EA036221B1 - Method for production of ceramic proppant on the basis of magnesia material - Google Patents

Abstract

The invention is directed to obtaining a high performance ceramic proppant, in particular, to increasing the strength of proppants obtained by said method at low cost. A method for production of proppant on the basis of magnesia material and silica sand comprises charge grinding, pelletizing and burning, wherein serpentinites with cryptocrystalline magnesite (MgCO3) in the amount of 1-10% are used as magnesia material, and dehydration burning is carried out at 750-800C. For magnesia component, serpentinite rocks are used, which are produced in cryptocrystalline magnesite (MgCO3) fields, e.g. serpentinite and magnesite raw materials from Khalilovskoye field. A ceramic proppant produced by said method.

Description

The invention relates to the oil and gas industry, namely to a technology for manufacturing ceramic proppants intended for use in oil or gas production by hydraulic fracturing (HF).

Hydraulic fracturing is the process of injecting fluids into an oil-bearing or gas-bearing subterranean formation at high enough speeds and pressures to create fractures in the formation that increase the flow of fluids from the oil or gas reservoir into the well. To keep the cracks in an open state, mechanically strong proppants, which do not interact with the well fluid, are introduced into them - spherical granules (proppants), which, penetrating with the fluid into the crack and at least partially filling it, create a strong proppant frame, permeable for oil and gas released from the reservoir. Proppants - artificially created granules must resist not only high formation pressure, which tends to deform proppant particles, which leads to the inevitable closure of the fracture, but also withstand the action of an aggressive downhole environment (moisture, acid gases, salt solutions) at high temperatures.

Several technical solutions are known for producing proppants, namely, for example, in patent RU No. 2235703 a method for producing ceramic proppants based on a magnesium silicate material with a forsterite content of 55 to 80% w / w is described. The starting material is crushed, granulated and fired at temperatures from 1150 to 1350 ° C.

The closest in technical essence to the claimed technical solution is a method of manufacturing a magnesium silicate proppant and proppant according to patent RU No. 2463329, including the preparation of the initial components of the charge, their grinding with a complex sintering additive to a fraction of less than 30 microns, granulation of the charge, roasting and screening of fired granules. As the specified additive, a mixture of brucite, colemanite, sodium fluorosilicate and fayalite is used in an amount of 0.4-3.0% of the weight of the charge based on magnesium silicate raw materials, with the following ratio,% of the weight of the charge: brucite 0.1-1.0 , colemanite 0.1-0.6, sodium fluorosilicate 0.1-0.4, fayalite 0.1-1.0, with the total MgO content in the charge being 19-48 wt%. Moreover, the roasting is carried out at a temperature of 1150-1220 ° C, and as the main component of the charge, natural magnesium silicate raw material is used - serpentinite; olivinite, dunite both on its own and in the form of a mixture with natural quartz feldspar sand.

The proppant obtained by this method has a bulk density of 1.52-1.7 g / cm, depending on the MgO content in the charge, has insufficient material strength, partly due to the fact that during granulation of the charge, crushed to a fraction of less than 30 μm, it is not possible significantly compact the raw proppant granule. As a result, after firing, the proppant granules contain an excessive amount of pores. For example, the bulk density of a proppant containing 24-28 wt.% MgO is 1.56-1.58 g / cm ³ .

The disadvantage of the known method and the product obtained therefrom is that, due to the very narrow sintering range (ΔΤ max, from 10 to 20 ° C), the manufacture of such proppants is complicated, laborious and expensive. In addition, this leads to the growth of crystals of magnesium metasilicate and phase transformation during the cooling process, which also reduces the quality of the proppant obtained, therefore, the proppant obtained according to this method has reduced strength values. As a consequence, this leads to a decrease in the conductivity of the proppant layer at elevated pressures. Also, the narrow sintering interval complicates the technological process of firing in industrial rotary kilns.

The object of the invention is to obtain a ceramic proppant with high performance characteristics, namely, to increase the strength of proppants obtained by this method at a low cost.

The technical result consists in combining the processes of decomposition of magnesite and dehydration of serpentinite.

The task is achieved by the fact that in the method of producing a proppant based on magnesia material and quartz sand, including grinding the charge, granulating the charge and burning it, serpentinites are used as magnesia material with the inclusion of cryptocrystalline magnesite (MgCO ₃ ) in an amount of 1-10%, and dehydration roasting is carried out at a temperature of 750-800 ° C.

Serpentinite rocks of deposits of cryptocrystalline magnesite (MgCO ₃ ) are used as a magnesian component, for example, serpentinite-magnesite raw materials of the Khalilovsky deposit. A distinctive feature of serpentenite host rocks of deposits of cryptocrystalline magnesite (MgCO ₃ ) is the presence of an impurity of cryptocrystalline magnesite (MgCO ₃ ) in an amount from 1 to 10% and a micro-fractured structure of the mineral.

