A solution to the problem of subsea pipeline blockages was well described in a 1999 patent application by Dr. Benton F. Baugh, a mechanical engineer with subsea oil and gas experience:
"Hydrates are a porous solid formed primarily of water with a mixture of gases, similar to ice. There is a tendency for hydrates to form in the pipelines departing from a subsea gas well, especially on well startup."
The temperature of seawater at depth will often approach 32°F, with the temperature in non-flowing pipelines being the same. When a subsea pipeline valve is opened, the gas expansion can cause substantial additional cooling. In these cold and high-pressure conditions, hydrates of the gas and water can quickly form.
Frequently, when hydrate forms in pipelines, it creates a blockage that is somewhat porous. At that time, high pressure will exist on the upstream side and lower pressure will exist on the downstream side of the blockage. This means that additional gas will move through the hydrate and expand, cooling during the process. The expansion of this gas will keep the formed hydrate cool, and can continue to grow additional hydrate blockage.
It is difficult to tell where the hydrates are actually located in deepwater pipelines, especially when the pipelines are buried.
Hydrates formed like this can last for weeks or months, with a substantial loss of gas flow, and therefore revenue to the owner of the pipelines and subsea wells.
Paraffins can form blockages in pipelines by building up on the inner diameter of the cold pipelines as relatively warm oil circulates out of an oil well and cools as it flows down a subsea pipeline. As the layer of paraffin builds up in a subsea pipeline, the inner diameter of the paraffin becomes smaller and smaller. Ultimately a pigging device intended to clean the paraffin will cause the paraffin to separate from the inner wall of the pipeline and become a plug. In some cases, the paraffin will release from the subsea pipeline inner diameter without a pig and cause a blockage. In either case, if the pressure in the pipeline is enough to move the plug along the pipeline, it will continue to collect additional paraffin as it moves until the length of the blockage cannot be moved by the available pressure.
The challenge of clearing subsea pipeline blockages in deep, cold water has inspired a variety of novel ideas. For example:
- Move a remotely operated vehicle along a subsea pipeline and repeatedly circulate heated seawater across the outer surface of the pipeline.
- Inductively heat the section of the oil line plugged with wax using an external coil positioned over the line at the seabed.
- Deliver high energy and volume pressure pulses into the pipeline, at the speed of sound, to the blockage.
Perhaps these ideas will work, but they appear on the surface to have considerable and unavoidable costs and risks. Fortunately, there’s a much simpler, cost-effective, low-risk—and proven—way to solve this problem: a temperature-independent, environmentally responsible chemical solution that easily withstands colder waters—even at temperatures below 34ºF.
Ideal Energy Services, LLC PipeRenew® treatment is a proprietary, water soluble, granular material that contains surfactants and encapsulated oxygen. Designed for offshore applications, it can be blended onsite with freshwater, saltwater, or produced water.
Temperature-independent PipeRenew® treatment is effective at removing paraffin, asphaltenes, or mineral scales at the coldest subsea temperatures. It is not limited by the diameter or length of the pipeline, making it suitable for trunk lines, transfer lines, or process lines.
When you consider the variety of methods and materials currently on offer to solve the problem of removing pipeline blockages in deep, cold water, consider the simplicity of PipeRenew® treatment. And, consider its unsurpassed record of success.
