Investigation of key parameters influence on properties of the green pellets and lightweight ceramic proppants obtained by mechanical granulation method
J Therm Anal Calorim
Investigation of key parameters influence on properties of the green pellets and lightweight ceramic proppants obtained by mechanical granulation method
J. Szymanska 0
P. Wisniewski 0
M. Malek 0
J. Mizera 0
K. J. Kurzydlowski 0
0 Faculty of Materials Science and Engineering, Warsaw University of Technology , Woloska 141 Street, 02-507 Warsaw , Poland
Ceramic proppants are determined as material designed for hydraulic fracturing in the shale gas industry. Shale formation is fractured due to pumping the fracturing fluid including proppants into the unconventional well. Ceramic granulates set in the newly created fissures act as a prop and permit the shale gas of flowing up the well. The aim of this research was to study and compare ceramic materials used as proppants. The investigation includes four kinds of industrial proppants in green state obtained in a way of mechanical granulation process without binder and with poly(acrylicstyrene) dispersion in amount of 5 mass% with respect to the powder. Green pellets and afterward sintered granulates with 16/20 and 20/40 mesh were also analyzed and compared. Usefulness of green pellets was estimated basing on bulk density, thermal analysis, thermogravimetry, roundness coefficient and porosity results. Structure, morphology and chemical composition of the green state samples were determined by scanning electron microscopy with energy-dispersive spectroscopy. The sintered proppants were also characterized with X-ray tomography, turbidity and solubility in acid. Mechanical strength of these samples was established during subjection to crush test. The outcomes show a suitability of the studied material and prove chemical composition and grain size influence on the integrity of created fractures and therefore the extraction of the unconventional gas out of the well.
Ceramic proppants; Thermal analysis; Hydraulic fracturing; Shale gas
Natural gas is one of the most important sources of energy on
the global market that reduces CO2 emissions more than
twice in case of coal and 40 % lower than oil. A real and
promising perspective for replacing conventional resources
can be deposits of unconventional natural gas that occurs in
shale . This group of hydrocarbons, formed by resources
trapped in impervious rocks, demands specific fracturing
ways. Standard permeability of conventional deposits totals
up 10−3 D (Darcy), while it is much lower on the scale for the
shale gas (10−9 D) . Actually, the unconventional
reservoirs in the world prevail nearly twice over conventional gas.
It is predicted that global shale gas extraction will increase
from 13 % in 2009 up to 23 % in 2035 which is equal to
1.6 bln m3 . Predominant areas in mining industry are
Asia, North and South America. Scale of European
unconventional reservoirs is thrice smaller (Sweden (1.2 bln m3),
Ukraine (1.2 bln m3), France (5.1 bln m3), UK (5 bln m3),
Norway (2.4 bln m3), Germany (7–22 bln m3) and Poland
(0.8 bln m3)) where deposits occur twice deeper (up to 6 km)
in comparison with US shales. Polish shale formations
consist of quartz, loamy, silica, marly and bituminous rocks
that determine more severe geological and geochemical
parameters than American ones .
The most widely practiced and enhanced extraction
technique is hydraulic fracturing with use of viscous liquid
medium transporting suspended proppants . Pumping
such pressurized fluid into a wellbore generates fractures in
the shale rock and thus free flow of hydrocarbons toward
surface. The main component of fracturing liquid is water
(90 %). The rest composes of proppants (9.5 %) and
chemical substances (0.5 %) .
The great importance constitutes the proppants which
act as eco-friendly material mainly used as a prop for
induced cracks; thus, the fractured rock cannot close when
injection is stopped and pressure removed. Then, the
permeable fissure allows the flow of gas to the well so that
output of natural gas from reservoir is possible . There
are currently four types of proppant: quartz sand,
resincoated sand, bauxites and ceramic granules. The last ones
demonstrate the most preferable parameters as uniform
round shape and much higher strength than quartz sand and
resin-coated sand. Such characteristics prove suitability for
the fracturing of deep gas stratum with high closure
pressure. Compared to the other propping materials, ceramic
ones have superiority of smoother surface, higher
fracturing strength and low solubility in acids .
