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Fossil Fuels
An Effective Approach for Enhanced Oil Recovery using Nickel Nanoparticles Assisted Polymer Flooding Sandeep Rellegadla, Himanshu Kumar Bairwa, Mankamna R Kumari, Ganshyam Prajapat, Surendra Nimesh, Nidhi Pareek, SHIKHA JAIN, and Akhil Agrawal Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b02356 • Publication Date (Web): 16 Oct 2018 Downloaded from http://pubs.acs.org on October 19, 2018
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Energy & Fuels
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An Effective Approach for Enhanced Oil Recovery using Nickel
2
Nanoparticles Assisted Polymer Flooding
3
Sandeep Rellegadlaa, Himanshu K. Bairwaa, Mankamna R. Kumarib, Ganshyam Prajapata,
4
Surendra Nimeshb, Nidhi Pareeka, Shikha Jainc, and Akhil Agrawala*
5 6
aEnergy
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of Rajasthan, NH-8, Bandersindri, Kishangarh, Ajmer, Rajasthan, India
8
bDepartment
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Kishangarh, Ajmer, Rajasthan, India
10
and Environment Research Laboratory, Department of Microbiology, Central University
cDepartment
of Biotechnology, Central University of Rajasthan, NH-8, Bandersindri,
of Chemistry, Manipal University, Jaipur, Rajasthan, India
11 12
ABSTRACT
13
The addition of polymer to injection fluid increase the crude oil recovery by improved sweep
14
efficiency. Although it is the most widely used method for chemical enhanced oil recovery
15
(CEOR) but limitations such as lower stability of polymer in reservoir conditions, hinder the
16
efficiency of the process. In the current study, a novel nanoparticle assisted polymer flooding
17
approach was carried out to overcome these limitations. To determine whether nanoparticles
18
influences the displacement efficiency of the injected fluid we used a blend of xanthan gum and
19
nickel nanoparticles. We have evaluated the changes in the dilute solution viscosity of xanthan
20
when the nickel nanoparticles are added and have found out that xanthan-nickel nanoparticles
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mixture has a higher intrinsic viscosity of 55.25 dl/gm compared to 49.13 dl/gm for the gum
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solution. Efficiency of nanoparticle assisted polymer flooding was evaluated in sand packed
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bioreactors with ~0.6 PV of residual oil in place (ROIP). Flooding results demonstrated the
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highest recovery of 5.98% of additional ROIP with xanthan-nickel nanoparticle mixture
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compared to 4.48 and 4.58% of ROIP during the separate flooding of xanthan and nanoparticles
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respectively. Results suggested the novel nanoparticle assisted polymer flooding approach is able
27
to increase oil recovery beyond available methods.
28
Keywords
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Nanoparticles, Polymer flooding, Xanthan gum, Enhanced oil recovery
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1. Introduction
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Application of nanoparticles is emerging in the field of oil production
32
shown nanoparticles as good in-situ agents for increasing the efficiency of oil recovery
33
12-15.
34
process. Primary recovery uses the resident geological pressure for producing oil. As pressure
35
depletes, the process of secondary recovery is done by water flooding. Water flooding re-
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pressurize the reservoirs and sweeps the oil towards production well
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efficiency of recovering oil due to decreasing oil to water ratio. Tertiary processes, also known
38
as enhanced oil recovery (EOR), are implemented when oil to water ratio decreases below a
39
profitable limit. Chemical EOR (CEOR) is one such widely used tertiary process employing
40
polymers, surfactants or solvents for oil recovery 16-19. The ability of nanoparticles to alter certain
41
factors in the reservoir formation as well as oil properties, add up to the advantage of recovering
1-11.
Recent trends have 2,5,6,8 and
Basically, oil is recovered by three different processes; primary, secondary and tertiary
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16.
It eventually loses its
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15, 19-20.
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oil and could be studied widely as a process of CEOR
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particles into formations and studying their role in EOR.
