Morphology, Rheology, and Kinetics of Nanosilica Stabilized Gelled

Subscriber access provided by UNIV OF LOUISIANA

Materials and Interfaces

Morphology, rheology and kinetics of nano-silica stabilized gelled foam fluid for hydraulic fracturing application Amit Verma, Geetanjali Chauhan, Partha Pratim Baruah, and Keka Ojha Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b04044 • Publication Date (Web): 12 Sep 2018 Downloaded from http://pubs.acs.org on September 20, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 34 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Silica Nanoparticles

Industrial & Engineering Chemistry Research

Aqueous medium

Polymer

Polymer

Surfactant micelles

Surfactant

nanoparticles dispersed in water

Base fluid Aerated at 4000 rpm

Highly Stable Foam

ACS Paragon Plus Environment

Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Morphology, rheology and kinetics of nano-silica stabilized gelled foam fluid for hydraulic fracturing application Amit Verma, Geetanjali Chauhan, Partha Pratim Baruah, Keka Ojha* Department of Petroleum Engineering, Indian Institute of Technology (ISM), Dhanbad Jharkhand 826004, India Abstract Stabilizing mechanism of silica nanoparticles on gelled foam prepared with a very low concentration of polymer (xanthan gum) and surfactant (α-olefin sulfonate) is reported in the present study. The morphology of the foam at optimized composition reveals its improved stability, owing to the adsorption of silica nanoparticles on the bubble interface, which was further confirmed by microscopic images. The foam decay experiments confirmed the slower drainage of liquids through the strong and rough bubble interface in presence of nanoparticles. The synergistic effects of nanoparticles-polymer-surfactant help to improvise rheology, viscoelastic properties and enhanced static proppant suspension capacity of the foam. Addition of nanoparticles helps in reducing the polymer concentration in the foam fluid without compromising in stability criterion. Thus, the prepared gelled foam offers less formation damage with improved rheology, and proppant carrying capacity without any limitation to low temperature application. Key words: Foam, stability, nanoparticles, rheology, microscopic image, hydraulic fracturing 1. Introduction Foam is assemblage of gas bubbles dispersed in a continuous liquid phase, where gas phase may be air and liquid phase consists of mostly surfactant solutions. Surfactants were used for the formation of foam in water by decreasing the interfacial tension between water-gas interfaces1, 2. Fundamental studies of foam have gained profound interest over the years because of their vast applications in various industries like food, froth floatation, cosmetics, fire-fighting and petroleum industry. Foam is being widely used in the upstream of petroleum industry, mainly in drilling, enhanced oil recovery and hydraulic fracturing jobs3, 4. In the late 80s of the last century, foam was introduced as fracturing fluid, mainly for various water sensitive reservoir, which becomes now an important choice for fracking and drilling of unconventional and matured reservoirs5. Foams have advantage of faster clean-up, low leak-off and less formation damage than conventional *

Corresponding author: [email protected]


Page 2 of 34

Page 3 of 34 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


water-based fracturing fluids, in addition to much lower volume of water requirement6, 7. However, the major problem of using the foam in hydraulic fracture job is its thermal stability8. Theoretically, foam is thermodynamically and kinetically unstable, and faster collapse makes it unfavorable for many practical and industrial applications. But, addition of polymer and nanoparticles to surfactant system helps to improve the foam stability by both thermally and kinetically9. The polymer and surfactant mixture in the solutions has been thoroughly studied for its major applications in industries such as food, pharmaceutical, cosmetics, and oil industries. The mixture of surfactant and polymer in the solutions can give rise to the molecular interactions and that may affect their rheological and physicochemical properties. The characteristic behavior of polymer with surfactant is similar to surfactant micellization in solution and occurs above a critical aggregation concentration (CAC) which is lower than the corresponding critical micellization concentration (CMC) 10. The interaction between water-soluble polymers and anionic surfactants by surface tension measurements were investigated by the many researchers for example, the interaction of anionic surfactant such as sodium dodecyl sulfonate and sodium dodecylbenzene sulfonate with water-soluble polymer such as xanthan gum, polyacrylamide and partially hydrolyzed polyacrylamide11, 12. In the present study, AOS, an anionic surfactant was selected due to its better foamability, stability and compatibility with formation compared to cationic or nonionic surfactants13, 14. Xanthan gum which is frequently used in drilling and enhanced oil recovery as a bio compatible polymer was used to stabilize the foam. In addition to polymer, various nanoparticles were found to get adsorbed onto the gas-liquid interface and thereby strengthening the interface8, 15. During past decades, there has been increasing interest in particle-stabilized foams using inorganic nanoparticles such as silica because of their well-defined shape, availability in the different sizes and narrow size distributions, and the chemical tenability of their surfaces16, 17, which mainly discussed about the interaction of nanoparticles with surfactant solution. Moreover, various studies have revealed that the nanoparticle-surfactant-polymer mixtures have a synergistic effect on foam stability due to the adsorption of surfactant-polymer homogenous mixture molecules onto particle surfaces18. But, very limited focus is made on the interaction between nanoparticles, polymer and surfactant system for improvising the foam stability and defoaming kinetics as a fluid for hydraulic fracturing18.