Production of proppants has been launched in the early
50 s of the twentieth century where the pioneer material
was the white quartz. In the 60 s, there ensued
improvement of its strength with simultaneous reduction in its
specific mass. Nowadays, the ceramic proppants are widely
used to replace other proppant materials (natural quartz
sand, fused zircon glass balls and metal balls), particularly
in deep situated wellbores to increase output of gas by 30–
50 % .
Polish extreme geological conditions in deep wells
determine application of light ceramic proppants
presenting the highest quality as thermal stability and crush
strength . Hence, there is a need of production of
ceramic proppants with higher amount of Al2O3 than SiO2 in
order to obtain superior mechanical parameters . It
means these propping agents have to resist closure stress
that surpasses 15,000 even to 20,000 psi–139 MPa
(temperature up to 260 °C) . Otherwise, the material will be
crushed into fines that will block the permeability of a
proppant over time. Five percentage of splinters affect
reduced flow through the fractures by 60 % . The
strength in ceramic materials is also dependent on pores
geometry, distance between pores, pore overlapping,
distance between pores and surface . Uniform size of
proppants ensures a proper level of porosity and thus
facilitated gas migration toward the wellbore for
subsequent extraction . Moreover, high roundness coefficient
prevents loss of fracture width and thus enhances gas flow.
Size of granules can vary between 8 and 140 mesh
corresponding to sphere diameters (106 µm–2.36 mm].
Permeability lowers with the growth of proppant diameter.
What is more, lower specific mass (~2 g cm−3) reduces not
only expenditures of the whole fracturing process but also
proppants settling velocity and thus placement into
fractures in larger concentration yielding . Acids as HCl/
HF mixture can be pumped down the hole to ensure
demanded fracturing conditions. Proppants suspended in
such environment should perform acid solubility resistance
to prevent their size distribution. High HF concentrations
result in increased proppants dissolvent .
Ceramic proppant is sintered mainly from bauxite mixed
with silicate, kaolin and iron–titanium oxide that prove
many works of Polish scientists [15–17]. However, in order
to increase its mechanical strength, resistivity to solubility in
acids and lower specific mass, polymer addition to the initial
raw materials mixture is a common operation. Thermal
analytical techniques seem to be useful to characterize their
thermomechanical properties. Differential scanning
calorimetry (DSC) is a versatile technique used for about
three decades that permits quantitative and qualitative heat
estimation that is taken or generated in materials phase
transition processes related to phase change, melting,
coagulation and other transitions connected with a heat flow.
Moreover, thermal conductivity, thermal diffusivity,
specific heat or thermo elasticity can be measured to provide
quantitative and qualitative information about physical and
chemical changes involving endothermic or exothermic
processes or heat capacity change . The critical
parameter is a glass transition temperature (Tg) that determines
thermal and dynamical properties and additionally the
detection of impurities or unidentified admixtures of used
polymers [19, 20]. In case of a drop of polymer temperature
below Tg, there increases its brittleness. As the temperature
rises above this critical value, the polymer becomes more
rubber-like, which have been investigated in many studies
[21, 22]. That is why, determination of Tg is a crucial issue in
polymer selection for the proppants production.
What is more, the thermal degradation of these materials
can be verified by thermogravimetry (TG). This technique is
based on measurement of the temperature changes that occur
in a substance as a result of chemical reactions or physical
changes. The analysis is carried out by a sample weighing
and continuous heating with constant rate. The mass change
of a sample corresponds to the temperature growth that can
be displayed as the thermogravimetric curve or the
differential thermogravimetric curve (rate of mass loss versus
temperature curve). The curves are the source of information
about the thermal stability and composition of the examined
sample, intermediates and wastes. Many works have been
devoted to the application of this method [23–27].
Studies of light ceramic proppants obtained by
mechanical granulation method basing of Polish raw
materials will be contribution to improvement their
properties and taking the lead on the global shale market.
Experimental samples of the proppants have been produced
from white clay (1G, particle diameter ~40 µm), china
clay-known as kaolin (1J, particle diameter ~40 µm) and
bauxite (1B, particle diameter ~20 µm) that have been
mixed in oscillatory and turret mills. Afterward, the
powder was subjected to granulation process in a turret
granulator and drying in a spray dryer.
