂ O ₃ ) - 5-11

CaO - 3-8

Others - less than 5

A method of manufacturing a proppant from the above glass composition, including obtaining a molten oxide with dispersion with a water jet to form glass crystallization spheres, annealing and cooling them, melting the glass is carried out at a temperature of 1500-170 ° C, and the subsequent dispersion of the melt jet is carried out with a water jet of 200 -1000 atm, and the ratio of water flow to the flow of molten glass is from 0.8 to 4.0. The diameter of the melt jet for dispersion is selected in the range of 5-50 mm. The dispersion of the jet of melt is carried out at a temperature of 1300-1700 ° C, and crystallization annealing at a temperature of 1100-1270 ° C.

Dispersion of a jet of molten glass by a jet of water, in contrast to dispersion by air or steam, has two features:

1. Water is an incompressible substance; therefore, the kinetic energy of water is transmitted to the melt stream, which causes fast and high-quality dispersion.

2. The jet of water leaving the nozzle under high pressure maintains continuity at a distance of more than 1 m, which facilitates the hardware design of the dispersion process.

Dispersion by a water jet imposes certain restrictions on the composition of the dispersible glass melt and its temperature:

- it is necessary to use slightly alkaline melt;

- a melt with low viscosity and high surface tension.

In addition, the dispersion of the melt jet with a water jet allows the melt to transfer significantly greater kinetic energy, which increases the yield of commodity fractions of glass beads (0.2-0.8 mm) up to 80-90% (when dispersed with air - 20-30%, steam - 25 -40%, with a stream of hot gases - 30-50%).

The undoubted advantage of water dispersion over dispersion by a rotating disk is both from the point of view of technical simplicity of the process, economy, productivity, safety measures, and the quality of the products obtained due to the sharp cooling of glass balls - the occurrence of compressive stresses in the surface layers of glass balls (toughened glass).

The amount of water supplied to the melt stream and its pressure determine both the yield of the product and the average size of the glass beads. At a water consumption of less than 0.8 kg per 1 kg of melt, even at a water pressure of 600-1000 atm, it is not possible to completely break the stream and nonspherical particles appear, and at a water consumption of more than 4 kg per 1 kg of melt, the average size of glass beads remains constant. Water pressure plays a significant role in dispersion technology. At a pressure of less than 200 atm, the water jet quickly loses its energy and impact on the melt stream leads to the formation of large glass beads, nonspherical particles of glass and wool.

The authors did not use water pressure above 1000 atm due to the high cost and scarcity of equipment. In addition, the difference in water pressure between 500 and 1000 atm was insignificant both in the average value of the size of glass beads and in the fraction of suitable production.

The size of the jet of molten glass is also of great importance: when the thickness of the jet is less than 5 mm, it rapidly cools, and with a thickness of more than 50 mm, the spread in the tangential (transverse) direction. In both cases, the proportion of nonspherical particles increases.

The ratio of oxides of silicon, magnesium, aluminum, calcium and iron was determined empirically. This composition has the optimal ratio of technological and quality indicators. Other oxides, the content of which should not exceed 5 wt.%, Are usually represented by oxides of chromium, manganese, nickel, boron, sulfur, potassium, sodium, titanium, fluorine and their effect on the strength of proppants is limited. These oxides are impurities in the feedstock.

The total content of silicon and aluminum oxides should not exceed 60%, since the melt viscosity at their content of more than 60% even at a temperature of 1700 ° C becomes high and a lot of cotton wool and needles are formed when dispersed by a water jet.

Example 1

The material of the calculated composition, in wt.% SiO ₂ - 52, MgO - 32, CaO - 5, Al ₂ O ₃ - 6,

(FeO + Fe ₂ O ₃ ) - 5 (impurities: Cr ₂ O ₃ , TiO ₂ , K ₂ O, Na ₂ O, F, S, P ₂ O ₅ , B ₂ O ₃ , etc., present in natural raw materials in an amount up to 5%, excluded from the calculation), was melted in an arc ore-furnace and drained through a refractory funnel with a flow rate of about 1200 kg / h at a melt stream temperature of about 1550 ° C + 20 ° C. The dispersion of the melt jet was carried out by a flat water jet with a pressure of 50 to 1000 atm and a water flow rate of 600 to 10,000 l / h. The content of glass beads less than 0.8 mm in size was taken as an optimization parameter. Table 1 shows the results of the experiments.

Table 1 The effect of pressure and water flow on the dispersion of a jet of molten glass No. p / p Water pressure at the nozzle exit (atm) Water consumption (l / h) Glass spheres less than 0.8 mm (%) one fifty 600 23 2 fifty 1000 31 3 fifty 4000 38 four one hundred 600 36 5 one hundred 5000 47 6 one hundred 8000 51 7 200 600 58 8 200 1000 73 9 250 1000 80 10 250 5000 86 eleven 500 600 65 12 500 1000 87 13 500 2000 91 fourteen 500 5000 94 fifteen 500 10,000 95 16 1000 5000 95 17 1000 10,000 96

From table 1 we can conclude that when dispersing a jet of melt with a water jet, the optimum pressure is 200-1000 atm, and the water flow rate from 0.8 to 4 relative to the flow rate of the molten glass.

