基于动态规划的碳封存注入井位置优化

Injection well site optimization of carbon geological sequestration based on dynamic programming

  • 摘要: 二氧化碳地质封存是降低碳排放、减小温室效应的重要手段之一,是地球科学研究的新兴领域. 注入井位置的选择对CO2封存量有重要影响,且受地质条件复杂性和施工条件限制,因而注入井位置的选取是一个复杂的优化问题. 本文基于几何方法和渗流理论构建了CO2地质封存模型,结合地层圈闭、溢出路径及溢出点等条件估计地层的封存能力. 在此基础上,将CO2地质封存注入井位置优化问题转化为动态规划问题,通过计算最优子结构和状态转移方程,从而确定最佳注入井位置. 利用动态规划法优化注入井位置,实现碳封存量最大化,将其用于挪威Utsira储层封存量估计和注入井位置优化,从而为CO2地质封存注入井位置的选择提供理论指导.

     

    Abstract: Geological storage of carbon dioxide (CO2) is one of the most effective methods for reducing carbon emissions and mitigating the greenhouse effect, critical challenges in combating climate change. This earth science technology involves capturing CO2 emissions from industrial processes and safely injecting them into deep underground geological formations for long-term storage. A key factor for its success is selecting appropriate injection well locations, which play a crucial role in determining storage capacity and the overall effectiveness of the geological storage system. Choosing injection well locations is a complex optimization problem; it involves assessing geological conditions at the target site and addressing technical and logistical constraints of well construction. Key geological factors include stratigraphic traps that prevent CO2 from migrating upward, potential spill paths that could allow CO2 leakage, and spill points where CO2 could escape from the reservoir. Poorly chosen injection sites can reduce storage capacity, increase risks of CO2 leakage, or lead to system failure. Therefore, optimizing well placement is critical for enhancing the viability and scalability of CO2 geological storage. This study developed a comprehensive CO2 geological storage model that integrates geometric methods and seepage theory to estimate the storage capacity of geological formations; it evaluates essential geological conditions, including stratigraphic traps, spill paths, and spill points. Building upon this model, the optimization problem of well placement was transformed into a dynamic programming framework. Dynamic programming, a mathematical optimization approach, is well-suited for solving problems that can be broken down into smaller subproblems with overlapping solutions. In this context, the optimization process defines an optimal substructure and a state transition equation to determine the best injection well location that maximizes CO2 storage capacity while minimizing potential risks. The dynamic programming method was applied to the Utsira formation, a prominent saline aquifer in the North Sea near Norway, widely studied as a potential site for large-scale CO2 storage. Using the model, the storage capacity of the Utsira formation was estimated, and optimal locations were identified. This approach not only maximized storage capacity but also offered practical insights into the technical and logistical aspects of well placement. The study underscores the importance of integrating advanced optimization techniques with geological models to address CO2 storage challenges. The methodology offers a systematic approach for selecting injection well locations and serves as a valuable tool for developing efficient, secure CO2 storage systems worldwide. As the demand for sustainable carbon management solutions grows, this work contributes valuable theoretical and practical guidance to the emerging field of CO2 geological storage.

     

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