Among six mixtures, five of them were composed of
20 % poly(acrylic–styrene) dispersion (5 mass% with
respect to the powder). The highest rotational speed of
mixing was equal to 350 RPM. Two series from obtained
raw proppants were sintered in a rotary kiln. During the
first and second firing (lasting 4 h), sintering temperature
amounted to 1200 °C (first firing) and 1240 °C (second
firing), whereas in a loading zone it totaled up to 500 °C.
The sintering exposition period averaged to 15 min, while
speed of the kiln heating to the maximum temperature was
0.5 RPM. The final granulated product was fractionated in
the sieves with proper mesh sizes.
X-ray diffraction (XRD) measurements of the ground raw
materials were taken out with D8 Advance X-ray Bruker
based on the powder dispersing onto single-crystalline
quartz sample holders and 30-min scan with 10–75°
scanning spectrum. The aim of this experiment was
crystalline phase estimation present in the raw materials and
polymorphous forms distinction.
Moreover, milled raw materials and proppants sample
specimens were subjected to investigate fracture surface,
size and shape in SEM analysis with HITACHI SU 8000
(Hitachi, Japan). The collected pieces were placed on
pinsample holders (1.5 cm diameter) using conducting
doublesided tape. The microstructure characterization was carried
out using BSE detector, voltage 5 kV, working distance
10.8 and 15.4 mm with magnification from 80 to 1000
In order to estimate chemical composition by located
particular elements, energy-dispersive spectroscopy (EDS)
was applied with use of Thermo Noran detector combined
with scanning electron microscope Hitachi SU 8000.
Roentgen microanalysis enabled an accurate identification
of surface topography by back-scattered electrons.
Roentgen tomography was conducted with use of
Roentgen Microtomograph SkySkan 1742. The proppant
samples were scanned with 2000 px 9 1000 px resolution
in range rotation 0–180° (results registration every 0.4°
with use of Al–Cu filter). Basing on scanning data, the
results were subjected to reconstruction to obtain cross
section. Every sample structure at x, y, z planes intersection
was also analyzed in software in order to 3D models
Bulk density study enabled to estimate proppants mass
required to unit volume filling. This parameter can change
depending on how the material handling. In this case, an
essential factor is also porosity. Bulk density determination
allows to mass of proppants preparation needed to crack
inlay during the shale gas extraction process and further
storage of the propping material. The experiment was
based on sleeve calibration (volume 150 mL) with a
defined mass (mf+gp) and then water pouring to its upper
rim (mass determination mf+gp+l). The sleeve volume Vt
was computed according to Eq. (1):
where mw, water mass (netto) from mf+gp+l − mf+gp/g;
0.9971/g cm−3, water density at temperature 21 °C.
Further step was dry and empty sleeve weighting (mp)
and the same procedure in case of beaker completely filled
with proppants (volume 150 mL, mass mf+p). Hence, the
bulk density ρbulk was obtained from Eq. (2):
where mp, mass of proppants from mf+p − mp/g; Vt, sleeve
The degree of roundness was determined with use of
MicroMeter 1.04 program where proppants stereoscopic
images (Nikon DS-F12) were analyzed. The granule
diameter and their areas were used to roundness coefficient
calculations according to Eq. (3):
where A, surface area of proppant/mm2; L perimeter of
Turbidity estimation was carried out in order to
determine amount of proppants particles suspended in a water
solution according to PN-EN ISO 13503-2 norm. Increased
turbidity level corresponds to growth of solid particles in a
suspension. The measurement was conducted with use of
TurbiDirect_4a Turbidimeter where a beam was directed
perpendicularly to the detector track.
Solubility in acids was estimated according to PN-EN
ISO 13503-2 norm. In the measurement, 5 g of proppants
put in 100 mL of 12:3 HCl:HF solution (12 mass% HCl,
3 mass% HF) in a bath at 66 °C temperature for 30 min.
