Natural Gas Hydrate

There are a lot of Natural Gas Hydrates

Natural Gas Hydrate: What and Where It Is

Natural gas hydrate (NGH) is a naturally occurring crystalline compound composed of water and natural gas (primarily methane) that forms as a highly reversible chemical reaction under natural conditions of elevated pressure and low temperature found in marine sediments and permafrost regions. NGH is known to be widespread in sediments of permafrost regions and beneath in the deepwater sediments of outer continental margins.

How Much Is There?

It has been generally accepted that the amount of natural gas contained in the world's NGH accumulations greatly exceeds the volume of known conventional gas reserves, and there is growing evidence that NGH can be commercially produced with existing conventional oil and gas production technology, even though the most likely producible NGH is only a small part of the potential resource that occurs concentrated in high grade sands, in fracture systems, and dispersed in muddy sediments.

HEI was part of the Global Energy Assessment conducted by the International Institute for Applied Systems Analysis (IIASA).  HEI utilized a petroleum systems approach in this analysis of the global abundance of NGH concentrated in sand bodies and has verified the enormous volume of natural gas contained in these reservoirs.

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One of the most significant aspects of this project was the confirmation that NGH resource potential is present along every continental margin, and includes nations that lack other energy resources.

A far larger volume of NGH also occurs in fine-grained (muddy) sediments. While this additional NGH is not viewed as a commercially viable resource, it is a significant component of the carbon cycle with implications for global climate.

Gas hydrate has significant implications for:

  • Energy Resources
  • Global Climate
  • Seafloor safety and sediment redistribution mechanisms

HEI and its principals are deeply involved in all of these issues.

NGH as an Energy Resource

NGH occurs within a zone that extends from the seafloor for some distance into the sediments. The lower limit of this "gas hydrate stability zone" is determined by a variety of factors including geothermal gradients, salinities, and gas composition. With increasing depth, the thickness of the hydrate stability zone typically increases. If a hydrate-forming gas (such as methane) is present within this zone at suitably high levels of concentration, NGH will form.

The opportunity for large conventional oil and gas reserves has made these same deepwater locations also places where economic deposits of NGH may occur and are important focus areas for exploration and production. This co-location factor means that some of the development costs for NGH may be absorbed by costs for exploration and development of conventional deepwater hydrocarbon deposits.

As an emerging gas resource, NGH offer potentially vast commercial opportunities for operating companies world-wide. The large global volumes of NGH suggest that it has the potential to be an enormous source of natural gas, a fuel with far cleaner and lower greenhouse gas emissions than coal or oil. While the volume of natural gas in NGH appears to be immense, extracting natural gas in an environmentally compatible and economically viable way is a significant challenge.

NGH development is most feasible in locations where the NGH is highly concentrated, such as in subsurface sands that have received an adequate methane-based natural gas flux. In locations where NGH is sufficiently concentrated, several production approaches are viable.

Production of gas from NGH is technically feasible at present, with the primary remaining hurdles being pipelines to transport the produced gas to market and the willingness of operators to pursue the opportunity to position themselves for entry into this profitable new business.

The vast energy potential of NGH has been the focus of several nations that have energy demand that far exceeds their domestic supply. Chief among these are Japan, India, China, and South Korea.

HEI conducts resource assessments using a petroleum systems approach that integrates stratigraphy and fluid migration with the pressure and temperature controls on NGH stability. In frontier areas, HEI can assist in the design of seismic programs for detailed evaluations. In addition, HEI has helped establish comprehensive national energy programs in which NGH development is one part of a total strategy. In all of our work, HEI considers safety and environmental impacts of development, and makes recommendations that help our clients address these issues.