Thermally Stable Gellable Fluids for Subterranean Blocking
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Solution Overview
Problem
Gelled treatment fluids used in subterranean operations typically break prematurely at high formation temperatures, making them unsuitable for extended downhole residence times, especially in high-temperature formations where thermal stability is a concern, and they can become overly crosslinked, causing issues with pumping and fluid loss.
Innovation Solution
A method using a treatment fluid comprising an aqueous carrier fluid, a crosslinking agent, and a terpolymer with 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, and acrylic acid monomer units, which forms a thermally stable gel that can persist for extended periods without breaking under in situ stress, allowing for complete crosslinking and effective blocking of fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If biopolymer-based gellable treatment fluids are used to block fluid flow in subterranean formations, then the treatment fluid can form a gel that blocks flow, but the gel breaks prematurely at high formation temperatures (275°F or above), making it unsuitable for extended downhole residence times
Solution Approach 1:
The patent changes the chemical composition parameters by using synthetic gellable polymers instead of biopolymers, and by controlling the crosslinking density and gel formulation parameters to achieve thermal stability at high temperatures (275°F or above) while maintaining gel integrity for extended downhole residence times
Solution Approach 2:
The patent creates a composite gel system by combining synthetic polymers with crosslinking agents to form a crosslinked gel structure that provides both the desired blocking function and enhanced thermal stability for prolonged downhole residence
2Temperature
If synthetic gellable polymers are used to extend the working temperature range, then the gel can withstand high temperatures, but the polymer can become crosslinked too rapidly or overly crosslinked, causing high friction pressures during pumping and difficulty in breaking the gel
Solution Approach 1:
The patent applies partial crosslinking rather than complete crosslinking, controlling the crosslinking density to achieve sufficient thermal stability and gel strength while maintaining pumpability and preventing excessive friction pressures during injection
Solution Approach 2:
The patent adjusts crosslinking parameters including the type and amount of crosslinking agent, crosslinking temperature, and reaction time to optimize the balance between thermal stability and pumping ease, ensuring the gel can be injected without excessive pressure while maintaining high-temperature performance
3Reliability
If the gel becomes overly crosslinked to improve thermal stability, then the gel can resist high temperatures, but the gel becomes too viscous and difficult to break, and may exhibit excessive syneresis
Solution Approach 1:
The patent uses partial crosslinking instead of complete crosslinking to achieve the minimum necessary thermal stability while avoiding excessive gel strength and viscosity that would make the gel difficult to break or cause syneresis
Solution Approach 2:
The patent optimizes crosslinking parameters including crosslinking agent concentration, crosslinking temperature, and reaction time to achieve the optimal balance between thermal stability and gel breakability, preventing excessive viscosity and syneresis
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 treatment fluid maintains a stable gel state for days to weeks at high temperatures, effectively blocking fluid flow and preventing formation damage, with the ability to break naturally or with a breaker, ensuring non-damaging and long-term fluid loss control without altering the subterranean formation's permeability.
Implementation Method 1
a crosslinking agent, and a terpolymer that comprises 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, and acrylic acid monomer units
Implementation Method 2
allowing the treatment fluid to form a gel in the subterranean formation
Implementation Method 3
high density brines can be particularly effective as a carrier fluid, since they can form a highly viscous gel that blocks the flow of fluids within the wellbore by exerting hydrostatic pressure therein
Implementation Method 4
breaking the gel after it has been in the subterranean formation for at least about one day
Data Source
AI summary
Gellable treatment fluids containing a terpolymer that comprises 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, acrylic acid monomer units can be used in various subterranean operations where it is necessary for the treatment fluid to remain in a gelled state for extended periods of time at high formation temperatures. Methods for treating a subterranean formation can comprise providing a treatment fluid comprising an aqueous carrier fluid, a crosslinking agent, a gel stabilizer, and a terpolymer that comprises 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, and acrylic acid monomer units, or any salt thereof; introducing the treatment fluid into a subterranean formation; allowing the treatment fluid to form a gel in the subterranean formation; and breaking the gel after it has been in the subterranean formation for at least about one day.