The solubility in such acid solution indicates soluble
compounds content (carbonates, micas, ferrous oxides,
loams) present in the investigated material. The solubility S
was obtained basing on formula (4):
where mS, mass of the sample/g; mF, mass of the filter/g;
mFS, mass of the dry filter with sample/g.
Thermal analysis of poly(acrylic–styrene) dispersion was
carried out through differential scanning calorimetry
analysis (DSC) with use of TA Instruments DSC Q1000
Fig. 1 SEM images of investigated proppants: a G1 green pellets, b
20/40 green pellets, c 16/20 green pellets, d G5 green pellets at 980
magnification, e 16/20 sintered proppants with 980 magnification, f
16/20 sintered proppants with 91000 magnification, g 20/40 sintered
proppants with 980, h 20/40 sintered proppants with 91000
apparatus. Temperatures characteristic for phase transitions
and their enthalpy values were determined. Temperature
calibration proceeded with use of indium model sample.
Measurements were taken out in a nitrogen atmosphere. The
samples with a mass of 10 mg were subjected to heating and
cooling with a constant speed (Vh = 10 °C min−1) in a
temperature range from −40 to 100 °C.
The thermogravimetric (TG) and derivative
thermogravimetric (DTG) curves for the polymeric dispersion
were obtained due to analysis conducted using TA
Instruments TGA Q 500 under nitrogen atmosphere at a
heating rate (Vh) of 10 °C min−1 from 20 to 800 °C. The
sample initial mass was about 45.00 mg. The onset
temperature of degradation (Tonset) was obtained by the
intersection of the tangent of the peak with the extrapolated
baseline from the first degradation peak of the TG curves.
Crush test was conducted of hydraulic press adjusted to
exert pressure up to 15,000 psi. Amount of the proppant
sample put in a cylinder was determined according to
Fig. 2 EDX analysis of G5 proppants sample
where ρbulk, a bulk density/g cm−3.
The material should fill the cylinder to specific height so
as exerted pressure on a piston’s surface averaged
1.95 g cm−3. The falling sample gave a flat surface of
material inside the cylinder. The piston was inserted into
the cylinder in centric position with reference to the
hydraulic press. Force exerted on the piston to obtain
Fig. 3 Tomographic images of G1 proopants: a 3D models, b interior tomography
Fig. 4 Tomographic images of G5 proppants: a 3D models, b interior tomography
required stress values was determined according to Eq. (6):
stress value. The stress was maintained for 2 min and then
reduced to zero value.
where Ftc, force exerted on the piston/N; Ơ, stress exerted
on the sample/MPa; dcell, inner diameter of the cylinder/
The force was increasing with a constant speed of
increasing piston loading corresponding to growth of the
stress (13.8 MPa min−1–2000 psi min−1) up to the final
Results and discussion
XRD analysis of raw materials used for the proppants
production indicated dominating presence of boehmite and
kaolinite, and in minor amounts phases of calcite, anatase,
rutile and hematite. Kaolin consists of kaolinite, quartz
Fig. 5 Tomographic images of 20/40 green proppants, a 3D models, b interior tomography
alpha and rutile, whereas white clay samples contain
kaolinite, potassium calcium aluminum silicate phase,
grossite and cristobalit as well.
Obtained granules were differentiated into green
proppants (named green pellets: G1, G5) and sintered proppants
(named: 16/20 and 20/40) with a chemical content based on
the G5 green pellets (addition of poly(acrylic–styrene)
dispersion). Analysis of the samples microstructure and
their shape were performed by scanning electron
microscopy. SEM images (shown in Fig. 1a–h) indicate that
there is a difference between all proppants size. G1
(Fig. 1a) demonstrates the smallest diameter, whereas G5
samples (Fig. 1d) exceeds their dimension few times
(~0.5 mm). Samples of the investigated green pellets
(Fig. 1a–d) are characterized by coarser surface in
comparison with the sintered ones (Fig. 1e–h). However, both
the green pellets and sintered proppants present similar
round shape. The most non-uniform particle size
distribution is attributed to G1 proppants (with any polymer
EDS analysis at microareas proved a huge conformity
according to chemical content among all studies proppant
series. Dominating elements are Al, Si, Mg, Ca, K and Ti
that are typical for such kind of materials based on mineral
Fig. 6 Tomographic images of 16/20 green proppants, a 3D models, b interior tomography
raw materials. Presence of Fe suggests the presence of
small amount of contaminants taken from mineral deposits
Basing on tomographic scanner data, results were
subject to reconstruction; thus, propping agent cross sections
were obtained. Software designed to ceramic materials
analysis provided structure images as the intersection of the
x, y, z planes and also 3D models (Figs. 3–8).
