School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK.
Proc Natl Acad Sci U S A. 2013 Jul 23;110(30):E2762-71. doi: 10.1073/pnas.1302156110. Epub 2013 Jul 8.
Geological storage of CO2 that has been captured at large, point source emitters represents a key potential method for reduction of anthropogenic greenhouse gas emissions. However, this technology will only be viable if it can be guaranteed that injected CO2 will remain trapped in the subsurface for thousands of years or more. A significant issue for storage security is the geomechanical response of the reservoir. Concerns have been raised that geomechanical deformation induced by CO2 injection will create or reactivate fracture networks in the sealing caprocks, providing a pathway for CO2 leakage. In this paper, we examine three large-scale sites where CO2 is injected at rates of ~1 megatonne/y or more: Sleipner, Weyburn, and In Salah. We compare and contrast the observed geomechanical behavior of each site, with particular focus on the risks to storage security posed by geomechanical deformation. At Sleipner, the large, high-permeability storage aquifer has experienced little pore pressure increase over 15 y of injection, implying little possibility of geomechanical deformation. At Weyburn, 45 y of oil production has depleted pore pressures before increases associated with CO2 injection. The long history of the field has led to complicated, sometimes nonintuitive geomechanical deformation. At In Salah, injection into the water leg of a gas reservoir has increased pore pressures, leading to uplift and substantial microseismic activity. The differences in the geomechanical responses of these sites emphasize the need for systematic geomechanical appraisal before injection in any potential storage site.
从大型点源排放源捕获的二氧化碳的地质储存代表了减少人为温室气体排放的一种关键潜在方法。然而，只有在保证注入的二氧化碳在地下封存数千年或更长时间的情况下，这项技术才可行。储存安全性的一个重大问题是储层的地质力学响应。人们担心，二氧化碳注入引起的地质力学变形将在封盖层中产生或重新激活裂缝网络，为二氧化碳泄漏提供途径。在本文中，我们研究了三个以 ~1 百万吨/年或更高的速度注入二氧化碳的大型场地：Sleipner、Weyburn 和 In Salah。我们比较和对比了每个场地的观测到的地质力学行为，特别关注地质力学变形对储存安全性构成的风险。在 Sleipner，大型高渗透储集含水层在 15 年的注入过程中经历了很少的孔隙压力增加，这意味着地质力学变形的可能性很小。在 Weyburn，45 年的采油导致孔隙压力下降，然后与二氧化碳注入相关的压力增加。该油田的悠久历史导致了复杂的、有时是非直观的地质力学变形。在 In Salah，向气藏水腿注入导致孔隙压力增加，从而导致隆起和大量微地震活动。这些场地的地质力学响应的差异强调了在任何潜在的储存场地进行注入之前，需要进行系统的地质力学评估。
