Crosslinked CMHEC Polymer for High-Temperature Well Treatment Fluids
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Solution Overview
Problem
Current well treatment fluids, particularly those using guar derivatives, face challenges with high viscosity requirements at elevated temperatures and the recycling of produced water with high total dissolved solids (TDS) and divalent cation content, which is costly and time-consuming, limiting their application in high-temperature formations and water conservation efforts.
Innovation Solution
A well treatment fluid comprising a crosslinked carboxymethyl hydroxyethyl cellulose (CMHEC) polymer with a degree of substitution (DS) of 0.2 to 0.6 and molar substitution (MS) of 2.0 to 2.5, crosslinked in an aqueous-based fluid at a pH of at least 6, achieving a viscosity of at least 100 cP at 100 sec−1, suitable for use with produced water and stable up to 300°F, using a crosslinker like zirconium and pH stabilizers such as magnesium oxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If guar derivatives are used to increase fluid viscosity for proppant transport, then adequate transport of larger proppant sizes is achieved, but the fluid becomes unsuitable for high formation temperatures and high TDS produced water
Solution Approach 1:
The patent changes the chemical parameters of the polymer system by using cellulose derivatives with specific degree of substitution (0.2-0.6) and molar substitution (2.0-2.5), and by adjusting crosslinking conditions to pH 6 or higher, enabling the fluid to maintain viscosity at high temperatures and in high TDS environments
Solution Approach 2:
The patent creates a composite system combining cellulose derivative polymers with specific crosslinkers that work synergistically to provide both high viscosity and stability in challenging conditions (high temperature and high TDS), overcoming the limitations of single-component systems
2Reliability
If produced water is treated to reduce TDS and divalent cation content for use in guar-based fracturing fluids, then water quality becomes suitable for the fluids, but the treatment becomes cost-prohibitive and time-consuming
Solution Approach 1:
The patent changes the chemical parameters of the fracturing fluid system to be compatible with high TDS produced water, eliminating the need for extensive water treatment by using cellulose derivatives that remain stable and effective in high-salinity conditions
3Strength
If crosslinkers are used to increase fluid viscosity for adequate proppant transport, then larger proppant sizes can be transported, but the fluid becomes limited to low pH environments and temperatures below 250°F
Solution Approach 1:
The patent changes the crosslinking chemistry parameters by using crosslinkers that function at pH 6 and higher, and by selecting cellulose derivative polymers that maintain stability and viscosity at temperatures up to 300°F, overcoming the temperature and pH limitations of conventional systems
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 provides a sustained increase in viscosity for extended periods, enabling effective well stimulation and recycling of produced water, overcoming the limitations of existing systems by maintaining stability and viscosity at high temperatures and in challenging water conditions, thus reducing operational costs and environmental impact.
Implementation Method 1
a crosslinker configured to crosslink the CMHEC polymer in the aqueous-based fluid
Implementation Method 2
The solution provides a sustained increase in viscosity for extended periods
Implementation Method 3
stable up to 300°F
Data Source
AI summary
A well treatment fluid includes an aqueous-based fluid, a crosslinked CMHEC polymer, and a crosslinker. The CMHEC polymer exhibits a DS of 0.2 to 0.6 and a MS of 2.0 to 2.5. The well treatment fluid exhibits a viscosity of at least about 100 cP. A well treatment method includes crosslinking a CMHEC polymer in an aqueous-based fluid at a pH of at least about 6. The crosslinking increases a viscosity of the well treatment fluid to at least about 100 cP. A well is treated with the well treatment fluid at a temperature of at least about 200° F. Another well treatment method includes forming a well treatment fluid from produced water that has a TDS content of at least about 150,000 ppm. The crosslinking increases a viscosity of the well treatment fluid to at least about 100 cP.