Method of producing ceramic proppants. RU patent 2513434.

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil and gas industry, and namely to the manufacturing procedure of ceramic proppants intended to be used as propping agents at production of oil or gas using the formation hydraulic fracturing method (FHF). According to the manufacturing procedure of ceramic proppants that includes pretreatment of feed stock, milling and formation of granules (granulation), drying and sintering of granules, treatment of their surface with reagent; at milling stage a special water-insoluble sintering agent is added to the feed stock and at granulation stage a cellulating agent containing a water-soluble mineral acid salt is diluted in the granulation liquid; sintering agent and cellulating agent have the following ratio in % in excess of the feed stock weight: cellulating agent - 0.1-1.5, sintering agent - 0.1-2.0, and the above treatment is made by capillary imbibition of the granules porous shell with the solution.

EFFECT: simplifying production technology for proppants surface-treated with agent in order to improve their strength.

2 cl, 1 tbl, 6 dwg, 1 ex

The invention relates to the oil and gas industry, namely to the technologies of production of ceramic proppants, which are intended for use as propping agents in the extraction of oil or gas by the method of hydraulic fracturing - fracturing. Because, as you extract the fluid pressure in the reservoir has continually decreased viability artificially formed of hydraulic fracture is guaranteed only in case, if they were formed by such agents as proppants (rasklinivanie). Accommodation sufficiently large packs of proppant helps to solve the problem of maintaining the productivity of wells over a long period of time.

More than 85% of currently used proppants are such simple materials as specially disseminated to obtain the necessary granulometric structure of quartz sand produced by natural deposits, and also it more durable version - the sand with a polymeric covering. However, as the depletion of easily accessible reserves of hydrocarbons, mining companies are forced to intensify exploration and development of difficult deposits, which implies more and more wide application of high-strength ceramic proppants highly sphericity and roundness. However, these characteristics of proppant were clearly insufficient for increasing the completeness of extraction of a product from a well. Because after fracturing the degree of extraction of hydrocarbons is largely determined by the permeability of the proppant pack to the proppant are additional special requirements - the product must be heat resistant, chemically inert, environmentally friendly, safe. In turn studies conducted in recent years, a number of organizations, show that the speed of the outflow of the fluid through a layer of proppant is determined not only by the characteristics of proppant, but the degree of eutrophication of spending channels situ bacterial culture, and the presence in the stack intact gel-media.

For removal of non-gel-media proppant use washing crack solutions of mineral acids. To prevent anaerobic growth of zhelezobetona and sulphate-reducing bacteria, which rapidly multiply in fracturing fluid, causing corrosion of equipment and pipelines, and the obliteration of channels proppants, fracture fluid include biocides. At that, the negative impact of hydraulic fracturing on the environment associated with possible pollution of the aquifer (reservoir) biocides and other chemicals used in hydraulic fracturing, carries the risk of a serious ecological disasters.

To solve these problems, the original technical solutions ensuring the application of the surface of proppant relevant substances.

Known US patent # 7721804 in which the proppant for oil and gas wells contains many of spherical particles, where the surface of each particle covered by a layer of the structure, including the destructor of the gel, and the destructor of the gel is selected from the group consisting of enzymes, oxidants, peroxides, persulfates, perborate, catalysts silver, iron, or copper, sodium bromates, acids, oxyacids, oxy-anions halogen derivatives of such substances, or their combination, and the layer of the structure, including the destructor gel, covered by an outer layer of PVC, where the outer layer of polyvinyl chloride delaying the release of the composition of the destructor of the gel. The proppant is selected from the group consisting of lightweight ceramic proppant, ceramic proppant intermediate strength, porous ceramic proppant, glass beads, and other ceramic proppants or payments with polymeric coating. The proppant contains from 1 to 10 wt.% destructor gel, and the outer layer contains 6 to 18 wt.% polyvinyl chloride.

