Results of the Indian National Gas Hydrate Program (NGHP) Expedition 01
In 2008 an international partnership led by the Directorate General of Hydrocarbons (DGH) under the Ministry of Petroleum and Natural Gas (Government of India) and the U.S. Geological Survey (USGS) released the results of the most complex and comprehensive gas hydrate field venture yet conducted. Upon the occasion of the Indian National Gas Hydrate Program Gas Hydrate Conference held February 6-8, 2008 in New Delhi, India, the leadership and participants in the Indian National Gas Hydrate Program (NGHP) Expedition 01 are pleased to release the results of the first modern, fully integrated gas hydrate research and exploration program conducted in the offshore of India.
Press Release: USGS Indian Ocean Hydrate Research Press Release
What Are Gas Hydrates?
Gas hydrates are a naturally occurring “ice-like” combination of natural gas (usually methane) and water that have the potential to provide an immense resource of natural gas from the world’s oceans and polar regions. In 1990’s, the U.S. Geological Survey made the first systematic assessment of the volume of gas stored in natural gas hydrates. That study suggested that the amount of gas in the gas hydrate accumulations of the world greatly exceeds the volume of known conventional gas resources. However, gas hydrates represent both a scientific and technologic challenge and much remains to be learned about the geologic, engineering, and economic factors controlling the ultimate energy resource potential of gas hydrates.
The amount of natural gas contained in the world's gas hydrate accumulations is enormous, but these estimates are speculative and range over three orders of magnitude from about 2,800 to 8,000,000 trillion cubic meters of gas. By comparison, conventional natural gas accumulations (reserves and technically recoverable undiscovered resources) for the world are estimated at approximately 440 trillion cubic meters as reported in the USGS World Petroleum Assessment 2000 (http://pubs.usgs.gov/dds/dds-060/). Gas recovery from hydrates is hindered because the gas is in a solid form and because hydrates commonly occur in remote Arctic and deep marine environments. Proposed methods of gas recovery from hydrates generally deal with dissociating gas hydrates in situ by heating the reservoir beyond the temperature of gas hydrate formation, or decreasing the reservoir pressure below hydrate equilibrium. The pace of gas hydrate energy characterization and assessment projects has accelerated over the past several years. Researchers have long speculated that gas hydrates could eventually be a commercial resource yet technical and economic hurdles have historically made gas hydrate development a distant goal rather than a near-term possibility. This view began to change with the realization that this unconventional resource could be developed in conjunction with conventional gas fields.
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. The primary goal of NGHP Expedition 01 was to conduct scientific ocean drilling/coring, logging, and analytical activities to assess the geologic occurrence, regional context, and characteristics of gas hydrate deposits along the continental margins of India in order to meet the long term goal of exploiting gas hydrates as a potential energy resource in a cost-effective and safe manner. During NGHP Expedition 01, dedicated gas hydrate coring, drilling, and downhole logging operations were conducted from 28 April, 2006 to the 19 August, 2006.
Based on analysis of geological and geophysical data, the Expedition was planned to visit ten sites in four areas: the Kerala-Konkan Basin in the Arabian Sea – western continental shelf of India; the petroliferous Krishna-Godawari Basin and Mahanadi Basin in the Bay of Bengal – eastern continental shelf of India; and the previously unexplored Andaman Islands. The goals of the cruise were to conduct scientific drilling, well logging, coring, and shipboard scientific analyses of recovered samples from each site to provide further insight into:
- the distribution and nature of gas hydrate in marine sediments
- the geologic controls on the formation and occurrence of gas hydrate in nature
- the processes that transport gas from source to reservoir
- the effect of gas hydrate on the physical properties of the host sediments
- the microbiology and geochemistry of gas hydrate formation and dissociation
- the calibration of geophysical and other predictive tools to the observed presence and concentration of gas hydrates.
NGHP Expedition 01 was planned and managed through a collaboration between the Directorate General of Hydrocarbons (DGH) under the Ministry of Petroleum and Natural Gas (Government of India), 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 (FUGRO). The platform for the drilling operation was the research drill ship JOIDES Resolution (JR), operated by ODL. Much of the drilling/coring equipment used was provided by the Integrated Ocean Drilling Program (IODP) through a loan agreement with the US National Science Foundation (NSF). Wireline pressure coring systems and supporting laboratories were provided by IODP/Texas A&M University (TAMU), FUGRO, USGS, U.S. Department of Energy (USDOE) and HYACINTH/GeoTek. Downhole logging operational and technical support was provided by Lamont-Doherty Earth Observatory (LDEO) of Columbia University.
The science team was led by Dr. Timothy Collett of the USGS, and consisted of more than 100 leading scientists and professionals representing the following organizations:
- Binghamton University
- Colorado School of Mines
- Directorate General for Hydrocarbons (India)
- Fugro-McClelland, Inc.
- GAIL (India) Ltd
- Geological Survey of Canada
- Geotek Ltd
- Idaho National Laboratory
- Integrated Ocean Drilling Program
- Joint Oceanographic Institutions, Inc.
