Swellable Downhole Packer Anti-Extrusion Design
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Solution Overview
Problem
Existing downhole packers face challenges in maintaining a reliable seal under varying fluid pressures and temperatures due to axial extrusion of swellable elastomers, which is exacerbated by the need for high axial forces to set compression packers and the complexity of expanding end rings.
Innovation Solution
A swellable downhole packer design featuring a mandrel with a bonded swellable elastomeric sleeve-shaped body and a rigid end ring, along with an elastomeric anti-extrusion member of higher rigidity to prevent axial extrusion, ensures a reliable seal by radially engaging the borehole or tubular surface, even under pressure differentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a swellable elastomeric body is used to seal the annulus, then the packer does not require a setting mechanism or setting operation, but the elastomer will flow axially under high pressure differential, causing extrusion and negating the pressure seal
Solution Approach 1:
An elastomeric anti-extrusion member is introduced as an intermediary component between the swellable elastomeric body and the rigid end ring. This anti-extrusion member has a modulus of rigidity substantially greater than the swellable elastomer, acting as a mediator that prevents axial flow of the elastomer under pressure while allowing the elastomer to maintain its sealing function.
Solution Approach 2:
The packer employs a composite structure combining multiple materials with different properties: a swellable elastomeric body for sealing, a rigid end ring for structural support, and an elastomeric anti-extrusion member with intermediate rigidity properties. This composite approach allows each material to perform its optimal function while working together as an integrated system.
2Reliability
If a rigid end ring is used to prevent axial extrusion of the elastomer, then the elastomer is constrained, but the radial space between the elastomer and borehole wall allows pressure-driven flow into this space
Solution Approach 1:
The anti-extrusion member is designed with varying radial thickness along its axial length, creating a dimensional gradient that directs the prevention of extrusion primarily in the axial dimension while managing radial space utilization. This dimensional approach allows the component to address axial extrusion without completely eliminating radial clearance.
3Ease of operation
If compression set packers with petal shaped end ring elements are used, then the packer can be set, but a significant axial force in excess of 50,000 pounds is required to deflect the petal shaped elements
Solution Approach 1:
The patent replaces the complex mechanical setting mechanism with petal-shaped elements requiring high axial force with a swellable elastomeric body that sets through chemical or physical swelling action. This substitution eliminates the need for mechanical deflection of rigid elements, dramatically reducing the setting force requirement from over 50,000 pounds to minimal or zero axial force.
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 packer effectively maintains a high-reliability seal across a range of downhole conditions by preventing elastomer extrusion through the use of a stiffer anti-extrusion member, which engages the wellbore surface, thus ensuring a consistent seal without requiring excessive axial force for setting.
Implementation Method 1
A swellable elastomeric sleeve-shaped body may be bonded to the exterior surface of the mandrel... swelling of the elastomeric member forces at least a portion of the elastomeric anti-extrusion member into engagement with the interior surface of the borehole or the interior surface of a downhole tubular
Data Source
AI summary
A swellable downhole packer (10) is provided for positioning downhole in a well to seal with the interior surface of a borehole or the interior surface of a downhole tubular. The packer includes a swellable elastomeric sleeve-shaped body (14) positioned over a mandrel (12) for swelling, and a rigid end ring (16,18). An elastomeric anti-extrusion member (20) is spaced axially between the sleeve-shaped body and the rigid end ring, and has a radial thickness adjacent the end ring greater than the radial thickness adjacent the sleeve-shaped body. A swellable elastomeric member (32) is spaced radially between the exterior surface of the mandrel and the elastomeric anti-extrusion member.