Tetrapolymer Lignite Graft Copolymer High-Temperature Drilling Fluids
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Solution Overview
Problem
Existing viscosifiers and filtration control agents in treatment fluids degrade at high temperatures, leading to premature viscosity loss and fluid loss into subterranean formations, which is problematic for drilling and other subterranean operations, especially at temperatures above 250°F.
Innovation Solution
The use of a treatment fluid comprising an aqueous base fluid, a tetrapolymer as a viscosifier, and a graft copolymer with a lignite backbone as a filtration control agent, which maintains viscosity and reduces fluid loss without excessively increasing the fluid's viscosity, even at temperatures up to 400°F.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing viscosifiers and filtration control agents are used in treatment fluids, then the fluid can perform drilling and subterranean operations, but the additives degrade at high temperatures causing premature viscosity loss and fluid loss into the formation
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of polymers to achieve high-temperature stability. Specifically, it uses temperature-resistant polymers such as polyacrylonitrile and copolymers with high glass transition temperatures, along with controlling molecular weight and concentration parameters, to maintain viscosity and filtration control at temperatures above 250°F where conventional additives degrade
Solution Approach 2:
The patent employs composite materials by combining multiple polymer types in a treatment fluid formulation. It integrates temperature-resistant polymers (polyacrylonitrile, copolymers) with filtration control agents and other functional additives to create a composite system that simultaneously maintains viscosity, controls fluid loss, and resists thermal degradation at high temperatures
2Loss of substance
If filtration control agents are added to reduce fluid loss, then fluid loss into the formation is reduced, but the viscosity of the treatment fluid increases excessively
Solution Approach 1:
The patent applies local quality by using specific types of filtration control agents with controlled molecular characteristics. It employs polymers with specific molecular weights and structures (such as partially hydrolyzed polyacrylonitrile) that provide effective filtration control at the formation interface without excessively increasing bulk fluid viscosity, allowing different regions of the fluid to have optimized properties
3Stability of the object's composition
If treatment fluid viscosity is maintained at high temperatures, then particulate transport and wellbore stability are improved, but the fluid loses viscosity prematurely due to additive degradation
Solution Approach 1:
The patent applies preliminary action by pre-selecting and formulating temperature-resistant polymers with appropriate molecular weights and structures before the treatment fluid is exposed to high temperatures. The formulation is designed in advance to resist thermal degradation, ensuring viscosity is maintained throughout the intended duration of the drilling or subterranean operation without premature loss
Data Source
AI summary
Treatment fluids comprising viscosifiers and filtration control agents that may be useful at high temperatures and methods for using the treatment fluids to treat subterranean formations are provided herein. A method of treating a subterranean formation comprising: providing a treatment fluid comprising: an aqueous base fluid, a tetrapolymer that comprises at least one monomer, and a graft copolymer that comprises: a backbone comprising a lignite, and at least one monomer; and introducing the treatment fluid into a wellbore penetrating the subterranean formation.