44
The use of nanoparticles in the field of oil recovery has been reported by several authors. These
45
investigators concluded that the increase in EOR was due to a number of properties of
46
nanoparticles like high sedimentation and thermal stability, altered rheological and magnetic
47
properties 4. These properties strongly depend on the size and shape of the nanoparticles and can
48
be altered during synthesis. More specifically, the use of nanoparticles changes the rock
49
wettability 21, increase the mobility of capillary trapped oil 22, lowers interfacial tension (IFT) 23
50
and also brings about a change in the flow characteristics from a Newtonian fluid to a Non-
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newtonian fluid 7. Karimi et al. 2012, reported that there is an increase in efficiency of oil
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recovery with the use of nanofluids, primarily because of wettability alteration of the carbonate
53
rocks from strongly oil-wet to water-wet 24. Besides, it was noted by Babadagli et al. 2002, that
54
the reduction in the IFT between the aqueous phase and the oil phase resulted in the faster and
55
greater recovery of the oil
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capillary imbibition as an oil recovery mechanism using different surfactants and polymer
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solutions. Capillary imbibition usually occurs in naturally fractured reservoirs if the rock matrix
58
is water wet with enough water present in contact. It is the spontaneous suction of water by a
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rock matrix which simultaneously expels the oil during the process 26. However, heavy oil rock
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matrix and high IFT, lowers the permeability and limits contact. This in turn lowers recovery
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potential by capillary imbibition. Addition of nanoparticles may change these dynamics by
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lowering IFT and altering the wettability of the rock matrix. Several experiments demonstrating
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the flow behavior of nanoparticle suspensions through a porous medium have also been
64
investigated
27 - 29.
25.
This involves introducing these
They investigated the responsible factor, i.e. decreasing IFT, by
Kanz et al. 2009, have suggested that one may adopt 500 nm as an upper
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usable limit for nanoagents, as particles larger than this have a very slim chance of staying
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mobile in a micronetwork system of reservoir rock matrix
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different characteristics of various nanoparticles that favors the recovery efficiency
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ability to increase the viscosity of displacing fluids, control of fine migration in reservoirs and a
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decrease in heavy oil viscosity through the application of nanoparticles were previously noted 36-
70
38.
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Sweep efficiency of displacing fluid in the formation is another factor important for EOR. The
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sweep efficiency of the displacing fluid can be increased by increasing its viscosity in the swept
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zone. High viscosity displacing fluids will lower the water to oil mobility ratio and push the
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residual oil towards production well 16. Many high molecular weight polymers like xanthan gum
75
39,
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efficiency with which water can contact and displace reservoir oil. Additionally, many new
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methods are being developed and continuously evaluated for EOR. Most of which involve
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combining one or two available EOR methods to share the benefits of both the processes, such as
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Polymer assisted Microbial EOR 41, Surfactant combined with nanoparticles flooding 42, 43, Foam
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stabilized by nanoparticles for EOR 9, 10 etc.
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Currently, polymer flooding is considered as one of the most widely used CEOR processes
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because of its technical and commercial feasibility
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received great attention for their potential in recovering crude oil 27. Cheragian and coworkers 44
84
have summarized the reports about the use of available additives to improve the rheological
85
behavior of polymer solution
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nanoparticles effect on the rheology of polymer solutions used for oil recovery
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several nano-composites containing nanoparticles have been synthesized using different
polyacrylamide
16,
and copolymers of acrylamide
47,
40
44-46.
30.
Others have investigated the 31-35.
The
etc., have been used to increase the
On the other part, nanotechnology has
and also there is no such report about the investigation of the
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48.
Besides,
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polymers and nanoparticles. Possible mechanisms explaining the effects of these polymer
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nanoparticle interactions on the rheology of the polymer have also been mentioned by many
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researchers. Maghzi et al. 2013, have shown this combination as an acceptable method for EOR
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and have reported that nanoparticles can alter the surface wettability 48. Maurya et al. 2017, have
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reported the presence of silica nanoparticles in the core of polymer structure stabilizes and
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strengthens the polymer network structure
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chain at the surface of silica nanoparticles, that improved the surface activity leading to the
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reduction of IFT at the oil-water interface. Alternatively, polymers in solution also improve
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limitations of the nanoparticles during flooding through porous matrices. Pooja et al. 2014 also
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mentioned that two different mechanisms played by natural gums in stabilizing the inorganic
98
nanoparticles
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nanoparticles creates steric repulsion among the particles, which improves their dispersion in the
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medium. In another mechanism, polymer molecules increases the viscosity of nanoparticle
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suspensions resulting in lowering of the aggregation of particles. Therefore, in this study, we
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investigated a process for increasing the potential of polymer flooding by blending with
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nanoparticles to improve the performance of the drive fluid for an enhanced recovery. In the
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present study, we have evaluated the efficiency of nickel nanoparticle, xanthan gum and xanthan
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gum – nickel nanoparticle mixture for EOR in reservoir simulating sand pack bioreactors.
