Pipeline Pig Launching with Flow-Entrained Plug Sequencing
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Solution Overview
Problem
Existing pig launchers for pipelines, especially those used in underwater applications like the offshore oil and gas industry, face challenges in efficiently launching multiple pigs due to complexity, bulkiness, and high costs. Traditional designs require frequent reloading and are not suitable for subsea use without extensive and expensive modifications.
Innovation Solution
A method and apparatus for launching multiple pipeline pigs successively, utilizing a launcher with a tubular body, a pig storage region, and a launching mechanism that releases spheres into the fluid flow to block the through-passage of each pig, creating a pressure differential to launch the pigs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a pig launcher contains only one pig with simple piping and valve arrangements, then the launcher is compact and simple, but it must be reloaded with another pig after each pig is launched which requires repeatedly opening an end cap containing pressurised fluid
Solution Approach 1:
The launcher is divided into multiple chambers (first chamber and second chamber) that can be independently sealed and pressurized. Each chamber can hold and launch a pig separately, allowing the launcher to operate multiple times without full reloading. The segmentation enables independent operation of each chamber, resolving the contradiction between simplicity and multi-pig capability.
Solution Approach 2:
Multiple pigs are loaded into the launcher chambers in advance before deployment. The end caps are pre-sealed with pressurized fluid, so when deployed, the pigs are already positioned and ready for sequential launching without requiring repeated opening and closing operations. This preliminary preparation eliminates the operational complexity of reloading.
2Productivity
If a pig launcher contains two or more pigs with separate pressure inlets and valves for each pig, then multiple pigs can be launched successively, but the launcher becomes complex, bulky and expensive
Solution Approach 1:
Multiple pigs share a common pressurized fluid source and control system. Instead of having separate pressure inlets and valves for each pig, the launcher uses a single pressurized chamber that can sequentially pressurize multiple pigs. This merging of resources maintains multi-pig launching capability while dramatically reducing the complexity of piping and valve arrangements.
Solution Approach 2:
The single pressurized chamber and control system serve multiple functions by being able to launch any number of pigs in sequence. The universal design allows the same hardware to handle different pig launching scenarios without requiring additional specialized components for each pig, reducing overall system complexity while maintaining productivity.
3Adaptability or versatility
If a multiple pig launcher is removed from a subsea pipeline after use, then it can be re-used elsewhere, but this requires the great expense of additional vessel intervention on site and proper sealing of the access opening
Solution Approach 1:
The launcher is designed with self-contained, pre-sealed chambers that can be deployed and left in place without requiring complex removal procedures. The system serves itself by maintaining its own pressurized environment and sealed configuration, eliminating the need for expensive vessel intervention for both deployment and removal. The launcher can be installed once and used multiple times in situ.
4Reliability
If traditional pig launchers are used in subsea applications, then pigs can be launched into pipelines, but ensuring safe and reliable operation for the entire life of the pipeline (excess of twenty years) would require extremely stringent and expensive design parameters
Solution Approach 1:
The launcher uses pre-sealed chambers filled with pressurized fluid before deployment, creating a cushioning effect that protects the system from subsea environmental variations over time. The pre-prepared pressurized environment compensates for potential failures or variations during the 20+ year pipeline lifespan, maintaining reliable operation without requiring extremely stringent design parameters for every possible scenario.
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
The solution enables simple, reliable, and efficient launching of multiple pigs in succession, reducing the complexity and cost associated with traditional launchers, and is suitable for subsea applications without the need for frequent reloading or extensive modifications.
Implementation Method 1
a pressure differential is created within the pipeline between a volume ahead of the pig and a volume behind the pig, with respect to the intended direction of travel
Implementation Method 2
the desired pressure differential is created by introducing high-pressure fluid through a pressure inlet into a volume behind the pig
Implementation Method 3
conveying a launching element to the pig by entraining the launching element in the flow of fluid
Implementation Method 4
a pig has a series of annular or disc-shaped circumferential seals that separate the volume within the pipeline ahead of the pig from the volume within the pipeline behind the pig
Implementation Method 5
The seals are suitably stiff enough to provide a scraping action so as to clean and flush the interior of the pipeline as the pig moves along the pipeline
Data Source
AI summary
A pipeline pig is launched by directing a flow of fluid to, and through, the pig while conveying a launching element to the pig, entrained in the flow. Interaction between the launching element and the pig then blocks the flow through the pig to launch the pig. The launching element can be a spherical plug that blocks a through-passage extending longitudinally through the pig, hence serving as a barrier to the flow through the pig, or can trigger a mechanism that blocks the flow through the pig. The flow entraining the launching element can be directed through at least one other pig to be launched subsequently, positioned upstream of the pig being launched. A succession of launching elements can be released into the flow, each configured to interact with a respective one of a series of pigs. Successively released launching elements can increase in diameter from element to element.