Expandable Liner Threaded Connection Strength
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Solution Overview
Problem
Expandable tubular liners in wellbores face significant tension loads due to trapped expansion forces, thermal changes, pressure changes, and end thrusts, leading to potential connection failure and pipe body failure, as existing connections are weak and unable to withstand these additive loads.
Innovation Solution
An expandable liner with strengthened threaded connections and a design that allows one end to shrink or grow in response to length changes, incorporating features like heat-treated ends, shearable connections, and external seals to manage tension loads and maintain pressure integrity, and using coiled tubing without threaded connections to eliminate weak points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If threaded connections are used to connect expandable liner joints, then the liner can be assembled in multiple sections, but the connection strength is reduced to about 50% of the pipe body strength
Solution Approach 1:
The expandable liner is divided into multiple joints (30-40 feet each) that can be connected together to achieve the required liner length. Each joint contains threaded connections that allow assembly while maintaining structural integrity through the connection design.
Solution Approach 2:
The connection regions are designed with different properties than the pipe body. Threaded connections are implemented with specific geometries and materials optimized for the connection function, accepting that these localized regions have reduced strength compared to the main pipe body while maintaining overall system functionality.
2Reliability
If external rubber seals are used to fix the expanded liner against the outer casing, then zonal isolation is achieved, but tension load builds up in the liner and connections
Solution Approach 1:
The rubber seals, which create tension load by fixing the expanded liner, are positioned and designed to trap expansion force. This trapped force pre-compresses the liner wall, which beneficially increases the burst pressure capacity of the liner, converting the harmful tension load into a beneficial pre-stress state.
Solution Approach 2:
The liner and connections are designed with safety factors and material properties that accommodate the anticipated tension loads from the rubber seals. The connection design includes features that prevent failure under the expected load conditions, cushioning against the harmful effects of the sealed-in tension.
3Ease of operation
If the liner is expanded using a tension constraint with the bottom fixed to parent casing, then expansion is controlled, but all tension in the liner is trapped and permanent between the anchor and expansion cone
Solution Approach 1:
The expansion process is controlled by pulling the expansion cone through the liner in a predetermined manner. The cone diameter progressively increases, expanding the liner in a controlled sequence that manages the tension loads applied during the expansion operation.
Solution Approach 2:
The expansion process is dynamic rather than static. The expansion cone moves through the liner, creating a moving zone of expansion that allows tension to be gradually applied and released as the cone progresses, rather than applying static tension to the entire liner length simultaneously.
4Temperature
If the liner is cooled by wellbore fluid during production, then the liner contracts, but the rubber seals prevent shrinkage causing tension load build up
Solution Approach 1:
The liner material exhibits thermal expansion and contraction in response to temperature changes. When cooled by wellbore fluid, the liner tends to shrink, but the rubber seals prevent this dimensional change, creating thermal stress that must be accommodated by the connection design.
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 manages tension loads and prevents connection failure, allowing for efficient fracturing operations by maintaining the integrity of the liner and reducing the risk of fracture, while also providing a larger bore for increased fluid supply and improved sealing.
Implementation Method 1
heat-treated ends
Implementation Method 2
the other end is allowed to freely move... allowing for thermal expansion
Implementation Method 3
the rib is configured to form a seal with the outer tubular
Data Source
AI summary
An expandable liner is used to re-complete a wellbore for a re-fracturing operation. The expandable liner may be used to cover the old perforations and provide a larger bore after expansion. The larger bore allows the new completion perforations and fracturing operation to be more easily achieved. In one embodiment, an expandable liner an expandable tubular having a threaded connection, wherein the threaded connection includes a groove configured to fail at a predetermined tension load. In another embodiment, the expandable liner may have a rib disposed around an outer diameter of the expandable tubular, wherein the rib is configured to form a seal with the outer tubular.