G1 green pellets (Fig. 3) demonstrate round shape.
However, their size distribution is non-uniform. It has
been investigated by many researchers that uniformity of
the all kinds of propping agents strictly determines shale
gas flow in the reservoir. A minimum 90 % of the settled
ceramic granules in the well must be within the specified
screen size, as it was discussed in another work .
Moreover, the G1 proppants tomography revealed
incorrect pores arrangement creating elongated cracks. This is
a ground of the substantial risk of insufficient crush
resistance of this material in the fracture. These elongated
cracks seen in the cross section might lead to the material
fracture into fines, blocking a permeability of the fissure.
Additionally, a high concentration of the fines
corresponds to improper proppants transportation and affects
the fracturing fluid rheology. Green proppants with
Fig. 7 Tomographic images of 20/40 sintered proppants: a 3D models, b interior tomography
polymer addition (G5, 16/20, 20/40) perform more
uniform size and draw analogy between spheres. However,
among the G5 proppants (Fig. 4), there is still an
inadmissible distinction in every single granule diameter. This
parameter should be as low as possible that rises the
material conductivity. The large proppants injected into
the wellbore, settle closer blocking the further smaller
proppants transportation in a narrow fissure and make
them useless. Unfortunately, still there is also a presence
of widely arranged macropores inside the material. It is
claimed that 50–80 % of pores in propping material
cannot be conjoined to assure a proper shale gas flow in a
The 20/40 (Fig. 5) and 16/20 (Fig. 6) green pellets
demonstrate more favorable structure. All of them present a
suitable pores geometry and distances between them,
which will have an effect on their high mechanical strength
after sintering. The 20/40 proppants are smaller than the
16/20 ones (but with similar coarse surface) which means
that they can cover a further distance in the fissure and
Fig. 8 Tomographic images of 16/20 sintered proppants: a 3D models, b interior tomography
create a bridge in the embedment. Finally, sintering process
affects the regular and small size pores distribution, where
best parameters are attributed to the 16/20 sintered granules
(Fig. 8). It means that these proppants can be settled in
higher amounts and the load will be distributed across more
particles. Thus, the large contact angle can reduce tensile
stress concentration, assuring a stable prop for the created
fracture in the shale formation and finally, enhanced
permeability of the material.
Bulk density of the green granules is slightly lower before
sintering process (Table 1). According to US 2011/0160104 A1
patent required value of this parameter falls on a range between
1 and 3 g cm−3. All of the samples fulfill this condition.
In Table 2, roundness coefficient of the granules has
been compared. Every proppant sample is characterized by
required round shape value that results enhanced shale gas
conductivity. The highest parameter was obtained for G5
Table 1 Bulk density of ceramic proppants
Bulk density/g cm−3
Table 2 Roundness coefficient of ceramic proppants
Vh = 10 °C min–1
Fig. 9 DSC analysis of poly(acrylic–styrene) dispersion
Vh = 10 °C min–1
Fig. 10 Mass loss of poly(acrylic–styrene) dispersion as a function of
temperature under nitrogen atmosphere—TG and DTG curves
Turbidity value varies from still critical
acceptable level: 60. 84 NTU for 16/20 sintered samples to 122
NTU in case of 20/40 proppants. With respect to the Polish
water quality norms, drinking water cannot exceed
turbidity equal to 1 NTU, while maximum permissible value
for proppants comes to 58 NTU. High turbidity value is
related to risk of hydraulic fluid contamination by
proppants disintegration. It may result with fracture clogging
during unconventional gas extraction.
