Geologic Controls on the Occurrence of Gas Hydrates in the Indian Continental Margin: Results of the Indian National Gas Hydrate Program (NGHP) Expedition-01

Authors: T.S. Collett and the India NGHP Expedition 01 Scientific Party

Venue: 2008 American Association of Petroleum Geologists Annual Meeting, April 20-23, 2008 San Antonio, Texas ( http://www.aapg.org/meetings/annual.cfm [external site] )

Abstract: Studies of geologic and geophysical data from offshore India have revealed two geologically distinct areas with seismically inferred gas hydrate occurrences: the passive continental margins of the Indian Peninsula, and along the Andaman convergent margin. The Indian National Gas Hydrate Program (NGHP) Expedition 01 was designed to study the gas hydrate occurrences both spatially and temporally off the Indian Peninsula and along the Andaman convergent margin with special emphasis on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these two diverse settings. During NGHP Expedition 01, dedicated gas hydrate coring, drilling, and logging operations were conducted from the 28th April, 2006 to the 19th August, 2006. NGHP’s Expedition 01 was planned and managed through collaboration with the Indian Directorate General of Hydrocarbons (DGH), the U.S. Geological Survey (USGS), and the Consortium for Scientific Methane Hydrate Investigations (CSMHI) led by Overseas Drilling Limited (ODL) and FUGRO McClelland Marine Geosciences. Other key participants included the members of Integrated Ocean Drilling Program, including the Joint Oceanographic Institutes, Texas A&M University, and the Lamont-Doherty Earth Observatory of Columbia University.

During its 113.5-day voyage, the JOIDES Resolution cored or drilled 39 holes at 21 sites (1 site in Kerala-Konkan, 15 sites in Krishna-Godavari, 4 sites in Mahanadi and one site in Andaman deep offshore areas), penetrated more than 9,250 meters of section and recovered nearly 2,850 meters of core with ~78% recovery. Twelve holes were logged with logging-while-drilling tools and an additional 13 holes were wireline logged. NGHP Expedition 01 established the presence of gas hydrates in Krishna-Godavari, Mahanadi and Andaman basins. The expedition discovered and closely examined one of the richest gas hydrate accumulations yet documented (Site 10 in the Krishna-Godavari basin), documented the thickest and deepest gas hydrate stability zone yet known (Site 17 in Andaman Sea), and established the existence of a fully-developed gas hydrate system in the Mahanadi basin (Site 19). In addition to the work accomplished on board, the science team also collected an unprecedented number of samples and data for analysis by an international team of experts in microbiology, sedimentology, geochemistry, and numerous other disciplines. A final synthesis of the project technical findings is expected to be published in 2008.

It is perceived that the NGHP effort will likely include future drilling, coring, and field production testing. It has been concluded that Site 10 represents a world class shale-dominated fractured gas hydrate reservoir. NGHP Expedition 01 also discovered significant sand- and silt-dominated gas hydrate reservoirs. It has been proposed that in a 2009-2010 time-frame, a drill ship of opportunity could be used to drill and log several of the most promising gas hydrate sand dominated prospects.

Related NETL Project:
This presentation is related to the NETL project DE-AI26-05NT42496, “Scientific Studies in Support of DOE Efforts to Evaluate and Understand Methane Hydrates.” The objective of this project is to conduct scientific studies of natural gas hydrates to support DOE efforts to evaluate and understand methane hydrates, their potential as an energy resource, and the hazard they may pose to ongoing drilling efforts.

Project Contacts
NETL – Robert Vagnetti (RobertVagnetti@netl.doe.gov or 304-285-1334)
USGS – Deborah R. Hutchinson (dhutchinson@usgs.gov or 508-427-2263)