Table 1 shows examples of the results of laboratory studies.

Table 2 shows production data for the deposits of the Badenov massif and Khalilovsky.

The graph shows a derivatogram of serpentenite-magnesian raw materials from the Khalilovskoye deposit, where TG-thermogravimetry (mass change upon heating) is indicated in green, and DSC is shown in blue - differential scanning calometry (the difference in heat fluxes between the sample and the standard).

It is known that, for example, the typical chemical composition of serpentinite-magnesite raw materials of the Khalilovskoye deposit in terms of the calcined substance is, wt%:

MgO 41.7 - 54.4%

SiO ₂ 36.2-42.3%

Fe ₂ O ₃ 5.7-8.1%

CaO 0.6-2.3%

A1 ₂ 0z 0.4-1.1%

Loss on ignition at 950 ° C 14.5-19.8%

Carrying out derivatographic studies of serpentinite-magnesite raw materials of the Khalilovsky deposit, which are presented in the graph (Fig. 1), showed that the dehydration of serpentinite occurs at temperatures of 570-670 ° C. The mass loss associated with the decomposition of magnesite (MgCO ₃ ) is superimposed on the dehydration of serpentines (600-700 ° C), which means that both processes occur simultaneously. At a temperature of 820 ° C, an exothermic effect is observed associated with the oxidation of FeO to Fe ₂ O ₃

During heat treatment of serpentinite-magnesite raw materials at temperatures of 700-800 ° C, the cryptocrystalline magnesite (MgCO ₃ ) present in the raw material decomposes into MgO and CO ₂ , while, unlike crystalline magnesite (MgCO ₃ ), granular aggregates are not formed, and MgO remains in the form individual particles, as a result of which it is more active in subsequent reactions. In addition, the material obtained after heat treatment is characterized by low strength.

As a result of the research, the authors found that the dehydration roasting of serpentinite-magnesite raw materials of the Khalilovskoye deposit should be carried out at lower temperatures than other types of serpentinite and magnesite raw materials, for example, serpentinite from the Beden massif.

This is due to the fact that during firing (under laboratory conditions) serpentinite containing magnesite (MgCO ₃ ) is sufficient to heat up to a temperature of 700-730 ° C, while iron oxide FeO remains in the form of a solid solution of magnesium oxides and iron oxides MgO-FeO. Serpentenite had to be heated to a higher temperature of 820-850 ° C, but the oxidation reaction of FeO is already taking place.

An increase in the strength of the proppant is achieved due to the fact that when the finished agents (proppants) are fired in a rotary kiln in an oxidizing atmosphere, magnesium oxide interacts faster with silicon oxide, the process is more complete, and there is no residual quartz, and the presence of FeO accelerates the reaction of magnesioferrite formation embedded in the lattice of enstatite, namely:

MgO + Si0 ₂ - + Mg ₂ SiO ₄

Mg ₂ SiO ₄ + SiO ₂ -> 2MgO * SiO ₂

2Mg ₂ SiO ₄ + 4FeO + O ₂ ^> 2MgO * SiO ₂ + 2MgO * Fe ₂ O ₃

Examples of implementation of the invention.

In order to test and confirm the above arguments for the implementation of the technical solution, laboratory samples were made and a pilot batch of proppants was produced in the amount of 2.5 thousand tons.

In the manufacture of these laboratory samples, serpentinite-magnesite raw materials underwent preliminary heat treatment in a laboratory high-temperature furnace at temperatures of 750 and 850 ° С, quartz sand was dried in a SNOL - 3.5.3.5.3.5 / 3.5 drying cabinet, at a temperature of about 100 ° С to a residual moisture content of no more than 2%, the clay was dried at a temperature of about 100 ° C to a residual moisture content of 8-10%. Joint grinding of magnesia-containing material with quartz sand and clay was carried out in a laboratory ball mill to a fraction of less than 40 μm, the resulting mixture was granulated on a laboratory plate granulator, then fired in a laboratory Nabertherm NT 16/18 furnace at temperatures of 1350-1450 ° C. The obtained proppants were determined for bulk density and crush strength in accordance with ISO 13503-2.

Example 1. (comparative). Serpentinite-magnesite raw material used was serpentinite from the Badenovskoe deposit (Karachay-Cherkess Republic) heat-treated at 750 ° C. A mixture of heat-treated serpentinite, dried quartz sand and montmorillonite clay for binder in a ratio of 63%: 33%: 4% was ground in a mill, then granulated and dispersed into various fractions. Fraction 16/20 (0.85-1.18 mm) was fired at temperatures of 1400 ° C, 1420 ° C, 1430 ° C, 1440 ° C.

