Nano-sized Metal Oxide Additives Stabilize Viscoelastic Surfactant Fluids
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Solution Overview
Problem
Conventional fracturing fluids used in hydrocarbon recovery operations face challenges such as instability at high temperatures and shear rates, premature settlement of proppants, and formation damage due to polymer-based gels, which lead to reduced effectiveness and increased damage to the reservoir.
Innovation Solution
The use of aqueous viscoelastic surfactant fluids with nano-sized particulate additives, specifically alkaline earth metal oxides, alkali metal oxides, and transition metal hydroxides, which improve thermal stability, reduce leak-off, and minimize formation damage by maintaining viscosity and preventing precipitation, allowing for more effective hydraulic fracturing and enhanced hydrocarbon production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymer-based gelling agents are used to thicken fracturing fluids, then the fluid can carry and suspend proppants effectively, but the fluid becomes unstable at high temperatures and shear rates, causing premature proppant settlement and requiring separate breaker compositions
Solution Approach 1:
The patent changes the chemical parameters of the gelling agent by using viscoelastic surfactants instead of conventional polymers. This substitution fundamentally alters the fluid's rheological properties, providing both thickening capability and thermal stability without requiring separate breakers or leaving harmful residues on proppants
Solution Approach 2:
The patent creates a composite fluid system combining viscoelastic surfactants with nanometer-sized particulate matter. This composite approach enhances the fluid's stability at high temperatures and shear rates while maintaining proppant suspension capabilities, resolving the contradiction between strength and stability
2Strength
If crosslinked polymer gels are used to maintain fluid viscosity, then proppants remain suspended during fracturing, but the polymers leave damaging coatings on proppants and cause formation damage through fish-eyes and microgels
Solution Approach 1:
The patent extracts and eliminates the harmful components (crosslinked polymer networks, fish-eyes, and microgels) from the fracturing fluid system. By using viscoelastic surfactants instead of crosslinked polymers, the fluid maintains proppant suspension without leaving damaging coatings or causing formation damage
Solution Approach 2:
The patent replaces persistent, harmful polymer gels with biodegradable viscoelastic surfactants that perform their thickening and suspending function temporarily during the fracturing operation, then naturally break down without leaving harmful residues on proppants or in the formation
3Use of energy by moving object
If conventional polymers are used as gelling agents, then the fluid achieves necessary viscosity to carry proppants, but the polymers are either cationic or anionic causing damage to producing formations and fracture conductivity
Solution Approach 1:
The patent changes the electrical charge parameter of the gelling agent from cationic or anionic polymers to zwitterionic viscoelastic surfactants. This parameter change eliminates the harmful electrostatic interactions with formation rocks while maintaining the necessary viscosity for proppant transport through micellar aggregation
4Object-affected harmful factors
If VES-gelled fluids are used to reduce formation damage, then the fluids are non-cake-building and less damaging, but the fluids still experience instability at high temperatures causing viscosity loss and proppant settlement
Solution Approach 1:
The patent creates a composite system combining viscoelastic surfactants with nanometer-sized particulate matter. This composite structure provides thermal stabilization to the VES gel, preventing viscosity loss and proppant settlement at high temperatures while maintaining the non-cake-building, low-damage characteristics of VES fluids
Solution Approach 2:
The nanometer-sized particulate matter acts as an intermediary stabilizer that mediates between the VES surfactant molecules and the high-temperature environment. These particles prevent thermal degradation of the micellar structure, maintaining viscosity stability without compromising the fluid's non-damaging properties
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The nano-sized additives enhance the thermal stability and viscosity of viscoelastic surfactant fluids, reducing leak-off and formation damage, thereby improving the efficiency and longevity of fracturing operations and increasing hydrocarbon recovery while minimizing reservoir damage.
Implementation Method 1
make the system stabilizers more effective in stabilizing the viscosity of VES fluid, particularly the gelled fluid which has leaked-off into the treated reservoir
Implementation Method 2
aqueous fluids gelled with viscoelastic surfactants (VESs) are also known in the art
Implementation Method 3
viscoelastic surfactant (VES) gelling agent
Implementation Method 4
alkaline earth metal oxides, alkaline earth metal hydroxides, transition metal oxides, transition metal hydroxides, and mixtures thereof, and in particular magnesium oxide may serve to inhibit or prevent fluid loss in aqueous fluids gelled with VESs
Data Source
AI summary
An aqueous, viscoelastic fluid gelled with a viscoelastic surfactant (VES) is stabilized and improved with an effective amount of an alkaline earth metal oxide, alkaline earth metal hydroxide, alkali metal oxides, alkali metal hydroxides, transition metal oxides, transition metal hydroxides, post-transition metal oxides, and post-transition metal hydroxides. These fluids are more stable and have a reduced or no tendency to precipitate, particularly at elevated temperatures. The additives may reduce the amount of VES required to maintain a given viscosity. These stabilized, enhanced, aqueous viscoelastic fluids may be used as treatment fluids for subterranean hydrocarbon formations, such as in hydraulic fracturing. The particle size of the magnesium oxide or other agent may be nanometer scale, which scale may provide unique particle charges that use chemisorption, crosslinking and/or other chemistries to associate and stabilize the VES fluids.