- Lamont-Doherty Earth Observatory
- Ministry of Petroleum and Natural Gas (India)
- McGill University
- National Energy Technology Laboratory
- National Institute of Oceanography (India)
- National Institute of Ocean Technology (India)
- Oil and Natural Gas Corporation (India)
- Ocean Drilling Limited
- Oregon State University
- OIL India Ltd
- Pacific Northwest National Laboratory
- Reliance Industries Limited (India)
- Technical University of Berlin
- Texas A&M University
- University of California, San Diego
- University of Cardiff
- University of New Hampshire
- Universität Bremen
- University of Rhode Island
- U.S. Department of Energy
- U.S. Geological Survey
- U.S. National Science Foundation
- Woods Hole Oceanographic Institution
During its 113.5-day voyage, the expedition cored or drilled 39 holes at 21 sites (one site in the Kerala-Konkan Basin, 15 sites in the Krishna-Godavari Basin, four sites in the Mahanadi Basin and one site in the Andaman deep offshore areas), penetrated more than 9,250 meters of sedimentary section, and recovered nearly 2,850 meters of core. Twelve holes were logged with logging-while-drilling (LWD) tools and an additional 13 holes were wireline logged. The operational highlights of NGHP Expedition 01 included the following:
- 113.5 days of operation without any reportable injury or incident.
- Only 1% of total operation time was down time due to equipment malfunction or weather.
- Examination of 9,250 meters of sedimentary section at 39 locations within 21 sites located in four geologically-distinct settings.
- Extensive sample collection to support a wide range of post-cruise analyses, including:
- Collected about 6,800 whole round core samples for examination of interstitial water geochemistry, microbiology, and other information.
Collected more than 12,500 core subsamples for paleomagnetic, mineralogical, paleontological, and other analyses.
- Collected about 140 gas-hydrate-bearing sediment samples for storage in liquid nitrogen.
- Collected five one-meter-long gas-hydrate-bearing pressure cores for analysis of the physical and mechanical properties of gas-hydrate-bearing sediment.
- Collected 21 re-pressurized cores (nine representing sub-samples from gas-hydrate-bearing pressure cores).
- Conducted 97 deployments of advanced pressure coring devices, resulting in the collection of 49 cores that contain virtually undisturbed gas hydrate in host sediments at near in situ pressure conditions.
Scientific Findings and Impact
The NGHP Expedition 01 Initial Reports, released at the conference in New Delhi, includes a series of integrated site chapters (Sites 1-21) describing the operational history and scientific data collected during the expedition. The Initial Reports volume also includes a companion publication that contains all downhole log data collected during the expedition.
The NGHP Expedition 01 science team utilized extensive on-board lab facilities to examine and prepare preliminary reports on the physical properties, geochemistry, and sedimentology of all the data collected prior to the end of the expedition. Although the data will continue to inform gas hydrates science for years to come, the following are some key scientific highlights of the expedition to date:
Conducted comprehensive analyses of gas-hydrate-bearing marine sediments in both passive continental margin and marine accretionary wedge settings.
- The calculated depth to the base of the methane hydrate stability zone, as derived from downhole temperature measurements, closely matches the depth of the seismic identified bottom simulating reflectors (BSRs) at most of the sites established during this expedition.
- Discovered gas hydrate in numerous complex geologic settings and collected an unprecedented number of gas hydrate cores.
- Most of the recovered gas hydrate was characterized as either pore-filling grains or particles disseminated in coarser grain sediments or as a fracture-filling material in clay dominated sediments.
- The occurrence of concentrated gas hydrate is mostly controlled by the presence of fractures and/or coarser grained (mostly sand-rich) sediments.
- Gas hydrate was found occurring in “combination reservoirs” consisting of horizontal or subhorizontal coarse grained permeable sediments (sands for the most part) and apparent vertical to subvertical fractures that provide the conduits for gas migration.
- Delineated and sampled one of the richest marine gas hydrate accumulations ever discovered (Site NGHP-01-10 in the Krishna-Godavari Basin).
- Discovered one of the thickest and deepest gas hydrate occurrences yet known (offshore of the Andaman Islands, Site NGHP-01-17) which revealed gas-hydrate-bearing volcanic ash layers as deep as 600 meters below the seafloor.
Established the existence of a fully developed gas hydrate system in the Mahanadi Basin of the Bay of Bengal.
- Most of the gas hydrate occurrences discovered during this expedition appear to contain mostly methane which was generated by microbial processes. However, there is also evidence of a thermal origin for a portion of the gas within the hydrates of the Mahanadi Basin and the Andaman offshore area.
- Gas hydrate in the Krishna-Godavari Basin appears to be closely associated with large scale structural features, in which the flux of gas through local fracture systems, generated by the regional stress regime, controls the occurrence and distribution of gas hydrate
NGHP Expedition 01 has shown that conventional sand and fractured-clay reservoirs are the primary emerging targets for gas hydrate production in India. Because conventional marine exploration and production technologies favor the sand-dominated gas hydrate reservoirs, investigation of sand reservoirs will likely have a higher near-term priority in the NGHP program. It is perceived that the NGHP effort will likely include future seismic studies, drilling, coring, and field production testing. It has been concluded that Site 10 represents a world class shale dominated fracture gas hydrate reservoir, worthy of further investigation. NGHP Expedition 01 also discovered significant sand and silt dominated gas hydrate reservoirs. It has been proposed that in a 2012-2013 time-frame, NGHP Expedition 02 may be constituted to drill and log several of the most promising gas hydrate sand-dominated prospects.
Project Website: Gas Hydrates
Assessment Website: National Oil and Gas Assessment