Secure retention of CO₂ in geological reservoirs is essential for effective storage. Solubility trapping, the dissolution of CO₂ into formation water, is a major sink on geological timescales in natural CO₂ reservoirs. Observations during CO₂ injection, combined with models of CO₂ reservoirs, indicate the immediate onset of solubility trapping. There is uncertainty regarding the evolution of dissolution rates between the observable engineered timescale of years and decades, and the >10 kyr state represented by natural CO₂ reservoirs. A small number of studies have constrained dissolution rates within natural analogues. The studies show that solubility trapping is the principal storage mechanism after structural trapping, removing 10–50% of CO₂ across whole reservoirs. Natural analogues, engineered reservoirs and model studies produce a wide range of estimates on the fraction of CO₂ dissolved and the dissolution rate. Analogue and engineered reservoirs do not show the high fractions of dissolved CO₂ seen in several models. Evidence from natural analogues supports a model of most dissolution occurring during emplacement and migration, before the establishment of a stable gas–water contact. A rapid decline in CO₂ dissolution rate over time suggests that analogue reservoirs are in dissolution equilibrium for most of the CO₂ residence time.

Supplementary material: Dissolution rate for all plots and exponential function curves for scenarios A and B are available at https://doi.org/10.6084/m9.figshare.c.5476199

Thematic collection: This article is part of the Geoscience for CO₂ storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

将 CO ₂安全地保留在地质储层中对于有效封存至关重要。溶解性捕集，即 CO ₂溶解到地层水中，是天然 CO ₂储层地质时间尺度上的主要汇。CO ₂注入过程中的观察结果与CO ₂储层模型相结合，表明溶解性俘获的立即开始。在几年和几十年的可观察工程时间尺度与天然 CO ₂代表的 >10 kyr 状态之间，溶解速率的演变存在不确定性水库。少数研究限制了天然类似物的溶出率。研究表明，溶解性捕集是结构捕集后的主要储存机制，可在整个储层中去除 10-50% 的 CO ₂。天然类似物、工程储层和模型研究对溶解的 CO ₂分数和溶解速率产生了广泛的估计。模拟和工程油藏没有显示出在几个模型中看到的高比例溶解 CO ₂。来自天然类似物的证据支持在建立稳定的气水接触之前发生在就位和迁移过程中的大多数溶解模型。CO ₂快速下降随时间变化的溶解速率表明模拟储层在大部分 CO ₂停留时间内处于溶解平衡。

补充 材料：所有图的溶解率和情景 A 和 B 的指数函数曲线可在 https://doi.org/10.6084/m9.figshare.c.5476199 获得

专题收藏：本文是 CO ₂储存地球科学收藏的一部分，可从以下网址获取：https://www.lyellcollection.org/cc/geoscience-for-co2-storage