The impact of hydrate production on the stability of hydrate-bearing reservoirs

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In Canada's northern frontier, under the permafrost and within the cold marine sediments on the Arctic continental slope, are enormous reserves of methane gas. These gas reserves are trapped in ice-like gas hydrate found occupying the pore spaces of course sediments. Recognizing the vast potential energy stored in hydrate form, small-scale field trials tried, and successfully produced, methane gas from hydrate. Hydrate production requires dissociation of the ice-like hydrate into its constituent parts of gas and water. Each production test expected and indeed relied on dissociation; yet, despite the increasing availability of data, every field test has encountered critical issues, in some cases causing shut down, directly as a result of changes in the geomechanical behaviour of the host sands. Realizing the energy potential of hydrate therefore requires robust numerical models that accurately capture, and then up-scale, the geomechanics to simulate the long-term response during hydrate production. The long-term goal of the proposed research is to enhance our fundamental understanding of the geomechanical response of hydrate-bearing sand to facilitate robust numerical modeling that assesses the economic and environmental risks associated with hydrate production. This will be realized through integrated research that combines innovative and novel laboratory testing, development of enhanced or new constitutive models and their inclusion in numerical models. The experimental stage will develop laboratory synthesized hydrate-bearing specimens whose geomechanical properties are analogous to that observed in recovered intact hydrate-bearing cores. We will subsequently test under in-situ conditions to determine the geomechanical properties, such as strength, stiffness, permeability, etc. These results will be used to refine existing, or develop new, constitutive models that define the constitutive level response of the sand during dissociation. These will subsequently be incorporated into numerical models to evaluate gas production from hydrate reservoirs, assess well-bore stabilities, and predict large scale slope instabilities associated with long-term hydrate reservoir productions scenarios. Realization of the proposed research will provide the critical information that is currently missing to accurately assess the economic and environmental risks associated with methane recovery from hydrate production. This will directly contribute to the successful development and safe stewardship of Canada's energy reserves. As hydrate is primarily located close to northern communities, successful hydrate production aligns with Canada's northern strategy to increase northern economic development and exercise northern sovereign rights. Finally, through this research program, engineers will emerge with highly desirable geomechanical skills involving both experimental and numerical techniques that incorporate highly coupled and non linear phenomena.