Crosslinked N-vinylpyrrolidone Polymers for High-Temperature Drilling Fluids
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Solution Overview
Problem
Current drilling and treatment fluids for subterranean formations face challenges in maintaining viscosity and fluid-loss control at high temperatures, particularly in divalent brines, where acrylamide homopolymers degrade and precipitate, leading to reduced effectiveness.
Innovation Solution
The use of crosslinked polymers comprising N-vinyl lactam monomeric units, such as N-vinylpyrrolidone, combined with specific crosslinkers like pentaerythritol allyl ether, which provide thermal stability and prevent precipitation, even in divalent brines at high temperatures, ensuring sustained viscosity and fluid-loss control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acrylamide homopolymers are used as viscosifiers in drilling fluids, then viscosity control is achieved at normal temperatures, but the polymers degrade and precipitate at high temperatures in divalent brines, leading to loss of fluid-loss control
Solution Approach 1:
The patent changes the chemical parameters of the polymer by using N-vinyl lactam monomers (such as N-vinylpyrrolidone) instead of acrylamide, and by incorporating crosslinking structures. This chemical parameter change enables the polymer to maintain stability at high temperatures while retaining viscosity control capabilities.
Solution Approach 2:
The patent creates a composite polymer structure by crosslinking N-vinyl lactam chains with divalent metal ions (such as calcium or barium) present in the brine. This composite structure combines the thermal stability of the crosslinked network with the viscosity-enhancing properties of the polymer chains, preventing degradation and precipitation at high temperatures.
2Reliability
If clay additives are used to improve fluid-loss control, then fluid-loss control is enhanced, but the complexity of the fluid formulation increases and performance at high temperatures is not sufficiently improved
Solution Approach 1:
The crosslinked N-vinyl lactam polymer performs multiple functions simultaneously: it acts as a viscosifier to maintain fluid viscosity, provides fluid-loss control by forming a protective filter cake, and ensures thermal stability at high temperatures. This multi-functionality eliminates the need for separate clay additives and simplifies the overall fluid formulation.
3Temperature
If polymers are used to maintain viscosity at high temperatures, then viscosity control is improved, but the polymers precipitate in divalent brines, leading to loss of rheological properties
Solution Approach 1:
The patent changes the chemical parameters of the polymer by using N-vinyl lactam monomers (such as N-vinylpyrrolidone) instead of acrylamide, and by incorporating crosslinking structures. This chemical parameter change enables the polymer to maintain stability at high temperatures while retaining viscosity control capabilities.
Solution Approach 2:
The patent creates a composite polymer structure by crosslinking N-vinyl lactam chains with divalent metal ions (such as calcium or barium) present in the brine. This composite structure combines the thermal stability of the crosslinked network with the viscosity-enhancing properties of the polymer chains, preventing degradation and precipitation at high temperatures.
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
These crosslinked polymers maintain desirable rheological properties and fluid-loss control at temperatures up to 300°F for extended periods without the need for clay additives, remaining soluble in brines and preventing precipitation, thus enhancing drilling and treatment fluid performance.
Implementation Method 1
The use of crosslinked polymers comprising N-vinyl lactam monomeric units, such as N-vinylpyrrolidone, combined with specific crosslinkers like pentaerythritol allyl ether, which provide thermal stability and prevent precipitation, even in divalent brines at high temperatures
Implementation Method 2
The use of crosslinked polymers comprising N-vinyl lactam monomeric units, such as N-vinylpyrrolidone, combined with specific crosslinkers like pentaerythritol allyl ether, which provide thermal stability and prevent precipitation, even in divalent brines at high temperatures
Implementation Method 3
These crosslinked polymers maintain desirable rheological properties and fluid-loss control at temperatures up to 300°F for extended periods without the need for clay additives
Data Source
AI summary
Compositions of crosslinked polymers and methods of using such compositions as viscosifiers and fluid-loss control additives in drilling and treatment fluids for subterranean applications are provided. In some embodiments, the methods include: (A) forming a treatment fluid comprising a divalent brine and a crosslinked polymer composition, wherein the crosslinked polymer composition includes: (i) at least one polymer that includes at least a first monomeric unit of one or more N-vinyl lactams; and (ii) a crosslinker selected from the group consisting of: divinyl ether, diallyl ether, vinyl or allyl ethers of polyglycols or polyols, divinylbenzene, 1,3-divinylimidazolidin-2-one, divinyltetrahydropyrimidin-2(1H)-one, dienes, allyl amines, N-vinyl-3(E)-ethylidene pyrrolidone, ethylidene bis(N-vinylpyrrolidone), and any combination of any of the foregoing; and (B) introducing the fluid into a portion of a well bore penetrating at least a portion of a subterranean formation.