The U.S. Geological Survey (USGS) has helped India to discover “a large, highly enriched accumulations of natural gas hydrate” in the Bay of Bengal—the first such discovery in the Indian Ocean that has the potential to be produced, the USGS said.

The USGS added that the discovery is the result of the most comprehensive gas hydrate field venture in the world to date—the Indian National Gas Hydrate Program Expedition 02 (INGHPR-02)—with participation of scientists from India, Japan and the U.S. Japan’s Chikyu deepwater drilling vessel was used for INGHPR-02.

So far, only four countries have collected samples of gas hydrates: the U.S., Japan, India and China.

There is currently no technology to commercially produce hydrates, although industry experts say that commercial, scaled development could be possible after 2030. Smaller scale output has even been touted as possible by 2018.

There has been growing interest in the search for natural gas hydrates, which are a naturally occurring, ice-like combination of natural gas and water found beneath the world’s oceans and polar regions, as it could potentially be an alternative energy source given that the amount of gas within the world’s gas hydrate accumulations is estimated to exceed the volume of all known conventional gas resources, the USGS noted.

Indian find could spark tech push

The India expedition conducted 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 offshore India.

“Advances like the Bay of Bengal discovery will help unlock the global energy resource potential of gas hydrates as well as help define the technology needed to safely produce them,” USGS’ Energy Resources Program Coordinator Walter Guidroz said.

INGHPR-02 is the second joint exploration for gas hydrate potential in the Indian Ocean after the first, also a partnership between scientists from India and the U.S., discovered gas hydrate accumulations, albeit in formations that are currently unlikely to be producible.

The USGS noted that while 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 revealed that gas hydrate at high concentrations in sand reservoirs is the type of occurrence that can be most easily produced with existing technologies.

INGHPR-02 therefore focused the exploration and discovery of highly concentrated gas hydrate occurrences in sand reservoirs. The USGS noted that the gas hydrate discovered during the 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 research team will now proceed to 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. 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,” said Tim Collett, USGS senior scientist.

Japan plans 2017 testing

Japan also has an ongoing methane hydrate project, which is looking to tap the fuel offshore the country’s southeastern coast.

Japan’s Ministry of Economy, Trade and Industry is now progressing plans for a second round of production testing in 2017 for methane hydrates off the coast of Aichi and Mie prefectures, which is believed to hold sufficient reserves to provide the country with a decade’s supply of natural gas.

If the production test is successful, Japan plans to start commercial methane hydrate production as soon as technology allows, although this will depend on the pace of technological development.

South China Sea discovery

In 2014, China made a major gas hydrate discovery in the northern part of the South China Sea.

China’s Ministry of Land and Resources (MLR) said the gas hydrate accumulation covers 55 sq km (21 sq miles) in the Pearl River Mouth Basin, with controlled reserves equivalent to 3.53 Tcf to 5.30 Tcf (100 Bcm to 150 Bcm) of natural gas.

This made the hydrates field equivalent to a major conventional natural gas field, such as in China’s Sichuan province.

Guangzhou Marine Geological Survey Bureau, a unit of MLR, collected samples of “high purity” gas hydrates over nearly four months of surveys and drilling of 23 wells in the waters off south China’s Guangdong province.

Two gas hydrate layers with a thickness of 15 m to 30 m (49 ft to 98 ft) were found just below the seabed at a water depth of 600 m to 1,000 m (1,969 ft to 3,281 ft).

“It marks a breakthrough in investigating the resource and proves that the Pearl River Mouth Basin is rich in gas hydrate,” said the MLR.

Hydrates potential

“Methane hydrates could, in theory, revolutionize the energy industry, potentially providing significant upside to natural gas production. However, to date, there haven’t been any commercial-scale developments,” said Michelle Gomez of consultant Douglas-Westwood.

“Whether methane hydrate projects off Japan can be commercialized at a competitive price is unknown, and there are significant technical issues to overcome, not least that the most viable accumulations are located in difficult environments, posing technical and environmental challenges. Indeed, Canada is abandoning its own 15-year U.S. $10 million program.

“With natural gas prices at four times U.S. levels, Japan has a greater incentive and has been drilling in its Nankai Trough since 1999. In March 2003, they produced 120 Mcm (4.24 MMcf) of methane gas from a depth of 1,000 m (3,281ft).

“It is reported that if test drilling continues to yield positive results and if technical issues can be resolved, commercial production could begin during as early as 2018. But one constant of the energy industry is that most projects take much longer than planned,” Gomez added.

—Steve Hamlen