Swellable Clay Slurry for Bore Sealing
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Solution Overview
Problem
Current methods for plugging wells, such as cementing and using bentonite compacts/cylinders, face limitations in accessing complex well geometries and irregular voids, leading to incomplete sealing and high costs due to time-consuming and labor-intensive processes, and are not effective for wells with perforated liners.
Innovation Solution
A method involving a slurry composition of swellable phyllosilicate clay, with a weight fraction of 70 wt % or less, is pumped into the well to compact and form a cake that effectively seals the bore by infiltrating through perforations and filling irregular voids, followed by a secondary plugging process to ensure complete sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cement slurry is placed in high amounts to cover the entire coal seam region, then sealing effectiveness is improved, but cement shrinkage causes leakage problems and the process must be conducted in steps
Solution Approach 1:
The patent changes the concentration parameter of swellable clay in the slurry composition, maintaining it at 70 wt% or less to optimize both sealing effectiveness and flow properties. This parameter optimization allows the slurry to be placed in high amounts without the shrinkage problems of cement, eliminating the need for stepwise placement and waiting periods.
Solution Approach 2:
The patent uses a composite slurry composition comprising swellable clay particles suspended in a fluid carrier. This composite material combines the sealing properties of clay with the flow and placement advantages of a slurry system, enabling single-stage high-volume placement that cements cannot achieve due to shrinkage constraints.
2Reliability
If tubing is inserted to apply down-load and test cement plug mechanical integrity, then mechanical integrity verification is improved, but labour and equipment costs increase
Solution Approach 1:
The swellable clay slurry performs self-verification of its sealing function through its natural swelling behavior. When the slurry is placed and the fluid carrier evaporates or is displaced, the clay particles automatically swell and compact to form an impermeable plug, eliminating the need for external tubing insertion, down-load application, and mechanical testing equipment.
Solution Approach 2:
The patent extracts the testing and verification functions from the plugging process itself. Rather than using separate tubing and testing equipment, the slurry composition inherently demonstrates its sealing effectiveness through its swelling and compaction behavior, removing the need for additional verification apparatus and procedures.
3Reliability
If cement is placed through slotted liners or perforated casing, then sealing of open zones is improved, but it is difficult to guarantee adequate flow out through restrictions to fully access the formation
Solution Approach 1:
The patent utilizes hydraulic principles by placing the swellable clay slurry as a fluid suspension that can flow through restrictions under pressure. The fluid carrier allows the clay particles to be transported through slotted liners and perforations, and subsequent evaporation or displacement of the fluid causes the clay to swell and seal the formation, ensuring complete access to irregular voids and complex geometries.
Solution Approach 2:
The patent optimizes the particle size parameter of the swellable clay to ensure adequate flow through restrictions. By controlling the clay particle size distribution, the slurry can effectively flow out through perforations and slotted liners while maintaining the ability to swell and seal upon contact with the formation, solving the detection and measurement difficulty of flow through restrictions.
4Productivity
If bentonite compacts are poured into the well to plug the bore, then deployment speed is improved, but they are prone to bridging within the casing and block at an elevation
Solution Approach 1:
The patent transforms the solid compact form into a fluid slurry suspension that can be pumped through the wellbore. This hydraulic approach eliminates bridging and blocking issues by allowing the clay particles to flow as a suspension, then swell and compact in place to form the plug, combining the deployment speed advantage with reliable delivery to the target zone.
Solution Approach 2:
The patent changes the physical state parameter of the bentonite from solid compact to fluid slurry suspension. By controlling the concentration and particle size parameters, the slurry flows easily through the wellbore without bridging, then swells and compacts upon placement to form an effective plug, eliminating the handling and delivery problems of solid compacts while maintaining deployment efficiency.
5Reliability
If the well bore shape is complex with cave-ins and irregular geometries, then sealing effectiveness is improved by filling all voids, but access to these geometries becomes difficult with conventional methods
Solution Approach 1:
The patent uses hydraulic flow principles to deliver the swellable clay slurry to complex and irregular wellbore geometries. The fluid carrier enables the slurry to flow into cave-ins, irregular voids, and difficult-to-access areas, and subsequent evaporation or displacement of the fluid causes the clay to swell and seal these complex geometries effectively, overcoming the access limitations of conventional solid plug methods.
Solution Approach 2:
The patent employs a composite slurry material that combines the flow properties of a fluid suspension with the sealing properties of swellable clay particles. This composite can be pumped into complex geometries as a fluid, then transforms in situ to seal irregular voids and cave-ins, providing both access to and sealing of difficult-to-reach areas that conventional solid compacts cannot reach.
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 method provides a cost-effective and efficient well plugging solution that verifies sealing effectiveness before completion, capable of handling complex geometries and maintaining impermeability with self-healing properties, reducing overall costs and ensuring durable well plugging.
Implementation Method 1
pumping a slurry composition comprising a swellable phyllosilicate clay in an amount of 70 wt % or less into a bore, and permitting compaction of the phyllosilicate clay in the slurry to plug the bore
Implementation Method 2
permitting compaction of the phyllosilicate clay in the slurry to plug the bore
Data Source
AI summary
In one aspect, a method for plugging a bore includes pumping a slurry composition comprising a swellable phyllosilicate clay in an amount of 70 wt % or less into the bore, and permitting compaction of the phyllosilicate clay in the slurry to plug the bore.