Acidic Internal Breaker for Viscoelastic Surfactant Fluids
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Solution Overview
Problem
Current methods for breaking viscoelastic surfactant fluids in oilfield treatments are inefficient due to limited interaction between pre-flush or post-flush fluids and the treatment fluids, relying on diffusion which is slow in highly viscous fluids, and often require mechanical or chemical triggers for breaker activation.
Innovation Solution
The use of acidic internal breakers, such as sulfuric acid, nitric acid, or acetic acid, which are soluble in the viscoelastic surfactant fluids and can be triggered by temperature or pH changes to gradually reduce viscosity, allowing for controlled breaking without mechanical or chemical activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pre-flush or post-flush fluids are used to break VES fluids, then fluid cleanup is improved, but the interaction between fluids is limited and diffusion is slow in highly viscous fluids
Solution Approach 1:
The VES fluid contains an internal breaker that enables self-degradation without requiring external flush fluids. The breaker is triggered by formation conditions (temperature, pH, dissolved CO2) to automatically reduce viscosity within the formation, eliminating the need for additional flush operations and the associated diffusion limitations.
Solution Approach 2:
Formation fluids (water, dissolved CO2, acids) act as intermediaries to trigger the breaker activation. These naturally present fluids in the formation environment provide the triggering mechanism without requiring external flush fluids, thereby improving cleanup efficiency while avoiding diffusion constraints.
2Productivity
If large volumes of flush fluids are used to improve breaking, then cleanup efficiency is improved, but the volume of fluid required increases
Solution Approach 1:
The VES fluid contains an internal breaker that enables self-degradation without requiring external flush fluids. The breaker is triggered by formation conditions (temperature, pH, dissolved CO2) to automatically reduce viscosity within the formation, eliminating the need for additional flush operations and the associated diffusion limitations.
3Ease of operation
If breakers are activated by mechanical or chemical triggers, then breaking can be controlled, but the system complexity increases
Solution Approach 1:
The breaker is activated by changes in formation parameters such as temperature, pH, and dissolved CO2 concentration. These naturally occurring parameter changes in the formation environment trigger the breaker without requiring complex mechanical or chemical activation mechanisms, maintaining operational control while minimizing system complexity.
4Speed
If breakers act immediately upon contact, then viscosity reduction is achieved, but the fluid cannot perform its function first
Solution Approach 1:
The breaker is incorporated into the VES fluid formulation in advance but remains dormant during injection and placement. The breaker is designed to activate only after the fluid has performed its intended function, triggered by formation conditions such as temperature increase, pH change, or dissolved CO2. This preliminary incorporation without immediate activation allows the fluid to maintain viscosity during placement while enabling subsequent breakdown for cleanup.
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
This approach enables efficient and controlled reduction of fluid viscosity within formation pores, improving fluid cleanup and treatment effectiveness in oilfield operations like hydraulic fracturing and gravel packing, with adjustable breaking times and compatibility with various formation chemistries.
Implementation Method 1
Breakers decrease viscosity by degrading surfactants or destroying micelles when viscosifiers are viscoelastic surfactant fluid systems
Implementation Method 2
can be triggered by temperature or pH changes to gradually reduce viscosity
Implementation Method 3
can be triggered by temperature or pH changes to gradually reduce viscosity
Data Source
AI summary
Compositions and methods are given for delayed breaking of viscoelastic surfactant gels inside formation pores, particularly for use in hydraulic fracturing. Breaking inside formation pores is accomplished without mechanical intervention or use of a second fluid. Acidic internal breakers such as sulfuric acid and nitric acid are used. The break may be accelerated, for example with a free radical propagating species, or retarded, for example with an oxygen scavenger.