Example 2

Melts of various compositions were dispersed with a flat stream of water. Water consumption was taken - 4000 l / h, water pressure - 400 atm, glass melt consumption - 1200 kg / h. The following parameters were taken as optimization parameters: strength of glass beads - proppants of fraction 40/70 (0.42-0.21 mm); the number of non-spherical particles (cotton, needles).

Table 2 shows the results of the experiments. The composition is calculated on the oxides of silicon, magnesium, calcium, aluminum and iron, excluding impurities (Cr ₂ O ₃ , TiO ₂ , K ₂ O, Na ₂ O, F, S, P ₂ O ₅ , B ₂ O ₃ , etc. )

table 2 The results of the experiments Number p / p The estimated chemical composition of the glass, wt.% Crushing strength of fraction 40/70 according to GOST at 680 atm The proportion of non-spherical particles (wool and needles) SiO ₂ MgO CaO Al ₂ O ₃ FeO + Fe ₂ O ₃ one 40 40 5 8 7 8.4 5 2 45 35 5 8 7 2,3 3 3 fifty thirty 5 8 7 2 7 four 55 25 5 8 7 7.4 12 5 60 twenty 5 8 7 9.0 thirty 6 fifty 26 8 5 eleven 3,1 2 7 fifty 40 2 2 6 8 fifty thirty 10 four 6 7.9 5 9 fifty 35 10 2 3 11.0 four 10 55 twenty 10 6 9 12.3 8 eleven 55 thirty 5 5 5 1.8 6 12 55 37 2 four 2 6.9 12 13 55 25 10.0 5 5 10,4 5 fourteen 52 29th 6 5 8 1.3 3 fifteen 57 21 four 6 12 14.8 8 16 60 twenty 10 5 5 11.6 19 17 65 twenty 5 5 5 12.9 45 eighteen 52 38 2 2 6 6.8 12 19 52 32 5 6 5 0.4 2 twenty 52 twenty 0 3 fifteen 8.4 5 21 52 31 8 3 6 0.8 5

Thus, the glass sphere of the claimed composition have the highest crushing strength (fewer destroyed granules, see examples 6, 11, 14, 19, 21) and can be recommended for use as proppants.

The glass of the claimed composition has an extremely high tendency to crystallization, and when the melt stream is dispersed with air or a stream of hot gases (for example, products of natural gas or kerosene combustion), slower cooling occurs, which leads to uncontrolled crystallization of the glass and a decrease in the strength of glass beads larger than 0.2 mm

It should be noted that crystallization firing of glass beads is effective only in the temperature range 1100-1270 ° C for a period of not more than 10-15 minutes for the formation of 20-40% small (less than 2 microns) crystals of forsterite and pyroxene by volume of glass. With longer exposures, an increase in the fraction of the crystalline phase causes deformation of the glass beads due to the fact that the crystalline phase has a higher density.

At temperatures below 1100 ° C, thermal stresses during crystallization cause cracking in the glass and a decrease in strength, in the range 1100-1270 ° C, the stresses relax due to plastic deformation of high-viscosity glass, and above 1270 ° C adhesion of glass beads due to a decrease in viscosity.

It should be noted that a significant increase in the strength of glass beads of the claimed composition and made according to the present invention compared with the glass beads available on the market has improved the quality of not only proppants, but glass beads for blasting the surface of metals and glass, as well as for a number of other specific applications (plastic fillers concrete, reflective surfaces).

Industrial tests conducted at the company LLC "FORES" showed that the dispersion of the melt jet of the inventive glass composition with a water jet allows you to:

- reduce the proportion of non-spherical particles, and this increases the yield of commercial proppant fractions;

- increase the strength of the proppants and their permeability for use at high pressures in deep wells.

Claims (5)

1. The glass composition for the manufacture of proppant, including SiO ₂ , MgO, Al ₂ O ₃ , characterized in that it contains FeO + Fe ₂ O ₃ , CaO in the following ratio of components, wt.%:
SiO ₂ 45-57 MgO 26-36 Al ₂ O ₃ 3-6 (FeO + Fe ₂ O ₃ ) 5-11 CaO 3-8 Other less than 5 2. A method of manufacturing a proppant from a glass composition according to claim 1, comprising obtaining a melt of oxides with dispersion of its jet to form glass crystallization spheres, their annealing and cooling, characterized in that the dispersion of the jet of molten glass is carried out with a water jet of 200-1000 atm, the ratio water flow to the flow rate of the molten glass is from 0.8 to 4.0. 3. The method according to claim 2, characterized in that the diameter of the melt stream for dispersion by a stream of water is selected within the range of 5-50 mm. 4. The method according to claim 2, characterized in that the crystallization annealing is carried out at a temperature of 1100-1270 ° C. 5. The method according to claim 2, characterized in that the glass is melted at a temperature of 1500-1700 ° C.