High Expandable Straddle for Annular Isolation in Restricted Tubing
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Solution Overview
Problem
Existing packers face challenges in providing effective annular isolation and expansion in small diameter tubing, such as standard 5½″ tubing, due to restricted outer diameters and narrower restrictions like valves, which limit the packer's ability to expand and seal effectively.
Innovation Solution
A high expandable straddle comprising first and second expandable pipe sections, a base pipe section, and end pipe sections, configured to expand radially outward when pressure is applied, allowing the straddle to be run through restrictions and expanded to straddle a repair location, providing annular isolation without the need for welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional packer is used in small diameter tubing, then the packer can provide annular isolation, but the packer cannot expand sufficiently to seal effectively due to restricted outer diameter and narrower restrictions like valves
Solution Approach 1:
The straddle is divided into multiple pipe sections (first pipe section, second pipe section, and intermediate pipe sections) that can be independently expanded. This segmentation allows each section to expand to different degrees, enabling the straddle to navigate through restrictions while achieving sufficient expansion for effective sealing against the casing.
Solution Approach 2:
Different pipe sections are positioned at different locations along the straddle to perform different functions. The intermediate pipe sections are configured to expand to a first degree for navigating restrictions, while the first and second pipe sections are configured to expand to a second degree (greater than the first) for creating the sealing barrier against the casing.
2Reliability
If the packer outer diameter is increased to improve sealing capability, then the seal quality improves, but the packer cannot be run through restrictions in the tubing
Solution Approach 1:
The straddle transitions from a collapsed low-profile configuration during insertion to an expanded high-profile configuration during operation. The multiple pipe sections can be dynamically expanded to different degrees, allowing the straddle to pass through restrictions in a compact state and then expand to create effective seals against the casing.
Solution Approach 2:
The straddle design allows the expandable pipe sections to be nested within each other in the collapsed state, enabling passage through restrictions. Upon expansion, the sections unfold and expand radially to achieve the required outer diameter for effective sealing, similar to nested dolls expanding outward.
3Reliability
If the packer is designed to expand to maximum ID of 5½″ tubing, then the seal capability is improved, but the packer cannot pass through narrower restrictions such as valves with reduced nipple ID
Solution Approach 1:
The straddle is segmented into multiple expandable pipe sections that can be independently controlled. The intermediate pipe sections can be expanded to a first degree sufficient to pass through restrictions like valves, while the end pipe sections can be expanded to a second degree (greater than the first) to create the sealing barrier against the casing.
Solution Approach 2:
The expansion degree of different pipe sections is varied as a key parameter. Intermediate pipe sections are expanded to a first expansion degree that allows passage through restrictions, while end pipe sections are expanded to a second expansion degree that provides sufficient seal capability against the casing.
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 high expandable straddle effectively provides annular isolation by expanding to match the inner diameter of the casing, creating a reliable seal and anchoring system, even in small diameter tubing, while avoiding the need for welding and ensuring compatibility with austenitic stainless steel materials.
Implementation Method 1
when pressure is applied to an inside surface of the pipe sections, the first and second expandable pipe sections expand radially outwards
Implementation Method 2
the metal structure will undergo elastic deformation to expand by a small percentage as contact is made
Data Source
AI summary
A high expandable straddle and a method of providing annular isolation at a location in a well bore. The straddle includes two expandable pipe sections with a base pipe section therebetween and end pipe sections for connection in a tubular string. The straddle may be run in tubing with restricted inner diameters and by the introduction of pressure to the saddle over 30% expansion can occur to the expandable pipe sections to seal and grip the tubing spanning a fault. An embodiment is described with the straddle being of unitary construction, the expansion pipe sections having thinned walls and being entirely formed of an austenitic stainless steel. An anchoring arrangement and/or seals may also be located on the expandable pipe sections.