The disadvantage of this technical solution is the need of the application to the surface of proppant protective polymer film, impeding the work of the destructor of the gel during the delivery of reclinatus to the place of hydraulic fracturing. Moreover, to prevent the violation of external coatings during transportation of proppant, the thickness of the protective film should be large enough, as indirectly proves the declared amount of the polymer. In this case, the coating layer-by-layer with mandatory drying and sieving of granules of proppant after application of each layer, which complicates the manufacturing process and significantly increases the cost of production. In addition, the presence on the surface of particles of proppant polymer coating in the significant number inevitably leads to a sharp decrease in the permeability of the proppant pack.

It should be noted that in the known technical solution after applying the destructor of gel on porous proppant its surface is still covered with a protective film. This need is dictated by the fact that well-known porous proppants contain both on the surface and in the volume quite a large pores, not able to keep the destructor. For this reason, impossible washing interporous surface from the destructor of water or other liquid, because in this case leaching destructor of the surface pores and reduce its concentration in addition absorption washing liquid in pores leads to a catastrophic loss of strength proppant.

The closest to the technical nature of the claimed solution is patent RF №2363720 in which the method of manufacturing of proppant includes applying for pellets reagent - bactericide and silicone repellent. Applying carry out the evaluation of the burnt ministerialnej granules solution antibacterial drugs in the amount of 0.2-2.5 wt.% from the weight of granules in terms of the active substance, and then specified repellent in the amount of 0.3-2.0 wt.% from the weight of granules with the subsequent washing with hot water. Moreover processing solution antibacterial preparation is carried out for 2-5 minutes.

The disadvantage of known technical solutions, as in the previous patent, is the necessity of application to the surface of proppant hydrophobic films preventing flushing bactericidal substances from a surface of granules. Although the thickness of protective coatings in this technical solution is much less than in the previous patent, the necessity of its application complicates the manufacturing process of proppant and increases the cost of production.

Technical task, which is aimed the claimed invention is a simplification of manufacturing technology of proppant coated on the surface of the reagent, due to the formation of external microporous the surface of particles, effectively holding the reagent, while maintaining the normative strength of granules.

This result is achieved in, a method of manufacturing of ceramic proppant, including the preparation of the initial charge, grinding, formation of granules - granulation, drying, calcination and processing of a surface of granules with a reagent in charge when grinding addition to impose sintering additive - water-insoluble substance and granulation - dissolved in a liquid for granulation pore-forming additive - water-soluble salts of mineral acids, and sintering and pore-forming additives are in the following ratio, in % over charge mass:

pore-forming additive

sintering additive

as specified processing performed by capillary saturation of porous shell granules with chemical solutions. And as a reagent used biocide or scale inhibitor, or the finisher gel-media proppant, or the destructor of the carrier liquid proppant.

Simultaneous introduction in the composition of the material water-soluble pore-forming additives and water-insoluble sintering leads to the fact that during the drying process, and in the initial stage of roasting of a pore-forming additive together with the evaporated water is moved to a surface of granules and sintering additive remains evenly distributed throughout the volume of the spheres. When the temperature of sintering kiln maximally increases the effect of sintering additives and results in the release of gas from a pore-forming. In the burnt pellet has in the surface layers channel micropores, and its internal volume is dead burnt. The surface of such granules with capillary saturation of the active substances has good holding power.

On manufactured by the claimed method granules capillary impregnation put the active substance, capable of a long time to be in the pore space. The activity of substantive increases with the increase of reservoir temperature, and when macrorestriction granules in areas of mutual contact after application of compressive loads. It is necessary to emphasize the fact that the formation of the outer layer of microporous implemented claimed by the way, does not render appreciable influence on the bulk density and the destruction of proppant.

When applying for pellets biocidal substances of biocidal effect is local and not beyond the surface of proppant. As biocides can be used as mass-produced products and newly developed substances, capable to work indefinitely long time, for example, selenium compounds, releasing in contact with bacterial environment reactive oxygen species that kill bacteria and prevent the formation of biofilms.

