RU2381202C2 - Method for manufacturing of ceramic proppants (versions) - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention is related to production of ceramic proppants used in technology of rock hydraulic fracture and assisting in improvement of bed oil recovery. In method of ceramic proppants manufacturing, including thin grinding of raw mix, granulation, drying, annealing of granules and screening into commercial-grade fractions, prior to screening into commercial-grade fractions, granules are exposed to tumbling, as per one version - by means of their rolling in a rotary drum for 20-60 min at 20-40% of its volume filling, besides, speed of drum rotation is selected so that it provides for rolling mode of granules motion, and as per the second version - by means of their vibration wear at the frequency from 50 to 200 Hz and amplitude from 0.8 to 0.3 mm, besides vibration wear is carried out for 1-3 min.

EFFECT: increased strength and conductivity of proppants in working layer.

4 cl, 2 tbl

Description

The invention relates to the production of ceramic proppants used in the technology of hydraulic fracturing of rocks as a support layer in artificial fractures and contributing to an increase in the return of oil reservoirs.

Proppants are strong spherical granules that keep cracks from closing after relieving hydraulic fracturing pressure and provide the necessary proppant layer permeability for oil product passage.

A known method of manufacturing proppants [1] of magnesium-silicate material based on forsterite with a content of the latter 55-80%, which is subsequently crushed, granulated and fired at a temperature of 1150-1350 ° C. The proppants obtained in this way have insufficiently high strength and relatively low permeability due to the formation of numerous surface defects of the granules, which are primarily destroyed when the layer is loaded with the formation of dusty fragments that block the liquid-conducting channels.

A known method of manufacturing aluminosilicate ceramic proppants on cordierite ligament [2], including wet grinding of the raw material mixture, drying the slip in a spray dryer, granulation, firing and sieving of granules into product fractions. The obtained proppants have unsatisfactory strength and relatively low permeability due to the formation of numerous defects on the surface and in the volume of granules formed due to the involvement of highly porous particle aggregates obtained in the process of spray drying of the slip.

Closest to the technical nature of the claimed is a method for the production of high-strength spherical ceramic granules [3], including the calcination of natural aluminosilicate raw materials, grinding, dosing and loading into a granulator, moistening the crushed raw materials, granulation, dosing and feeding into the granulator an additional amount of crushed raw materials, sieving granules obtained for the selection of the target fraction, its firing in a rotary kiln and sieving of sintered granules. While 60-90% of calcined aluminosilicate raw materials are crushed to a particle size of 20-40 microns, and 10-40% are crushed to a particle size of less than 20 microns. In the granulation process, finely ground raw materials are fed to the granulator after wetting the ground raw materials and the nucleation of the granules and until the granulation is completed.

The proppants made by this method have better roundness in the raw material, but after firing they are characterized by a high degree of surface imperfection, which prevents the proppant layer from being densely packed, and a high degree of layer sedimentation under load, which leads to intensive proppant destruction both from the surface and in volume granules, abundant dust formation and reduced conductivity.

Underestimated strength and conductivity values are also observed for proppants made from other types of raw materials, if the nature of their surface prevents the formation of the most dense packing of granules in the layer. In addition, since there are almost always numerous protrusions, depressions, and pores on the surface of granules, the fluid flow through the proppant layer has a mixed — laminar and turbulent mode, and the turbulent mode significantly reduces the permeability of the ceramic proppant layer. Another circumstance that reduces the strength and permeability of the layer is the increased surface destruction of the granules due to their relative movement during compaction of the layer under load, the occurrence of shear stresses and critical wedging loads.

The technical result, the solution of which the claimed invention is directed, is to increase the strength and conductivity of proppants in the working layer by increasing their roundness.

The proposed method for the manufacture of ceramic granules allows us to eliminate these disadvantages and increase the yield of granules with high roundness, thereby contributing to an increase in the strength and conductivity of proppants in the working layer.

The specified technical result is achieved by the fact that in the known method of manufacturing ceramic proppants, including fine grinding of the raw material mixture, granulation, drying, calcining the granules and sieving them into commercial fractions, granules are subjected to tumbling before sieving into commercial fractions by rolling them in a rotating drum for 20 -60 min at 20-40% filling of its volume, and the rotation speed of the drum is chosen such that it provides an erratic regime of movement of the granules.

In another embodiment, the technical result is achieved by the fact that in a method comprising granulating the raw material mixture, drying, calcining the granules and sieving the product fractions, the granules are subjected to tumbling before sieving the product fractions by vibration abrasion at a frequency of 50 to 200 Hz and an amplitude of 0, 8 to 0.3 mm for 1-3 minutes.

Tumbling in these modes leads to surface grinding of the granules, removal or smoothing of microprotrusions, which reduces the friction coefficient and abrasiveness, increases the flow of powders and, accordingly, workability of proppants in the layer. The effect is confirmed by an increase in proppant bulk density (~ by 3.5–5%).

An increase in the layer density indicates the practical absence of large cavities (a consequence of arch formation), i.e. about increasing the coordination number and the number of points of mutual contact of the granules, which provides a significant increase in the bearing capacity of the working proppant layer (~ 25-40%).

With an increase in the density and strength of the layer, its conductivity also increases, which also contributes to the lack of movement of the granules in a denser layer during the process of increasing the load, the degree of sedimentation of the layer and the surface destruction of the granules, leading to the formation of dusty particles blocking the conductive channels, decrease. The smoothing of surface defects helps to increase the average fluid flow rate in the layer.

Indicated in the proposed method, the parameter limits are determined experimentally and going beyond these limits reduces the effectiveness of its application.

The possibility of implementing the proposed method is confirmed by examples of its specific implementation in the laboratory of the applicant.

