490. 西班牙南部的Marismas 3枯竭气田的CO₂封存潜力——一种地球化学方法

CO₂ sequestration potential in Depleted Hydrocarbon fields – A geochemical approach

减少CO₂排放对能源转型至关重要。目前，针对CO₂捕集与封存（CCS）技术的研究正在不断发展，其中枯竭油气田（DHF）因其已有的储层知识和现有基础设施而备受关注。然而，在DHF中进行CO₂封存时，注入的CO₂与残留流体之间的相互作用是一个主要问题。本研究以西班牙南部的Marismas 3气田为模型区域，利用PHREEQC软件研究了碳酸盐-硅质岩储层中CO₂与储层岩石、水和残留气体（CH₄）的相互作用。研究结果表明，在CO₂注入过程中，形成了碳酸，导致多种矿物溶解，并伴随着菱铁矿和黏土矿物的沉淀，可能对储层的渗透性造成问题。CMG-GEM软件进一步验证了CO₂羽流建立的关键阶段。研究表明，所选的DHF在技术上适合用于CEEGS技术的实际地下应用，且新形成的矿物（可能导致问题）可以通过人为改变储层参数进行控制。

CMG软件应用情况

CMG-GEM软件在本研究中用于模拟CO₂在枯竭油气田中的长期封存过程。该软件结合了动态流体流动和地球化学反应，考察了CO₂通过溶解封存、残余封存和侧向迁移的封存机制。研究中模拟了一个类似Marismas气田的储层模型，但深度更深，以适应CEEGS技术的要求。模拟结果显示，CO₂注入后形成了明显的羽流，并且在储层中以超临界态、溶解态和残余态存在。CMG-GEM软件的模拟结果验证了CO₂羽流建立的关键阶段，并为评估枯竭油气田作为CO₂封存场地的可行性提供了重要依据。

结论

枯竭油气田（DHF）因其现有的储层知识和基础设施而成为CO₂封存的有吸引力的选项。本研究通过地球化学模拟方法评估了DHF的CO₂封存潜力，结果表明，尽管在CO₂注入过程中可能会导致一些矿物沉淀并影响储层渗透性，但这些潜在问题可以通过人为调整储层参数（如pH值）来控制。研究还强调了建立稳定的CO₂羽流的重要性，这对于恢复储层压力和优化地下部分的效率至关重要。此外，评估枯竭气田的地球化学完整性对于安全、长期封存CO₂至关重要。研究结果表明，枯竭气田在技术上适合用于CEEGS技术的实际应用。

Abstract

Background

The CO₂ emissions reduction is crucial for the energy transition. New technologies for CO₂ capture and storage are under development, such as CEEGS ^1,2 . Porous media and rock caverns are geological formations of high interest for such technology. Among them, depleted hydrocarbon fields (DHF) gain ground due to existing reservoir knowledge and already established infrastructure which decreases the cost. However, one of the major problems caused during CO₂ storage in DHF is the interactions between the injected CO₂ and the remaining fluids.

Methods

In this study, the potential CO₂ storage in DHF was investigated. Marismas 3 was used as a hypothetical model area for the examination of CO₂ interactions with a carbonate-silisiclastic reservoir. PHREEQC software ¹ was used to investigate reservoir rock/water/remained gas (CH₄) interactions followed by interactions taking place after the CO₂ injection. Different scenarios were used for the CO₂ concentration and behaviour in the reservoir. To make the system more complex and generic, the CMG-GEM software ³ was utilized to examine the long-term sequestration of CO₂ through dissolution trapping, residual trapping, and lateral migration in a reservoir analogue to the Marismas field, but at higher depth, compatible with the CEEGS technology.

Results

During the CO₂ injection, carbonic acid was formed, causing a dissolution of several minerals, leading to siderite and clay minerals precipitation, which may cause problems to the permeability of the system. The colloidal nature of siderite and the Ca-montmorillonite swelling properties are of high concern for pore throat clogging. The other newly formed mineralogical phases are not threatening the reservoir quality. CMG-GEM validated the critical phase of CO₂ plume establishment.

Conclusions

The proposed DHF is promising for real-world underground applications fitting to CEEGS technology as the newly formed minerals that could cause failures can be easily controlled by anthropogenic changes in the reservoir parameters.