Valve Assembly for Cementing Liner with Stinger Mechanism
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Solution Overview
Problem
Current methods for cementing liner strings in wellbores face challenges in ensuring effective cement placement and retention, particularly when drilling deeper requires components that cannot be retrieved, such as drill bits, and existing systems lack efficient mechanisms for sealing and preventing cement backflow.
Innovation Solution
A valve assembly biased to a closed position is attached to a running tool, allowing fluid flow during cementing and then blocking it to prevent backflow, with a stinger mechanism that pivots flapper valves to seal in both directions, ensuring cement retention and allowing for subsequent drilling through drillable components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liner string is cemented in place to prevent cement backflow, then cement retention is improved, but the ability to drill deeper with retrievable components is lost
Solution Approach 1:
The system is divided into two separate components: a cement shoe that remains in the liner string to provide cement retention, and a separate drill bit that can be retrieved and replaced. This segmentation allows the cementing function to be permanent while the drilling function remains adaptable and retrievable.
Solution Approach 2:
A bridge plug is introduced as an intermediary component that seals the annulus between the liner string and the drill string. This intermediary allows the cement shoe to remain in place for cement retention while enabling the drill bit to be retrieved and replaced for deeper drilling operations.
2Reliability
If a seal is installed to prevent cement backflow, then cement placement effectiveness is improved, but device complexity increases
Solution Approach 1:
The bridge plug is designed to self-set automatically when it is pulled back up the drill string. The expansion element expands against the liner string wall upon withdrawal, creating a seal without requiring additional setting operations or complex control mechanisms.
Solution Approach 2:
The bridge plug is a disposable component that is set in place and then discarded after use. This approach simplifies the overall system by eliminating the need for complex retrieval and reuse mechanisms, focusing instead on a simple, reliable seal that can be easily installed and left in place.
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
This solution enables effective cementing and sealing of liner strings while allowing for deeper drilling without retrievable components, ensuring cement slurry retention and preventing backflow, thus enhancing well completion efficiency.
Implementation Method 1
Each flapper valve element is secured by a hinge to one of the seats for pivotal movement between open and closed positions
Implementation Method 2
A spring is secured to the valve body and engages the flapper valve element to bias the flapper valve element to the closed position
Data Source
AI summary
A method of cementing a liner in a well includes mounting a valve assembly that is biased in a closed position to a running tool assembly. The running tool assembly has a stinger inserted through the valve assembly, retaining the valve assembly in an open position. The stinger has a cement retainer releasably mounted to it. After lowering the running tool assembly into engagement with the liner string into latching engagement with a lower portion of the liner string. Afterward, the operator lifts the stinger from the valve assembly, causing the valve assembly to move to the closed position. The valve assembly blocks upward flow of fluid from the well conduit through the valve assembly in the event of leakage of the cement retainer.