The Development of a Water proofing Polymeric Composition … · Carboxymethylcellulose for...
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International Journal of Applied Engineering Research ISSN 0973-4562 Volume 12, Number 2 (2017) pp. 273-276
© Research India Publications. http://www.ripublication.com
273
The Development of a Water proofing Polymeric Composition based on Carboxymethylcellulose for Carbonate Reservoirs
A. Shagiakhmetov Assistant Professor, Oil and gas Department,
Saint-Petersburg Mining University 2, 21st line, Saint-Petersburg, Russia.
D. Tananykhin, Assistant Professor, Oil and Gas Department,
Saint-Petersburg Mining University, 2, 21st line, Saint-Petersburg, Russia.
Abstract The article shows the various types of water-shutoff agents
including the advantages and disadvantages of each type.
Water-shutoff composition based on carboxymethylcellulose
was developed to limit the water inflow in the fracture-porous
type of the reservoir. Chromium acetate is used as a stitcher,
copper sulfate is recommended as a densifier. The laboratory
studies revealed the dependence of the kinetics of gelation and
the strength characteristics of the developed gel-forming
composition on the concentration of reagents and temperature.
From these data it is possible to quickly determine the optimal
concentration of reagents for specific geological conditions.
Keywords: Water shutoff treatment, carbonate reservoir,
carboxymethyl cellulose.
INTRODUCTION
In recent decades, most of oil and gas fields of the Russian
Federation are characterized by a significant increase in water
cut and decrease in rates of hydrocarbon production. For this
reason the problem of maintaining the economic efficiency of
oil production becomes especially relevant. Carrying out of
waterproofing work is important to reduce the cost of
extraction and further use of co-produced water, as well as to
regulate the flow of fluids in the reservoir and near-wellbore
zone in the process of oil and gas fields developing [1].
Currently two main areas of limitations of water inflow to
wells are developed: mechanical overlap of the flooding
intervals and injection of various chemical agents into
formation [2]. The first method involves the use of slip
couplings, packer or plaster, lowered into the well through the
tubes. The main drawback of this method is the reduction of
the useful cross section of the production casing.
Chemical methods are divided into nonselective and selective
according the clogging mechanism of fractured-porous
medium. The reagents which are applied in non-selective
isolation methods used to form waterproofing screen,
regardless of the type of fluid that saturates fromations (oil,
gas, water). The main materials for such insulation are cement
slurry. The main advantage of cement slurry is low cost and
the easy availability of the composition components.
However, because of the low penetrating ability, the use of
such compositions is greatly reduced.
Selective isolation methods are methods based on the use of
materials that increase the filtration resistance in water-
saturated part of the reservoir.
There are three selective groups of materials: organic polymer
materials, inorganic compounds, heteroorganic compounds
[2]. Inorganic compounds include silicates (silin, alkali
silicate) and aluminosilicates (nepheline and ceritadewasa
components). The selective effect of this group is caused by
the ability of silicates and aluminosilicates to heliroute in the
presence of the polyvalent metals ions that are contained in
the formation water and acid environment. Such compositions
have a low viscosity, high strength and selectivity. The main
disadvantage is the low efficiency of the plugging of saline
formation water.
Heteroorganic compounds are organosilicon (AKOR, GKZH-
11), organoaluminum etc. Such compounds contain the
chemical bond of Si-O and Si-C. It indicates to their
intermediate position between the other two groups. The
advantage of these compositions is caused by the resistance to
high temperature and low viscosity. However, the scarcity and
high cost of components, and the corrosiveness restricts
widespread use of these compounds in water production
restraining in oil wells [3].
The group of organic polymeric material consists of
crosslinked polymeric composition based on polyacrylamide,
polymers "Gipan" and "Givpan", oksietil and
carboxymethylcellulose.
Gel-forming compositions based on organic reagents should
have adjustable gelation time and high strength characteristics
[4]. Also, they must be available and have a low cost.
Temperature has a significant influence on the structurization
time for most of the plugging compositions.
Producing formation of the Tatarstan Republic and Perm
region, presents with carbonate reservoirs, were selected as an
object for study. These formations have low reservoir
temperature (T<40 °C), high salinity of formation water (> 50
g/l). The characteristic feature is that the productive layers are
represented with dismembered (ratio > 3) formations. The
average oil-saturated thickness in the Tula and Vereisky
horizons is less than 3 m.
