CO2高注入压力对海底断层泄漏特性的影响机理研究

二氧化碳捕集与封存（CCS）技术被认为是应对气候变化和清洁能源利用的有效方法而成为国际研究热点。但海底地下封存CO2的安全性和风险控制仍是CCS技术亟待解决的核心问题。然而目前对海底断层泄漏机理的认识还很肤浅，对海底断层的泄漏特点和主控因素认识有待深入研究。本申请拟以广东沿海陆架惠州21-1油气田待选封存场地为例，在对海底断层基本地质特征深入分析基础上，通过地质学、地质力学以及数值模拟研究方法，分析CO2高注入压力对地应力场以及断层面受力状态的影响方式或机理，进而分析断层受力情况对断层稳定性、断层渗透性的影响，揭示海底断层应力-渗漏耦合规律，探讨海底断层起隔挡与泄漏作用机理，建立海底断层泄漏性的评价标准与方法。本项目不仅可深化对于海底断层CO2泄漏机理的认识，而且对CO2海上地质封存长期安全稳定性评价和风险控制具有重要指导意义，同时也为未来开展CO2海上地质封存提供基础资料和科学依据。

Carbon dioxide(CO2) capture and sequestration (CCS), which was considered to be an effective method to deal with climate change and clean energy use, became one of the hot topics in the world already. Although the CO2 offshore geological storage have an number of important advantages over onshore sites, the safety and risk control of offshore CCS are core issues that need to be solved. Currently, the understanding of leakage mechanism through submarine fault is still very superficial, and the submarine fault-seal characteristics and main controlling factors need further studies. So it is important to estimate the potential amount of leakage and corresponding pressure changes in formations connected through a vertically leaky submarine fault. In this application, the HZ21-1 gas and oil field, which located on the continental shelf along Guangdong coast, would be studies for an instance. According to geological characteristics and also petrophysical and geomechanics parameters of the HZ21-1 trap, the impacts of high CO2 injection pressure on formation pressure and in situ stress will be analysized through discrete fracture models and fluid flow simulation. And then the impacts of the stress changes on fault stability and leakage should be studied. The coupling rules between stress and permeability of submarine fault will be discussed, and then to summarized the characteristics of CO2 leakage through submarine fault. Approach of assessing submarine fault seal capacity would be discussed and established. The result of this project will enhance understanding of the CO2 leakage mechanism through submarine fault, and on the other hand, it is important significance for long-term security stability evaluation and risk control of the CO2 offshore geological storage and will also provide basic information and scientific basis for the future research.