Quantitative Measures for Characterizing the Sealing Ability of Caprock with Pore Networks in CO2 Geological Storage 

Bing Bai, Guangzhong Lü, Xiaochun Li, Zhipeng Li , Yongsheng Wang, Qifang Hu 

Abstract

Existence of high quality caprocks is one of the necessary conditions to realize effective geological sequestration of CO2. Existing measures for the evaluation of caprock sealing ability cannot represent the sealing effect of formation thickness. New quantitative measures for characterizing the sealing ability of caprock with pore networks were developed for CO2 geological storage. The new measures, actually as a synthesis of numerous conventional and commonly used parameters, are related to the maximum pressure the caprock can sustain to prevent the CO2 leak to the topmost position of the caprock. The measures are capable of reflecting the role that formation thicknesses play in addition to the traditional capillary sealing mechanism and the formation pressure sealing mechanism. It is also anticipated the new measures are applicable to evaluations of natural gas caprocks. Case study shows that the new measure usually predicts higher sealing ability than that by the traditional measure mainly due to the consideration of formation thickness.

摘要【翻译】

     优质盖层的存在是实现CO2有效地质封存的必要条件之一。现有的盖层封闭性评价方法不能代表地层厚度的封闭效果。针对CO2地质封存，开发了表征盖层封闭能力的新的定量方法。实际上，作为许多传统和常用参数的综合，新指标涉及防止CO2泄漏到盖层的最顶部位置时盖层能够承受的最大压力。除了传统的毛细管密封机制和地层压力（超压）密封机制之外，这些指标还能够反映盖层厚度封闭效应。预计新指标也适用于天然气盖层评价。实例分析表明，与传统方法相比，新方法通常预测出更高的密封能力，这可能主要是由于考虑了地层厚度。