Non-Crosslinked Copolymer Fluid Loss Control for High-Temperature Wells

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Solution Overview

Problem

Existing water-based drilling fluids face significant fluid loss issues at high temperatures and pressures, leading to problems like filter cake buildup, drill pipe sticking, and formation damage, with traditional fluid loss control agents being unstable and potentially causing formation damage.

Innovation Solution

A non-crosslinked copolymer of non-carboxylated monomers is used as a fluid loss control agent in water-based wellbore fluids, effectively reducing fluid loss at high temperatures and pressures without significantly increasing viscosity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional fluid loss control agents are used in water-based drilling fluids, then fluid loss control is achieved under normal conditions, but the agents become unstable and ineffective at high temperatures and pressures

Engineering Contradiction:

Improvefluid loss control effectivenessVSAvoiddownhole temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent modifies the chemical structure of the fluid loss control agent by using non-carboxylated monomers (such as vinyl acetate, butyl acrylate, and 2-ethylhexyl acrylate) instead of traditional carboxylated polymers. This parameter change in molecular structure provides thermal stability at high temperatures while maintaining fluid loss control effectiveness. The copolymer composition ratios and molecular weight are optimized to ensure stability under downhole conditions of up to 400°F.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a copolymer composed of multiple non-carboxylated monomers (vinyl acetate, butyl acrylate, 2-ethylhexyl acrylate) in specific ratios. This composite material approach combines the beneficial properties of different monomers to achieve both thermal stability and effective fluid loss control. The copolymer structure provides resistance to degradation at high temperatures while maintaining film-forming capability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If synthetic styrene/butadiene copolymers are used as fluid loss control agents, then fluid loss is reduced, but formation damage occurs

Engineering Contradiction:

Improvefluid loss controlVSAvoidformation damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs a water-soluble copolymer that can be easily degraded and removed from the formation. The non-carboxylated monomer structure provides adequate fluid loss control during drilling operations, but the polymer can be broken down by common degradation agents (enzymes, acids, bases) to prevent long-term formation damage. This approach sacrifices some durability in favor of ease of removal and reduced formation harm.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent converts the potential harm of polymer persistence in formation into a benefit by designing a polymer that degrades easily into harmless components. The copolymer structure is specifically chosen to be biodegradable or chemically degradable, transforming what would be a harmful long-term presence into a beneficial temporary control mechanism that leaves no harmful residue.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Loss of substance

If more traditional polymer additives are added to control fluid loss, then fluid loss reduction is achieved, but viscosity of the drilling fluid increases significantly

Engineering Contradiction:

Improvefluid lossVSAvoidfluid viscosity

Core Design Contradiction:

Loss of substanceVSForce

Solution Approach 1:

The patent uses a copolymer with specific local structural characteristics - the non-carboxylated side chains (vinyl acetate, butyl acrylate, 2-ethylhexyl acrylate units) provide film-forming capability for fluid loss control without creating extensive intermolecular interactions that would increase bulk viscosity. The localized film formation at the wellbore interface occurs without requiring high overall polymer concentration, thus maintaining low fluid viscosity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention changes the molecular parameters of the fluid loss control agent by eliminating carboxyl groups and using non-polar or weakly polar side chains. This parameter change reduces polymer-polymer interactions and polymer-solvent interactions, allowing effective fluid loss control at lower concentrations and thus maintaining lower fluid viscosity compared to traditional carboxymethylcellulose or polyacrylamide systems.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12391862B2Fluid loss control agent for aqueous wellbore fluids

Publication Date: 2025.08.19 SCHLUMBERGER TECH CORP

AI summary

Fluid loss control agents for use in a water-based wellbore fluid. The fluid loss control agents generally include non-crosslinked copolymers of non-carboxylated monomers. Water-based wellbore fluids containing the above fluid loss control agents and methods of servicing a wellbore in a subterranean formation by placing the water-based wellbore fluids in the wellbore.