Sulfonated Lignite Filtration Control Agent for Drilling Fluids
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Solution Overview
Problem
Existing filtration control agents for high-density drilling fluids face challenges in controlling filtration loss, viscosity, and rheological behavior, especially at high temperatures and salt concentrations, often requiring increased dosages and complex synthesis processes, which increase costs and labor intensity while providing inadequate filtration loss reduction.
Innovation Solution
A filtration control agent is developed by reacting humic acid or modified humic acid with an aldehyde and a sulfonate polymer at 180-220°C, resulting in a product with at least 30 wt% sulfonate groups in its molecular chains, which is used to create a drilling fluid that reduces filtration loss and improves rheological behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filtration control agents (high molecular weight polymers) are used in high density drilling fluid, then filtration loss control is improved, but viscosity increases and rheological behavior worsens
Solution Approach 1:
The patent changes the molecular weight parameter of the filtration control agent from high (conventional) to ultra-low (5,000-50,000), and modifies the chemical structure by introducing sulfonate groups and carboxyl groups. This parameter change allows the agent to maintain filtration control effectiveness while significantly reducing viscosity increase in high density drilling fluids
Solution Approach 2:
The patent creates a composite chemical structure by grafting acrylonitrile onto sulfonated lignite to form a graft copolymer. This composite material combines the benefits of sulfonate groups (for salt and temperature resistance) with acrylonitrile units (for filtration control), achieving both filtration loss reduction and low viscosity effect
2Reliability
If existing filtration control agents are used under high temperature and high salt conditions, then some filtration control effect is achieved, but the effect is not obvious and dosage must be increased
Solution Approach 1:
The patent introduces sulfonate groups into the molecular structure of the filtration control agent, which significantly enhances temperature and salt resistance. The sulfonate groups maintain charge stability and molecular conformation under high temperature and high salt conditions, enabling effective filtration control where conventional agents fail
Solution Approach 2:
The patent creates local quality enhancement by concentrating sulfonate groups at specific positions in the polymer chain (through sulfonation of lignite). This localized functional group distribution provides targeted resistance to temperature and salt effects, improving adaptability without requiring increased dosage
3Reliability
If complex synthesis processes (multiple steps including oxidative degradation, extraction, sulfomethylation, graft polymerization) are used to prepare filtration control agents, then temperature and salt resistance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges multiple synthesis steps into a more streamlined process. By using sulfonated lignite as starting material and performing graft polymerization in a simplified manner, the patent combines what were previously separate complex operations (oxidative degradation, extraction, sulfomethylation, graft polymerization) into a more efficient sequence, reducing manufacturing complexity while maintaining product performance
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 new filtration control agent effectively reduces filtration loss and viscosity while maintaining good temperature and salt resistance, making it suitable for deep and ultra-deep well drilling operations with improved industrial application prospects.
Implementation Method 1
reacting humic acid or modified humic acid with an aldehyde and a sulfonate polymer at 180-220°C, resulting in a product with at least 30 wt% sulfonate groups in its molecular chains
Data Source
AI summary
The present invention provides a filtration control agent and a drilling fluid containing the same. The filtration control agent comprises the product obtained from the reaction of water, lignite, aldehyde and sulfonate polymer at 180-220° C. and the units containing sulfonate groups in the molecular chains of sulfonate polymer are at least 30 wt %. The filtration control agent provided by the present invention features a good filtration loss reduction effect and a low viscosity effect and can improve the rheological behavior of the drilling fluid, thereby meeting the requirements of the drilling of deep wells, ultra-deep wells and ultra high pressure formations.