Crosslinked Polymer Compositions for Subterranean Fluid Viscosity Control
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Solution Overview
Problem
Subterranean formation treatment fluids face challenges in maintaining viscosity and preventing fluid loss, which can lead to inadequate suspension of solids and delivery of chemicals, resulting in reduced hydrocarbon recovery and undesirable filter cake buildup.
Innovation Solution
The use of crosslinked polymers comprising a sulfonic acid-containing monomer, an N-vinyl amide or terminal double bond-containing monomer, and a crosslinker with olefinic bonds, which are incorporated into treatment fluids to enhance viscosity and fluid loss control, thereby stabilizing wellbores and improving fluid transport efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymers are used in treatment fluids, then the fluid can be circulated and perform basic functions, but the viscosity is insufficient to suspend solids and transport chemicals effectively
Solution Approach 1:
The patent employs composite polymer structures combining multiple monomer types (sulfonic acid-containing monomers, N-vinyl amide monomers, and terminal double bond-containing monomers) crosslinked with olefinic bond-containing crosslinkers. This composite approach creates a network structure that significantly enhances viscosity and solids suspension capability compared to conventional single-polymer systems, directly resolving the contradiction between achieving high viscosity and managing structural complexity.
Solution Approach 2:
The invention utilizes chemical crosslinking to fundamentally change the physical parameters of the polymer system. By introducing crosslinks between polymer chains through olefinic bonds, the system transitions from a simple viscous fluid to a gel-like structure with enhanced viscosity and elasticity, enabling effective solids suspension and chemical transport without requiring excessively complex polymer architectures.
2Speed
If treatment fluid viscosity is reduced to improve flow, then circulation efficiency increases, but the fluid loses ability to suspend solids and maintain hydrostatic pressure
Solution Approach 1:
The crosslinked polymer system exhibits dynamic rheological properties that allow it to adapt to different flow conditions. Under low stress conditions (when circulation speed is low), the gel structure maintains high viscosity for solids suspension. Under high stress conditions (when circulation speed increases), the gel structure breaks down and flows more easily, enabling efficient circulation. This dynamic behavior resolves the contradiction between circulation speed and viscosity maintenance.
Solution Approach 2:
The crosslinking degree and polymer concentration can be adjusted to change the viscosity-flow relationship. By optimizing these parameters, the treatment fluid achieves a balance where sufficient viscosity is maintained at circulation speeds to suspend solids, while still allowing adequate flow through the wellbore. The crosslinked network provides shear-thinning behavior that facilitates this balance.
3Reliability
If crosslinked polymers are used to enhance viscosity and fluid loss control, then wellbore stability improves, but the complexity of fluid formulation and handling increases
Solution Approach 1:
The patent provides specific parameter ranges for monomer composition (e.g., sulfonic acid-containing monomers at 1-45 wt%, N-vinyl amide monomers at 55-99 wt%) and crosslinker content (0.1-25 wt%). By controlling these parameters within specified ranges, the formulation achieves reliable wellbore stability and fluid loss control while managing complexity through standardized composition guidelines rather than requiring complex proprietary formulations.
Solution Approach 2:
The use of composite polymer systems with defined component ratios provides predictable and reliable performance. The combination of different monomer types and crosslinkers creates a synergistic effect that enhances wellbore stability and fluid loss control more effectively than single-polymer systems, while the standardized composite formulation approach manages complexity through established composition protocols.
4Duration of action of stationary object
If treatment fluids are designed to maintain high viscosity for extended periods, then solids suspension and chemical delivery improve, but fluid loss to the formation increases
Solution Approach 1:
The crosslinking degree and polymer concentration are optimized to achieve the desired balance between viscosity maintenance duration and fluid loss. By adjusting these parameters, the treatment fluid maintains sufficient viscosity for the required operational duration while controlling fluid loss through the formation. The crosslinked network structure provides long-term viscosity stability without excessive fluid loss when parameters are properly controlled within the ranges specified in the patent.
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 polymers effectively maintain viscosity and prevent fluid loss, ensuring the stable suspension of solids and efficient delivery of chemicals, thereby enhancing hydrocarbon recovery and reducing filter cake formation.
Implementation Method 1
crosslinked polymers comprising a sulfonic acid-containing monomer, an N-vinyl amide or terminal double bond-containing monomer, and a crosslinker with olefinic bonds
Data Source
AI summary
A crosslinked polymer comprising reactants of a first repeating unit, a second repeating unit, and a crosslinker that react to form the crosslinked polymer, wherein the first repeating unit is a sulfonic acid-containing monomer present from 1% to 45% by weight of the reactants, wherein the second repeating unit is selected from the group consisting of an N-vinyl amide-containing monomer, a terminal double bond-containing monomer, and any combination thereof, and is present from 55% to 99% by weight of the reactants, and wherein the crosslinker comprises at least two olefinic bonds.