GLDA-Chelated Fracturing Fluid for Stable Seawater Viscosity
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Solution Overview
Problem
High salinity waters, such as seawater, cause issues in hydraulic fracturing due to ion-induced viscosity reduction and formation damage, necessitating the development of compositions that stabilize viscosity and prevent formation damage.
Innovation Solution
A composition comprising a saline fluid with a carboxymethyl hydroxypropyl guar (CMHPG) polymer, a zirconium crosslinker, and L-glutamic acid N, N diacetic acid (GLDA) chelating agent is used to enhance viscosity and prevent ion interference, maintaining stability up to 300°F (148.9°C).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If seawater is used as the saline fluid, then the availability and cost-effectiveness are improved, but the viscosity is reduced and formation damage occurs due to divalent ions
Solution Approach 1:
The patent introduces a chelating agent as an intermediary substance that binds to divalent ions (calcium, magnesium) in seawater, preventing them from interfering with polymer crosslinking and viscosity stability. This mediator allows the use of seawater while mitigating its harmful ionic effects.
Solution Approach 2:
The patent modifies the chemical parameters of the fracturing fluid by adjusting the concentration of chelating agent (1-10 wt%) and polymer (0.1-5 wt%), thereby changing the fluid's interaction with seawater ions to maintain viscosity stability despite high salinity.
2Quantity of substance
If divalent ions are present in the saline fluid, then the ionic composition is maintained, but the viscosity decreases and formation damage occurs
Solution Approach 1:
The chelating agent acts as a mediator that selectively binds to divalent ions, sequestering them in stable complexes that no longer interfere with polymer crosslinking. This allows high ion concentration to coexist with stable viscosity.
Solution Approach 2:
The patent converts the harmful effect of divalent ions into a beneficial chelation complex formation. By introducing the chelating agent, the divalent ions are transformed from viscosity-reducing interferents into bound complexes that stabilize the fluid system.
3Stability of the object's composition
If a polymer is added to increase viscosity, then the rheology is enhanced, but the polymer hydrates slowly and crosslinking mechanism changes in seawater
Solution Approach 1:
The chelating agent serves as a mediator that facilitates polymer hydration and crosslinking in seawater by removing interfering ions, thereby accelerating the hydration process and maintaining the expected crosslinking mechanism despite the saline environment.
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 composition achieves stable viscosity between 50 and 1000 cP, preventing formation damage and ensuring effective proppant transport in high salinity waters.
Implementation Method 1
a chelating agent, the chelating agent includes L-glutamic acid N, N diacetic acid (GLDA)
Implementation Method 2
a polymer, the polymer operable to react with a crosslinker to increase a viscosity of the saline fluid, a zirconium crosslinker, the zirconium crosslinker operable to react with the polymer
Data Source
AI summary
A composition for use in well stimulation operations, the composition comprising a saline fluid, the saline fluid comprising between 50,000 ppm and 70,000 ppm; a polymer, the polymer operable to react with a crosslinker to increase a viscosity of the saline fluid; a zirconium crosslinker, the zirconium crosslinker operable to react with the polymer; and a chelating agent, the chelating agent comprises L-glutamic acid N, N diacetic acid (GLDA), wherein the GLDA is present in an amount between 1 wt % and 8 w t %.