Polyelectrolyte complex nanoparticles for protection and delayed release of enzymes in alkaline pH and at elevated temperature during hydraulic fracturing of oil wells

Ghahfarokhi, Reza Barati; Johnson, Stephen J.; McCool, S.; Green, Don W.; Willhite, G.P.; Liang, Jenn‐Tai

doi:10.1002/app.36845

Cited by 43 publications

(22 citation statements)

References 11 publications

(15 reference statements)

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“…where z i is the valence of the ionic species i. Equations (7) and (8) are valid both inside and outside the PE brushes. We shall solve this equation separately inside and outside the brush.…”

Section: Thermodynamics and Electrostatics Of Ph-responsive End-chargmentioning

confidence: 99%

Thermodynamics, electrostatics, and ionic current in nanochannels grafted with pH‐responsive end‐charged polyelectrolyte brushes

Chen

Das

2017

Electrophoresis

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In this paper, we study the thermodynamics, electrostatics, and an external electric field driven ionic current in a pH-responsive, end-charged polyelectrolyte (PE) brush grafted nanochannel. By employing a mean field theory, we unravel a highly nonintuitive interplay of pH and electrolyte salt concentration in dictating the height of the end-charged PE brush. Larger pH or weak hydrogen ion concentration leads to maximum ionization of the charge-producing group-as a consequence, the resulting the electric double layer (EDL) energy get maximized causing a maximum deviation of the brush height from the value (d ) of the uncharged brush. This deviation may result in enhancement or lowering of the brush height as compared to d depending on whether the PE end locates lower or higher than h/2 (h is the nanochannel half height) and the salt concentration. Subsequently, we use this combined PE-brush-configuration-EDL-electrostatics framework to compute the ionic current in the nanochannel. We witness that the ionic current for smaller pH is much larger despite the corresponding magnitude of the EDL electrostatic potential being much smaller-this stems from the presence of a much larger concentration of H+ ions at small pH and the fact that H+ ions have very large mobilities. In fact, this ionic current shows a steep variation with pH that can be useful in exploring new designs for applications involving quantification and characterization of ionic current in PE-brush-grafted nanochannels.

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Section: Thermodynamics and Electrostatics Of Ph-responsive End-chargmentioning

confidence: 99%

Thermodynamics, electrostatics, and ionic current in nanochannels grafted with pH‐responsive end‐charged polyelectrolyte brushes

Chen

Das

2017

Electrophoresis

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“…Delayed release systems capable of delaying the activity of breakers or crosslinking of guar during the injection are another important focus of the oil and gas industry. 34,35,69,70 Slickwater Fluids The current focus of the industry is on the following items: Development of a system that can use less or no water, in order to address the concerns regarding high water volumes being used and also other concerns regarding near fracture damage. Development of gas-based fracturing systems and efficient fluid loss additives for smaller pore size formations are currently being pursued for this purpose.…”

Section: Breaker-free Fluidsmentioning

confidence: 99%

“…Moreover, the industry is focused on development of environmentally‐ and equipment‐friendly breakers that can be applied at high temperatures and extremely low or high pH conditions. Delayed release systems capable of delaying the activity of breakers or crosslinking of guar during the injection are another important focus of the oil and gas industry …”

Section: Introductionmentioning

confidence: 99%

“…It is a function of yield stress and is caused by concentrated fracturing fluid and the conductivity of fracture. 7 To carry higher concentrations of enzyme breakers while delaying the reaction of breakers with guar-based fluid during the injection time and prevent premature degradation, Barati et al 34,35 developed a polyelectrolyte nanoparticle system that is capable of delaying the release of enzyme breakers and protecting the enzyme against alkaline conditions and elevated temperatures.…”

Section: Introduction Of Encapsulated Breakers Allows High Concentra-mentioning

confidence: 99%

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A review of fracturing fluid systems used for hydraulic fracturing of oil and gas wells

Barati

Liang

2014

J of Applied Polymer Sci

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589

341

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Hydraulic fracturing has been used by the oil and gas industry as a way to boost hydrocarbon production since 1947. Recent advances in fracturing technologies, such as multistage fracturing in horizontal wells, are responsible for the latest hydrocarbon production boom in the US. Linear or crosslinked guars are the most commonly used fluids in traditional fracturing operations. The main functions of these fluids are to open/propagate the fractures and transport proppants into the fractures. Proppants are usually applied to form a thin layer between fracture faces to prop the fractures open at the end of the fracturing process. Chemical breakers are used to break the polymers at the end of the fracturing process so as to provide highly conductive fractures. Concerns over fracture conductivity damage by viscous fluids in ultra-tight formations found in unconventional reservoirs prompted the industry to develop an alternative fracturing fluid called "slickwater". It consists mainly of water with a very low concentration of linear polymer. The low concentration polymer serves primarily to reduce the friction loss along the flow lines. Proppant-carrying capability of this type of fluids is still a subject of debate among industry experts. Constraints on local water availability and the potential for damage to formations have led the industry to develop other types of fracturing fluids such as viscoelastic surfactants and energized fluids. This article reviews both the traditional viscous fluids used in conventional hydraulic fracturing operations as well as the new family of fluids being developed for both traditional and unconventional reservoirs.

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“…In the process, hydraulic fracturing fluids play a principal role in passing the pressure, creating the strata crack, and carrying solid proppant . To implement these functions, viscosity is the critical parameter for most kinds of fracturing fluids …”

Section: Introductionmentioning

confidence: 99%

Thermal stability enhancement of guar‐based hydraulic fracturing fluids by phosphate treatment

Wang

Boyd

et al. 2018

J of Applied Polymer Sci

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Guar gum (GG), along with its derivatives [e.g., hydroxypropyl guar (HPG)], is an important thickening agent in the hydraulic fracturing fluid system. However, as the oil reservoir gets deeper, GG is unable to tolerate the elevated temperature. In this study, the thermal stability of GG and HPG can be increased up to 95% and 80%, respectively, when phosphates are used as thermal stabilizer. The thermal stability is highest when the usage of phosphate is 1.84 mmol L −1 KH 2 PO 4 for GG and 2.27 mmol L −1 K 2 HPO 4 for HPG and the pH is 6.25-6.90 for GG and 6.25-8.75 for HPG. Furthermore, the heated GG with phosphate treatment demonstrates excellent crosslinking ability, which suggests that phosphate can be a good alternative for current thermal stabilizers and has potential application in the high-temperature formation oil or gas production.

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Polyelectrolyte complex nanoparticles for protection and delayed release of enzymes in alkaline pH and at elevated temperature during hydraulic fracturing of oil wells

Cited by 43 publications

References 11 publications

Thermodynamics, electrostatics, and ionic current in nanochannels grafted with pH‐responsive end‐charged polyelectrolyte brushes

Thermodynamics, electrostatics, and ionic current in nanochannels grafted with pH‐responsive end‐charged polyelectrolyte brushes

A review of fracturing fluid systems used for hydraulic fracturing of oil and gas wells

Thermal stability enhancement of guar‐based hydraulic fracturing fluids by phosphate treatment

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