Wellhead Load Support Structure Redirecting Rig Loads to Ground
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Solution Overview
Problem
Conventional snubbing units place significant loading on wellhead components, particularly threaded connections, due to vertical gravity loads, working loads, and lateral wind loading, which can compromise wellhead integrity and lead to bending stresses.
Innovation Solution
A load-bearing support structure with a support plate and ground-engaging members that distribute the rig's load into the ground, reducing the stress on wellhead components, and includes vertically adjustable jack stands and outrigger arms for enhanced stability and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a stand alone snubbing unit is supported on a structure that is in turn supported from the wellhead, then the rig can be positioned above the wellhead for tubular manipulation, but significant loading is placed on the wellhead which compromises wellhead integrity
Solution Approach 1:
The support structure acts as an intermediary element between the rig and the wellhead. It includes a support plate that interfaces with the wellhead and multiple ground-engaging members (legs with feet) that transfer loads to the ground. This intermediary structure absorbs and redirects the significant gravitational and operational loads away from the wellhead, preventing direct transmission of bending moments and vertical loads that would compromise wellhead integrity while still enabling the rig to be positioned and operated above the wellhead.
2Adaptability or versatility
If threaded wellhead connections are used to support the rig, then the rig can be mounted above the wellhead, but the threaded connections are particularly vulnerable to bending loads imposed on the wellhead
Solution Approach 1:
The support plate serves as an intermediary mounting surface that replaces direct threaded connections to the wellhead for supporting the rig's weight. The support plate attaches to the wellhead in a manner that distributes loads, and then transfers the rig's gravitational and operational loads through its ground-engaging members to the ground. This intermediary arrangement protects the threaded wellhead connections from vulnerable bending loads while maintaining the capability to mount and operate the rig above the wellhead.
3Strength
If the support structure directs loads into the ground, then stress on wellhead components is minimized, but the structure requires additional ground-engaging members and adjustment mechanisms
Solution Approach 1:
The support structure is segmented into distinct functional components: a support plate for interfacing with the wellhead, multiple ground-engaging members (legs) for load distribution, feet for ground contact, and adjustment mechanisms (jacks) for positioning. This segmentation allows each component to perform its specific function efficiently - the support plate protects the wellhead, the legs distribute loads to the ground, and the adjustment mechanisms enable positioning. While this increases structural complexity, it achieves the critical goal of minimizing stress on wellhead components through proper load path design.
Data Source
AI summary
A support structure for a rig above a wellhead, such as a snubbing unit, is provided which directs loads from the rig into the ground to minimize stress on the wellhead components. The support structure generally comprises a support plate to be secured onto a wellhead and onto which the rig is secured and at least three ground engaging members distributed around and connected to the support plate, with the ground engaging members accepting the load placed on the support plate. The ground engaging members can be independently vertically adjustable, such as jack stands, for distributing the load between the ground engaging members. The support structure can also be adapted to be movable between a compact shipping position and a deployed operating position.