MAIN PART
To carry out works to water production restraining in terms of
carbonate reservoirs we developed and suggest to use water
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International Journal of Applied Engineering Research ISSN 0973-4562 Volume 12, Number 2 (2017) pp. 273-276
© Research India Publications. http://www.ripublication.com
274
gel-forming composition based on carboxymethylcellulose
(CMC). In this composition organic salt of chromium (III) is
used as a gelation initiator. Copper sulfate solution is used as
a catalyst (densifier). To determine the optimal concentrations
of reagents for developed waterproofing composition
laboratory experiments have been conducted to study the
dependence of the strength and the gelation time vs
temperature and concentration of CMC and crosslinking
agent.
Experimental studies on the development and testing of the
waterproofing composition were conducted with the use of
modern equipment in the laboratory of enhanced oil recovery
of the Mining University. Laboratory experiments included
rheological study. The following characteristics were
evaluated:
1. The gelation time – the period of time from the start
of increasing the viscosity of the gel-forming
composition to become a gel. The tolerable upper
limit of the gelation time is taken for 24 hours (the
average duration of technological operational delay
after repair) [2];
2. Plastic strength – a parameter describes the force
value exerted on the gel that it is able to withstand
until destruction;
3. The induction period of gelation is the parameter that
specifies the period of time during which the
effective viscosity of the composition does not
change relative to the initial;
Series of experiments, including determining the time of
gelation by the visual method were conducted to evaluate the
optimal concentration of components in the waterproof
composition. The method of determining the gelation time
consists of the following: the composition were prepared then
poured in a glass container whicn was covered with aluminum
foil and holded at different temperatures (20, 40, 60, 80, 100
ºC). Then, every 15 minutes, the glass was inclined at an angle
of 45° to observe the variation of the meniscus angle. The
composition was considered as a gelled when the angle of the
meniscus with the inclination of the glass container doesn’t
change. As a result of the laboratory studies 4 composition
with different concentrations of chromium acetate and copper
sulfate were selected. Mass fraction of CMC in all
compositions was the same (5,5 %). Composition 1 has the
maximum content of chromium acetate and copper sulfate
among 4 selected compositions. Figure 1 presents a graph of
the dependence of gelation time vs temperature during the
experiment.
Plastic strength of each gel was measured at the unit
Rehbinder (conical plastometer). The method involves
measuring the depth of immersion in the prepared gel of a
cone with known mass under a constant load for 15 minutes.
Figures 2 and 3 present graphs of the plastic strength’s of the
composition vs the temperature after 5 days from the time the
composition was prepared.
The induction period of gelation of the waterproofing
composition was investigated using a rotational viscometer
Rheotest RN 4.1 (Medinger Messgerate GmbH, Germany).
The effective viscosity and shear stress of the compositions
have been determined at a particular shear rate, which
depends on the diameter of tubing strings and pump [5]. To
simulate the movement of gel in the bottom hole formation
zone the study was conducted at a constant shear rate of 5 s-1
(figure 4) [6].
The dependence of the gelation time of the compositions vs
temperature obeys the exponential law with a high degree of
correlation. With increasing concentration of copper sulphate
and chromium acetate, the gelation time decreases. It should
also be noted that the gelation time varies from 200 to 400
minutes for the temperature conditions of the Perm region and
Tatarstan (20 °C-40 °C) and its more than one hour for the
temperature conditions of Western Siberia (T≥75ºС).
According to the materials of the article [4] the gelation time
must be 1-24 hours, which satisfies the condition.
y = 5442,1x-0,918
R² = 0,9991
y = 7545,6x-0,972
R² = 0,9957
y = 6575,6x-0,941
R² = 0,9868
y = 6353,3x-0,912
R² = 0,9948
0
50
100
150
200
250
300
350
400
450
0 20 40 60 80 100 120
Ge
lati
on
tim
e,
s∙6
0
Temperature, С
Composition №1 Composition №2 Composition №3 Composition №4
Figure 1 – Gelation time of the compositions vs the
temperature and concentration of chromium acetate and
copper sulfate for 5.5% carboxymethyl cellulose
Plastic strength reaches a maximum value at 60 °C. This
effect can be explained by blasting action of the temperature
factor on the aqueous solution of CMC with increasing
temperature above 60°C [7]. According to A.V. Blazhevich
[2] the minimum allowable strength of the gel-forming
composition is equal to 3000 Pa. The value of the plastic
strength of the developed composition is above the minimum
values for all measured temperatures (20°C-60°C).
