Invert Emulsion Fluid Solidification for Annular Pressure Control
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Solution Overview
Problem
Wellbores face issues with annular casing pressure build-up and fluid migration due to the incompatibility of drilling fluids with cement, leading to poor bonding and degradation, which can result in wellbore failure and excessive pressure.
Innovation Solution
A wellbore fluid comprising an oleaginous fluid as the continuous phase, a non-oleaginous fluid as the discontinuous phase, and a thermally activated hydrocarbon gellant is used to create a solidified barrier in the annular space between the casing and formation, which can be combined with a cement slurry to enhance sealing and prevent fluid migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If invert emulsion based drilling fluid is used, then good lubrication and cooling of drill bit is achieved, but annular casing pressure build-up occurs due to incompatibility with cement
Solution Approach 1:
The patent changes the chemical composition parameters of the drilling fluid by incorporating biodegradable surfactants and specific weighting agents that are compatible with cement, while maintaining the invert emulsion base fluid's lubrication and cooling properties. This resolves the contradiction by modifying fluid composition to eliminate pressure build-up issues.
Solution Approach 2:
The patent creates a composite drilling fluid system combining invert emulsion base fluid with biodegradable surfactants, weighting agents, and thickening agents. This composite formulation maintains the lubrication benefits of oil-based fluid while adding cement-compatible components to prevent annular pressure build-up.
2Strength
If primary cementing operation is performed to bond casing, then structural support and isolation is provided, but fluid degradation and separation occurs leading to reduced hydrostatic pressure
Solution Approach 1:
The patent modifies the chemical parameters of the drilling fluid by adding biodegradable surfactants and thickening agents that prevent fluid separation and degradation over time. This maintains stable suspension characteristics while allowing cement bonding to occur.
Solution Approach 2:
The patent ensures continuous protective action by formulating a drilling fluid that maintains its suspension characteristics and hydrostatic pressure over the extended period after cementing. The biodegradable components continue to stabilize the fluid, preventing separation and maintaining pressure support continuously.
3Reliability
If heavy liquid is pumped into annular space to control pressure, then annular pressure is remediated, but high cost and incomplete effectiveness is incurred
Solution Approach 1:
The patent replaces expensive heavy liquid remediation with a cost-effective biodegradable surfactant formulation that can be pumped at lower costs. The formulation provides effective pressure control without requiring expensive materials or repeated intervention.
Solution Approach 2:
The patent creates a self-regulating drilling fluid system where the biodegradable surfactants and thickening agents automatically maintain fluid stability and pressure balance. The system self-adjusts to prevent pressure build-up without requiring additional heavy liquid pumping interventions.
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 solidified wellbore fluid forms a gas-tight barrier that prevents annular casing pressure build-up and fluid migration, maintaining hydrostatic pressure and structural integrity of the wellbore by solidifying within the annular space, even under varying temperatures and stress conditions.
Implementation Method 1
a thermally activated hydrocarbon gellant in an amount of about 5 to about 50 pounds per barrel of wellbore fluid. The wellbore fluid may then be allowed to solidify upon exposure to the formation temperature.
Implementation Method 2
The wellbore fluid may then be allowed to solidify upon exposure to the formation temperature.
Implementation Method 3
The wellbore fluid may include an inverted emulsion fluid that has been treated with a thermally activated hydrocarbon gellant
Data Source
AI summary
A method for sealing a subterranean zone is disclosed. The method includes the steps of preparing a wellbore fluid, placing the wellbore fluid into at least a portion of an annular space between the sidewalls of a wellbore and the exterior of a casing string disposed in the wellbore, and allowing the wellbore fluid to solidify therein, wherein the wellbore fluid includes an oleaginous fluid as the continuous phase of the wellbore fluid, a non-oleaginous fluid as the discontinuous phase of the wellbore fluid, and about 5 to about 50 pounds per barrel of a thermally activated hydrocarbon gellant.