Re-latchable Cementing Bushing for Liner Hanger Pressure Integrity
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Solution Overview
Problem
Prior art cementing bushings in liner hanger assemblies have limitations in cementing pressure capability and reliability due to small locking lugs, leading to potential cementing failures when the running tool is picked up beyond a certain length, resulting in loss of pressure integrity.
Innovation Solution
A lockable and re-latchable cementing bushing design with a circumferential loading ring and axially movable C-rings that allow reinsertion into the liner, enabling reestablishment of pressure integrity and enhanced cementing pressure capability, allowing upward movement of the running tool without breaking the seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple small locking lugs are used to lock the bushing into the liner, then the bushing can be secured in place, but the cementing pressure capability is limited
Solution Approach 1:
The locking mechanism is divided into multiple discrete locking lugs that can be independently positioned around the circumference. These lugs are distributed segments that collectively provide enhanced locking capability and pressure resistance compared to a single locking element, while maintaining modular simplicity
Solution Approach 2:
The locking lugs are strategically positioned at specific locations around the bushing circumference where maximum mechanical advantage is achieved. Each lug is placed to engage with corresponding features on the liner hanger, concentrating locking force at optimal points to maximize cementing pressure capability
2Ease of operation
If the running tool is picked up above a certain length, then the operator can retrieve the tool, but the packoff bushing may disengage from the liner hanger causing cementing failure
Solution Approach 1:
The locking lugs are designed with dynamic engagement features that maintain secure locking throughout the range of motion during tool retrieval. The lugs can accommodate axial movement and radial displacement while maintaining engagement, allowing the running tool to be picked up and retrieved without disengaging from the liner hanger
Solution Approach 2:
The bushing design incorporates pre-positioned locking lugs that engage with the liner hanger before any upward movement occurs. This preliminary engagement creates a mechanical interlock that prevents disengagement during subsequent tool retrieval operations, cushioning against the harmful effect of potential bushing displacement
3Adaptability or versatility
If the running tool is raised above the liner, then the operator can check for release, but pressure integrity is lost
Solution Approach 1:
The locking lugs act as intermediary mechanical elements that maintain the connection between the bushing and liner hanger during operator checks. These lugs serve as a mediating structure that allows the running tool to be raised for verification purposes while the lugs maintain mechanical engagement and preserve pressure integrity throughout the operation
Data Source
AI summary
A liner hanger assembly comprises a tool mandrel (104) suspended on a running string, and a slip assembly (120) for engaging a casing to support the liner hanger and liner from the casing. The release assembly (175) releases the set liner hanger from portions of the assembly to be retrieved to the surface. A cementing bushing (130) is releasable and reinsertable into the liner, and includes a circumferential loading ring (226).