Large, highly enriched accumulations of natural gas hydrates have been discovered in the Bay of Bengal, India, according to the US Geological Survey (USGS).
It is the first discovery of its kind in the Indian Ocean that has the potential to be producible, says the USGS, which assisted in the exploration program.
Natural gas hydrates are a naturally occurring, ice-like combination of natural gas and water found in the world’s oceans and polar regions. The amount of gas within the world’s gas hydrate accumulations is estimated to greatly exceed the volume of all known conventional gas resources.
“Advances like the Bay of Bengal discovery will help unlock the global energy resource potential of gas hydrates as well help define the technology needed to safely produce them,” said Walter Guidroz, USGS Energy Resources Program coordinator. “The USGS is proud to have played a key role on this project in collaboration with our international partner, the Indian Government.”
Scientists from India, Japan and the US helped in the exploratoin program, conducting ocean drilling, conventional sediment coring, pressure coring, downhole logging and analytical activities to assess the geologic occurrence, regional context and characteristics of gas hydrate deposits in the offshore of India.
This program, the Indian National Gas Hydrate Program Expedition 02, was the second joint exploration for gas hydrate potential in the Indian Ocean. The first expedition, also a partnership between scientists from India and the US, discovered gas hydrate accumulations, but in formations that are currently unlikely to be producible.
Although it is possible to produce natural gas from gas hydrates, there are significant technical challenges, depending on the location and type of formation. Previous studies have shown that gas hydrate at high concentrations in sand reservoirs is the type of occurrence that can be most easily produced with existing technologies.
The second expedition focused the exploration and discovery of highly concentrated gas hydrate occurrences in sand reservoirs. The gas hydrate discovered during the second expedition are located in coarse-grained sand-rich depositional systems in the Krishna-Godavari Basin and is made up of a sand-rich, gas-hydrate-bearing fan and channel-levee gas hydrate prospects. The next steps for research will involve production testing in these sand reservoirs to determine if natural gas production is practical and economic.
“The results from this expedition mark a critical step forward to understanding the energy resource potential of gas hydrates,” said USGS Senior Scientist Tim Collett, who participated in the expedition. “The discovery of what we believe to be several of the largest and most concentrated gas hydrate accumulations yet found in the world will yield the geologic and engineering data needed to better understand the geologic controls on the occurrence of gas hydrate in nature and to assess the technologies needed to safely produce gas hydrates.”
The international team of scientists was led by the Oil and Natural Gas Corp. on behalf of the Ministry of Petroleum and Natural Gas India, in cooperation with the USGS, Japan Drilling Company, and Japan Agency for Marine-Earth Science and Technology. In addition, USGS is working closely with the National Institute of Advanced Industrial Science and Technology Japan on the analysis of pressure core samples collected from sand reservoirs with high gas hydrate concentrations.