GLDA Salt Viscosity Control in Hydraulic Fracturing Fluids
Solution Overview
Problem
Current hydraulic fracturing gels in low-permeability subterranean formations face challenges in transporting large-sized or large quantities of proppant due to insufficient viscosity at ambient temperatures, and existing rheology modifiers do not provide sufficient flexibility in viscosity control for optimal well treatment.
Innovation Solution
A well servicing fluid comprising a GLDA salt, a viscosifying agent, and a crosslinker is used, where the GLDA salt contains a metal cation chelated with a GLDA anion, allowing for controlled viscosity increase and subsequent decrease through chelation, enabling efficient proppant transport and fracture management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cross-linkers are used to increase fluid viscosity, then proppant transport capability is improved, but gel removal difficulty increases
Solution Approach 1:
The patent employs a breakdown agent that chemically modifies the cross-linked gel structure by breaking cross-links between polymer chains. This parameter change transforms the gel from a highly viscous cross-linked state to a lower viscosity non-cross-linked state, enabling easy removal after proppant transport is complete
Solution Approach 2:
The fluid system dynamically transitions between two viscosity states: initially maintaining high viscosity through cross-linking for proppant transport, then switching to low viscosity through breakdown agent action for easy removal. This dynamic property allows the same fluid to serve dual functions at different stages
2Volume of moving object
If gel viscosity is increased for proppant transport, then fracture width increases, but gel removal becomes more difficult
Solution Approach 1:
The breakdown agent chemically alters the gel structure by cleaving cross-links, changing the viscosity parameter from high to low. This allows the gel to have been high-viscosity during injection to create wide fractures, then becomes low-viscosity for easy cleanup
Solution Approach 2:
The breakdown agent selectively removes the cross-linking component from the gel structure without affecting the polymer backbone or proppant. This extraction of the cross-linking function reduces viscosity while preserving the gel's ability to have created wide fractures
3Loss of time
If cross-linking delay additives are used, then viscosity development timing is controlled, but fluid composition complexity increases
Solution Approach 1:
The breakdown agent is pre-incorporated into the fracturing fluid composition in an inactive or dormant state. Upon injection into the formation, it becomes activated and begins breaking cross-links. This preliminary inclusion allows timing control without requiring separate delayed-action mechanisms
Solution Approach 2:
The breakdown agent is designed to automatically activate and function based on down-hole conditions (temperature, pressure, chemical environment) without requiring additional control mechanisms or complex timing devices. The fluid system self-regulates the breakdown timing through the inherent properties of the breakdown agent
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 solution achieves a significant reduction in viscosity, facilitating the transport of larger proppant sizes and quantities while maintaining desirable gel properties during fracturing, thereby enhancing hydrocarbon production and simplifying gel removal.
Implementation Method 1
viscosity of the well servicing fluid in the well is decreased to a second viscosity less than the first viscosity by chelating the crosslinker with the GLDA anion, which counteracts the crosslinking
Data Source
AI summary
A well servicing fluid includes ingredients including a GLDA salt, a crosslinker, and a viscosifying agent that is not crosslinked by the crosslinker. A well treatment method includes forming a well servicing fluid with ingredients including a GLDA salt, a viscosifying agent, and a crosslinker, the GLDA salt containing a metal cation chelated with a GLDA anion. The well servicing fluid is inserted into a well in a formation. The method includes crosslinking the viscosifying agent and attaining a first viscosity of the well servicing fluid using the crosslinker. After the attaining of the first viscosity, viscosity of the well servicing fluid in the well is decreased to a second viscosity less than the first viscosity by using the GLDA anion. The GLDA salt may be a GLDA calcium salt and the crosslinker may be a zirconium crosslinker.