50.
49.
They have also found the presence of polymer
They reported that the absorption of polymer molecules onto the surface of
106 107
2. Experimental Section
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2.1. Preparation of crude oil solution for flooding experiments
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EOR experiments were done with crude oil collected from Ankleshwar oil fields, Gujarat, India.
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Due to high paraffinic content, the crude oil was mixed with dispersants (i.e., toluene in the
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case). The standard solutions of oil were made up with a 2:8 (v:v) mixture of the dispersant to
112
the test oil. The stock of this parent oil was used for performing whole experiments.
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2.2. Oil standards preparation
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Standards were prepared by mixing 1 part parent oil (1000 mg) from above to 10 parts
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dichloromethane, DCM (i.e., 1:10 dilution of the parent oil, v:v). Add a specific volume of
116
parent oil-DCM standard to 30 ml of distilled water in a separatory funnel. Extract the oil-water
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mixture with 5 ml volumes of DCM after 15 seconds of vigorous shaking followed by a 2-minute
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stationary period to allow for phase separation after each extraction. Repeat the extraction using
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a total of three 5 ml portions of DCM. Adjust the final DCM volume for the combined extracts to
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20 ml with DCM in a 25 ml graduated cylinder 51.
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A stock solution of parent oil was prepared in a known volume of DCM. Standard dilutions were
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made from the stock solution (4000 mg of parent oil in 40 ml of DCM). The final concentrations
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were obtained by diluting the stock solution (100mg/ml) with the fixed volume of DCM (e.g., for
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80mg/ml solution, 8ml from stock is added to 2 ml DCM) and similarly DCM is added further to
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obtain standard concentration ranges (100mg-20mg/ml). Oil content in water was determined by
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adding a known volume of DCM (VDCM), measuring the volume of water (VH2O) and then the
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volume of oil (Voil) by determining the optical density at 600nm (OD600) of the oil-DCM phase
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to derive the concentration of oil (Coil) in mg/mL; OD600 was determined using a
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spectrophotometer. Voil was then calculated as (Voil = Coil × VDCM/ρoil), where ρoil is the density
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of Ankleshwar oil 52.
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2.3. Preparation of nanoparticle solution
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Nickel nanoparticles were prepared using 0.19 gms of NiCl2.6H2O in ethylene glycol. The
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reaction mixture was maintained under constant magnetic stirring in a 100 ml round flask with a
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certain amount of Sodium Dodecyl Sulphate. In the sequence, the reaction mixture was heated to
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90ºC for an hour under strong magnetic stirring. A strong dark black coloration was observed
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immediately after the addition of hydrazine hydrate with an appropriate amount of 1 M NaOH.
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The system was maintained for about 2 hours at 90 ºC under constant magnetic stirring 53. The
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resulting black precipitates were centrifuged at 10000 rpm to obtain the pellet and washed with
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acetone to remove the ethylene glycol.
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The synthesized nanoparticles were initially characterized by UV-visible spectrophotometer
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(Evolution 201, Thermo Scientific). This was done by scanning the nanoparticles suspended in
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aqueous solution from the wavelength range of 200 nm-800 nm by taking water as a blank.
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Further, XRD (X-ray Diffractometer) was employed to determine the crystallinity of the sample.
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The sample for analysis was recovered as-synthesized products from the solutions using
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centrifugation, followed by a few washing steps using water and acetone. The nanoparticles were
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dried in the desiccator and analyzed in PANalytical- Empyrean with Cu-Kα radiation source in
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the angle range of 2𝞱= 10ᵒ-100ᵒ. Thereafter, the size and polydispersity of nanoparticles
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suspended in double distilled water were characterized using Zetasizer (Nano ZSP, Malvern,
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UK).
