Natural gas hydrates: A major resource for natural gas
Article by Dr. Praveen Linga, PhD, Assistant Professor, Department of Chemical and Biomolecular Engineering, National University of Singapore.
Gas hydrates are ice-like solid crystals formed as a combination of gas and water molecules at low temperature and high pressure. In general, gas hydrates are found in nature, they form in oil and gas flow lines and can also be easily synthesized in the lab. Since natural gas hydrates contain gas and water, upon supply of heat, they can readily dissociate to gas and water and can ignite when contacted with a flame during dissociation. However, it is noted that natural gas hydrates are safe to handle and non-explosive. The major areas of interest on gas hydrates are flow assurance, energy resource and innovative applications and they are presented in Figure 1. Flow assurance to inhibit the formation of hydrates in oil and gas production and transmission equipment remains a major research topic in gas hydrates. Natural gas hydrates are a huge energy resource that is evenly distributed. Recently, several innovative applications have been proposed based on gas hydrates like natural gas storage and transport, carbon capture, desalination, hydrogen storage etc.
The most common form of gas hydrate found in nature is methane hydrate, which are found in permafrost region and continental margins. Methane hydrates in nature was first inferred from Siberian Russia gas field in the late 1960s. Since then, resource estimation studies have revealed that the amount of natural gas in hydrate reservoir is about ~20,000 TCM. It is found that gas hydrates exist in various forms in nature (e.g. sand-dominated sediments, clay-dominated sediments, massive hydrate mounds on seafloor surface), with the sand-dominated hydrate reservoir to be most promising in energy recovery due to its compatibility with the existing oil and gas infrastructure.
It is widely believed that conventional production techniques can be employed for production of methane from these deposits with some specific technical challenges like water and sand management during production that are needed to be addressed. So far, production tests have been carried out in three hydrate reservoirs in Canada (Mallik), Japan (Nankai Trough) and USA (Ignik Sikumi in Alaska). Currently, a major effort to realize natural gas production from hydrate reservoirs is primarily done in Asia in countries like Japan, South Korea, China, India etc. The commercialization of gas hydrate resource will depend on the regulatory framework, knowledge to the resource and their production profiles, cost of production and regional gas price.
Figure 1. Significance of gas hydrate research.
Are gas hydrates a large potential resource? Will gas hydrates play a key role in the future of natural gas? Let us know your views below.
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