Snubbing Unit Slip Configuration for Subsea Tubular Buckling Prevention
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Solution Overview
Problem
Subsea snubbing operations face challenges in preventing buckling of tubular members, particularly coiled tubing, due to the lack of a riser, which complicates the insertion process and increases the risk of material failure under high pressure and remote underwater conditions.
Innovation Solution
A snubbing unit with additional traveling slips and a pipe guide apparatus that includes a set of stationary slips, two sets of traveling slips, and hydraulic cylinders, where the pipe guide apparatus provides consistent support and protection against buckling by coordinating with the snubbing unit's slips to maintain engagement and release positions, ensuring reliable insertion without a riser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional snubbing unit without a riser is used for subsea tubular insertion, then equipment complexity and deployment difficulty are reduced, but the risk of tubular buckling increases due to lack of continuous support
Solution Approach 1:
The support function is segmented into multiple discrete slip sets (stationary slips and traveling slips) distributed along the tubular member length, providing distributed support points rather than continuous support, which prevents buckling while maintaining system simplicity
Solution Approach 2:
The slips act as intermediary support elements between the snubbing unit and the tubular member, providing localized support points that prevent buckling without requiring a continuous riser structure
2Adaptability or versatility
If coiled tubing is used instead of conventional pipe for subsea snubbing, then adaptability to subsea conditions is improved, but susceptibility to buckling increases due to material composition and smaller diameter
Solution Approach 1:
The slips are positioned and engaged in advance to provide preemptive support against compressive forces before buckling can occur, counteracting the inherent susceptibility of coiled tubing to buckling under compression
Solution Approach 2:
The snubbing unit and pipe guide apparatus are configured and positioned beforehand to provide structured support pathways, ensuring coiled tubing maintains stability during the snubbing operation despite its material characteristics
3Reliability
If multiple sets of traveling slips and stationary slips are added to prevent buckling, then tubular member support and safety are improved, but device complexity and operational coordination increase
Solution Approach 1:
Multiple slip sets are merged into a coordinated system where stationary slips and traveling slips work together as an integrated support mechanism, sharing the load and providing redundant support to prevent buckling
Solution Approach 2:
The slip sets serve multiple functions: providing support points, preventing buckling, and enabling controlled movement of the tubular member, reducing the need for separate specialized components
Data Source
AI summary
The snubbing unit inserts a tubular member into a well without a riser. The snubbing unit includes a set of stationary slips in a first base plate, a first set of traveling slips in a second base plate, a second set of traveling slips in a third base plate, and a plurality of hydraulic cylinders connecting the base plates. Each set of slips has an engaged position and a released position relative to the hydraulic cylinders. The base plates are cooperative with a pipe guide so that movement of the tubular member between the base plates corresponds to consistent support of the tubular member to preventing buckling. The snubbing unit increases safety and support for inserting into the well without a riser.