Crosslinked Sulfonate Polymers for High-Density Brine Stability
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Solution Overview
Problem
Current drilling fluids used in high-temperature drill-in operations face challenges due to thermal degradation of polymeric viscosifiers and high salt content in heavy brines, which affects viscosity and fluid stability, making it difficult to maintain adequate viscosity over time.
Innovation Solution
The development of crosslinked sulfonate-containing polymers dispersed in monovalent brines with specific monomers and crosslinkers, such as sulfonic acid-containing monomers and N-vinyl amide-containing monomers, which provide stability and adjustable viscosity within a density range of 8 to 20 lb/gal, enhancing rheological properties and fluid loss control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If biopolymers are used as viscosifiers in drill-in fluids, then fluid viscosity is improved at lower temperatures, but thermal degradation occurs above 300°F causing viscosity loss
Solution Approach 1:
The patent changes the chemical parameters of the polymer by introducing crosslinked sulfonate-containing groups into the polymer structure. This chemical modification enables the polymer to maintain viscosity stability at high temperatures (above 300°F) where conventional biopolymers degrade, thus resolving the temperature-stability contradiction
Solution Approach 2:
The patent creates a composite polymer system combining sulfonate-containing monomers with crosslinking agents to form a crosslinked polymer network. This composite structure provides both thermal stability and viscosity control, overcoming the limitations of single-component biopolymers
2Quantity of substance
If heavy brines are used to set fluid density, then density control is improved, but high salt content causes polymer degradation and reduced viscosity
Solution Approach 1:
The patent modifies the polymer's chemical parameters by adding sulfonate groups that are specifically designed to be salt-tolerant. These groups allow the polymer to maintain its viscosifying properties in high-salt heavy brine environments where conventional polymers would degrade, thus resolving the density-polymer stability contradiction
3Loss of substance
If conventional water-soluble polymers are used in high-salt brines, then fluid loss control is improved, but viscosity efficiency is reduced due to salt interference
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer by incorporating sulfonate groups that resist salt interference. This enables the polymer to maintain high viscosity efficiency and fluid loss control simultaneously in heavy brine conditions, resolving the productivity-efficiency contradiction
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 crosslinked sulfonate-containing polymers maintain viscosity and fluid stability at high temperatures, effectively addressing the thermal degradation issues and providing consistent performance during drill-in operations, as demonstrated by their thermal stability and filtration control in high-temperature, high-pressure conditions.
Implementation Method 1
The crosslinked sulfonate-containing polymers maintain viscosity and fluid stability at high temperatures, effectively addressing the thermal degradation issues
Implementation Method 2
as demonstrated by their thermal stability and filtration control in high-temperature, high-pressure conditions
Data Source
AI summary
Crosslinked sulfonate-containing polymers may be stable in high density, monovalent brines, which may render such polymers particularly useful in drilling fluids in general and, especially, in the subclass of drilling fluids known as drill-in fluids. For example, a drilling fluid may include a crosslinked sulfonate-containing polymer dispersed in a monovalent brine having a density of about 8 lb/gal to about 20 lb/gal, wherein the crosslinked sulfonate-containing polymer comprises: reactants of a first repeating unit and a crosslinker that react to form the crosslinked sulfonate-containing polymer, wherein the first repeating unit is a sulfonic acid-containing monomer present from 50% to 99.99% by weight of the reactants, and wherein the crosslinker comprises at least two olefinic bonds.