Coarse Hydratable Polymer Particulates Delay Viscosity in Well Fluids
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Solution Overview
Problem
Existing well treatment fluids face challenges in delaying hydration and viscosification of polymeric viscosifying agents, leading to premature viscosity increase and fluid loss, especially in high-pH environments like cement slurries, which affects mixing and stability.
Innovation Solution
Incorporating particulates with a minimum of 40% retention on a 60 mesh screen and 1% retention on a 20 mesh screen in well treatment fluids, which delays hydration and viscosification until the fluid reaches the desired location, reducing friction pressure and preventing fluid loss into permeable zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If finely ground polymeric viscosifying agents are used, then viscosity is increased quickly, but fluid loss increases and mixing becomes difficult
Solution Approach 1:
The patent changes the particle size parameter of the polymeric viscosifying agent from fine powder to coarse particulate form (retaining 40% or more on a 60 mesh screen). This parameter change delays the hydration and viscosification process, allowing the fluid to be pumped at low viscosity while preventing fluid loss into permeable zones, thereby resolving the contradiction between quick viscosification and fluid loss prevention
2Loss of substance
If polymeric viscosifying agents are added to increase viscosity, then fluid loss is prevented, but friction pressure increases
Solution Approach 1:
The patent applies preliminary action by adding a crosslinking delay agent to the fluid before pumping, which prevents premature crosslinking and viscosity increase. The coarse particulate polymeric viscosifying agent further delays hydration until the fluid reaches the formation. This ensures the fluid remains low viscosity during pumping (minimizing friction pressure) while still preventing fluid loss into permeable zones
3Use of energy by moving object
If crosslinking is delayed to minimize friction pressure, then pumping efficiency improves, but viscosity control becomes challenging
Solution Approach 1:
The patent introduces a crosslinking delay agent as an intermediary substance that temporarily prevents crosslinking reactions. This mediator allows the fluid to be pumped at low viscosity while preventing premature gelation. The coarse particulate polymeric viscosifying agent acts as another intermediary that delays hydration until the fluid reaches the formation, providing controlled viscosity development without compromising pumping efficiency
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
This approach allows for a low viscosity fluid to be pumped, minimizing friction pressure and preventing fluid loss, while maintaining slurry stability and reducing mixing energy requirements, even at elevated temperatures.
Implementation Method 1
Polymer hydration typically results from the formation of a sheath of water molecules around the polymeric strand by hydrogen bonding
Implementation Method 2
Polymer hydration typically results from the formation of a sheath of water molecules around the polymeric strand by hydrogen bonding
Implementation Method 3
The high pH environment of cement slurries accelerates hydration
Data Source
AI summary
The disclosure relates to a method of delaying viscosification of a well treatment fluid within a well or within a subterranean formation penetrated by a well by introducing into the well a hydratable viscosifying agent of particulates having a minimum of 40% retention on a 60 mesh screen and a minimum of 1% retention on a 20 mesh screen.