The Development of a Water proofing Polymeric Composition … · Carboxymethylcellulose for...

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



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).



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


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.


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.



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.

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