Fig. 11 Crush test results of 20/40 sintered proppants
Fig. 12 Crush test results of 16/20 sintered proppants
Both the 16/20 and 20/40 sintered granules demonstrate
low susceptibility to acids activity (2.61 and 2.39 %,
respectively) where acceptable solubility limit is equal to 7 %.
DSC analysis of the applied water-thinnable poly
(acrylic–styrene) dispersion (present in all the samples with
the exception of the G1 samples) indicates that copolymer
demonstrates low glass transition temperature (Tg) close to
the room temperature (as shown in Fig. 9). This value is a
consequence of many factors. First of all, there is a lack of
groups able to hydrogen bonds formation. Moreover, the
presence of a phenyl group, which acts as “a stiff group,”
causes reducing of the copolymer rotation and therefore
raising Tg value to the room temperature . What is
more, an irregular structure of the copolymer chain and
increase in a length of aliphatic radicals lowers Tg due to
increased rotation energy of a single particle around the
bonds in the main chain. Therefore, there occurs
simultaneously increase in plasticity of polymer that
behaves as amorphous material. The sufficiently low Tg
value and the presence of suitable functional groups in the
copolymer ensure good cohesion of polymer dispersion
separately and adhesion of the copolymer to the powder
grains surface as well. Such a relation prevents the
formation of raw materials agglomerates. All these parameters
correspond to wettability of the powder by the polymer,
and thus the strength of the final sintered proppants owing
to the ceramic filler–copolymer interface. The estimated
glass transition temperature is much lower than proppants
granulation (40 °C) and the sintering temperature; thus,
there is no need to add plasticizers to the initial raw
mixture. What is more, the final sintered material demonstrates
high mechanical strength.
The thermal decomposition of the polymers can take
place in few stages. It was examined that the polymer
degradation due to thermal exposition is dependent on its
chemical structure. This phenomenon is initiated by the
decomposition of the weakest bonds at the temperature
specific for every compound corresponding to the presence
of the diverse groups attached to the main chain. Usually,
this temperature value is related to the 5 % mass loss. In
case of the examined copolymer (poly(acrylic–styrene), the
initial degradation relates to drop in the mass of 2 %,
noticed for 272 °C which is a result of macromonomers
release from the end chains. The rapid material degradation
(5 % mass loss) started at 331 °C (presented in Fig. 10)
where the polymer fragments with high activity (and thus
low activation energy) decomposed first in the dispersion.
The sharp change in the mass is observed to 425 °C, leaving
7 % of the mass sample, corresponding to the continuous
decomposition into monomers and side chains containing
phenyl groups. Further slower copolymer decomposition
occurs in the temperature range of 425–523 °C (98 % of
mass loss), expected for unbranched hydrocarbon chains.
The last, in trace amounts, mass loss step is observed
between 523 and 600 °C. The copolymer behaves as
thermal stable at 600 °C with the final mass of 0.2761 mg. It
corresponds to the general 99.3876 % decomposition of the
copolymer for the whole heating process. The remaining
mass may relate to the part of impurities that could not be
removed from the polymer. The results calculated from the
DTG curve (Fig. 10) revealed that the dynamics of the
degradation proceeds between 346 and 516 °C. The onset
temperature (Tonset) for the thermal degradation of the poly
(acrylic–styrene) dispersion is noticed at 404 °C, which
indicates a rapid decomposition into monomers. According
to the DTG data, the definitely slower thermal degradation
occurs also at 516 °C, verified as a new small peak in the
temperature range between 450 and 530 °C. It can be
attributed to the defragmentation of additional bonds or
groups in the material.
Conducted crush tests proved that 16/20 proppant series
are more resistant to mechanical strength in comparison
with 20/40 granules (Figs. 11, 12) which is related to the
pores size and distribution inside the material. A total of
16/20 proppants were able to resist even in the highest
stress of 210 kN (103 MPa–15,000 psi), whereas 20/40
series crushed after 4 min of exerted pressure (51.71 MPa–
105.5 kN–7500 psi).
