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

在加拿大北部边境，在永久冻土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储量。这些天然气储量被困在冰状天然气水合物中，这些水合物当然占据了沉积物的孔隙空间。认识到以水合物的形式储存的巨大潜在能量，小规模的现场试验尝试并成功地从水合物中生产甲烷气体。水合物的生产需要将冰状的水合物分解成气体和水的组成部分。每一次生产测试都预料到并实际上依赖于离析；然而，尽管数据的可用性越来越高，但每一次现场测试都遇到了严重问题，在某些情况下，直接由于寄主砂岩地质力学行为的变化而导致关闭。因此，实现水合物的能量潜力需要强大的数值模型，准确地捕捉并放大地质力学，以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了解，以促进强大的数值模拟，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，结合创新和新颖的实验室测试，开发增强的或新的本构模型，并将其纳入数值模型来实现。实验阶段将开发实验室合成的含水合物样品，其地质力学性质与在回收的完整含水合物岩心中观察到的相似。我们随后将在现场条件下进行测试，以确定地质力学特性，如强度、刚度、渗透率等。这些结果将用于改进现有的或开发新的本构模型，定义砂在离解过程中的本构水平响应。这些随后将被纳入数值模型，以评估水合物储集层的天然气产量，评估井筒稳定性，并预测与长期水合物储集层生产情景相关的大范围斜坡不稳定性。拟议研究的实现将提供目前缺少的关键信息，以准确评估与从水合物生产中回收甲烷有关的经济和环境风险。这将直接有助于加拿大能源储备的成功开发和安全管理。由于水合物主要位于北部社区附近，成功的水合物生产符合加拿大增加北部经济发展和行使北部主权的北部战略。最后，通过这项研究计划，工程师将获得非常令人满意的地质力学技能，包括实验和数值技术，包括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.