In the framework of a Spanish project focused on carbon capture and storage technologies, the Gañuelas-Mazarrón Tertiary Basin (SE Spain) was studied as a natural analogue of a CO₂ reservoir affected by anthropogenic leakages. It has been accepted that the main objective of natural analogue studies is to predict the long-term performance of a natural CO₂ reservoir to be extrapolated to the operation of a CO₂ deep geological storage, but these studies can also provide valuable information to select a site for CO₂ storage. Thus, the comprehensive study performed in this Spanish basin has allowed the establishment of a guide to be applied to other similar natural systems with deep saline aquifers that are able to store CO₂. This guide comprises 5 phases: (1) the compilation of existing information from the site; (2) the geological and structural study of the natural CO₂ reservoir; (3) the characterisation of the main components (waters–rocks–gases) of the natural CO₂ reservoir; (4) the identification of analogies between the natural CO₂ reservoir and a potential site for CO₂ geological storage; and (5) the implications for the long-term behaviour and safety of a CO₂ storage system. Whilst the three first stages are well known since they are exclusively focused on the site characterisation, the latter two are poorly developed. For this reason, it has been considered convenient to go deeper into both the identification of analogies and the assessment of their performance in storing CO₂. The main results of this study are aimed at elaborating a practical guide for regulatory agencies that are responsible for making decisions about sites that have been selected for anthropogenic CO₂ geological storage.

在一个专注于碳捕集与封存技术的西班牙项目框架内，Gañuelas-Mazarrón第三纪盆地（西班牙SE）被研究为受人为泄漏影响的CO _2气藏的天然类似物。人们已经接受了自然类似研究的主要目的是预测将被推断用于CO ₂深层地质封存作业的天然CO ₂储层的长期性能，但是这些研究也可以提供有价值的信息以供选择一个用于CO ₂储存的站点。因此，在这个西班牙盆地进行的全面研究已使该指南得以建立，并适用于其他具有深层盐水层的类似自然系统，这些深层含水层能够储存CO ₂。该指南包括五个阶段：（1）从站点收集现有信息；（2）天然CO ₂储层的地质构造研究；（3）表征天然CO ₂储层的主要成分（水-岩-气）；（4）识别天然CO ₂储层与潜在的CO ₂地质封存地点之间的类比；（5）对CO _2的长期行为和安全性的影响存储系统。虽然前三个阶段是众所周知的，因为它们仅专注于站点表征，而后两个阶段则开发欠佳。由于这个原因，已经认为更方便的是对类比的识别和对它们在存储CO ₂中的性能的评估两者进行更深入的研究。这项研究的主要结果旨在为监管机构制定实用指南，这些机构负责对已被选为人为CO ₂地质存储的地点做出决策。