Saline Fracturing Fluid Composition for Stable Viscosity and Scale Control
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Solution Overview
Problem
The high salinity of seawater and produced water affects the viscosity and stability of hydraulic fracturing fluids due to divalent and monovalent ions, leading to scale formation, reduced fracture conductivity, and corrosion issues, necessitating the use of costly freshwater.
Innovation Solution
A composition comprising a saline fluid with a carboxymethyl hydroxypropyl guar (CMHPG) polymer, a zirconium-containing crosslinker, and diethylenetriaminepentaacetic acid (DTPA) chelating agent is used to enhance viscosity and prevent scale formation, utilizing high salinity waters like seawater and produced water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If high salinity water (seawater or produced water) is used in hydraulic fracturing, then freshwater consumption is reduced, but viscosity stability and fluid reliability deteriorate due to ion-induced polymer precipitation and scale formation
Solution Approach 1:
The patent introduces a chelating agent as an intermediary substance that binds to divalent ions (Ca2+, Mg2+) in high salinity water, preventing them from interacting with the polymer and crosslinker. This mediator approach allows the use of seawater or produced water while maintaining fluid stability, thus reducing freshwater consumption without sacrificing reliability
Solution Approach 2:
The patent modifies the chemical parameters of the fracturing fluid by selecting specific polymers and crosslinkers that are resistant to high salinity conditions. The composition parameters are adjusted to accommodate high concentrations of dissolved solids while maintaining adequate viscosity and stability, enabling the use of high salinity water sources
2Ease of manufacture
If high salinity water is used, then cost is reduced by avoiding freshwater procurement, but fracture conductivity deteriorates due to scale formation and precipitation
Solution Approach 1:
The patent converts the harmful effect of high salinity by using the chelating agent to bind divalent ions, transforming them from scale-forming contaminants into stable chelate complexes. This approach eliminates the harmful scale formation while maintaining the cost advantage of using high salinity water, effectively converting a potential harm into a beneficial solution
Solution Approach 2:
The chelating agent serves as an intermediary that prevents direct interaction between divalent ions and formation minerals, thereby preventing scale deposition. This mediator approach maintains fracture conductivity while allowing the use of cost-effective high salinity water sources
3Stability of the object's composition
If divalent ions (Ca2+, Mg2+) are present in high salinity water, then viscosity reduction occurs, but this same presence causes hydroxide precipitation and pH reduction
Solution Approach 1:
The chelating agent acts as an intermediary that binds to divalent ions, preventing them from forming hydroxide precipitates and interfering with pH control. This allows the fluid to maintain stable viscosity while using high salinity water containing natural divalent ion content
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 total dissolved solids; a polymer, the polymer operable to react with a crosslinker to increase a viscosity of the saline fluid; a zirconium-containing crosslinker, the zirconium-containing crosslinker operable to react with the polymer, and a chelating agent, the chelating agent comprises diethylenetriaminepentaacetic acid (DTPA), wherein the DTPA is present in an amount between 0.1 wt. % and 0.4 wt. %.