Results of conducted research studies indicate that raw
materials used to proppants production consist of
compounds typical for loamy deposits where Al2O3 and SiO2
are dominating compounds. All of the proppants
demonstrate proper roundness coefficient, whereas the most
uniform shape reveal the 20/40 and 16/20 proppant
samples. The studied granules are characterized by slightly
coarse surface. The regular pores arrangement is
characteristic for the 16/20 sintered samples which results in their
high mechanical strength. The 20/40 granules perform
insufficient resistivity to high stress values; thus, there is a
risk of these proppants will flatten and pack together under
high closure stresses during shale gas extraction.
The sintered proppants are stable in strong acidic
environment. However, the 20/40 proppants are prone to
disintegration in water making a risk of fracture clogging
and a straitened gas flow. All the samples are characterized
by low thus bulk density that results in their facilitated
transport in liquid medium.
The glass transition temperature analysis was a very
crucial part of the polymeric binder investigation and
enabled determination of its impact on the rheological
properties of applied powders as well as the critical
parameters of the ceramic materials obtained with them.
The implemented copolymer dispersion (to G5, 16/20 and
20/40 proppants) demonstrates the low glass transition;
thus, the sintered propping agents perform increased
mechanical strength. What is more, Tg value nearly equal
to the room temperature also influences the manufacturing
costs, because there is no need to add other dispersants
lowering the binder Tg value.
The thermal decomposition results obtained by
thermogravimetry method reveal the material is prone to thermal
degradation starting at 272 °C. Further exposition to 600 °C
causes almost total material degradation, where is only
0.6124 % material residue. The TG and DTG curves data
indicate that the poly(acrylic–styrene) dispersion can be
applied as a binder in the initial proppants manufacturing
(granulation process), where is functional and thermal stable.
To sum up, the investigated light ceramic proppants
perform properties which enable their application for
hydraulic fracturing in strict geological conditions
determined by extremely high pressure, temperature and low
permeability of shale formations. The granules fulfill the
norms and thus state a prospective material on a global
Acknowledgements Financial support of BLUE GAS Programme
financed from The National Centre for Research and Development
Project: “Optimizing the lightweight high strength and low specific
gravity ceramic proppants production technology maximally using
naturally occurring Polish raw materials and fly ash,” No. BG1/
BALTICPROPP/13 is gratefully acknowledged.
Open Access This article is distributed under the terms of the
Creative Commons Attribution 4.0 International License (http://crea
tivecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided you give
appropriate credit to the original author(s) and the source, provide a
link to the Creative Commons license, and indicate if changes were
1. Osikowicz R. Paliwa i Energetyka . Rynek gazu na s´wiecie. Mar 2012 .
2. Woz´niak P , Janus D. Gaz z łupko´w, szczelinowanie i ceramiczne proppanty cz . 1. Wiadomos´ci. 2013 ; 3 : 7 - 12 .
3. BP. BP Energy Outlook 2035 . 2014 . http://www.bp.com/content/ dam/bp/ pdf/energy-economics/energy-outlook-2016/bp-energyoutlook-2014 .pdf. Accessed Apr 2014 .
4. Przybylik M , Stangierski P , Oswald K. Paliwa i Energetyka . Apr 2013 .
5. Baltic Ceramics . Memorandum. Warsaw University of Technology ; 2012 .
6. Woz´niak P , Janus D. Jaki proppant jest kaz˙dy widzi-czyli o metodach wyznaczania parametro´w charakterystycznych i o producentach . Wiadomos´ci . 2013 ; 8 : 14 - 8 .
7. Woz´niak P , Janus D. Gaz z łupko´w, szczelinowanie i ceramiczne proppanty cz . 2. Wiadomos´ci. 2013 ; 4 : 13 - 8 .
8. Beckiwith R. Proppants : Where in the world . 2011 .
9. Ciechanowska M , Kasza P , Lubas´ J, Matyasik I , Such P. Instytut Nafty i Gazu . Raport nt. Uwarunkowania rozwoju wydobycia gazu z polskich formacji łupkowych . Forum Energetyczne. Sopot : 2012 .
10. Schlumberger . High pressure, High temperature (HPHT) , 2014 ; http://www.slb. com/services/technical_challenges/high_pressure_ high_temperature.aspx. Accessed 15 Oct 2015 .
