Dissolvable Casing Liner for Perforation Isolation
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Solution Overview
Problem
Conventional refracturing methods in the oil and gas industry face challenges such as incomplete isolation of existing perforations, permanent casing liners that hinder further production, and costly removal processes, especially in tight formations requiring higher pressures.
Innovation Solution
Deployment of a dissolvable casing liner that can be secured to the casing string to isolate perforations through expansion or fluid sealing, allowing for refracturing operations and subsequent dissolution for removal without additional operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If permanent casing liners are used to block existing perforations, then isolation of perforations is achieved, but removal requires expensive and dangerous operations
Solution Approach 1:
The patent applies the disposable principle by using a dissolvable casing liner made from materials that can degrade or dissolve under specific downhole conditions (such as exposure to certain chemicals, temperature, or time). This allows the liner to serve its isolation function temporarily during refracturing operations and then automatically disappear, eliminating the need for costly and dangerous removal operations while maintaining reliable isolation when needed.
Solution Approach 2:
The patent applies parameter changes by designing the casing liner with properties that change under specific downhole conditions. The liner material is selected or engineered to undergo transformation (dissolution, degradation, or phase change) when exposed to particular temperature ranges, chemical environments, or time periods, enabling automatic removal after serving its isolation purpose without requiring additional intervention.
2Reliability
If permanent casing liners are installed, then perforations are sealed, but flow diameter is reduced limiting treatment rate
Solution Approach 1:
The dissolvable casing liner provides temporary sealing during the refracturing operation to prevent fluid loss into existing perforations, then automatically dissolves to restore full flow capacity. This eliminates the permanent flow restriction imposed by traditional casing liners while maintaining sealing reliability during the critical treatment phase.
Solution Approach 2:
The patent applies dynamics by creating a liner system that transitions from a sealed state to an open state. The liner dynamically changes its permeability and structural integrity in response to downhole conditions, providing sealing when needed and then automatically transitioning to allow full flow, thereby optimizing both isolation and production capabilities at different stages.
3Ease of operation
If fluids are pumped to temporarily restrict zones, then some isolation is achieved, but complete isolation is not provided causing fluid loss
Solution Approach 1:
The dissolvable casing liner provides complete and reliable isolation by forming a physical barrier that completely blocks fluid flow into existing perforations during refracturing operations. Unlike fluid-based temporary restriction methods that only provide partial isolation, the solid liner ensures complete sealing, preventing fluid loss into treated zones.
Solution Approach 2:
The patent likely employs composite materials that combine the structural integrity needed for complete sealing with degradation properties that enable subsequent dissolution. The composite structure provides both the mechanical strength to achieve complete isolation and the chemical or thermal responsiveness to allow automatic removal after serving its purpose.
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 dissolvable casing liner provides temporary and effective isolation, allowing for higher pressure capabilities and complete restoration of perforations post-re-stimulation, eliminating the need for costly removal procedures.
Implementation Method 1
a dissolving fluid may be pumped downhole, whereby the casing liner is dissolved and the perforations are uncovered
Data Source
AI summary
Dissolvable casing liners are utilized to isolate existing perforations. A dissolvable casing liner is deployed downhole along the interior of a casing string having a plurality of perforations. The casing liner is then secured against the casing string, thereby effectively sealing the perforations. Once the perforations are isolated, refracturing operations may be conducted. At some time thereafter, the casing liner is dissolved and removed from the wellbore.