Flexible Submarine Pipe Clearing via Flexitube Extraction
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Solution Overview
Problem
Conventional methods for clearing obstructions in flexible submarine pipes are often ineffective, particularly for complex cases involving hydrates, and require lengthy and costly interventions with a rig.
Innovation Solution
A method using a flexitube from a well intervention rig, which involves opening a submarine connection, assembling a hoisting assembly, draining internal pressure, and using a flexitube to clear obstructions by pumping a solubilizing or mechanical fluid through it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rig intervention methods are used to clear submarine pipes, then hydrate removal is effective, but intervention duration becomes excessively long (15-100 days)
Solution Approach 1:
The intervention process is segmented into distinct phases: initial depressurization to dissociate hydrates, followed by mechanical clearing operations. This segmentation allows the most time-consuming depressurization phase to be performed once, enabling subsequent quicker interventions without full rig mobilization.
Solution Approach 2:
The method performs preliminary depressurization and hydrate dissociation before the main mechanical clearing operation. By pre-dissociating hydrates through pressure reduction, the subsequent mechanical clearing becomes faster and more effective, reducing overall intervention time.
2Reliability
If conventional rig intervention with submarine tools is used, then hydrate dissociation is achieved, but equipment availability and mobilization time increase costs
Solution Approach 1:
The method extracts and removes the obstructed flexible pipe section from the submarine environment and brings it to the surface for clearing operations. This eliminates the need for expensive submarine intervention tools and rig mobilization, using instead simpler surface-based equipment.
Solution Approach 2:
The flexible pipe section is treated as a disposable component that can be quickly removed, cleared or replaced at the surface, rather than investing in expensive, complex submarine intervention equipment. The low cost of the flexible pipe section makes this economically viable.
3Productivity
If depressionurization cycles are used to clear pipes, then some obstructions are removed, but mechanically resistant obstructions remain
Solution Approach 1:
The method merges chemical/biological clearing agents with mechanical clearing actions. clearing agents are injected through the flexible pipe to dissolve or break down obstructions, while simultaneous or subsequent mechanical operations (pressure cycles, pigging) physically remove the degraded material, achieving comprehensive clearing of all obstruction types.
Solution Approach 2:
Clearing agents serve as intermediaries between the pressure system and the obstruction. These agents chemically or biologically degrade the obstruction material, making it easier to remove mechanically, thus bridging the gap between chemical and mechanical clearing methods.
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 method reduces the time and cost of clearing obstructions by allowing direct mechanical action on the obstruction, effectively addressing complex cases that conventional methods cannot handle.
Implementation Method 1
pumping a solubilizing or mechanical fluid through it
Data Source
AI summary
The present invention addresses to a method of clearing submarine pipes, in which the method solves the most complex cases of obstruction of flexible submarine pipes, where the conventional approach is ineffective. Additionally, the present invention represents a cheaper alternative to the clearance of pipes in scenarios where the conventional approach is applicable. The method of clearing flexible pipes using flexitube from a well intervention rig of the present invention comprises as one of its main steps: with the aid of a remotely operated vehicle (51), opening a flanged connection (10) between two flanges (15) of the legs (12 and 14) of a submarine pipe (40) and installing a pull head (16 and 17) in each of these legs (12 and 14); and using well intervention rig (120) operations; assembling the hoisting assembly (58) for hoisting the leg (14) of the submarine pipe (40) with the drill string (50); hoisting the leg (14) of the submarine pipe (40) through its end using the hoisting assembly (58) coupled to the pull head (16); draining the internal pressure of the pipe by means of the connection of a tube (67) with the pull head (16); assembling the Surface Flow Tree (70) at the end of the leg (14) of the submarine pipe (40), using the connection adaptation parts (90) and (91) to make the end of the leg compatible with the Surface Flow Tree; assembling the Flexitube (80) on the Surface Flow Tree (70) and surface lines (72); carrying out the operation of clearing the leg (14) of the submarine pipe (40) with Flexitube (80).