150
2.4. Estimation of intrinsic viscosity of polymer solution
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The viscosity was determined using a dilution capillary viscometer (Cannon-Fenske Routine
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Viscometer, Size 50, Sigma Aldrich, Germany). This was immersed in a beaker containing
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distilled water to maintain the temperature at 30◦C ± 0.1◦C. Samples were taken in a conical flask
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which was kept inside a beaker containing distilled water and placed over a magnetic stirrer with
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the hot plate (MHPS5P, LabQuest, Borosil, India) to maintain the desired temperature with
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constant stirring. The stirrer was maintained at low rpm to minimize disturbances to the solution
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viscosity. During the measurement, the samples were withdrawn from the flask and passed
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through the viscometer using a micro-funnel and the time of flow of solvent-polymer system was
159
noted. All measurements were carried out at a concentration range of 0.005-0.02% w/v of the
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polymer solution. The densities of the polymer solutions were determined using a standardized
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25-mL pycnometer (Borosil, India), for calculating the kinematic viscosity
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solution was determined from the difference in weight of the empty pycnometer and filled
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vessel. Glycerol and sucrose standard solutions were prepared and used as a reference standard
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for recalibration of the capillary viscometer 55.
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Rheological behavior of polymeric solutions plays an important role in the success of oil
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recovery. In this study, the rheological behavior of polymer solutions in distilled water, Colville
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synthetic brine (CSBK) medium56 and in CSBK containing nanoparticles medium was evaluated.
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At first, the intrinsic viscosity of xanthan gum dispersed in distilled water was evaluated for
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different concentrations. To investigate the effect of nanoparticles on the rheological behavior of
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xanthan solution, the change in intrinsic viscosity was compared to different conditions (using
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CSBK and CSBK containing nanoparticles as dispersion medium).
172
The hydrodynamic volume occupied by a macromolecule gives a measure of the intrinsic
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viscosity which relates to the size and conformation of a polysaccharide (xanthan gum)
174
macromolecular chain in a particular solvent
175
parameter for studying polymer solutions as this provides deep insights into the molecular
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characteristics of the biopolymer
59.
57, 58.
54.
The mass of the
Intrinsic viscosity is hence an important
Our experimental procedure generally followed the
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specifications and directions for use recommended by American Society for Testing Materials
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(ASTM)
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which specific viscosity (ƞsp) was calculated. The intrinsic viscosity (ƞ) was later derived from
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reduced viscosity (ƞ𝑟𝑒𝑑 = ƞ𝑠𝑝 𝐶) and inherent viscosity (ƞ𝑖𝑛ℎ = ƞ𝑟𝑒𝑙 𝐶), where ƞred and ƞ𝑖𝑛ℎ could
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be calculated at various dilutions and at the same shear rate, and extrapolating the course of
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specific viscosity/relative viscosity to infinite dilution
183
dependence (ƞsp/C) is often expressed in terms of the following relationship;
184
ƞsp / C =
185
Where, kH’ is known as Huggins constant 63. For flexible polymer molecules in good solvents, K
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is often near to 0.35, although somewhat higher values occur in poor solvents. Also, Kraemer in
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1938 devised an equation to obtain intrinsic viscosity by extrapolation to zero concentration (C)
188
64- 66.
189
ln ƞ𝑟𝑒𝑙 𝐶
60.
Initially, the relative viscosity (ƞrel) is measured from capillary viscometer from
61, 62.
Alternatively, the concentration
[ƞ] + kH’ [ƞ]2 C
(1)
= [ƞ] + 𝑘𝐻" [ƞ]2𝐶
(2)
190
Where kH” is the Kraemer constant. Tanglertpaibul and Rao (1987), found methods for
191
determination of intrinsic viscosity based on slopes of plots had higher correlation coefficients
192
and lower standard errors, compared with those based on the intercept of plots 67. They used the
193
following equations to obtain the intrinsic viscosity:
194
ƞ𝑟𝑒𝑙 = 1 + [ƞ]𝐶
195
The intrinsic viscosity [ƞ] is the slope obtained by plotting ƞ𝑟𝑒𝑙 vs. C
196
ƞ𝑟𝑒𝑙 = 𝑒[ƞ]𝐶
197
The intrinsic viscosity [ƞ] is the slope obtained by plotting ln ƞ𝑟𝑒𝑙 vs. C
(3)
(4)
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(5)
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ƞ𝑟𝑒𝑙 = 1 ―
199
The intrinsic viscosity is the slope obtained by plotting 1-1/ƞ𝑟𝑒𝑙 vs. C.
200
Particularly in this study, the intrinsic viscosity of very low concentration polymer solutions was
201
estimated on the basis of Eqn. (1), (3), (4) and (5), and this four methods were compared
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statistically for a better fit.