11. Don L. Proppants open production Pathways . 2011 . https://www. slb.com/~/media/Files/stimulation/industry_articles/201101_ep_ proppant_design.ashx. Accessed 20 Apr 2014 .
12. Richerson DW . Modern ceramic engineering: properties, processing and use in design . 3rd ed. CRC Press; 2006 . p. 29 .
13. Szymanska J , Wisniewski P , Wawulska-Marek P , Malek M , Mizera J. Selecting key parameters ot the green pellets and lighweight ceramic proppants for enhanced shale gas exploitation . Procedia Struct Integr . 2016 ; 1 : 297 - 304 .
14. Ottestad E. Proppants , properties and Requirement. NTNU . 2013 .
15. Wisniewski P , Szymanska J , Malek M , Mizera J. Optimizing the lightweight ceramic proppants properties . Acta Phys Pol , A. 2016 ; 129 : 501 - 3 .
16. Szymanska J. Studies of the lightweight ceramic proppants using naturally occurring Polish raw materials . MSc Thesis . Warsaw University of Technology ; 2014 .
17. Wisniewski P , Malek M , Szymanska J , Zarzycka-Dziedzic D , Mizera J , Kurzydlowski KJ . Studies on receiving ceramic proppants by the spray drying method . Ceram Mater . 2015 ; 67 : 448 - 53 .
18. Pratap A , Sharma K. Applications of some thermo-analytical techniques to glasses and polymers . Budapest. 2012 ; 107 : 171 - 82 . doi:10.1007/s10973- 011 - 1816 -y.
19. Zhouyue L , Wang X , Jinrong W , Guangsu H , Xiaoan W , Lijuan Z. The proper glass transition temperature of amorphous polymers on dynamic mechanical spectra . J Therm Anal Calorim . 2013 ; 116 : 447 - 53 . doi:10.1007/s10973- 013 - 3526 -0.
20. Fueglein E , Kaisersberger E. About the development of databases in thermal analysis . J Therm Anal Calorim . 2015 ; 120 : 23 - 31 . doi:10.1007/s10973- 014 - 4381 -3.
21. Szafran M , Wisniewski P , Rokicki G. Effect of glass transition temperature of polymeric binders on properties ceramic material . J Therm Anal Calorim . 2004 ; 77 : 319 - 27 .
22. Wisniewski P. Badania nad procesem prasowania tlenku glinu z udziałem nowych wodorozcien´czalnych spoiw polimerowych . PhD Thesis . Warsaw University of Technology, 2003 .
23. Rodr´ıguez Mart´ınez AD , Dom´ınguez Patin˜o ML , Melgoza Alema´n RM, Rosas Trejo GA. Characterization by thermogravimetric analysis of polymeric concrete with high density polyethylene mechanically recycled . J Miner Mater Charact Eng . 2014 ; 2 : 259 - 63 .
24. Zhang T , Howell BA , Smith PB. Thermal degradation of carboxy-terminal trimethylolpropane/adipic acid hyperbranched poly(ester)s . J Therm Anal Calorim . 2015 ; 122 : 1159 - 66 . doi:10. 1007/s10973- 015 - 4790 -y.
25. Zhang GZ , Zhang J , Wang F , Li HJ . Thermal decomposition and kinetics studies on the poly (2,2-dinitropropyl acrylate) and 2,2- dinitropropyl acrylate-2,2-dinitrobutyl acrylate copolymer . J Therm Anal Calorim . 2015 ; 122 : 419 - 26 . doi:10.1007/s10973- 015 - 4687 -9.
26. Maciejewska M. Synthesis and characterization of textural and thermal properties of polymer monoliths . J Therm Anal Calorim . 2015 ; 121 : 1333 - 43 . doi:10.1007/s10973- 015 - 4538 -8.
27. Zhang GZ , Zhang J , Li HJ , Zhao S. Synthesis and thermal behavior of gem-dinitro valerylated olystyrene . J Therm Anal Calorim . 2014 ;. doi:10.1007/s10973- 014 - 3840 -1.