Gelled Barrier Fluid Specific Gravity Matching
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Solution Overview
Problem
Existing barrier fluids used in subsurface apparatus are prone to displacement due to differences in specific gravity with undesired fluids, and they can cause salt corrosion in sensitive metals, necessitating the development of fluids with specific gravity matching that of the undesired fluids to prevent ingress and minimize corrosion.
Innovation Solution
A gelled barrier fluid with a specific gravity matching that of the undesired fluid, typically composed of a base fluid (such as fresh water, alcohol, or hydrocarbons) and a gellant system, is used to prevent the ingress of fluids like salt water, fresh water, and hydrocarbons into subsurface apparatus, with the specific gravity adjusted to be within ±0.05 of the undesired fluid, and formulated to minimize gas content and chloride levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional barrier fluids are used to prevent fluid ingress, then the barrier function is provided, but the fluid is displaced due to specific gravity differences
Solution Approach 1:
The patent applies parameter changes by adjusting the specific gravity of the barrier fluid to match the specific gravity of the undesired fluid. This is achieved by modifying the base fluid composition (using salts, sugars, or other substances) to change its density, thereby eliminating the displacement problem while maintaining the barrier function.
2Strength
If traditional base fluids are used in gelled barrier fluids, then the gel structure is formed, but salt corrosion occurs in sensitive metals
Solution Approach 1:
The patent changes the chemical composition parameters of the base fluid by selecting non-corrosive alternatives such as alcohols, glycols, or hydrocarbons instead of traditional water-based fluids. This eliminates chloride content and prevents salt corrosion while still allowing gel structure formation through appropriate gellant selection.
Solution Approach 2:
The patent creates a composite barrier fluid system combining non-corrosive base fluids (alcohols, glycols, hydrocarbons) with specific gellants and crosslinking agents. This composite formulation maintains the necessary gel strength and barrier properties while eliminating the harmful salt corrosion effect.
3Quantity of substance
If high chloride content fluids are used, then the barrier fluid properties are achieved, but intergranular stress crack corrosion is caused in stainless steel alloys
Solution Approach 1:
The patent fundamentally changes the chemical composition by eliminating chloride-containing substances from the base fluid formulation. Alternative substances such as alcohols, glycols, or hydrocarbons are used to achieve the necessary barrier fluid properties without introducing chloride ions that cause intergranular stress crack corrosion in stainless steel alloys.
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 gelled barrier fluid effectively reduces the tendency of displacement from subsurface apparatus and minimizes salt corrosion, ensuring the specific gravity match prevents fluid ingress while maintaining low chloride levels, thus protecting sensitive metals and maintaining apparatus integrity.
Implementation Method 1
The gelled barrier fluid typically has a specific gravity which is ±0.05, preferably ±0.01, most preferably ±0.003, of the specific gravity of the undesired fluid. When the specific gravity of the barrier fluid is substantially equal to the specific gravity of the undesired fluid, the tendency of the gelled fluid to be displaced from the subsurface apparatus dramatically decreases.
Implementation Method 2
Gel plugs often consist of water-based crosslinked viscosifying polymers, such as guar. Once the viscosifying polymer is hydrated in water, chemicals are added to adjust the pH and to crosslink the polymer.
Implementation Method 3
Once the viscosifying polymer is hydrated in water, chemicals are added to adjust the pH and to crosslink the polymer.
Data Source
AI summary
Gelled barrier fluids preventing the ingress of undesired fluids from subsurface environments into subsurface apparatus have a specific gravity which is within ±0.05 of the specific gravity of the undesired fluid.