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

在加拿大的北方边境，在永久冻土层下和北极大陆斜坡上寒冷的海洋沉积物中，蕴藏着巨大的甲烷气体。这些天然气储量被困在冰状天然气水合物中，这些水合物占据了天然沉积物的孔隙空间。 认识到巨大的潜在能量储存在水合物的形式，小规模的现场试验尝试，并成功地生产，从水合物的甲烷气体。 水合物的生产需要将冰状水合物分解成气体和水的组成部分。 每个生产测试都预期并确实依赖于解离;然而，尽管数据的可用性不断增加，但每个现场测试都遇到了关键问题，在某些情况下直接由于宿主砂的地质力学行为的变化而导致关闭。因此，实现水合物的能源潜力需要强大的数值模型，准确地捕捉，然后放大，地质力学模拟水合物生产过程中的长期响应。** 拟议研究的长期目标是加强我们对含水合物砂的地质力学响应的基本理解，以促进可靠的数值建模，评估与水合物生产相关的经济和环境风险。这将通过综合研究来实现，该研究结合了创新和新颖的实验室测试，增强或新的本构模型的开发及其在数值模型中的应用。实验阶段将开发实验室合成的含水合物样品，其地质力学性质类似于在回收的完整含水合物岩心中观察到的地质力学性质。随后，我们将在现场条件下进行测试，以确定地质力学性能，如强度，刚度，渗透性等，这些结果将用于完善现有的，或开发新的，本构模型，定义本构水平的反应，在分离过程中的沙子。 这些将随后纳入数值模型，以评估水合物储层的天然气产量，评估井筒稳定性，并预测与长期水合物储层生产方案相关的大规模斜坡不稳定性。实现拟议的研究将提供目前缺少的关键信息，以准确评估与水合物生产中甲烷回收相关的经济和环境风险。这将直接有助于成功开发和安全管理加拿大的能源储备。由于水合物主要位于北方社区附近，成功的水合物生产符合加拿大的北方战略，以增加北方经济发展和行使北方主权权利。最后，通过这项研究计划，工程师将出现非常理想的地质力学技能，涉及实验和数值技术，结合高度耦合和非线性现象。

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.*****