What is a Natural Gas Hydrate?
At a specific combination of pressure and temperature, water molecules arrange themselves into structures known as hydrates. A natural gas hydrate is an ice-like form of water. In its natural formation, it contains natural gas molecules, mostly methane. However, in the oil and gas industry, it often consists of multiple hydrocarbons.
Although methane hydrate has an appearance similar to the ice, its behaviour is very different. It burns when lit, which is why it is also referred to as burning ice.
Formation of Hydrates
Oil and gas companies use a network of pipelines to transport natural gas. In colder climates, these pipelines may become obstructed due to ice-like crystals forming inside the pipeline. These substances were found to be methane hydrates. Operators and engineers have been trying for years to find ways to reduce the formation of hydrates. This is because it hinders the flow of gas in the pipeline, causing operational problems, maintenance issues, and safety concerns.
Removal of Water
The best way to prevent hydrates is to remove the water from the natural gas before it enters the pipeline. This is because it will create gas hydrate crystals once the temperature begins to decline.
There are a few methods for the removal of water at the well site to the extent required to prevent the formation of natural gas hydrate. A few common ways to remove water are as follows:
- Wellsite Separation and Methanol Injection
Separating out the free water from the natural gas stream at the wellsite is the most economical way of preventing hydrates. Its limitation though is that this process only removes the free water. Methanol will also need to be injected to prevent the saturated water from forming hydrates.
- Refrigeration or Glycol Dehydrator
Refrigeration or glycol dehydration are the best ways to remove water (both free and saturated water) from a natural gas stream. Both of these methods involve extensive equipment processes and are typically used for higher gas flow rates.
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The temperature at which gas hydrates are formed is higher than the temperature at which water-ice forms. The specific pressure/temperature value or PT value depends on the dissolved salt content in the water and the composition of hydrocarbon-gas.
Preventing the Formation of Hydrates Using Line Heaters
Alternatively, heating the natural gas stream with a line heater above the temperature (PT value) at which hydrates form can also work. Using an indirect line heater helps to maintain the temperature to prevent the formation of hydrates.
We Can Help You Reduce the Formation of Hydrates
Aspire provides fabrication and design services to the energy industry. We aim to offer accurate solutions by understanding the requirements of our customers. We have the resources and expertise to manage and complete our projects on time and within the given budget. We use the best practices to give the desired results.
If you need help to select the right equipment to control the formation of hydrates in your pipeline or industrial processes, we can help you. We carry a wide range of line heaters for lease or sale to suit your needs. For more information about our products and services, reach out to us by calling 403-314-5422 or 1-800-993-9958. Our experts will be glad to help you.