To demonstrate the method, samples of proppants of fraction 12/18 of magnesia-silicate, mullite-siliceous and mullite (prototype) compositions made using a technology comprising fine grinding of a raw material mixture of the appropriate composition, granulation, drying and firing of granules were taken. After determining the properties of the sample, they were subjected to tumbling in a rotating drum with a diameter of 0.75 and a length of 1.6 m and in a vibratory gutter (half cylinder with a diameter of 219 mm), changing the duration of the process and the volume of drum loading, the amplitude, frequency and duration of passage of granules through the vibratory gutter. After processing, the properties of the obtained proppants were determined. The starting and tumbling powders were compared by the following property indicators: bulk density, crush resistance, and the fraction of dust particles in the fracture products (see Tables 1 and 2).

Table 1 Properties of proppants 12/18 in size before and after rolling Tumbling Options Proppants Mullite-siliceous Mullite (prototype) Magnesia silicate Bulk density, g / cm ³ Fracture rate under load of 7500 psi incl. fractions <0.3 mm,% Bulk density, g / cm ³ Fracture rate under load of 7500 psi incl. fractions <0.3 mm,% Bulk density, g / cm ³ Fracture rate under load of 7500 psi incl. fractions <0.3 mm,% Duration of tumbling in the drum with a filling of 40%, min: 0 1,56 13.7 / 3.2 1.74 7.9 / 1.3 1,56 9.5 / 1.8 twenty 1,58 11.4 / 2.1 1.78 6.6 / 1.1 1,61 7.5 / 1.5 40 1,61 9.5 / 1.5 1.81 4.8 / 0.6 1,64 5.9 / 0.8 60 1,61 9.2 / 1.3 1.82 4,5 / 0,3 1,66 5,6 / 0,4 40 minutes of tumbling in a drum with filling in: twenty% 1,61 9.3 / 1.4 1.82 4.4 / 0.5 1.65 5.7 / 0.6 thirty% 1,61 9.5 / 1.5 1.81 4.6 / 0.6 1.65 5.7 / 0.6

table 2 Properties of proppants 12/18 in size before and after vibrating Tumbling Options Proppants Mullite-siliceous Mullite (prototype) Magnesia silicate Bulk density, g / cm ³ Fracture rate under load of 7500 psi incl. fractions <0.3 mm,% Bulk density, g / cm ³ Fracture rate under load of 7500 psi incl. fractions <0.3 mm,% Bulk density, g / cm ³ Fracture rate under load of 7500 psi incl. fractions <0.3 mm,% Duration of vibration damping with an amplitude of 0.8 mm and a frequency of 50 Hz, min: 0 1,56 13.7 / 3.2 1.74 7.9 / 1.3 1,56 7.9 / 1.3 one 1,57 11.8 / 2.0 1.77 6.8 / 1.2 1,58 6.8 / 1.2 2 1,62 9.3 / 1.4 1.82 4,5 / 0,5 1,63 5,4 / 0,5 3 1,64 9.0 / 1.1 1.82 4.3 / 0.3 1,67 5.3 / 0.3 Vibration for 2 minutes with an amplitude of 0.5 mm and a frequency of 100 Hz 1,63 9.1 / 1.2 1.82 4.6 / 0.5 1,64 5.5 / 0.5 Vibration for 2 minutes with an amplitude of 0.3 mm and a frequency of 200 Hz 1,64 8.9.0 / 1.0 1.83 4.4 / 0.3 1,66 5.2 / 0.3

The results obtained indicate an increase in the quality of granules made by the proposed method, compared with proppants of industrial production, including with the closest analogue, which is expressed in an increase in bulk density, strength and a decrease in dust formation during failure under load. The effect was achieved by improving the roundness of the granules, which ensured a denser packing of the layer, reducing the degree of movement of the granules in the working layer when it was loaded, corresponding to a decrease in the surface and volumetric destruction of proppants and the yield of dust fractions.

The implementation of the method with technological parameters close to the maximum installed, reduces the effectiveness of its application.

The use of galvanized proppants obtained according to the 2 variants of the proposed methods solve the same problem with obtaining almost the same technical result (increased roundness, which allows to increase the strength and conductivity of the proppants in the working layer of the well).

Bibliography

1. A method of manufacturing a ceramic oil proppant: Pat. 2235703 Russia, IPC ⁷ C04B 35/20; C04B 35/622 / Shmotiev S.F., Pliner S.Yu., Publ. 09/10/2004.

2. Snegirev A.I., Slobodin B.V. Production technology and properties of spherical granules in the MgO-Al ₂ O ₃ -SiO _{2 system} // Refractories and technical ceramics. 1998. No. 10. S.21-23.

3. Method for the production of high-strength spherical ceramic granules: Pat. 2133716 Russia, IPC ⁶ C04B 20/04 / Migal V.P., Mozherin V.A., Novikov A.N. et al., Publ. 07.27.99, Bull. No. 21.

Claims (4)

1. A method of manufacturing ceramic proppants, including granulating the raw material mixture, drying, firing the granules and sieving into commercial fractions, characterized in that before sieving into commercial fractions, the granules are subjected to tumbling by rolling them in a rotating drum for 20-60 minutes at 20-40 % filling its volume. 2. The method according to claim 1, characterized in that the rotational speed of the drum is chosen such that it provides an erratic mode of movement of the granules. 3. A method of manufacturing ceramic proppants, including granulating the raw material mixture, drying, firing the granules and sieving into product fractions, characterized in that before sieving the product fractions, the granules are subjected to tumbling by vibration abrasion at a frequency of 50 to 200 Hz and an amplitude of 0.8 up to 0.3 mm. 4. The method according to claim 3, characterized in that the vibration abrasion is carried out for 1-3 minutes