Example 2. (comparative). Serpentinite-magnesite raw material used was serpentinite from the Badenovskoye deposit (Karachay-Cherkess Republic) heat-treated at 850 ° C. A mixture of heat-treated serpentinite, dried quartz sand and montmorillonite clay for binder in a ratio of 63%: 33%: 4% was ground in a mill, then granulated and dispersed into various fractions. Fraction 16/20 (0.85-1.18 mm) was fired at temperatures of 1400 ° C, 1420 ° C, 1430 ° C,

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1440 ° C.

Example 3. Serpentinite-magnesite raw material was used serpentinite-magnesite of the Khalilovsky deposit with a low content of cryptocrystalline magnesite (MgCO ₃ ) (about 2%), heat-treated at 750 ° C. A mixture of heat-treated serpentinite, dried quartz sand and montmorillonite clay for binder in a ratio of 63%: 33%: 4% was ground in a mill, then granulated and dispersed into various fractions. Fraction 16/20 (0.85-1.18 mm) was fired at temperatures of 1400 ° C, 1420 ° C, 1430 ° C, 1440 ° C.

Example 4. Serpentinite-magnesite raw material used was serpentinite-magnesite of the Khalilovsky deposit with an average content of cryptocrystalline magnesite (MgCO ₃ ) (about 7%), heat-treated at 750 ° C. A mixture of heat-treated serpentinite, dried quartz sand and montmorillonite clay for binder in a ratio of 55%: 41%: 4% was ground in a mill, then granulated and dispersed into various fractions. Fraction 16/20 (0.85-1.18 mm) was fired at temperatures of 1400 ° C, 1420 ° C, 1430 ° C, 1440 ° C.

Example 5. Serpentinite-magnesite raw material used was serpentinite-magnesite of the Khalilovsky field with an average content of cryptocrystalline magnesite (MgCO ₃ ) (about 7%), heat-treated at 750 ° C. A mixture of heat-treated serpentinite, dried quartz sand and montmorillonite clay for binder in a ratio of 60%: 36%: 4% was ground in a mill, then granulated and dispersed into various fractions. Fraction 16/20 (0.85-1.18 mm) was fired at temperatures of 1380 ° C, 1400 ° C, 1410 ° C, 1420 ° C, 1440 ° C.

Example 6. Serpentinite-magnesite raw material was used serpentinite-magnesite of the Khalilovsky deposit with an average content of cryptocrystalline magnesite (MgCO3) (about 7%), heat-treated at 750 ° C. A mixture of heat-treated serpentinite, dried quartz sand and montmorillonite clay for binder in a ratio of 65%: 31%: 4% was ground in a mill, then granulated and dispersed into various fractions. Fraction 16/20 (0.85-1.18 mm) was fired at temperatures of 1380 ° C, 1400 ° C, 1410 ° C, 1420 ° C, 1440 ° C.

Example 7. Serpentinite-magnesite raw material was used serpentinite-magnesite of the Khalilovsky field with an average content of cryptocrystalline magnesite (MgCO3) (about 7%), heat-treated at 850 ° C. A mixture of heat-treated serpentinite, dried quartz sand and montmorillonite clay for binder in a ratio of 60%: 36%: 4% was ground in a mill, then granulated and dispersed into various fractions. Fraction 16/20 (0.85-1.18 mm) was fired at temperatures of 1380 ° C, 1400 ° C, 1420 ° C, 1430 ° C, 1440 ° C.

Example 8. Serpentinite-magnesite raw material was used serpentinite-magnesite of the Khalilovsky deposit with a high content of cryptocrystalline magnesite (MgCO ₃ ) (about 10%), heat-treated at 750 ° C. A mixture of heat-treated serpentinite, dried quartz sand and montmorillonite clay for binder in a ratio of 60%: 36%: 4% was ground in a mill, then granulated and dispersed into various fractions. Fraction 16/20 (0.85-1.18 mm) was fired at temperatures of 1370 ° C, 1380 ° C, 1390 ° C, 1400 ° C, 1420 ° C.

The specific examples provided in this application, and reference to specific options are provided only to illustrate the principles and applications of this invention. Were tried other options, and additional options for use, which may be obvious to specialists in this field after reading and understanding this description. It is contemplated that all such uses of said method should also be included within the scope of this invention. Therefore, it should be understood that numerous modifications can be made to the illustrative reproductions without departing from the spirit and scope of the present invention as defined in the claims of the present invention.

The release of a pilot batch was carried out in the following order: serpentinite-magnesite raw materials were calcined in a rotary kiln at temperatures in the firing zone of 750-800 ° C.