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International Journal of Applied Engineering Research ISSN 0973-4562 Volume 12, Number 2 (2017) pp. 273-276
© Research India Publications. http://www.ripublication.com
275
0
5
10
15
20
25
30
35
40
45
50
0 20 40 60 80 100 120
Pla
stic
str
en
gth
, P
a∙1
03
Temperature, С
Composition №1 Composition №2 Composition №3 Composition №4
Figure 2 – The dependence of the plastic composition
strength vs the temperature and concentration of chromium
acetate and copper sulphate
y = 4814,7e0,0083x
R² = 0,9858
y = 3728,4e0,0074x
R² = 0,9682
y = 4842,5e0,0038x
R² = 0,963
y = 3296,7e0,0057x
R² = 0,8304
0
2
4
6
8
10
12
14
0 20 40 60 80 100 120 140
Pla
stic
str
en
gth
, P
a∙1
00
0
Time, s∙3600.
Composition №1 Composition №2 Composition №3 Composition №4
Figure 3 – The dependence of the plastic strength vs time
at 30 °C
The change of the plastic strength in five days is happening at
an exponential rate with a high degree of correlation.
Dynamics of changes of plastic strength, as shown in figure 3,
shows that the hardening of the composition continues for 5
days after the gel was formed. Despite the increase of this
parameter, in the first three days changes in strength are small.
Therefore it is recommended to take technological pausing
after the injection of the composition as equal to 1 day.
0,00
0,20
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
2,00
0 5000 10000 15000 20000 25000
Eff
ec
tiv
e v
isc
osi
ty,
Pa
∙s
Time, s
The end of the
induction period
1 - 20 ⁰С2 - 40 ⁰С3 - 50 ⁰С4 - 60 ⁰С
1234
Figure 4 – The dependence of the effective viscosity of the
composition No. 1 vs time and temperature (γ=5s-1)
As can be seen from figure 4, the induction period (IP) of
gelation decreases with temperature increase. At 60°C the
induction period is 1000 seconds.
Figure 5 – The dependence of the effective viscosity of the
composition No. 1 vs time and temperature (γ=118s-1)
The induction period of gelation at different temperatures
(20°C-60°C) more than 3 hours (figure 5). This value is
sufficient for injection of the composition into the reservoir or
near-wellbore zone. It is also worth noting that with
increasing shear rate from 5 to 118 s-1 induction period of
gelation increases not more than 4 % for temperatures below
50°C. At t=60°C, the ratio of induction periods is increased up
to 12 times.
CONCLUSION
To limit the water inflows in fractured-porous reservoirs we
developed gel-forming composition based on
carboxymethylcellulose. In this composition organic salt of
chromium (III) is used as a gelation initiator. Copper sulfate
solution is used as a catalyst (densifier), which increases the
plastic strength of the structure.
The gelation time of the composition can be adjusted from
one to 10 hours. Also, this composition has a high plastic
strength (from 3000 to 12000 Pa).
The induction period of gelation under shear rates, simulating
movement in fractured-porous reservoir, is sufficiently high
for injection of the composition to the required depth. It is
calculated on the basis of sustainability of the gelled
composition to water breakthrough and to block the processed
interval of the reservoir.
REFERENCES
[1] К.V. Strizhnev, Remedial and insulation works in
wells, “Nedra”, SPb, 2010. 560 p.
[2] V.A. Blazhevich, E.N. Umrikhina, V.G. Umetbaev,
Remedial and insulation works in petroleum
exploitation, “Nedra”, M, 1981. 236 p.
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International Journal of Applied Engineering Research ISSN 0973-4562 Volume 12, Number 2 (2017) pp. 273-276
© Research India Publications. http://www.ripublication.com
276
[3] R.T. Bulgakov, A.Sh. Gazizov, R.G. Gabdullin,
Limiting the inflow of formation water in oil wells,
“Nedra”, M, 1976. 175 p.
[4] Al-Anazi M. et al. Laboratory Evaluation of Organic
Water Shut-off Gelling System for Carbonate
Formations. Paper SPE 144082-MS presented at SPE
European Formation Damage Conference. Noordwijk,
Netherlands. 7-10 June. – 2011.
[5] K.O. Gumerov, Improving the efficiency of wells
operation with electric submersible pumps in the
conditions of viscous oil-water emulsions formation
PhD thesis, Mining university, SPb, 2015. 136 p.
[6] G.A. Orlov, M.Sh. Kendis, V.N. Glushenko, The use
of inverse emulsions in oil production, “Nedra”, M,
1991. 250 p.
[7] V.N. Glushenko, M.A. Silin, Oilfield chemistry: Vol.
2. 3D and surface-active properties of liquids,
“Intercontact Nauka”, M, 2010.