The mechanism of action of scale inhibitor as the active substance similar to the action of the biocide.

On manufactured by the claimed method granules capillary impregnation put substance, razlagalsa gel media proppant. After applying the destructor granules proppant may be washed with water to remove destructor of interporous space in order to reduce its impacts on the gel during the delivery of reclinatus to the place of hydraulic fracturing. When washing the proppant does not lose its strength characteristics, since most of the granules is dead burnt.

Use as the active substance staple linear fluid fracturing can reduce the settling of proppant during its transportation through the crack at the expense of cross-stitching gel around each pellet, accompanied by a local increase in the viscosity of hydraulic fracturing. This effect makes it possible transportation of proppants with a high bulk weight using the straight-line gels as fluid fracturing, which greatly facilitates the downloading of proppant and cheapens the process of hydraulic fracturing.

Most clearly the use of proppant, obtained by the claimed method shows an example using as the active substance of the biocide.

An example of implementation of the invention

To 10 kg of charge for making ministerialnej proppants, which contains, mass%: MgO - 27,9, SiO 2 - 58,3, Fe 2 O 3 - 8,1, impurity - the rest was added to 1 wt.% (100 g) of cryolite and subjected to a material joint milled to the required particle size distribution. Granulation resulting mixture was performed on the water solution of sodium sulfate in such a way that its content is in the charge was 1% above its weight. Granules faction 20/40 mesh burned and scattered. Then granular material quantities of 1 kg was supplied in a paddle mixer, which was added to 100 ml of an aqueous solution of antibiotic "Altosan-bactericide, containing 10 g of the active substance, and was stirred for 2 minutes To check the holding capacity surfaces impregnated with biocide payments for 5 hours were washed under running water with a temperature of about 18 degrees C and placed in the bacterial environment, in parallel to the same environment were placed granules without antibacterial treatment. In this way were made proppants with different content of sintering and perebratsy additives and proppants by the patent RF №2363720 using polimetilsiloxan (PMS) as hydrophobic coating. The number of biocide in all samples was the same. Antibacterial activity of proppant were investigated by Bacillus subtilis culture within 28 days. The research results are presented in Appendix photo 1-6.

In addition, the comparative assessment of destructible and bulk density of proppant, obtained by the claimed method, and proppant - analogues. The survey data presented in the table.

Destructible proppant faction 20/40 mesh

Name of proppant

Bulk plotnosti, g/cm 3

Destructible, wt.% at 7500 psi

Standard magicality proppant production of LLC "FORES"

Magicality proppant by the patent RF №2363720

The proppant, obtained by the claimed method *

1,58-1,61

* the dispersion of the values due to the ratio of sintering and proobrazom additives.

The analysis of the results shows that the proppant made by the claimed method, the carrying capacity is not inferior to the proppant coated with good strength characteristics. Eliminating the need to apply for pellets external protective coating simplifies the technology of manufacture of sand and reduces its cost, and the absence of a polymeric covering favorably affects the permeability of the proppant pack. Thus, the proposed method allows to obtain the proppant, which can be used as the carrier of any of soluble active substance.

1. A method of manufacturing of ceramic proppant, including the preparation of the initial charge, grinding, formation of granules - granulation, drying, calcination and surface treatment of pellets reagent, characterized in that the charge when grinding addition to impose sintering Supplement - water-insoluble substance and granulation is dissolved in a liquid for granulation pore-forming additive - water-soluble salts of mineral acids, and sintering and pore-forming additives are in the following ratio, in % over charge mass:

pore-forming additive

sintering additive

as mentioned treatment is carried out by means of capillary saturation of porous shell granules with chemical solutions.

2. The method according to claim 1, characterized in that, as of reagent is used biocide or scale inhibitor, or the finisher gel-media proppant, or the destructor of the carrier liquid proppant.