Threadless Casing Hanger Interface for Casing String Rotation
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Solution Overview
Problem
Existing methods for rotating casing strings during cement jobs in directional drilling, especially in hard subterranean formations, rely on complex threaded connections that can vary and introduce challenges, necessitating improvements in the interface between the casing hanger and the casing string.
Innovation Solution
A threadless interface design featuring a casing hanger with grooves and protrusions, combined with a mechanical rotational locking feature using castellated profiles, allows for torque transfer between the casing hanger and string without threads, enabling rotation and support even in compact formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded connections are used to connect casing hanger and casing string, then torque transfer is achieved, but the device complexity increases and reliability decreases due to variation in thread types
Solution Approach 1:
The invention extracts and eliminates the threaded connection component from the casing hanger-casing string interface. Instead of using threads, the patent employs a direct bearing surface with a shouldered configuration that provides torque transfer without the complexity of threaded assemblies, thereby improving reliability and reducing device complexity
Solution Approach 2:
The invention replaces the mechanical threaded connection system with a bearing surface-based torque transfer mechanism. The shouldered configuration creates a direct mechanical interface that transfers torque through friction and normal forces on the bearing surface, substituting the threaded mechanical system with a simpler bearing-based system
2Ease of operation
If threaded connections are used for casing rotation, then torque transfer is enabled, but ease of operation deteriorates due to difficulty in rotation during cement jobs
Solution Approach 1:
The invention removes the threaded connection that impedes rotation, allowing the casing string to rotate freely during cement jobs. The shouldered bearing surface configuration enables smooth rotation without the binding effects of threaded interfaces, significantly improving ease of operation
Solution Approach 2:
The invention creates a dynamic interface that allows for rotation during cementing operations. The shouldered configuration with bearing surfaces enables the casing to rotate dynamically while maintaining connection, whereas threaded connections create static, rigid interfaces that resist rotation
3Strength
If standard bearing surfaces are used between casing hanger and string, then assembly is simple, but torque transfer capability is insufficient for hard formations
Solution Approach 1:
The invention applies local quality enhancement by creating a shouldered configuration with increased bearing surface area at the interface between casing hanger and casing string. This localized geometric modification concentrates the torque transfer capability at the bearing surface, providing sufficient strength for hard formations without requiring complex overall interface design
Solution Approach 2:
The invention transitions from a simple axial connection to a multi-dimensional shouldered configuration. The shoulder creates a radial offset that increases the moment arm for torque transfer, adding a dimensional element (radial distance) to the interface design that enhances torque capability without increasing connection complexity
Data Source
AI summary
A system includes a casing hanger that includes a first castellated profile and a casing string that includes a second castellated profile such that the first castellated profile is configured to assemble with the second castellated profile to form a mechanical rotational locking feature configured to enable transfer of a rotational torque between the casing hanger and the casing string.