Hydraulic fracturing has been used in Azerbaijan since 1954 to increase oil production from low permeability reservoirs. About 1100-1200 acid treatments and 1000-1200 hydraulic fracturing treatments are conducted annually. Thickened oil is used as the fracturing fluid, which improves the fracturing process by maintaining higher viscosity over longer periods compared to pure oil. Case studies showed wells fractured with thickened oil experienced higher subsequent oil production increases than those fractured with pure oil. However, hydraulic fracturing application has declined in recent years at SOCAR due to financial constraints and aging equipment.

1. Hydraulic fracturing in Azerbaijan
During long development of many on- and off- shore fields of Azerbaijan highly productive
layers have been considerably worked out and there is an increase observed in the amount of
hardly recoverable oil reserves confined to lower permeable reservoirs, high-viscous oil, water-
oil zones, deposits at late development stage. There are different physical and chemical treatment
methods to be applied in the well bottom zone in order to increase well productivity: hydraulic
and hydro-acid fracturing, pumping of coarse-grained sand into plug-forming wells, acid
treatment, treatment with different (dis-) solvents etc. About 1100-1200 acid treatments of
bottom zone and hydro-acid formation fracturings, more than 1000 hydraulic formation
fracturing and sands pumping, 2000-2500 treatments of bottom zone with HC (dis-) solvents etc.
are held annually.
Formation hydraulic fracturing (FHF) in oil fields of Azerbaijan was used in 1954.
Hydrofracturing is one of mechanical methods to
influence the bottomhole formation zone. Liquid is
being injected under pressure into permeable layer;
under its influence the layer is splitted either by bedding
planes or along natural fractures. To prevent fractures
from closing, coarse sand is being injected together with
liquid; it maintains permeability of these fractures
which by 1000 times exceeds permeability of the intact
rock structure.
Liquids for hydraulic fracturing (sand-carriers)- are
low filterable liquids with non-newtonian properties to
keep liquid in the fracture for a long time. Heavy
Kirmaki oil for a long time was a main liquid for
fracturing and sand carrier in Azerbaijan. According to
the standard measuring device used to determine water
loss of mud, filterability of oil, as mentioned above, his
from 10 up to 130 cm3
per 30 min.
Physical properties of Kirmaki oil
Viscosity by
Kepler, MPa.s
Viscosity by
capillary
viscometer,
MPa.s
Specific gravity
with 30ºC,
gr/cm3
Bound water, % Paraffin, %
198.5 196.6 0.935 - 4.86
Infilling with breakdown agent. In order to decrease the filtration ability of breakdown agent
and fully use hydraulic power of pumping units, chemical agents are used to inject breakdown
agent. However, due to their deficiency they were not used in Azerbaijan. In practice during
formation hydraulic fracturing waste material from oil refinery plant named after K. Karaev
(Baku) is used as a thickener- calcic salt of acid tar, which is obtained while producing oily
additives. Adding such thickener (calcic salt) to Kirmaki oil strongly changes rheophysical
properties and improves formation structure. In order to determine a type of such thickened oil

2. 2
(mixture), capillary types were studied using viscometer. The results show that such a mixture is
not subject to Newton's law of motion.
Gravimetric relation of liquid, % Structural
viscosity with
20ºC, centipoise
Stress limit of
shift,
mgr/cm2
Filterability,
cm3
per 30 minoil thickener
100 - 189 56 44
95 5 220 105 5
90 10 248 282 105
85 15 265 510 0
80 20 318 675 0
75 25 360 870 0
70 30 420 1010 0
Efficiency in application of thickened oil. Due to low filterability of thickened oil, amount of
breakdown agent and sand-carrier, and also their pumping rates, were somewhat lower than for
FHF with pure oil. Oil production increase is higher as a result of applied thickened oil compared
to pure oil.
Well
N
Breakdown
agent (oil +
thickener)
Sand-carrier
(oil +
thickener)
Amount
of sand
Oil production increase
with FHF:
original
without use of
thickener
repeated with
use of
thickener
in tons
2307 5+1 20+4 10 without result 1270
2208 5+0,75 30+5 12 1872 175
2190 5+1 28+1 10 498 75
1935 5+1 30+4 10 without result 164
1734 5+0,75 30+4,5 10 without result 548
446 5+0,75 30+4,5 10 without result 56
1984 4+1 20+4 10 without result 100
2364 5+1 30+5 10 without result 385
2138 6+0,75 30+4 10 without result without result
Sand for hydraulic fracturing is quartz sand with grain size of up to 2-3 mm. In practice not
only one but several sandy fractures are used; they are introduced into the fracture successively.
Sand for hydraulic fracturing was delivered to Azerbaijan from Volgograd region. Sand on
the plant in Baku was used for washing, drying, sifting etc. Currently the plant is not
operating.
Rate for liquid pumping. It is known from FHF theory and practice, the higher pump rate - the
higher process efficiency. Actual data shows that injection rate of breakdown agent and sand
mixed with liquid does not exceed 55-60 l/s.
Efficiency of hydraulic fracturing. FHF covered targets with productive series having different
geological and physical properties. FHF efficiency has different values in different targets. Thus
in Lower Kirmaki and Kirmaki Sandy horiozns the efficiency does not exceed 45 %, in the
Maycopian horizons- 55-60 %, and over fields in Azerbaijan - 50 % in total.

3. 3
In addition to the number of treatment technological factors, the condition of bottom zone,
properties of fracturing liquid and sand-carrier, well choice etc., FHF is also affected by
physical-chemical characteristics of produced oil. In the wells where oil has high paraffin,
asphaltene and tar content, efficiency from FHF is 42-45 %, and its effect does not exceed 5-7
months. In the wells not producing non-newtonian oil, the effect lasts for13-14 months.
Hydro-acid formation fracturing- is one of mechanical types to impact a layer. It is based on
the ability of hydrochloric acid to dissolve carbonaceous, dolomite and quartz rocks. This
method also facilitates cleaning of filtered well zones, production from which has a considerable
amount of mechanical solids. Once hydro-acid formation fracturing was used in
Muradkhanly field, that has a complicated geological structure with abnormally high
formation pressures and temperature. Main production targets are in the Lower .
Cretaceous horizons. The productive horizons are at 3500-4500 m depth.
Work status as of today. Hydraulic fracturing in Azerbaijan was taken over by the Department
on plugging and increase of oil recovery. As of today, according to the obtained information,
FHF application by State oilcompany of Azerbaijan Republic (SOCAR) declined due to financial
reasons and worn out technical base. There is no information about FHF applied by joint
ventures or operation companies.