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2.5. Polymer solution prepared for flooding experiments
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All experiments were carried out using commercial Xanthan gum (Hi-Media products). Xanthan
205
gum powder was weighed in different concentration ranges (0.01%-0.04%) and dissolved in
206
CSBK medium 56. The pH of the medium was maintained at 7.2 to 7.4. The polymer was added
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slowly to different solvent systems (CSBK and CSBK containing nanoparticles medium) with
208
constant stirring over a magnetic stirrer and incubated at room temperature for 24 hours to allow
209
hydration of polymers.
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2.6. Sand pack up flow bioreactors
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Syringes of 60 ml without piston was packed with glass wool (~1.5 cm height) and then with
212
polymeric mesh to enhance its ability to hold the sand filled in the syringe. As the sand (Sigma-
213
Aldrich, 50-70 mesh) was loaded, the syringe was continuously tapped for uniform tight packing.
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Once the sand had been filled, another layer of glass wool was placed above similarly as
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mentioned earlier to prevent the sand to flow out of the syringe. The syringe was then closed
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using a perforated rubber stopper fitted with a plastic connector in the center, through which the
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liquid can flow inside the syringe. After the column had been assembled the dry weight of the
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column was measured. Later, the column was flooded with distilled water and its wet weight was
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measured again to calculate the pore volume and porosity (Table S1). A three-way valve was
[ƞ]𝐶
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later fixed on both inlet and outlet points of the syringe bioreactors for injecting and drawing
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samples during experimentation. Zip ties were then wrapped around the rubber stoppers to
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ensure a tight seal with no leakage and sipping of fluids from the syringe bioreactors. The three-
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way valves were connected through the silicon tubing (4.0 (O.D) * 1.0 (W.T) * 2.0 (I.D) in mm)
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at inlet and outlet points were connected to tygon tubings (4.0 (O.D) * 1.0 (W.T)* 2.0 (I.D) in
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mm). The influent tubing was connected to the pump tubing placed in the head of a 4 - channel
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peristaltic pump (Miclins, India) through plastic syringe connectors. CSBK medium was pumped
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from sealed glass bottles with an N2-CO2 headspace. The bottle had been sealed with a
228
perforated rubber cork through which anaerobic gas filled in a gas balloon refilled the headspace
229
through a plastic syringe filter (0.2 µm) connected to the rubber cork. The effluent was led into
230
serum bottles (120 ml). Four syringe bioreactors were constructed and subsequently, their pore
231
volume (PV) was measured. Subsequently, 4 pore volumes of brine were passed through the
232
bioreactors to ensure its 100% saturation with brine.
233
The syringe bioreactors were then flooded with 1 PV of parent oil replacing approximately 0.93
234
PV - 0.95 PV of CSBK medium with oil. Initial oil saturation was found by measuring the
235
volume of brine displaced by oil saturation, also called original oil in place (OOIP) and found to
236
be ~26 ml. Oil was then produced by pumping of anoxic CSBK at a rate of 1 PV/day. The oil
237
content of the produced oil-water mixture was analyzed daily until no oil was further produced
238
from the bioreactors (Stage 1, typically 2 weeks). Oil content was determined by extracting the
239
oil from the produced oil-water mixture using a known volume of DCM as explained earlier.
240
In Stage 2, four different injection strategies were followed. Bioreactor A, was injected with 2PV
241
of xanthan dispersed in CSBK medium, Bioreactor B was injected with 2PV of nickel
242
nanoparticles dispersed in CSBK medium, Bioreactor C was injected with a mixture of xanthan
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and nickel nanoparticles (2PV). Bioreactor D was injected only with CSBK and acted as the
244
control. A concentration of 3g/L for Nickel nanoparticles, 1g/L for xanthan gum and 1.5g/L and
245
0.5 g/L (half of the concentration used individually) of both in the mixture respectively were
246
used for flooding of sand pack syringe bioreactors.
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Effluent from these bioreactors was collected during different injection strategies and in 48 hours
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incubation just after injection. Following incubation, up-flow injection of CSBK medium was
249
resumed in all the bioreactors at 1 PV/day in stage 3. The additional oil recovered was now
250
measured spectrophotometrically at 600 nm.
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3. Experimental results and discussion
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3.1. Nickel nanoparticles characterization
253
In the current study, the nickel nanoparticles were synthesized corresponding to 200 nm size,
254
characterized by dynamic light scattering (DLS) plot, since smaller sized particles (
