Shear-Thinning Liquid Plug for Wellbore Fluid Separation
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Solution Overview
Problem
In wellbore operations, existing methods fail to effectively prevent intermixing of different fluids within the annulus of a wellbore, particularly during cementing operations where mechanical plugs cannot be used to separate fluids.
Innovation Solution
Introducing a second fluid with a viscosifier and stabilizer that exhibits high shear thinning behavior, acting as a solid plug at low pump rates and transitioning to a liquid at higher rates, to inhibit or prevent intermixing between the first and third fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical plug is used to separate fluids in the wellbore, then fluid intermixing is prevented, but the device cannot be used in annulus configurations and adds mechanical complexity
Solution Approach 1:
The patent replaces mechanical plugs with a rheologically engineered fluid composition that uses shear-thinning behavior and gel strength to function as a separatrix. The fluid maintains gel-like properties at low shear rates to prevent intermixing, while flowing like a liquid at high shear rates during pumping operations, eliminating the need for mechanical components.
Solution Approach 2:
The invention changes the rheological parameters of the separating fluid by incorporating polymers and additives that provide shear-thinning behavior. The fluid's viscosity and gel strength are specifically tuned to be high at low shear rates (when stationary or moving slowly) to maintain separation, and low at high shear rates (during pumping) to allow easy placement and displacement.
2Reliability
If a fluid with high viscosity is used to prevent intermixing, then fluid separation is maintained, but the fluid cannot be pumped efficiently at high rates
Solution Approach 1:
The patent employs a dynamic rheological fluid that adapts its viscosity based on shear rate. At low shear rates (when the fluid is stationary or moving slowly), the fluid exhibits high viscosity and gel-like behavior to maintain separation. At high shear rates (during pumping), the fluid's viscosity decreases dramatically, allowing efficient pumping and placement without requiring excessive pump power.
Solution Approach 2:
The invention utilizes shear-thinning polymers and additives that cause the fluid's viscosity to decrease as shear rate increases. This parameter change allows the fluid to maintain high viscosity for separation when needed, while automatically becoming pumpable at high rates during injection and displacement operations.
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 second fluid effectively separates and prevents intermixing of different fluids, maintaining its gel-like properties at low shear rates and flowing like a liquid at higher rates, ensuring effective fluid separation and preventing alterations in fluid properties.
Implementation Method 1
a viscosifier, wherein the viscosifier forms hydrogen bonds with the water
Implementation Method 2
exhibits high shear thinning behavior, acting as a solid plug at low pump rates and transitioning to a liquid at higher rates
Data Source
AI summary
A method of treating a subterranean formation can include: introducing a first fluid into a wellbore penetrating the subterranean formation; introducing a second fluid into the wellbore after introduction of the first fluid, wherein the second fluid comprises: a base fluid comprising water; a viscosifier; and a stabilizer, and wherein the second fluid has a rheological 3-rpm dial reading to 300-rpm dial reading ratio in the range of 1:1 to 1:3; and introducing a third fluid into the wellbore after introduction of the second fluid, wherein the second fluid inhibits or prevents the first fluid from mixing with the third fluid. The second fluid can be a liquid plug that substantially inhibits or prevents the first fluid from mixing with the third fluid. The first fluid can be a drilling mud or spacer fluid. The third fluid can be a spacer fluid or a cement composition.