Side Entry Sub Hub Sealing for High-Pressure Fluid Injection
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Solution Overview
Problem
Existing side entry subs in the drilling and servicing of oil and gas wells face issues related to fluid sealing and secure attachment of the hub to the main body, leading to potential leaks and detachment during high-pressure operations.
Innovation Solution
A side entry sub design featuring a resilient seal element, such as an O-ring, and a flange with locking washers or NORD-LOCK® washers, ensuring a secure and pressure-tight connection between the hub and main body, using straight threads for ease of assembly and alignment of bolt holes for additional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a side entry sub is used to pump fluid into a drillstring, then fluid flow capability is improved, but sealing reliability deteriorates due to potential leaks at the hub-main body connection
Solution Approach 1:
A resilient seal element (O-ring) is installed in a groove on the hub nose portion to create a flexible sealing barrier between the hub and main body. This flexible membrane approach prevents fluid leakage while maintaining the side entry flow capability, resolving the contradiction between productivity and sealing reliability.
Solution Approach 2:
The seal element groove is pre-formed on the hub nose portion before assembly, and the O-ring is pre-installed in this groove. This preliminary preparation ensures that sealing is established before high-pressure fluid flow begins, preventing leaks from occurring during operation.
2Productivity
If a side entry sub is used to pump fluid into a drillstring, then fluid flow capability is improved, but connection stability deteriorates due to potential hub detachment during high-pressure operations
Solution Approach 1:
Multiple attachment mechanisms are merged into a single hub structure: threaded connection (internal threads in main body engaging external threads on hub), flange contact (flange face bearing against main body), and flange bolts (securing the flange connection). This combination of mechanical fastening methods provides redundant stability to prevent hub detachment during high-pressure fluid injection operations.
Solution Approach 2:
The hub includes a rounded nose portion that fits into the side passage opening, creating a geometric interlock that resists pull-out forces. This curved geometry complements the threaded and flange connections by providing additional mechanical stability against detachment.
3Strength
If tapered threads are used for hub connection, then connection strength is improved, but assembly difficulty increases due to alignment requirements
Solution Approach 1:
The connection system is segmented into multiple independent elements: threaded connection for primary attachment, flange contact for secondary support, and flange bolts for tertiary securing. This segmentation allows the threaded portion to use simpler straight threads for easier assembly, while overall connection strength is maintained through the combined action of all segments.
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
Provides a reliable and leak-proof connection that withstands high-pressure conditions, ensuring secure attachment and efficient fluid flow through the side passage into the drillstring bore.
Implementation Method 1
A resilient seal element, which may be an O-ring or similar seal element, is preferably disposed on the nose portion and provides a fluid and pressure seal between the hub and the main body
Implementation Method 2
The side entry element, which may be referred to as the 'hub,' has a nose portion with mating threads to make up into the threads of the passage
Implementation Method 3
The locking means may comprise locking washers and wired bolts. Alternatively, and in a presently preferred embodiment, the locking means comprises NORD-LOCK® locking washers, providing an extra element of security to the connection
Data Source
AI summary
A side entry sub has an elongated main body with a longitudinal bore and a side passage intersecting the longitudinal bore. A removable hub has a nose portion which threadably engages mating threads in the side passage, with a resilient seal on the nose portion providing a fluid seal with the main body. The threads are formed such that a flange on the hub advances into contact with the main body with a desired contact force as holes in the flange come into alignment with threaded holes in the main body. Threaded flange bolts through the flange holes engage the threaded holes in the main body. Locking washers are used on the flange bolts. The removable hub is structurally connected to the main body by the threaded connection and contact of the flange with the main body, and pressure and fluid-sealed by the resilient seal.