Then produced a joint grinding of the calcined obtained material, dried quartz sand and montmorillonite clay for binder in the ratio (59-63%): (34-37%): (3-4%). The grinding was carried out to a fraction of less than 40 μm. At the same time, the hourly productivity in comparison with the serial technology has increased by 1.5 times.

Granulation was carried out on disc granulators with a diameter of 3 m. Drying was carried out in a drying drum at a temperature of 180-200 ° C.

Firing was carried out in a rotary kiln with a diameter of 3 m and a length of 51 m, at a temperature of 13801410 ° C.

Data on the release of a pilot batch in comparison with the serial technology are given in table. 2.

As can be seen from the above results, the crushing resistance of the proppants obtained by this method is lower in relation to those compared (Table 2), which indicates an increase in the strength of the proppant obtained from the serpentenite-magnesite raw materials of the Khalilovskoye deposit.

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Table 1

Sample 1 (for comparison) Sample 2 (for comparison) Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Magnesia-containing material Serpentinite Serpentinite Serpentite with 2% magnesite (MgCO ₃ ) Serpentinite with 7% magnesite (MgCO ₃ ) Serpentinite with 7% magnesite (MgCO ₃ ) Serpentinite with 7% magnesite (MgCO ₃ ) Serpentinite with 7% magnesite (MgCO ₃ ) Serpentinite with 10% magnesite (MgCO ₃ ) Pre-heat treatment temperature, ° C 750 850 750 750 750 750 850 750 Chemical composition of magnesia-containing material, wt% MgO 42.6 42.6 44.2 50.1 50.1 50.1 50.1 52.7 SiO2 42.1 42.1 40.8 37.9 37.9 37.9 37.9 36.6 Loss on ignition at 1000 ° C 14.6 14.6 15.7 17.9 17.9 17.9 17.9 19.5 Raw mix composition, wt% Preliminary heat treated magnesia material 63 63 63 55 60 65 60 60 Quartz sand 33 33 33 41 36 31 36 36 Clay 4 4 4 4 4 4 4 4 Firing temperature, ° С 1430 1430 1420 1430 1410 1400 1430 1390 Bulk density of the finished agent, fraction 16/20, g / cm3 1.55 1.56 1.55 1.53 1.54 1.56 1.54 1.55 Crushing resistance at a pressure of 68.9 MPa,% 20.7 18.9 17.7 19.5 16.0 16.8 18.1 17.1

table 2

Name Experimental industrial batch for based on serpentenite magnesite of the Khalilovsky deposit Serial production based on serpentinite from the Vedensky massif (for comparison) 1. Preliminary heat treatment of serpentenite 1.1 Firing temperature, оС 750-800 900-1000 1.2 Loss on ignition after firing,% 0-0.8 0-1.0 1.3 Water absorption 11-14% 4-8% 2. Joint grinding of materials 2.1 Content of raw materials,% - burnt serpentinite 59-63 61-65 - quartz sand 34-37 32-35 - montmorillonite clay 3-4 3-4 2.2 Average hourly productivity of the mill SM2x10, t / h 6.12 3.96 2.3 Sieve residue 40 μm,% 0.4-1.0 0, s, 5 3. Granulation and drying 3.1. Bulk density, g / cm3 1.18-1.20 1.17-1.22 3.2 Moisture content of semi-finished product,% 0.2-0.8 0.4-1.0 4 Proppant firing 4.1 Firing temperature, оС 1380-1400 1380-1450 4.2 Bulk density of the finished proppant, fraction 16/20, g / cm3, average / (min-max) 1.55 (1.53-1.56) 1.56 (1.54-1.58) 4.3 Resistance to crushing at a pressure of 68.9 MPa,%, average / (minmax) 18.3 (16.3-21.0) 20.2 (18.1-22.6)

CLAIM

Claims (2)

CLAIM 1. A method of producing a ceramic proppant based on magnesia material and quartz sand, including grinding a charge containing magnesia material and quartz sand, granulating the charge and firing it, characterized in that serpentinites with the inclusion of cryptocrystalline magnesite (MgCO ₃ ) are used as magnesia material in the amount of 110%, while additional dehydration roasting of raw materials is carried out at a temperature of 750-800 ° C. 2. The method according to claim 1, characterized in that serpentinite-magnesite raw material of the Khalilovsky deposit is used as the magnesia material with the inclusion of cryptocrystalline magnesite (MgCO ₃ ) in an amount of 1-10%, and obtained using dehydration roasting of raw materials at a temperature of 750-800 ° С, while serpentinite-magnesite has the following chemical composition, wt.% In terms of the calcined substance: MgO 41.7-54.4; SiO2 36.2-42.3; Fe2O3 5.7-8.1; CaO 0.6-2.3; Al ₂ O ₃ 0.4-1.1.