In this investigation, synergic effects of nanoparticles and polymer on foam properties made of aqueous solution of AOS surfactant were studied in detail. The foam prepared with varying combinations of these chemicals were studied based on surface tension, foam stability, foam quality, half-life time and its drainage kinetics. The prepared foam was further characterized by its morphology and bubble size distribution was investigated using Cryo-TEM, DLS, CLSM and microscopic tests, in addition to its rheological parameters and proppant suspension capacity. 2. Material and Methods: 2.1 Material The anionic surfactant, α-olefin sulfonate (AOS) was procured from Stefan Company, USA. The silica dioxide (SiO2) nanopowder, 10-20 nm particle size (99.5% trace metal basis) was purchased from sigma Aldrich, USA. Xanthan gum was obtained from Sigma Aldrich, USA. Ethanol was purchased from Fisher Scientific Mumbai, India and inorganic salt, potassium chloride (KCl > 99%) was obtained from SRL Pvt. Ltd., Mumbai, India. All the products were of analytical reagent grade and used without further purification. 2.2 Foam Preparation Method In order to prepare well dispersed nanoparticles suspensions, silica nanopowder was first wetted with ethanol (2%), then mixed with deionized water. To remove the ethanol, sedimentationredispersion cycles in water was repeated until the residual ethanol concentration falls below 0.001 wt. %. Figure 1 shows the workflow process for the preparation of foam in the laboratory. For the preparation of foam, base solution was first made with 1.0% KCl in the 100ml of distilled water. The required concentration of nanoparticles was added to brine solution and then stirred for 24 hours using magnetic stirrer. This step was followed by mixing with handheld ultrasonic homogenizer (UP200Ht; at a frequency of 26 kHz and 200 W) for 30 minutes to prevent nanoparticles aggregation and to improve the interfacial bonding the components. The predetermined quantity of polymer (xanthan gum) was then added to the nanoparticles dispersed aqueous solution and homogenized for 6 hours with magnetic stirrer at 500 rpm, followed by addition of AOS surfactant to this solution with continued stirring for another 60 minutes at the same speed. The water bath was used to maintain the temperature of aqueous dispersion solution at 30ºC. Finally, the prepared stock solution was sealed for use. The procedure is described in flow chart (Figure 1) given below.


Page 4 of 34

Page 5 of 34 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Desired volume (Vl) of stock solution was taken and agitated at 4000 rpm with waring blender for minimum 2 minutes and stop when desired quality of foam was generated19. The prepared foam was poured into a 500 ml measuring cylinder to measure its quality as the percentage volume of gas from aerated foam (Vf) present in the total volume of gas and liquid, 𝑉𝑙 is the volume of drain free liquid from foam i.e. quality =

𝑉𝑓 −𝑉𝑙 𝑉𝑓

× 100%. All the experiments related to the characteristic

evaluation of foam were performed in the sealed cylinder to obtain precise and accurate results without having any contact with the atmosphere. The foam sample temperature was maintain by using the specific temperature of water during the preparation stage of foam. 2.3 Foam Stability Measurement Half-life time is considered as the main scale to quantify the foam stability, which is defined as the time taken to drain out the half of the liquid from prepared foam8, 15, 19. It also may be measured in term of foam height decay i.e. the time taken by a foam to reach half of its height from the initial stage (t=0)8, 14, 20. To measure the half-life time, the foam generated from 100 ml of base fluid was poured immediately after preparation into a 500 ml of measuring cylinder. The changes in drained volume of liquid from the foam and foam height decay were noted as function of time. Each experiment was performed at constant temperature ranging from 30ºC to 80ºC and ambient pressure. To ensure reproducibility and accuracy of the reported data, each test was repeated at least three times under the same conditions and average values were reported. 2.4 Dynamic size of nanoparticles measurement The size distribution of nanoparticles was determined with dynamic light scattering (DLS) method, using Horiba SZ-100 nanoparticles analyzer. The laser wavelength and scattering angles were 235 nm and 90º respectively. The electrode cell was made of carbon with 6mm diameter and the electrode voltage was 2.4 V. The refractive index of the base solution of foam was measured by the portable refractometer (Refracto 30PX/30GS). The temperature for the experiments was kept constant at 30 ºC.



Page 6 of 34

Start Mix 100ml distilled water with 1% KCl Magnetic Stirrer at 200 rpm (until system homogenous)

Silica nanoparticles added in the brine solution

Magnetic Stirrer silica nanoparticles solution at 500 rpm for 24 hours

Ultrasonic homogenizer for 30 minutes (nanoparticles dispersed solution)

Homogenous Yes Polymer added to dispersed silica nanoparticles solution

Magnetic stirrer the homogenous solution at 500 rpm for 6 hours AOS added to homogenous aqueous

Magnetic Stirrer the homogenous solution at 500 rpm for 60 minutes

Agitated at 4000 rpm using waring blender for 2 minutes

System not Suitable

Quality

Morphology, Rheology, and Kinetics of Nanosilica Stabilized Gelled

Recommend Documents