Thermal Liner Strain Relief via Non-Axial Slots
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Solution Overview
Problem
Conventional thermal liners used in hydrocarbon recovery processes experience significant thermal strain and compressive stress due to temperature changes, leading to buckling, collapse, and steam bypass leakage, which are not effectively addressed by existing strain relief solutions.
Innovation Solution
The configuration of thermal liners with non-axial strain relief slots and filter elements that provide axial strain relief by forming bending members interspersed with base regions, allowing for fluid transfer while filtering out particulates and accommodating thermal expansion, thereby reducing compressive stress and preventing liner failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional axially slotted liners are used to maintain slot dimensions and filter properties, then filtration effectiveness is improved, but axial strain relief capability deteriorates
Solution Approach 1:
The liner is divided into discrete slot segments separated by strain relief features. The slots are not continuous axially but broken into segments that can move independently, allowing the liner to expand and contract axially while maintaining filtration capability in each segment.
Solution Approach 2:
Different regions of the liner have different properties: slots provide filtration with precise dimensions, while the regions between slots (strain relief features) provide axial flexibility. This local differentiation allows simultaneous achievement of filtration precision and strain relief.
2Reliability
If bellows strain relief sections are added to relieve axial strain, then thermal strain relief is improved, but device complexity and cost worsen
Solution Approach 1:
The strain relief function is merged with the filtration structure itself. The strain relief features are not separate bellows components but are integrated into the liner wall as alternating槽and solid section patterns, combining structural support, filtration, and strain relief in a single integrated design.
Solution Approach 2:
The strain relief features use simple geometric patterns (alternating slots and solid sections) that are inexpensive to manufacture compared to complex bellows structures. The design achieves strain relief through basic structural geometry rather than expensive specialized components.
3Strength
If liner bending stiffness is increased to resist differential ground motion, then structural strength is improved, but susceptibility to buckling and collapse worsens
Solution Approach 1:
The liner transitions from a static rigid structure to a dynamic structure that can adapt its stiffness. The alternating slot and solid section pattern allows the liner to bend and flex in response to ground motion while maintaining overall structural integrity, preventing both excessive rigidity and buckling.
Solution Approach 2:
The strain relief features create a corrugated or undulated profile along the liner axis, similar to bellows but simpler. This curved/undulated geometry provides inherent flexibility to accommodate bending and differential ground motion while maintaining structural strength through the alternating solid sections.
4Ease of manufacture
If conventional slotted liners are constrained in situ, then installation simplicity is improved, but thermal stress accumulation worsens
Solution Approach 1:
The strain relief features effectively 'remove' or extract stress from the liner system by providing designated zones (the slot regions) that can move independently. These extracted stress zones allow thermal expansion and contraction without building up harmful compressive stresses, while the liner remains installed in the wellbore.
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 solution effectively relieves high thermal strain in thermal liners, preventing buckling and collapse, and maintaining fluid integrity by allowing for controlled expansion and filtering of particulates, thus enhancing the durability and efficiency of hydrocarbon recovery processes.
Implementation Method 1
the bending members relieve axial tubular strain caused by thermal changes
Implementation Method 2
a conventional axially slotted recovery liner heated from 20° C. to 350° C. experiences a 330° C. increase in temperature, such as in Cyclic Steam Stimulation (CSS) of a heavy oil resource. This typically causes a 0.43% thermally induced expansion or strain
Data Source
AI summary
A method of forming a slotted liner, having a wall comprising a plurality of non-axial bending members axially separated by non-axial slots and circumferentially interspersed with bases, for providing strain relief, the method comprising: forming the bending members and the non-axial slots by one of: cutting non-axial slots, and winding a rod; configuring the circumferential lengths of the plurality of non-axial slots and bases relative to the liner circumference; wherein positioning a first base axially adjacent to a non-axial slot; configuring the non-axial slot circumferential length longer than the circumferential length of the first base; and positioning a second base axially adjacent to a first base; providing connections between the pair of bases or leaving uncut the wall between the base pair; configuring the plurality of non-axial slots and adjacent base pairs.