Branched Sulfonated Polymer for Drilling Fluid Loss and Viscosity
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Solution Overview
Problem
Existing drilling fluids face challenges in maintaining high viscosities and effective fluid loss control under high temperature, high pressure, and high salinity conditions, with current viscosifiers being unstable or affected by ions and salts, leading to the need for improved additives that are thermally stable and resistant to shear and contamination.
Innovation Solution
A water-soluble branched sulfonated amphoteric polymer is developed through precipitation polymerization, using N,N'-dialkyl(meth)acrylamide, sulfonic acid-containing monomers, and tetraallylammonium halide as a branching agent, providing enhanced fluid loss control and viscosifying properties under extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional viscosifiers (xanthan gum, polyacrylamides) are used to maintain high viscosity, then viscosity is improved, but thermal stability deteriorates under high temperature conditions
Solution Approach 1:
The invention changes the chemical parameters of the viscosifier by using a copolymer with specific composition (acrylamide and AMPS monomers in controlled ratios) and molecular weight (10^6 to 10^8), which maintains viscosity through parameter optimization rather than relying on conventional polymers that degrade thermally
Solution Approach 2:
The invention creates a composite polymer structure combining acrylamide and AMPS monomers in a copolymer chain, where the AMPS component provides thermal stability while the acrylamide component contributes to viscosifying properties, achieving both high viscosity and thermal resistance simultaneously
2Strength
If larger amounts of viscosifier are used to compensate for high temperatures, then viscosity is maintained, but cost increases and fluid loss control worsens
Solution Approach 1:
The invention optimizes the viscosifier concentration parameter to 0.01-5% by weight, achieving effective viscosity with minimal polymer amount through enhanced molecular efficiency of the copolymer structure, reducing both cost and fluid loss compared to conventional approaches requiring higher concentrations
3Reliability
If starches and cellulose materials are used for fluid loss control, then filter cake formation is improved, but high temperature stability deteriorates
Solution Approach 1:
The invention employs a composite copolymer material integrating acrylamide and AMPS monomers, where the sulfonated AMPS component provides cationic cross-linking capability for robust filter cake formation while the overall polymer structure maintains stability at high temperatures, overcoming the limitations of pure starch or cellulose systems
4Reliability
If polyacrylates and polyacrylamides are used for fluid loss control, then filter cake sealing is improved, but resistance to salt and divalent cation contamination deteriorates
Solution Approach 1:
The invention creates a composite copolymer where the AMPS monomer unit provides sulfonate groups that resist cationic cross-linking by divalent cations, while the acrylamide units maintain hydrophilicity and filter cake sealing, achieving fluid loss control that is insensitive to salt and cation contamination
Solution Approach 2:
The invention modifies the chemical composition parameters by incorporating AMPS monomers with sulfonate groups that have higher resistance to cationic cross-linking compared to conventional carboxylate groups, changing the polymer's interaction parameters with divalent cations to reduce sensitivity
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 polymer maintains nearly constant viscosity and effective fluid loss control for up to 7 days at temperatures between 200°F to 400°F, demonstrating stability against high shear, pressure, and salt contamination.
Implementation Method 1
A water-soluble branched sulfonated amphoteric polymer is developed through precipitation polymerization
Data Source
Figure 1
AI summary
The invention relates to a water-soluble branched sulfonated amphoteric polymer, for a water- based drilling fluid, wherein the polymer is obtained by precipitation polymerization, in a mixture of polar solvents, of at least one N,N'-dialkylacrylamide monomer and one sulfonic acid-containing monomer, in the presence of tetraallylammonium halide as branching agent. The invention also relates to a water-based drilling fluid for subterranean boreholes, including: - an aqueous fluid, said aqueous fluid being selected from sea water, brine, or salt-containing aqueous solution, - between 0.1 and 5.0 weight percent of the water-soluble branched sulfonated amphoteric polymer described above.