Nano-encapsulated triggered-release viscosity breakers

a technology of triggered release and viscosity breakers, which is applied in the direction of enzyme stabilisation, sealing/packing, and wellbore/well accessories, etc., can solve the problems of subterranean formation closing and crushing beads, and achieves environmental and economic favorable effects, simple operation, and huge flexibility in material composition

Inactive Publication Date: 2010-10-21
RICE UNIV +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0016]The herein presented method to encapsulate and release breakers and various other species using hybrid microcapsules offers several advantages. The method is extremely simple to carry out, allows huge flexibility in materials composition, and can be made environmentally and economically favorable. The ease of encapsulating a wide variety of compounds makes it viable for a broad spectrum of applications. The one-step method of encapsulation during the assembly of NACs occurs in one pot, and thus there is no need for a large synthesis set-up. NACs can be used to encapsulate both enzymatic and oxid...

Problems solved by technology

When a fracturing fluid containing such beads passes or leaks off into the formation or the fluid is...

Method used

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  • Nano-encapsulated triggered-release viscosity breakers
  • Nano-encapsulated triggered-release viscosity breakers
  • Nano-encapsulated triggered-release viscosity breakers

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[0029]According to preferred embodiments, one method for preparing nanoparticle assembled microcapsules (NACs) involves poly-L-lysine (PLL) as the polyamine, citrate (cit) as the multivalent anion and silica nanoparticles. β-Mannanase (Megazyme) is used as the enzymatic breaker. For the enzyme encapsulation in NACs, 25 μL of the enzyme solution (9 U / ml β-Mannanase) was mixed with 21 μL of PLL and aged for 25 minutes. The resulting solution was added to a previously aged (25 min) PLL / cit suspension. The suspension was then aged for another 5 minutes. To this, a colloidal sol of silica nanoparticles was added and formed a thick shell surrounding the aggregates.

[0030]Optical brightfield and confocal images of silica microcapsules encapsulating β-Mannanase enzyme show circular microcapsules. The composition comprises: 21 μL PLL-FITC (2 mg / ml, 68.6 kD)+125 μL Na3Cit (5.36 mM)+50 μL β-Mannanase enzyme (9 units / ml)+125 μL SiO2 NP (20 wt %).

[0031]The encapsulation of the enzyme within the r...

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Abstract

A method for the encapsulation and triggered-release of water-soluble or water-dispersible materials. The method comprises a) providing an amount of electrolyte having a charge, b) providing an amount of counterion having a valence of at least 2, c) combining the polyelectrolyte and the counterion in a solution such that the polyelectrolyte self-assembles to form aggregates, d) adding a compound to be encapsulated, and e) adding nanoparticles to the solution such that nanoparticles arrange themselves around the aggregates. Release of the encapsulated species is triggered by disassembly or deformation of the microcapsules though disruption of the charge interactions. This method is specifically useful for the controlled viscosity reduction of the fracturing fluids commonly utilized in the oil field.

Description

FIELD OF THE INVENTION[0001]The present invention relates to methods and compositions for controlled viscosity reduction of fracturing fluids used in subterranean formations. The method involves both encapsulation and release of viscosity breakers by using microcapsules assembled from charged nanoparticles and polyelectrolytes. During the microcapsule assembly process, breakers such as enzymes, persulphate, aminocarboxylates, etc., are encapsulated into the shell. The encapsulated species are released during the disassembly or deformation of the microcapsules induced by the addition of salt (NaCl, brine, sea water, etc.). The methods and compositions are designed in such a way that the reduction of viscosity is initiated by contacting fracturing fluids with brine solution.[0002]This method can more generally be utilized for encapsulating water-soluble or water-dispersible materials in microcapsules assembled from nanoparticles and, as such, is useful for the encapsulation and releas...

Claims

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Application Information

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IPC IPC(8): C09K8/92B01J13/22
CPCA61K8/11A61K2800/412A61K2800/413A61Q19/00C12N11/04B82Y5/00C09K8/706C09K2208/10C12N9/96B01J13/02
Inventor RANA, ROHIT K.MURTHY, VINIT S.WONG, MICHAEL S.NORMAN, LEWIS R.
Owner RICE UNIV
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